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[Music]

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hello and welcome to another devon

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carmen lecture series rising tides i am

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nikki weirich from jpl's office of

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communications and education

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tonight as we approach the one-year

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anniversary of nasa's earth flagship

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mission sentinel 6 michael freilich we

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will take a look at how we study our

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oceans our planet and what is coming

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next

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joining us as co-host fielding your

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questions this evening is earth public

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outreach specialist jocelyn argeta hi

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jocelyn

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hey nikki

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great to be here tonight and i want to

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take a moment to just remind all of our

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viewers that this is your space program

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and we want you to be involved in the

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conversation tonight so from wherever

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you're watching this feel free to add

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your questions to the chat our amazing

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social media team is going to get those

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questions to us and we'll try to get

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through as many as we can and if for

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whatever reason you don't see the chat

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just hit refresh and it should come

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right up

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awesome thank you jocelyn we're so glad

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to have you with us this evening

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fielding all those wonderful questions

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uh just a reminder to all of you

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watching this evening if we do run into

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any technical difficulties we do ask

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that you stick with us as we get these

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sorted out

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now our speaker this evening dr josh

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willis is the lead nasa scientist for

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the jason and sentinel 6 satellites

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which measures sea level from space

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he is also the lead scientist for nasa's

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recent airborne mission ocean's melting

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greenland or omg

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josh will discuss these missions and how

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understanding and predicting sea level

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rise is one of the most urgent problems

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in climate science today

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hi josh how are you doing tonight

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hi so good to be here thank you

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we are so happy to have you and i'm

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going to turn it over to you because

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you've got a lot of great information to

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share with us tonight

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fantastic well thank you so much and

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i just want to say before we start if

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you're watching this live it's veterans

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day and i'd like to take a moment if

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you're a veteran whether you're watching

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live or not to thank you for your

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service

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so let's get started uh

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why am i here

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well i'm an oceanographer and i study

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the oceans using data from nasa

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satellites of all different kinds

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but

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as nikki said i'm also the lead nasa

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scientist for the sentinel 6 and jason

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missions which measures sea level from

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space

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so what i really want to talk to you

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about tonight is climate change or the

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warming of our planet now when we think

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of the planet warming we typically think

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of the atmosphere warming and that's

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what this first graph that i'm going to

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show you

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tells us now i'll i promise i won't show

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you too many plots like this

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but if you'll bear with me uh on the on

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the bottom axis we have time this plot

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goes back to the 1880s

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and what we have on the vertical axis is

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temperature and this is not just any

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temperature it's the average temperature

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of the entire planet and this tells us a

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very simple story that the earth is

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getting warmer and it's getting warmer

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pretty fast a degree of warming a degree

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celsius of warming may not seem like a

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lot but it's actually a huge change to

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our climate and it's happening

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right now and the big question of course

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is why

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and the answer is actually us

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we are actually warming the planet's

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climate by adding carbon dioxide to the

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atmosphere and

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increasing the amount of heat that we

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trap from the sun now if we look back in

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time at the record of carbon dioxide

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since about a half million years ago it

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looks something like this where you can

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see

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carbon dioxide's gone up and down and up

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and down for

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about every hundred thousand years

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and right now we were actually in a warm

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period about

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twenty thousand years ago

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we were in a cold period and carbon

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dioxide levels were low on the planet

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and then it started to warm up naturally

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it warmed up and we've been in a warm

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period for about 10 000 years and during

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that time co2 increased in the

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atmosphere and we trapped more and more

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heat but if you look back at the last

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half million years

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carbon dioxide today is higher than at

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any time in the last half million years

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and the reason why is right here on the

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back of this slide we've been burning

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fossil fuels which

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add carbon dioxide to the atmosphere and

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this is trapping extra heat

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now how does that happen well

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extra heat is actually added to the

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atmosphere

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when sunlight passes through the

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atmosphere

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it actually warms the surface of the

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earth and that warm surface

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sends heat back out towards space

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but as the heat goes back towards space

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it's actually different than the light

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coming from the sun the light coming

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from the sun is in the form of visible

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light and it goes right through the

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atmosphere but the energy that heads

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back out towards space

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gets stuck and the amount that gets

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stuck depends on how much carbon dioxide

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there is in the atmosphere

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so if we trap this extra heat in the

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atmosphere if we add carbon dioxide to

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the atmosphere we trap the extra heat

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and keep it from leaving back out

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towards space

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so what happens to the heat now i said

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at the beginning i'm an oceanographer so

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you probably have a hint

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but you may not realize just how big an

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influence the ocean is on our planet's

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climate

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and this chart is a stark reminder of

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just how important the oceans are

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for understanding what's happening to

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our planet over 90 percent of the extra

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heat that we're trapping with the

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greenhouse gases is warming the oceans

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now the very first

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graph that i showed you showed that the

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atmosphere is warming up but in fact

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the real action the real place where

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most of global warming is occurring is

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in the oceans and you can think of the

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atmosphere as sort of like a piece of

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aluminum foil wrapped around a potato in

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the oven

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if you reach into an oven that's 350

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degrees and you grab a piece of aluminum

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foil it actually won't burn you if it's

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all by itself because the aluminum foil

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can't carry that much heat but if you

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wrap it around a hot potato then you're

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in big trouble and the oceans are sort

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of like the world's

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heat potato

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they trap

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over 90 of this heat

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and they can absorb heat very quickly

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and and very efficiently so

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really when we think about global

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warming we should be think about we

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should be thinking about ocean warming

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because

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that's where most of it is happening

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now

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as the planet warms we see effects all

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over the world the oceans are warming

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the air is warming and as this happens

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we can see that ice around the planet is

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actually melting as well

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and if you look at the black and white

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picture here this is a picture of an

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alaskan glacier taken in 1941

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and you can see the ice

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running through this canyon as it snakes

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around between mountains

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but in 2004 someone went back to the

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exact same spot and took the exact same

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photograph and you can see that the ice

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has now retreated

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far into the canyon many miles into the

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canyon

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and this is something that's actually

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happening all over the planet over 90

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percent of all the glaciers in the world

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are retreating and getting smaller as

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the climate warms

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and as that happens it actually raises

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sea levels around the planet as well

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because the ice that's lost from the

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glaciers runs off into the oceans and

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adds that extra water to the ocean level

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raising sea levels everywhere

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now we know that sea levels are rising

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for some really interesting reasons

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and one of my favorite uh one of my

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favorite plots one of my favorite graphs

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i told you i wouldn't show you too many

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graphs but i'm going to show you a

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couple more

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but one of my favorite most interesting

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records

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is this record of sea level change

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from northern care alliance from north

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carolina

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along the coast

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collected in a salt marsh and

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this is one of my colleagues who went

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out and they drill holes to this salt

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marsh and

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dig up the mud and it gives them a

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record back in time of how high sea

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level was

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along the north carolina coast

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and if you look back at the record you

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can actually see that from

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the year 0 to about 1 000

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sea levels really were not changing in

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the atlantic ocean they were very stable

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and that's because we had reached a warm

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climate and sea levels had stopped

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rising after the end of the last ice age

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and they were very very stable

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and then about 1000 a.d we entered what

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was called the little the medieval warm

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period and this was a period where there

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was a little bit of warming and there's

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a little bit of sea level rise you can

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see right here

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uh

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um after that in about 1500 there was

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the little ice age where there was a

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small amount of cooling so maybe sea

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levels fell just a little bit but what

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really leaps out in this record is the

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beginning of the industrial revolution

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in the 1850s or so we began adding a lot

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of carbon dioxide to the atmosphere we

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begin heating up the planet as you saw

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in the very first slide

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and sea levels began to take off and

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rocket upward and the salt marshes which

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are shown there in the red curve

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actually tell the same story as the tide

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gauge which goes back over 100 years

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nearby in this location and they both

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show that sea levels were rising very

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quickly

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after the industrial revolution began so

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what's happening to our oceans is

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something that hasn't happened in

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thousands of years and it's a reminder

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of just how big an impact we're having

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on the climate now of course i've talked

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a lot about climate change but where is

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nasa in all this well nasa actually

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00:11:32,150 --> 00:11:31,040
flies satellites that measure sea level

