How do scientists predict future climate?

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How do scientists predict future climate?. Models. Scientists use models to predict future climate: including temperature, CO2 levels in the atmosphere, precipitation and more Scientists must create these models using information and science they know - PowerPoint PPT Presentation


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How do scientists predict future climate?


Scientists use models to predict future climate: including temperature, CO2 levels in the atmosphere, precipitation and more

Scientists must create these models using information and science they know

Scientists also test or calibrate the models to make sure they are accurateWhat is a model?In this case, an equation or lines of programming that has inputs and outputs

fortran code from Dennis Shea

Very simple climate modelT = T0 + S log2 (C / C0) is the new/current temperatureT0 is the know temperature at some reference time (for example, 14.3 C in the year 2000)S is the "climate sensitivity" factor; we've been using 3 C (more on that below); the temperature rise as a result of CO2 doublingC is the new/current atmospheric CO2 concentrationC0 is the known atmospheric CO2 concentration at some reference time (must be the same time as T0; 368 ppm in 2000 would match the T0 example mentioned above)

3Climate ModelingUsing computers to do the most impossible math homework known to manWhat do we know about CO2?

Over the past 425,000 years, cool periods have coincided with times when the CO2 concentration in the atmosphere was lower. When there is less CO2 in the atmosphere, the greenhouse effect is reduced and the world cools.The blue and red line indicates the variation in average global temperature compared with the 19611990 average. The green line shows the concentration of CO2 in the atmosphere. (Pay close attention to the right-hand edge of the graph.)This graph shows four eras when the world was cooler than it is today. These are separated by brief warm periods, like the one we are now in.

5What do we know? AtmosphereLand & PlantsFossil FuelsOceansSimplified carbon cycleMake sure students know what is traveling between each sphere6Calibrating a modelScientists need to make sure the model works They check the model by comparing the models prediction with measured dataCalibrate the model with the students, correct percent = 80%7Resolution

Graph that includes temperature predictions from 20 different models

The more different models that show something similar, the more likely it is to be an accurate prediction

A typical graph from the IPCC's AR4 showing predicted global temperatures between 2000 and 2100. The graph displays the results from more than 20 different climate models (various colors) as well as the "ensemble average" of all the models (black dotted line).Credit: Image courtesy of the IPCC (AR4 WG1 Report "The Physical Science Basis" Chapter 10 page 763 Figure 10.5). 9Several Models Show the Same Trend

10Climate Modeling You be the climate scientist!What might cause carbon emissions to change in the future? (brainstorm)Brainstorm in small groups, then share out as a class, record on a chart, Have students choose a scenario they want to test11What does the future hold?What will happen if we keep emitting CO2?

1 gigaton = 1 billion tonsScenarioCO2 Emissions (Gt/year)What this meansCurrent9 Same fossil fuel usageHigh18High economic growth, increased fossil fuel usageMedium11Steady economic growth, slightly increased fossil fuel usageLow4Decreased fossil fuel usageReview with students the relationship between CO2 emissions and temperatureHandout worksheet to students


What is IPCC?Intergovernmental Panel on Climate Change (IPCC) is an international organization that includes scientists and representatives of governments around the world.

It reviews the most recent scientific, technical and socio-economic information relevant to climate changeHOWEVERIt does not conduct any research

It provides policy makers (congress or governments) with an objective report of the scientific evidence of climate change, its impacts and possible responses.

How Does it Work?Thousands of scientists from all over the world contribute to the work of the IPCCNone of them are paid by the IPCCIPCC aims to reflect a range of views and expertiseReview is an essential part of the IPCC processEnsures an objective and complete assessment of current information

Optional slide15nearly 1300 authors2500 reviews of the report

a consensus report (consensus = everyone agrees)

report intended to be neutral (for policy), to reflect a broad range of views and perspectives, and to include the most up-to-date scientific information.IPCC Scientific Assessment Report16The IPCC Panel is composed of representatives appointed by governments and organizations. Participation of delegates with appropriate expertise is encouraged. Plenary sessions of the IPCC and IPCC Working Groups are held at the level of government representatives. Non Governmental and Intergovernmental Organizations may be allowed to attend as observers. Sessions of the IPCC Bureau, workshops, expert and lead authors meetings are by invitation only.[51] Attendance at the 2003 meeting included 350 government officials and climate change experts. After the opening ceremonies, closed plenary sessions were held.[52] The meeting report[53] states there were 322 persons in attendance at Sessions with about seven-eighths of participants being from governmental organizations.[53]

An Assessment is Different From a Review A review compiles work in a certain area

An assessment compiles work in a certain area, evaluates that work, and comes to conclusions regarding our state of knowledge and understanding at that point in time

An IPCC assessment is policy relevant but not policy prescriptiveOslo, 10 December 2007

The Intergovernmental Panel on Climate Change and Al Gore were awarded of the Nobel Peace Prize "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change". Many Different Scenarios for the Future

Ipcc AR4 SYR18

Chapter 5 - Emission Scenarios: Figure 5-1

Many different Scenarios for the FutureCarbon emissions are too low for 2010 (graph is an earlier one) that green is best case, red worst case19IPCC predictsshort video of IPCC projectionsNEXT TIMEWhat do models predict for the future climate of Colorado?Future projections Observed and Projected Temperature Rise for the Southwest

The average temperature in the Southwest has already increased roughly 1.5F compared to a 1960-1979 baseline period. By the end of the century, average annual temperature is projected to rise approximately 4F to 10F above the historical baseline, averaged over the Southwest region. The brackets on the thermometers represent the likely range of model projections, though lower or higher outcomes are possible.From (Southwest factsheet)22Future projections Projected Change in Spring Precipitation, 2080-2099

Percentage change in March-April-May precipitation for 2080-2099 compared to1961-1979 for a lower emissions scenario (left) and a higher emissions scenario (right). Confidence in the projected changes is highest in the hatched areas.From (Southwest factsheet)23Future Drought Projections(Courtesy Wiley Interdisciplinary Reviews, redrawn by UCAR. drought. These four maps illustrate the potential for future drought worldwide over the decades indicated, based on current projections of future greenhouse gas emissions. These maps are not intended as forecasts, since the actual course of projected greenhouse gas emissions as well ase natural climate variations could alter the drought patterns.

The maps use a common measure, the Palmer Drought Severity Index, which assigns positive numbers when conditions are unusually wet for a particular region, and negative numbers when conditions are unusually dry. A reading of -4 or below is considered extreme drought. Regions that are blue or green will likely be at lower risk of drought, while those in the red and purple spectrum could face more unusually extreme drought conditions. (Courtesy Wiley Interdisciplinary Reviews, redrawn by UCAR. This image is freely available for media use. Please credit the University Corporation for Atmospheric Research. For more information on how individuals and organizations may use UCAR images, see Media & nonprofit use*)



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