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the earth is a complex system and

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scientists are continually investigating

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the intricate workings of our home

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planet

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part of what makes the earth so unique

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is its climate

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many scientists are concerned that

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earth's climate is changing at an

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unprecedented rate

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how do scientists study how warm the

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planet is

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here's a look at the tools nasa

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scientists use to take earth's

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temperature

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models are powerful tools for

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understanding earth's complex systems

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to create a model scientists must first

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characterize a system by identifying the

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processes that govern its evolution

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those processes are represented by

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equations and are solved on powerful

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computers

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this animation comes from an atmospheric

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assimilation

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it uses observations of temperature

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moisture and winds to provide a picture

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of earth's hydrological cycle

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once a model is in place the resulting

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simulation must be proven to match real

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world measurements

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well models are important for the

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scientific community because they

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capture really the essence and basic

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understanding that we have of how our

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system works

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on a lot of different time scales and

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space scales for a lot of different

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applications from weather all the way

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through to climate

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in the 1970s dr james hansen and

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colleagues at nasa built a simple

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climate model to simulate how changes in

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the atmosphere cause earth's average

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temperature to change over time

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hansen's early climate model showed that

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both human and natural activities could

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force earth's climate to change

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the model revealed that natural forcings

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like volcanic eruptions or changes in

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the sun's activities tend to go up and

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down over long periods of time

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but human forcings from greenhouse gas

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emissions are steadily increasing

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hansen's early simulation revealed that

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human forcings on climate would dominate

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in the future but he needed real-world

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temperature data on a global scale to

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determine when

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the most reliable measurement of global

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temperature came from weather stations

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scattered around the globe

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hanson knew that weather fluctuations

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would cause short-term changes at

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individual stations but he reasoned that

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taking averages over several years and

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appropriately weighting each station's

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data would deliver meaningful

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a consistent trend of warming is visible

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in both the global temperature data and

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the global climate model

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we have a pretty good understanding now

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of how sensitive the climate is to

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the increases in greenhouse gases this

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comes particularly from

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the history of the earth i mean our

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climate models give us an answer too but

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there there are a lot of uncertainties

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in the climate models the challenges

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associated with modeling a manifold the

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earth really acts as a system you know

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the ocean interacts with the atmosphere

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interacts with the land surface so

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representing all of this sort of complex

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system really are a major challenge

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in 2008 nasa plans to launch glory a

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mission that will measure two key

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climate forcings solar irradiance and

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atmospheric aerosols

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these measurements will help to improve

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the accuracy of global climate models

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nasa missions like glory will help

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scientists fine-tune their understanding

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of earth's climate providing a more