283
00:11:35,269 --> 00:11:32,160
directly

284
00:11:38,069 --> 00:11:35,279
and this is the sentinel-6 satellite it

285
00:11:41,430 --> 00:11:38,079
works in a very simple way it bounces a

286
00:11:43,829 --> 00:11:41,440
radar off of the ocean and measures how

287
00:11:44,550 --> 00:11:43,839
long it takes to go down and come back

288
00:11:46,949 --> 00:11:44,560
up

289
00:11:50,150 --> 00:11:46,959
this tells the satellite how far away

290
00:11:52,949 --> 00:11:50,160
the water is and then using positioning

291
00:11:54,310 --> 00:11:52,959
systems like gps and a couple of others

292
00:11:56,230 --> 00:11:54,320
we can tell

293
00:11:58,470 --> 00:11:56,240
where the satellite is so if we know

294
00:12:01,670 --> 00:11:58,480
where the satellite is and how far away

295
00:12:04,470 --> 00:12:01,680
the water is we can say how high the

296
00:12:06,550 --> 00:12:04,480
water is how high sea levels are

297
00:12:07,430 --> 00:12:06,560
everywhere in the world once every 10

298
00:12:09,509 --> 00:12:07,440
days

299
00:12:11,990 --> 00:12:09,519
and this gives us a really powerful tool

300
00:12:13,990 --> 00:12:12,000
for measuring sea level rise and one

301
00:12:17,829 --> 00:12:14,000
that we've actually been

302
00:12:20,069 --> 00:12:17,839
using for almost 30 years now

303
00:12:21,590 --> 00:12:20,079
but as we heard at the very beginning of

304
00:12:24,389 --> 00:12:21,600
the program

305
00:12:26,629 --> 00:12:24,399
our latest sea level mission sentinel 6

306
00:12:29,350 --> 00:12:26,639
michael freilich was launched on

307
00:12:31,990 --> 00:12:29,360
november 21st 2020

308
00:12:34,550 --> 00:12:32,000
and this is actually the most

309
00:12:37,590 --> 00:12:34,560
accurate mission to date to measure

310
00:12:39,670 --> 00:12:37,600
global sea levels it'll give us

311
00:12:41,509 --> 00:12:39,680
all kinds of really fascinating

312
00:12:43,910 --> 00:12:41,519
information but one of the most

313
00:12:46,870 --> 00:12:43,920
important things is it's the satellite

314
00:12:49,430 --> 00:12:46,880
so nice we built it twice in fact

315
00:12:51,670 --> 00:12:49,440
there's two sentinel 6 satellites the

316
00:12:54,790 --> 00:12:51,680
sentinel 6 michael freilich was launched

317
00:12:57,030 --> 00:12:54,800
last year and in 2025

318
00:12:59,910 --> 00:12:57,040
an exact copy of the satellite will

319
00:13:02,230 --> 00:12:59,920
launch and replace the sentinel 6

320
00:13:05,430 --> 00:13:02,240
michael freilax satellite so each one

321
00:13:08,310 --> 00:13:05,440
will last 5 years giving us a 10 year

322
00:13:11,910 --> 00:13:08,320
extension to our record of sea level

323
00:13:14,069 --> 00:13:11,920
rise which goes back to the early 1990s

324
00:13:15,509 --> 00:13:14,079
now the launch of michael freilick was

325
00:13:18,230 --> 00:13:15,519
kind of exciting

326
00:13:20,629 --> 00:13:18,240
because it it launched on a rocket that

327
00:13:22,870 --> 00:13:20,639
went up but the rocket actually came

328
00:13:24,790 --> 00:13:22,880
back down and it landed on the same

329
00:13:26,069 --> 00:13:24,800
launch pad it took off from

330
00:13:28,069 --> 00:13:26,079
i was there and it was kind of an

331
00:13:29,750 --> 00:13:28,079
exciting day because when the rocket

332
00:13:31,350 --> 00:13:29,760
came back down

333
00:13:34,470 --> 00:13:31,360
it's going faster than the speed of

334
00:13:36,790 --> 00:13:34,480
sound so it creates a sonic boom and i

335
00:13:38,870 --> 00:13:36,800
happen to get a little video of it where

336
00:13:41,509 --> 00:13:38,880
you can hear the sonic boom so

337
00:13:42,790 --> 00:13:41,519
if you're listening to this really loud

338
00:13:44,870 --> 00:13:42,800
you may want to turn your volume down a

339
00:14:03,350 --> 00:13:44,880
little bit here we go check out this

340
00:14:09,590 --> 00:14:06,230
well it wasn't just the rocket that made

341
00:14:12,629 --> 00:14:09,600
a boom that day uh in fact um sentinel 6

342
00:14:14,949 --> 00:14:12,639
michael freilich was a huge boom for

343
00:14:17,910 --> 00:14:14,959
advancing our knowledge of sea level

344
00:14:19,189 --> 00:14:17,920
rise and uh the fact that it launched

345
00:14:22,629 --> 00:14:19,199
successfully

346
00:14:25,269 --> 00:14:22,639
was incredibly satisfying and uh um in

347
00:14:27,750 --> 00:14:25,279
fact we've gotten the very first data

348
00:14:29,430 --> 00:14:27,760
back from it uh was released in june

349
00:14:32,230 --> 00:14:29,440
publicly

350
00:14:35,110 --> 00:14:32,240
this image shows the height of the

351
00:14:37,509 --> 00:14:35,120
oceans uh in the pacific and a little

352
00:14:40,310 --> 00:14:37,519
bit in the atlantic red is higher than

353
00:14:41,430 --> 00:14:40,320
average by about 10 or 20 centimeters in

354
00:14:42,629 --> 00:14:41,440
blue

355
00:14:45,030 --> 00:14:42,639
and and

356
00:14:46,870 --> 00:14:45,040
green or a little bit lower than

357
00:14:49,189 --> 00:14:46,880
average sea level but what you can

358
00:14:51,350 --> 00:14:49,199
notice is actually most of the globe is

359
00:14:54,629 --> 00:14:51,360
pretty red that's because sea levels

360
00:14:56,870 --> 00:14:54,639
have been rising now for about 30 years

361
00:14:58,470 --> 00:14:56,880
and i mentioned that

362
00:15:01,269 --> 00:14:58,480
michael fry like the sentinel six

363
00:15:04,389 --> 00:15:01,279
michael freilax satellite is was part of

364
00:15:07,829 --> 00:15:04,399
uh a set of missions that go back to the

365
00:15:09,990 --> 00:15:07,839
early 1990s and this slide gives us a

366
00:15:12,790 --> 00:15:10,000
sense of just how

367
00:15:14,949 --> 00:15:12,800
lucky we are in the oceanographic

368
00:15:17,430 --> 00:15:14,959
community and the climate community to

369
00:15:20,230 --> 00:15:17,440
have had a series of satellites that go

370
00:15:22,389 --> 00:15:20,240
all the way back to 1992

371
00:15:24,310 --> 00:15:22,399
which starting with topex poseidon which

372
00:15:26,069 --> 00:15:24,320
is actually the satellite that got me my

373
00:15:29,189 --> 00:15:26,079
phd

374
00:15:32,230 --> 00:15:29,199
that satellite and its successor jason 1

375
00:15:33,509 --> 00:15:32,240
jason 2 and now jason 3

376
00:15:34,870 --> 00:15:33,519
have

377
00:15:37,110 --> 00:15:34,880
overlapped

378
00:15:40,310 --> 00:15:37,120
one after the next going all the way

379
00:15:42,949 --> 00:15:40,320
back to 1992 and that overlaps

380
00:15:45,269 --> 00:15:42,959
incredibly important because it gives us

381
00:15:48,710 --> 00:15:45,279
a continuous record of how sea level is

382
00:15:51,269 --> 00:15:48,720
changing that is incredibly accurate in

383
00:15:54,870 --> 00:15:51,279
fact it is so accurate that we can

384
00:15:57,829 --> 00:15:54,880
measure the rise of the oceans

385
00:16:00,150 --> 00:15:57,839
with an accuracy of just about

386
00:16:01,350 --> 00:16:00,160
half a centimeter that's about a quarter

387
00:16:05,110 --> 00:16:01,360
of an inch

388
00:16:08,389 --> 00:16:05,120
once every 10 days and so every 10 days

389
00:16:11,430 --> 00:16:08,399
we get this incredibly accurate look at

390
00:16:13,590 --> 00:16:11,440
the average height of the entire planet

391
00:16:15,910 --> 00:16:13,600
that's a huge feat because remember more

392
00:16:18,870 --> 00:16:15,920
than two-thirds of the planet's surface

393
00:16:21,110 --> 00:16:18,880
are covered by oceans so as we watch the

394
00:16:23,269 --> 00:16:21,120
sea levels change globally we're

395
00:16:24,790 --> 00:16:23,279
literally watching how the earth is

396
00:16:27,030 --> 00:16:24,800
reshaped

397
00:16:29,590 --> 00:16:27,040
one week after the next

398
00:16:32,870 --> 00:16:29,600
and when we look at the data you can see

399
00:16:35,189 --> 00:16:32,880
right here this uh up and down that

400
00:16:37,829 --> 00:16:35,199
happens every year this

401
00:16:40,949 --> 00:16:37,839
sort of rise and fall

402
00:16:44,230 --> 00:16:40,959
in global sea level and this is actually

403
00:16:47,030 --> 00:16:44,240
due to the exchange of water between the

404
00:16:49,509 --> 00:16:47,040
oceans and the land every year in the

405
00:16:51,269 --> 00:16:49,519
summertime in the northern hemisphere

406
00:16:53,269 --> 00:16:51,279
the ocean uh

407
00:16:56,150 --> 00:16:53,279
evaporates lots of water up into the

408
00:16:58,389 --> 00:16:56,160
atmosphere and it rains down over land

409
00:17:00,710 --> 00:16:58,399
it takes that water some time to reach

410
00:17:05,270 --> 00:17:00,720
the ocean again and during that time sea

411
00:17:07,590 --> 00:17:05,280
level actually falls um until the

412
00:17:09,270 --> 00:17:07,600
until the water begins to run back off

413
00:17:11,590 --> 00:17:09,280
the seasonal cycle shifts to the

414
00:17:15,510 --> 00:17:11,600
southern hemisphere and sea levels begin

415
00:17:18,549 --> 00:17:15,520
to rise again so this rise and fall of

416
00:17:21,189 --> 00:17:18,559
the oceans which is about a centimeter

417
00:17:23,669 --> 00:17:21,199
every year or about half an inch

418
00:17:26,150 --> 00:17:23,679
that is sort of like the heartbeat of

419
00:17:29,669 --> 00:17:26,160
our planet it's it's like the exchange

420
00:17:31,669 --> 00:17:29,679
of water uh is really telling us

421
00:17:33,909 --> 00:17:31,679
how our planet's changing in an

422
00:17:39,029 --> 00:17:33,919
incredibly

423
00:17:40,950 --> 00:17:39,039
but what's fascinating really to me is

424
00:17:42,470 --> 00:17:40,960
that if you look at this

425
00:17:45,430 --> 00:17:42,480
if you look at this record that goes

426
00:17:46,789 --> 00:17:45,440
back from the early 1990s to today

427
00:17:49,110 --> 00:17:46,799
the most

428
00:17:51,510 --> 00:17:49,120
visible part of it the the thing that

429
00:17:54,310 --> 00:17:51,520
jumps out at you the most is the steady

430
00:17:57,750 --> 00:17:54,320
rise of the oceans and i say steady but

431
00:18:00,390 --> 00:17:57,760
it's actually really not steady because

432
00:18:03,190 --> 00:18:00,400
the rate of rise has increased and you

433
00:18:05,430 --> 00:18:03,200
can almost see it in this curve but in

434
00:18:07,590 --> 00:18:05,440
the early nineties the rate of rise was

435
00:18:09,669 --> 00:18:07,600
about two millimeters per year

436
00:18:12,630 --> 00:18:09,679
in the 2000s it was three millimeters

437
00:18:14,710 --> 00:18:12,640
per year and today it's between four and

438
00:18:16,950 --> 00:18:14,720
five millimeters per year so we're

439
00:18:19,669 --> 00:18:16,960
literally watching the rate of sea level

440
00:18:22,070 --> 00:18:19,679
rise increase from one decade to the

441
00:18:24,390 --> 00:18:22,080
next and it's satellites like the

442
00:18:26,390 --> 00:18:24,400
sentinel six michael freilick mission

443
00:18:28,950 --> 00:18:26,400
and the jason missions before it that

444
00:18:31,510 --> 00:18:28,960
allow us to do this

445
00:18:34,789 --> 00:18:31,520
now i want to shift gears just a little

446
00:18:39,830 --> 00:18:37,110
talk for a second about the causes of

447
00:18:43,270 --> 00:18:39,840
this rise and one of the reasons we're

448
00:18:46,070 --> 00:18:43,280
seeing this increase in sea level is the

449
00:18:49,350 --> 00:18:46,080
melting of the ice sheets now nasa has

450
00:18:50,310 --> 00:18:49,360
another neat tool in collaboration with

451
00:18:52,630 --> 00:18:50,320
uh

452
00:18:55,029 --> 00:18:52,640
with the german space agency

453
00:18:58,070 --> 00:18:55,039
it's called the grace mission or now the

454
00:19:00,549 --> 00:18:58,080
grace follow-on mission and this

455
00:19:03,110 --> 00:19:00,559
satellite is actually a pair of

456
00:19:05,110 --> 00:19:03,120
satellites these two satellites chase

457
00:19:07,510 --> 00:19:05,120
each other around the earth their names

458
00:19:09,430 --> 00:19:07,520
are tom and jerry in fact

459
00:19:11,110 --> 00:19:09,440
just like the cartoon characters and

460
00:19:13,270 --> 00:19:11,120
whenever the first one goes over

461
00:19:16,630 --> 00:19:13,280
something heavy the pull of gravity

462
00:19:19,590 --> 00:19:16,640
causes it to speed up and move away from

463
00:19:21,669 --> 00:19:19,600
the second satellite just a little bit

464
00:19:23,590 --> 00:19:21,679
so what we do is we measure the distance

465
00:19:25,750 --> 00:19:23,600
between the two satellites very very

466
00:19:29,669 --> 00:19:25,760
accurately and by watching them move

467
00:19:31,830 --> 00:19:29,679
together and apart we can infer how

468
00:19:34,549 --> 00:19:31,840
heavy the things are that we're flying

469
00:19:36,870 --> 00:19:34,559
over so for instance when we fly over a

470
00:19:38,789 --> 00:19:36,880
mountain with this satellite we see the

471
00:19:40,150 --> 00:19:38,799
satellites pull apart at the beginning

472
00:19:41,830 --> 00:19:40,160
and then come back together when the

473
00:19:43,669 --> 00:19:41,840
mountain is between them

474
00:19:46,630 --> 00:19:43,679
so using this information we can

475
00:19:49,909 --> 00:19:46,640
literally weigh the continents and when

476
00:19:52,950 --> 00:19:49,919
we weigh the continents or the islands

477
00:19:55,430 --> 00:19:52,960
like greenland that are covered in ice

478
00:19:58,310 --> 00:19:55,440
we see that the ice in greenland is

479
00:19:59,510 --> 00:19:58,320
actually disappearing now

480
00:20:02,149 --> 00:19:59,520
this

481
00:20:04,390 --> 00:20:02,159
animation shows

482
00:20:07,029 --> 00:20:04,400
the ice beginning to disappear and

483
00:20:09,270 --> 00:20:07,039
you'll see the reds start to appear

484
00:20:10,870 --> 00:20:09,280
around the edges of greenland

485
00:20:13,830 --> 00:20:10,880
that represents

486
00:20:16,070 --> 00:20:13,840
tons and tons of ice that are being lost

487
00:20:21,350 --> 00:20:16,080
from the edges of the ice sheet

488
00:20:23,270 --> 00:20:21,360
and during the last 15 or so years

489
00:20:27,590 --> 00:20:23,280
greenland has lost

490
00:20:30,230 --> 00:20:27,600
5 trillion tons of ice and that's enough

491
00:20:31,909 --> 00:20:30,240
to raise sea levels by more than a

492
00:20:34,630 --> 00:20:31,919
centimeter

493
00:20:37,110 --> 00:20:34,640
almost three quarters of an inch so

494
00:20:39,830 --> 00:20:37,120
this rise that we're seeing in the

495
00:20:42,470 --> 00:20:39,840
oceans is directly driven

496
00:20:44,710 --> 00:20:42,480
by the loss of ice in the great ice

497
00:20:46,230 --> 00:20:44,720
sheets like greenland

498
00:20:48,950 --> 00:20:46,240
now uh

499
00:20:50,789 --> 00:20:48,960
before we uh get too deep into greenland

500
00:20:52,950 --> 00:20:50,799
i'm going to shift gears again and we're

501
00:20:56,230 --> 00:20:52,960
going to talk a little bit about a

502
00:20:57,430 --> 00:20:56,240
mission that i uh helped propose

503
00:21:00,710 --> 00:20:57,440
about

504
00:21:03,510 --> 00:21:00,720
in 2014 many many years ago called

505
00:21:05,590 --> 00:21:03,520
ocean's melting greenland or omg for

506
00:21:06,950 --> 00:21:05,600
short and i'll show you just a quick

507
00:21:08,710 --> 00:21:06,960
little video

508
00:21:11,570 --> 00:21:08,720
to give you an introduction to what that

509
00:21:19,270 --> 00:21:11,580
mission's all about

510
00:21:24,549 --> 00:21:21,510
there's enough ice here in greenland to

511
00:21:26,549 --> 00:21:24,559
raise sea levels by 25 feet all the way

512
00:21:28,070 --> 00:21:26,559
around the world it's an incredible

513
00:21:30,630 --> 00:21:28,080
amount of ice

514
00:21:32,230 --> 00:21:30,640
and it's melting and adding to sea level

515
00:21:34,230 --> 00:21:32,240
rise

516
00:21:36,950 --> 00:21:34,240
for oceans melting greenland what we

517
00:21:39,590 --> 00:21:36,960
really want to do is measure the oceans

518
00:21:41,430 --> 00:21:39,600
measure the ice and watch them change

519
00:21:43,590 --> 00:21:41,440
together year on year

520
00:21:45,270 --> 00:21:43,600
and try and answer the question how much

521
00:21:47,270 --> 00:21:45,280
are the oceans

522
00:21:49,750 --> 00:21:47,280
melting away the ice as opposed to the

523
00:21:49,930 --> 00:21:49,760
air which is what most people studied so

524
00:21:57,270 --> 00:21:49,940
far

525
00:22:02,230 --> 00:21:59,990
it's really a breathtaking landscape

526
00:22:04,950 --> 00:22:02,240
these giant mountains and

527
00:22:06,549 --> 00:22:04,960
canyons are all along the coast

528
00:22:08,950 --> 00:22:06,559
when you look out the window you really

529
00:22:11,750 --> 00:22:08,960
get a sense of just how huge these

530
00:22:12,390 --> 00:22:11,760
glaciers are these gigantic rivers of

531
00:22:15,990 --> 00:22:12,400
ice

532
00:22:17,430 --> 00:22:16,000
greenland into the ocean

533
00:22:20,070 --> 00:22:17,440
and then they reach the ocean and it

534
00:22:25,669 --> 00:22:20,080
gets all broken and craggy and big

535
00:22:30,390 --> 00:22:28,230
coolasuke is just a tiny little town in

536
00:22:32,230 --> 00:22:30,400
southeast greenland and

537
00:22:35,029 --> 00:22:32,240
we've been launching probes out of here

538
00:22:37,190 --> 00:22:35,039
for the past four or five days

539
00:22:39,580 --> 00:22:37,200
it's already been a fantastic year for

540
00:22:41,029 --> 00:22:39,590
omg measuring the oceans

541
00:22:43,110 --> 00:22:41,039
[Music]

542
00:22:45,190 --> 00:22:43,120
we launch them right out of this tube

543
00:22:47,270 --> 00:22:45,200
right over here open up the tube you can

544
00:22:49,430 --> 00:22:47,280
look right down and see the water

545
00:22:50,870 --> 00:22:49,440
passing by or sometimes the icebergs or

546
00:22:53,110 --> 00:22:50,880
clouds or whatever it is we're flying

547
00:22:54,789 --> 00:22:53,120
over

548
00:22:57,110 --> 00:22:54,799
we slow down a little bit and we just

549
00:22:59,029 --> 00:22:57,120
push these big gray cylinders out of the

550
00:23:01,190 --> 00:22:59,039
bottom of the plane and they fall to the

551
00:23:03,270 --> 00:23:01,200
ocean and measure the temperature and

552
00:23:05,590 --> 00:23:03,280
salinity when they get there and radio

553
00:23:07,590 --> 00:23:05,600
it back to the plane

554
00:23:09,669 --> 00:23:07,600
we're really trying to look at the ice

555
00:23:12,870 --> 00:23:09,679
and ocean all the way around greenland

556
00:23:14,789 --> 00:23:12,880
so we're dropping 250 profilers we're

557
00:23:17,990 --> 00:23:14,799
going to cover the coastline all the way

558
00:23:20,950 --> 00:23:18,000
around and in the spring we map out the

559
00:23:23,270 --> 00:23:20,960
glaciers with a radar also all the way

560
00:23:25,029 --> 00:23:23,280
around so we're really looking at

561
00:23:27,110 --> 00:23:25,039
mapping all of the ocean ice

562
00:23:32,310 --> 00:23:27,120
interactions in greenland as best we can

563
00:23:37,590 --> 00:23:34,630
so there's a little information about

564
00:23:40,310 --> 00:23:37,600
oceans melting greenland or omg for

565
00:23:43,909 --> 00:23:40,320
short and as you're probably wondering

566
00:23:45,750 --> 00:23:43,919
yes i did come up with the name omg

567
00:23:47,830 --> 00:23:45,760
in part because

568
00:23:50,070 --> 00:23:47,840
i wanted people to remember how

569
00:23:52,230 --> 00:23:50,080
surprising it is that we're having such

570
00:23:55,190 --> 00:23:52,240
a big impact on greenland but also

571
00:23:57,590 --> 00:23:55,200
because those three words really embody

572
00:24:00,230 --> 00:23:57,600
what the mission's all about which is

573
00:24:03,669 --> 00:24:00,240
that the oceans are playing a big role

574
00:24:05,909 --> 00:24:03,679
in the ice loss in greenland so we

575
00:24:08,789 --> 00:24:05,919
started out really thinking about how

576
00:24:11,990 --> 00:24:08,799
the earth was warming and the oceans

577
00:24:14,789 --> 00:24:12,000
reminded us that they play an enormous

578
00:24:17,269 --> 00:24:14,799
role in how the climate is changing well

579
00:24:20,230 --> 00:24:17,279
ocean's melting greenland is

580
00:24:24,310 --> 00:24:20,240
zooming in on how they're changing the

581
00:24:26,710 --> 00:24:24,320
ice in greenland now the idea behind omg

582
00:24:29,830 --> 00:24:26,720
as i said in the video was to measure

583
00:24:32,789 --> 00:24:29,840
both the oceans and the ice and try and

584
00:24:36,310 --> 00:24:32,799
understand how changes in the ocean

585
00:24:38,549 --> 00:24:36,320
could lead to changes in the glaciers

586
00:24:40,390 --> 00:24:38,559
all around the edges of greenland you're

587
00:24:42,149 --> 00:24:40,400
probably also wondering if i'm wearing

588
00:24:43,830 --> 00:24:42,159
the same shirt as i was in that video

589
00:24:46,630 --> 00:24:43,840
and yes would be the answer to that

590
00:24:51,590 --> 00:24:46,640
question so uh let's take a little

591
00:24:52,470 --> 00:24:51,600
deeper dive into the uh into the process

592
00:24:55,590 --> 00:24:52,480
that

593
00:24:57,990 --> 00:24:55,600
allows the oceans to reach in and melt

594
00:25:00,710 --> 00:24:58,000
these glaciers now we normally think of

595
00:25:03,350 --> 00:25:00,720
greenland as melting from above like a

596
00:25:05,830 --> 00:25:03,360
big ice block under a hair dryer but

597
00:25:08,230 --> 00:25:05,840
actually the ice on greenland is sliding

598
00:25:10,630 --> 00:25:08,240
off into the ocean in the form of these

599
00:25:13,269 --> 00:25:10,640
glaciers and if we look at how the

600
00:25:15,430 --> 00:25:13,279
glaciers are changing we can actually

601
00:25:18,310 --> 00:25:15,440
get an idea of why the oceans might be

602
00:25:20,710 --> 00:25:18,320
playing such an important role now many

603
00:25:21,909 --> 00:25:20,720
of the glaciers in greenland reach right

604
00:25:26,070 --> 00:25:21,919
to the sea

605
00:25:28,470 --> 00:25:26,080
and as melt from the surface

606
00:25:31,909 --> 00:25:28,480
accumulates on the ice it actually

607
00:25:34,149 --> 00:25:31,919
drills a hole down through the glacier

608
00:25:36,789 --> 00:25:34,159
and it allows the water to run

609
00:25:37,909 --> 00:25:36,799
underneath the glacier along the glacier

610
00:25:40,230 --> 00:25:37,919
bed

611
00:25:43,029 --> 00:25:40,240
this melt water when it reaches the

612
00:25:45,590 --> 00:25:43,039
ocean it's actually very fresh which

613
00:25:48,950 --> 00:25:45,600
means it's much lighter than normal

614
00:25:52,470 --> 00:25:48,960
seawater so this fresh water begins to

615
00:25:55,190 --> 00:25:52,480
rise up the face of the glacier and as

616
00:25:57,430 --> 00:25:55,200
it does it runs into a very interesting

617
00:25:59,269 --> 00:25:57,440
situation because the water around

618
00:26:02,310 --> 00:25:59,279
greenland is

619
00:26:04,950 --> 00:26:02,320
warm down deep it's warm in the deep

620
00:26:08,230 --> 00:26:04,960
parts because that water is salty and

621
00:26:10,549 --> 00:26:08,240
from the atlantic ocean now as the water

622
00:26:12,630 --> 00:26:10,559
rises up the face of the glacier it

623
00:26:15,190 --> 00:26:12,640
actually eats away at the bottom and

624
00:26:17,909 --> 00:26:15,200
eventually breaks off a chunk of the

625
00:26:21,269 --> 00:26:17,919
glacier in a process called calving

626
00:26:24,390 --> 00:26:21,279
and as calving increases

627
00:26:27,510 --> 00:26:24,400
then the glacier can actually retreat

628
00:26:29,430 --> 00:26:27,520
and if it retreats it speeds up dumping

629
00:26:32,310 --> 00:26:29,440
more and more ice into the ocean more

630
00:26:33,510 --> 00:26:32,320
quickly and driving sea levels higher

631
00:26:36,310 --> 00:26:33,520
and higher

632
00:26:37,510 --> 00:26:36,320
so the ocean temperature the water

633
00:26:39,269 --> 00:26:37,520
that's actually

634
00:26:40,390 --> 00:26:39,279
reaching up towards the glacier and

635
00:26:42,870 --> 00:26:40,400
warming it

636
00:26:46,870 --> 00:26:42,880
is actually really important for the

637
00:26:49,430 --> 00:26:46,880
speed at which the glaciers cave off

638
00:26:52,710 --> 00:26:49,440
and the rate at which they speed up and

639
00:26:55,430 --> 00:26:52,720
dump ice into the oceans so that's sort

640
00:26:58,070 --> 00:26:55,440
of how the oceans can affect greenland

641
00:27:01,029 --> 00:26:58,080
and for oceans melting greenland this

642
00:27:03,269 --> 00:27:01,039
was an airborne mission so we used

643
00:27:05,590 --> 00:27:03,279
airplanes to try and understand these

644
00:27:08,710 --> 00:27:05,600
two questions and we flew the airplanes

645
00:27:11,510 --> 00:27:08,720
around uh for two different surveys each

646
00:27:14,710 --> 00:27:11,520
year for five or six years in the four

647
00:27:16,470 --> 00:27:14,720
or six years in the case of the ocean um

648
00:27:17,909 --> 00:27:16,480
for the ocean part of the survey we

649
00:27:19,029 --> 00:27:17,919
dropped those cylinders out of the

650
00:27:21,750 --> 00:27:19,039
airplane

651
00:27:24,549 --> 00:27:21,760
they fall to the water and actually

652
00:27:26,630 --> 00:27:24,559
split into two parts one part stays at

653
00:27:29,269 --> 00:27:26,640
the surface and radios the data back to

654
00:27:31,510 --> 00:27:29,279
the plane and the other part falls down

655
00:27:32,870 --> 00:27:31,520
connected by a very thin wire and

656
00:27:35,029 --> 00:27:32,880
measures the temperature and the

657
00:27:37,269 --> 00:27:35,039
saltiness as it goes

658
00:27:41,990 --> 00:27:37,279
the ice survey looked at how the ice

659
00:27:43,750 --> 00:27:42,000
edge changed with a radar so when we

660
00:27:46,230 --> 00:27:43,760
looked at these things together we tried

661
00:27:48,470 --> 00:27:46,240
to understand how changes in the ocean

662
00:27:50,630 --> 00:27:48,480
could lead to changes in the ice and our

663
00:27:53,909 --> 00:27:50,640
records really showed us that the oceans

664
00:27:56,549 --> 00:27:53,919
are playing a huge role in how quickly

665
00:27:59,430 --> 00:27:56,559
the ice retreats

666
00:28:00,830 --> 00:27:59,440
now uh one of the things we saw were

667
00:28:04,310 --> 00:28:00,840
really beautiful

668
00:28:07,269 --> 00:28:04,320
uh scenes like this one which show

669
00:28:08,950 --> 00:28:07,279
the ice edge with a large plume this is

670
00:28:10,549 --> 00:28:08,960
what the plumes actually look like in

671
00:28:11,669 --> 00:28:10,559
real life when they reach all the way to

672
00:28:13,909 --> 00:28:11,679
the surface

673
00:28:15,669 --> 00:28:13,919
we flew past this plume and dropped the

674
00:28:17,590 --> 00:28:15,679
sensor into it measuring it all the way

675
00:28:20,310 --> 00:28:17,600
down to the sea floor was a very

676
00:28:22,230 --> 00:28:20,320
exciting day now these plumes as you can

677
00:28:24,950 --> 00:28:22,240
imagine are important places for us to

678
00:28:27,110 --> 00:28:24,960
measure and this year when we were in

679
00:28:30,310 --> 00:28:27,120
greenland in august

680
00:28:32,630 --> 00:28:30,320
we found in september we found a single

681
00:28:36,630 --> 00:28:32,640
plume on a very big glacier in east

682
00:28:39,909 --> 00:28:36,640
greenland and this picture on uh this

683
00:28:41,350 --> 00:28:39,919
this picture here with the blue plume uh

684
00:28:45,990 --> 00:28:41,360
pointed out

685
00:28:47,909 --> 00:28:46,000
actually a satellite image that i saw

686
00:28:49,350 --> 00:28:47,919
the day before we

687
00:28:51,110 --> 00:28:49,360
got in the airplane

688
00:28:52,710 --> 00:28:51,120
and flew all the way across the ice

689
00:28:54,070 --> 00:28:52,720
sheet and

690
00:28:56,149 --> 00:28:54,080
we did this

691
00:28:59,430 --> 00:28:56,159
just on the basis of this picture

692
00:29:01,269 --> 00:28:59,440
because in that tiny plume uh we

693
00:29:03,830 --> 00:29:01,279
realized that there would be

694
00:29:05,510 --> 00:29:03,840
water coming up um and reaching the

695
00:29:07,909 --> 00:29:05,520
surface and it was an opportunity to

696
00:29:10,470 --> 00:29:07,919
measure the oceans right next to the

697
00:29:14,470 --> 00:29:10,480
glacier edge when we got there what we

698
00:29:17,510 --> 00:29:14,480
saw was here where you can see this huge

699
00:29:19,909 --> 00:29:17,520
open area of water which is about 300

700
00:29:21,510 --> 00:29:19,919
feet across in diameter

701
00:29:24,549 --> 00:29:21,520
right next to

702
00:29:27,269 --> 00:29:24,559
the ice edge which is a couple hundred

703
00:29:29,590 --> 00:29:27,279
feet tall so it was an incredibly uh

704
00:29:31,909 --> 00:29:29,600
beautiful thing to see but one that we

705
00:29:34,070 --> 00:29:31,919
were actually able to

706
00:29:35,669 --> 00:29:34,080
to measure because

707
00:29:37,909 --> 00:29:35,679
we were able to use

708
00:29:39,510 --> 00:29:37,919
satellite images like this one

709
00:29:41,269 --> 00:29:39,520
and get from one place to the other

710
00:29:44,230 --> 00:29:41,279
across the ice sheet

711
00:29:47,190 --> 00:29:44,240
with our really cool looking airplane

712
00:29:49,029 --> 00:29:47,200
which was a dc-3 now we also got to fly

713
00:29:51,669 --> 00:29:49,039
around and see neat things

714
00:29:54,549 --> 00:29:51,679
like icebergs which you can see here in

715
00:29:56,389 --> 00:29:54,559
this uh in this flyby you'll notice as

716
00:29:58,549 --> 00:29:56,399
the wing tip goes by

717
00:30:00,789 --> 00:29:58,559
the iceberg is actually higher than our

718
00:30:03,350 --> 00:30:00,799
wingtip so some of these things are

719
00:30:05,990 --> 00:30:03,360
really enormous and it's a reminder of

720
00:30:07,430 --> 00:30:06,000
just how much ice is coming off of the

721
00:30:09,990 --> 00:30:07,440
ice sheet

722
00:30:10,870 --> 00:30:10,000
which is important for sea level rise

723
00:30:13,190 --> 00:30:10,880
now

724
00:30:14,789 --> 00:30:13,200
in the first couple years of omg we

725
00:30:17,510 --> 00:30:14,799
actually

726
00:30:20,630 --> 00:30:17,520
measured one of its biggest glaciers

727
00:30:22,149 --> 00:30:20,640
and found that this glacier was actually

728
00:30:24,149 --> 00:30:22,159
growing

729
00:30:26,230 --> 00:30:24,159
this was a big surprise because

730
00:30:28,710 --> 00:30:26,240
greenland's fastest moving glacier

731
00:30:31,350 --> 00:30:28,720
called jakob saban had actually been in

732
00:30:33,750 --> 00:30:31,360
retreat for about 20 years now

733
00:30:37,269 --> 00:30:33,760
jakobsovin is on the

734
00:30:40,470 --> 00:30:37,279
western coast of greenland and it's

735
00:30:42,070 --> 00:30:40,480
next to a huge bay right here

736
00:30:43,990 --> 00:30:42,080
and inside

737
00:30:46,470 --> 00:30:44,000
this long fjord

738
00:30:49,510 --> 00:30:46,480
right where the pointer is right now

739
00:30:52,870 --> 00:30:49,520
is the edge of this mighty glacier which

740
00:30:55,230 --> 00:30:52,880
is known locally as the alulasac glacier

741
00:30:56,870 --> 00:30:55,240
now this glacier is famous among

742
00:30:59,590 --> 00:30:56,880
glaciologists because it's been

743
00:31:02,230 --> 00:30:59,600
retreating so fast but in the first year

744
00:31:04,070 --> 00:31:02,240
of omg or the first two years of omg we

745
00:31:05,509 --> 00:31:04,080
found that the glacier was actually

746
00:31:08,630 --> 00:31:05,519
growing

747
00:31:10,070 --> 00:31:08,640
and these images which were taken by our

748
00:31:12,389 --> 00:31:10,080
aircraft

749
00:31:14,710 --> 00:31:12,399
measuring the glacier show

750
00:31:16,950 --> 00:31:14,720
in blue where the glacier was actually

751
00:31:21,029 --> 00:31:16,960
getting thicker from one year to the

752
00:31:25,830 --> 00:31:21,039
next and this happened from 2016 to 2017

753
00:31:28,230 --> 00:31:25,840
2017 to 2018 and 2018 to 2019. so why

754
00:31:30,710 --> 00:31:28,240
was it getting thicker well it turned

755
00:31:32,470 --> 00:31:30,720
out the answer much like

756
00:31:35,269 --> 00:31:32,480
all the answers to the questions in this

757
00:31:37,990 --> 00:31:35,279
talk was the oceans

758
00:31:40,470 --> 00:31:38,000
when we looked at the oceans nearby in

759
00:31:44,070 --> 00:31:40,480
this bay in disco bay

760
00:31:45,110 --> 00:31:44,080
we found that the oceans had cooled down

761
00:31:47,590 --> 00:31:45,120
after

762
00:31:49,669 --> 00:31:47,600
uh decades of being two almost two

763
00:31:52,549 --> 00:31:49,679
decades of being warm

764
00:31:54,630 --> 00:31:52,559
the the waters in front of this glacier

765
00:31:57,029 --> 00:31:54,640
actually cooled off

766
00:31:59,509 --> 00:31:57,039
and when they cooled as part of a

767
00:32:02,070 --> 00:31:59,519
natural cycle in the atlantic ocean

768
00:32:05,909 --> 00:32:02,080
the glacier began to grow again

769
00:32:07,350 --> 00:32:05,919
so omg essentially proved its major

770
00:32:10,470 --> 00:32:07,360
hypothesis

771
00:32:13,190 --> 00:32:10,480
which was that the oceans are playing a

772
00:32:15,430 --> 00:32:13,200
huge part in controlling how fast the

773
00:32:18,630 --> 00:32:15,440
glaciers are retreating because when we

774
00:32:20,789 --> 00:32:18,640
saw this particular glacier react so

775
00:32:23,110 --> 00:32:20,799
strongly to the oceans we knew without a

776
00:32:24,870 --> 00:32:23,120
doubt they were playing a big role in

777
00:32:26,470 --> 00:32:24,880
greenland's ice loss

778
00:32:27,750 --> 00:32:26,480
now if you'd like to learn more about

779
00:32:36,149 --> 00:32:27,760
omg

780
00:32:38,549 --> 00:32:36,159
you can see yet another picture of me

781
00:32:40,310 --> 00:32:38,559
wearing this red shirt and watch all the

782
00:32:42,470 --> 00:32:40,320
fun videos that i showed

783
00:32:45,269 --> 00:32:42,480
so far now before

784
00:32:48,470 --> 00:32:45,279
i uh wrap up i want to talk about one

785
00:32:51,990 --> 00:32:48,480
last thing which is the future of these

786
00:32:55,110 --> 00:32:52,000
kinds of uh missions to study sea level

787
00:32:56,950 --> 00:32:55,120
and at nasa and the front with in

788
00:33:00,870 --> 00:32:56,960
collaboration with the french space

789
00:33:03,269 --> 00:33:00,880
agency uh canes um and also uh with the

790
00:33:07,110 --> 00:33:03,279
canadians and the british

791
00:33:08,789 --> 00:33:07,120
we're hoping to launch in 2022

792
00:33:11,669 --> 00:33:08,799
late 2022

793
00:33:14,230 --> 00:33:11,679
the next revolution in sea level

794
00:33:16,710 --> 00:33:14,240
measuring missions from space this is

795
00:33:20,070 --> 00:33:16,720
called swat which stands for surface

796
00:33:22,950 --> 00:33:20,080
water and ocean out uh ocean topography

797
00:33:25,669 --> 00:33:22,960
and essentially what it will do

798
00:33:27,590 --> 00:33:25,679
is look down and measure sea level but

799
00:33:30,470 --> 00:33:27,600
instead of measuring it in one small

800
00:33:32,310 --> 00:33:30,480
spot and taking 10 days to fly around

801
00:33:34,310 --> 00:33:32,320
the world and cover pretty much the

802
00:33:37,909 --> 00:33:34,320
entire oceans

803
00:33:40,950 --> 00:33:37,919
swat will measure an entire swath of the

804
00:33:44,389 --> 00:33:40,960
ocean all at once as it flies by

805
00:33:47,830 --> 00:33:44,399
and this will sweep out a much

806
00:33:50,789 --> 00:33:47,840
finer look at the oceans you can think

807
00:33:54,070 --> 00:33:50,799
of it as sort of like turning turning in

808
00:33:57,830 --> 00:33:54,080
your old standard definition tv

809
00:34:00,710 --> 00:33:57,840
um and getting a high definition tv

810
00:34:03,509 --> 00:34:00,720
or maybe even a 4k tv

811
00:34:05,909 --> 00:34:03,519
swat will allow us to see very small

812
00:34:08,550 --> 00:34:05,919
structures in the ocean allow us to see

813
00:34:10,069 --> 00:34:08,560
sea level as it changes right up next to

814
00:34:12,230 --> 00:34:10,079
the coastline

815
00:34:14,790 --> 00:34:12,240
and really be a powerful tool for

816
00:34:17,109 --> 00:34:14,800
measuring how the oceans are changing

817
00:34:19,669 --> 00:34:17,119
their shape over time

818
00:34:20,790 --> 00:34:19,679
it's exciting too because it will also

819
00:34:23,909 --> 00:34:20,800
allow

820
00:34:25,030 --> 00:34:23,919
hydrologists folks who study water on

821
00:34:28,230 --> 00:34:25,040
land

822
00:34:30,470 --> 00:34:28,240
a much broader look at lakes and rivers

823
00:34:32,389 --> 00:34:30,480
all around the world so it's a really

824
00:34:36,230 --> 00:34:32,399
exciting mission coming down

825
00:34:38,389 --> 00:34:36,240
the pipeline uh it'll launch in 2022 and

826
00:34:41,349 --> 00:34:38,399
we're all really excited about it

827
00:34:43,430 --> 00:34:41,359
and with that i will stop and be happy

828
00:34:45,349 --> 00:34:43,440
to answer some questions

829
00:34:47,349 --> 00:34:45,359
yeah absolutely josh you've given us a

830
00:34:49,030 --> 00:34:47,359
ton of information and i'm sure we've

831
00:34:52,389 --> 00:34:49,040
got a ton of great questions out there

832
00:34:54,470 --> 00:34:52,399
so jocelyn what are they asking us

833
00:34:55,829 --> 00:34:54,480
yes we do have a lot of really great

834
00:34:58,069 --> 00:34:55,839
questions coming in through our social

835
00:35:00,950 --> 00:34:58,079
media uh the first one let's kick it off

836
00:35:05,349 --> 00:35:00,960
with filanka on youtube wants to know

837
00:35:09,510 --> 00:35:07,109
well that's a great question you know a

838
00:35:10,310 --> 00:35:09,520
lot of people want to know

839
00:35:12,390 --> 00:35:10,320
how

840
00:35:15,190 --> 00:35:12,400
much of the current warming of the

841
00:35:16,550 --> 00:35:15,200
planet is part of a natural cycle but if

842
00:35:17,670 --> 00:35:16,560
you remember back at the beginning of

843
00:35:20,630 --> 00:35:17,680
the talk

844
00:35:21,750 --> 00:35:20,640
the planet was already in a very warm

845
00:35:24,069 --> 00:35:21,760
period

846
00:35:26,870 --> 00:35:24,079
and what's happened in the last 150

847
00:35:28,790 --> 00:35:26,880
years has been warming on top of that

848
00:35:31,349 --> 00:35:28,800
already warm period

849
00:35:34,390 --> 00:35:31,359
so the warming that's happening today

850
00:35:37,510 --> 00:35:34,400
the warming that's happened since 1850

851
00:35:40,310 --> 00:35:37,520
that's almost entirely human caused and

852
00:35:41,030 --> 00:35:40,320
it's driven by adding fossil fuels to

853
00:35:42,870 --> 00:35:41,040
the

854
00:35:45,270 --> 00:35:42,880
burning fossil fuels and adding carbon

855
00:35:48,470 --> 00:35:45,280
dioxide and other greenhouse gases to

856
00:35:53,589 --> 00:35:49,349
great

857
00:35:56,230 --> 00:35:53,599
follow-up question to that they want to

858
00:35:59,510 --> 00:35:56,240
know does nasa keep up with all the

859
00:36:02,150 --> 00:35:59,520
underwater volcanic activity going on

860
00:36:02,870 --> 00:36:02,160
and does the volcano have anything to do

861
00:36:05,109 --> 00:36:02,880
with

862
00:36:07,190 --> 00:36:05,119
oceans heating up

863
00:36:09,510 --> 00:36:07,200
well that's a great question you know

864
00:36:11,510 --> 00:36:09,520
there are sources of heat in the ocean

865
00:36:13,430 --> 00:36:11,520
from down below their underwater

866
00:36:15,910 --> 00:36:13,440
volcanoes there are things like

867
00:36:18,150 --> 00:36:15,920
hydrothermal vents but when you compare

868
00:36:20,790 --> 00:36:18,160
the amount of heat that comes out of all

869
00:36:21,910 --> 00:36:20,800
of those volcanoes and vents all around

870
00:36:23,910 --> 00:36:21,920
the world

871
00:36:27,349 --> 00:36:23,920
with the heat that we get from the sun

872
00:36:30,550 --> 00:36:27,359
every day it's really really tiny way

873
00:36:33,270 --> 00:36:30,560
too small to be a major impact on

874
00:36:36,069 --> 00:36:33,280
today's warming so

875
00:36:38,069 --> 00:36:36,079
do we track every volcano from space we

876
00:36:40,550 --> 00:36:38,079
don't track every volcano from space but

877
00:36:42,870 --> 00:36:40,560
we do know about how many there are and

878
00:36:45,589 --> 00:36:42,880
about how much heat is coming up and

879
00:36:48,790 --> 00:36:45,599
we're pretty sure that it's way too

880
00:36:51,270 --> 00:36:48,800
small to be a major cause of today's

881
00:36:53,829 --> 00:36:51,280
warming not to mention that if you look

882
00:36:57,510 --> 00:36:53,839
at the planet it's warming from the top

883
00:37:00,870 --> 00:36:59,510
interesting and now switching gears to a

884
00:37:03,910 --> 00:37:00,880
little bit about your time out in

885
00:37:05,990 --> 00:37:03,920
greenland with omg dt on youtube wants

886
00:37:08,150 --> 00:37:06,000
to know what kind of aircraft does the

887
00:37:10,230 --> 00:37:08,160
team fly with

888
00:37:13,670 --> 00:37:10,240
oh that's a great question

889
00:37:15,910 --> 00:37:13,680
we actually fly with uh and we for the

890
00:37:20,150 --> 00:37:15,920
last few years we've been flying with an

891
00:37:23,430 --> 00:37:20,160
old dc-3 aircraft that was modified and

892
00:37:26,310 --> 00:37:23,440
more or less rebuilt to carry out

893
00:37:28,390 --> 00:37:26,320
science in the arctic and these old

894
00:37:30,710 --> 00:37:28,400
planes are really neat um they the

895
00:37:33,430 --> 00:37:30,720
pilots call them tail draggers because

896
00:37:35,750 --> 00:37:33,440
when they're parked they're sitting on a

897
00:37:38,069 --> 00:37:35,760
slant the rear tail wheel is much

898
00:37:40,230 --> 00:37:38,079
smaller than the main landing gear and

899
00:37:42,630 --> 00:37:40,240
so when you take off

900
00:37:44,950 --> 00:37:42,640
you're already tilted up and then the

901
00:37:47,589 --> 00:37:44,960
tail comes up like this and you take off

902
00:37:49,430 --> 00:37:47,599
and when you land the opposite happens

903
00:37:52,230 --> 00:37:49,440
the main wheels come down and then the

904
00:37:54,310 --> 00:37:52,240
rear wheel goes down so you tilt back up

905
00:37:55,510 --> 00:37:54,320
almost like you're taking off again but

906
00:37:58,710 --> 00:37:55,520
they're really

907
00:38:01,910 --> 00:37:58,720
really neat planes and fanta fantastic

908
00:38:03,589 --> 00:38:01,920
tools for science and omg benefited

909
00:38:06,310 --> 00:38:03,599
enormously from

910
00:38:08,310 --> 00:38:06,320
being able to use them

911
00:38:10,310 --> 00:38:08,320
amazing and i know that you get a lot of

912
00:38:12,270 --> 00:38:10,320
great data from up there mike on

913
00:38:14,950 --> 00:38:12,280
facebook wants to know how much

914
00:38:18,470 --> 00:38:14,960
uncertainty is in the measurements plus

915
00:38:19,270 --> 00:38:18,480
or minus what's a rough estimate

916
00:38:21,510 --> 00:38:19,280
well

917
00:38:23,270 --> 00:38:21,520
of course with any measurement the

918
00:38:25,190 --> 00:38:23,280
uncertainty depends on what it is you're

919
00:38:27,829 --> 00:38:25,200
trying to measure so when we're talking

920
00:38:29,349 --> 00:38:27,839
about things like global sea level rise

921
00:38:32,950 --> 00:38:29,359
for example

922
00:38:34,550 --> 00:38:32,960
every 10 days we get an estimate of the

923
00:38:35,910 --> 00:38:34,560
height of the average height of the

924
00:38:38,950 --> 00:38:35,920
oceans

925
00:38:40,870 --> 00:38:38,960
with an error bar and uncertainty of

926
00:38:44,150 --> 00:38:40,880
about half a centimeter or a few

927
00:38:46,790 --> 00:38:44,160
millimeters now we get many of these per

928
00:38:49,910 --> 00:38:46,800
year so if we average together a year of

929
00:38:52,550 --> 00:38:49,920
data we can really say how high the

930
00:38:55,349 --> 00:38:52,560
oceans are from one year to the next

931
00:38:56,150 --> 00:38:55,359
with an accuracy of just a millimeter or

932
00:38:58,870 --> 00:38:56,160
so

933
00:39:01,190 --> 00:38:58,880
and that's what allows us to see

934
00:39:03,349 --> 00:39:01,200
the rise and fall of the oceans that i

935
00:39:05,190 --> 00:39:03,359
talked about with the exchange of water

936
00:39:07,349 --> 00:39:05,200
between ocean and land like the

937
00:39:10,710 --> 00:39:07,359
heartbeat of the planet but it's also

938
00:39:12,550 --> 00:39:10,720
what allows us to see the increasing sea

939
00:39:17,829 --> 00:39:12,560
levels caused by the warming of the

940
00:39:22,230 --> 00:39:19,190
interesting

941
00:39:24,790 --> 00:39:22,240
dan cooper on youtube is asking don't

942
00:39:27,589 --> 00:39:24,800
the oceans absorb most of the carbon

943
00:39:29,750 --> 00:39:27,599
dioxide as well

944
00:39:31,510 --> 00:39:29,760
that is a really great question the

945
00:39:34,230 --> 00:39:31,520
oceans absorb a lot of the carbon

946
00:39:36,150 --> 00:39:34,240
dioxide it's between a quarter or a

947
00:39:38,950 --> 00:39:36,160
third something like that depending on

948
00:39:41,589 --> 00:39:38,960
how long a period you look at but it's

949
00:39:43,990 --> 00:39:41,599
important to remember that the co2 is

950
00:39:46,230 --> 00:39:44,000
not just staying in the atmosphere

951
00:39:48,550 --> 00:39:46,240
a big chunk of it is being absorbed by

952
00:39:50,950 --> 00:39:48,560
the oceans and that means that even if

953
00:39:53,589 --> 00:39:50,960
we were to somehow which would be very

954
00:39:56,069 --> 00:39:53,599
difficult take carbon dioxide out of the

955
00:39:58,230 --> 00:39:56,079
atmosphere some of what we added to the

956
00:39:59,990 --> 00:39:58,240
oceans could come back

957
00:40:02,550 --> 00:40:00,000
to haunt us so

958
00:40:05,030 --> 00:40:02,560
we're not just adding co2 to the air

959
00:40:07,670 --> 00:40:05,040
we're adding it to the oceans which also

960
00:40:10,309 --> 00:40:07,680
makes the oceans more acidic and this

961
00:40:12,309 --> 00:40:10,319
has a big impact on marine life and

962
00:40:16,390 --> 00:40:12,319
marine ecosystems and one that we're

963
00:40:19,990 --> 00:40:18,150
you've given us so many so much great

964
00:40:21,910 --> 00:40:20,000
information about

965
00:40:23,670 --> 00:40:21,920
sea level rise and how it's happening

966
00:40:26,150 --> 00:40:23,680
and looking to the future

967
00:40:28,150 --> 00:40:26,160
tko scar loves on youtube wants to know

968
00:40:29,990 --> 00:40:28,160
what do you think will happen

969
00:40:32,390 --> 00:40:30,000
to the future at this rate with sea

970
00:40:35,190 --> 00:40:32,400
levels rising

971
00:40:37,430 --> 00:40:35,200
well one thing that's clear is that sea

972
00:40:40,230 --> 00:40:37,440
levels are going to continue to rise for

973
00:40:42,630 --> 00:40:40,240
a very long time the warming that we've

974
00:40:45,589 --> 00:40:42,640
already caused is going to continue to

975
00:40:47,190 --> 00:40:45,599
raise sea levels at a slow rate

976
00:40:49,270 --> 00:40:47,200
for up to

977
00:40:52,230 --> 00:40:49,280
thousands of years from now

978
00:40:54,950 --> 00:40:52,240
so we're looking at continued rise but

979
00:40:59,109 --> 00:40:54,960
the question really is how much rise do

980
00:41:01,829 --> 00:40:59,119
we want to allow and some scenarios are

981
00:41:05,190 --> 00:41:01,839
are feasible where we could have many

982
00:41:07,670 --> 00:41:05,200
feet of sea level rise in the next 50 or

983
00:41:09,910 --> 00:41:07,680
even more in the next hundred years

984
00:41:11,270 --> 00:41:09,920
and if we allow that to happen it will

985
00:41:13,910 --> 00:41:11,280
it would really be

986
00:41:15,829 --> 00:41:13,920
devastating to millions and millions of

987
00:41:18,470 --> 00:41:15,839
people along the coast

988
00:41:20,870 --> 00:41:18,480
in fact every centimeter or about a half

989
00:41:23,109 --> 00:41:20,880
an inch of sea level rise

990
00:41:24,630 --> 00:41:23,119
affects another 3 million people

991
00:41:27,430 --> 00:41:24,640
worldwide

992
00:41:29,910 --> 00:41:27,440
with increased frequency of flooding

993
00:41:31,750 --> 00:41:29,920
erosion of coastlines and damage to

994
00:41:35,430 --> 00:41:31,760
infrastructure so

995
00:41:39,829 --> 00:41:35,440
it's really a creeping problem and one

996
00:41:43,510 --> 00:41:41,510
well josh thank you for answering those

997
00:41:45,349 --> 00:41:43,520
wonderful questions and for sharing this

998
00:41:47,349 --> 00:41:45,359
very important information for us

999
00:41:49,430 --> 00:41:47,359
unfortunately that is all the time we

1000
00:41:51,750 --> 00:41:49,440
have for tonight i want to thank you

1001
00:41:54,230 --> 00:41:51,760
josh as our speaker dr josh willis for

1002
00:41:55,829 --> 00:41:54,240
your insight and excitement tonight i

1003
00:41:58,150 --> 00:41:55,839
also want to take a moment to thank you

1004
00:42:00,230 --> 00:41:58,160
jocelyn for being our wonderful co-host

1005
00:42:02,550 --> 00:42:00,240
and for all the people behind the scenes

1006
00:42:04,870 --> 00:42:02,560
who really make these talks possible

1007
00:42:06,950 --> 00:42:04,880
and finally a big thank you to all of us

1008
00:42:08,390 --> 00:42:06,960
who join us every month for these

1009
00:42:10,550 --> 00:42:08,400
wonderful talks

1010
00:42:13,349 --> 00:42:10,560
please remember you can watch past von

1011
00:42:15,589 --> 00:42:13,359
carmen lectures on jpl's website or

1012
00:42:18,309 --> 00:42:15,599
youtube channel as this is the final

1013
00:42:20,790 --> 00:42:18,319
lecture of 2021 we hope you have a happy

1014
00:42:23,510 --> 00:42:20,800
and safe holiday season and we will see

1015
00:42:25,670 --> 00:42:23,520
you next year for our january talk where

1016
00:42:27,990 --> 00:42:25,680
we will continue this conversation with

1017
00:42:31,030 --> 00:42:28,000
the surface water and ocean topography

1018
00:42:32,870 --> 00:42:31,040
mission or swat thanks again for joining

1019
00:42:38,740 --> 00:42:32,880
us this evening and we'll see you in