The Changing Climate
Chapter 14

Climate Change & Variability: Lab Related




Time history of atmospheric CO2 from 800,000 years BP to January 2012.


What Do Scientists Do?


Scientific Law vs. Theory: a law describes what nature does under certain conditions, and will predict what will happen as long as those conditions are met. A theory explains how nature works in a more general sense.






The Changing Climate


Male, capital city of the Maldives


What is climate change?


Global warming


The sun and atmosphere keep Earth warm


Greenhouse gasses warm the lower atmosphere


Carbon dioxide (CO2) is of primary concern



What caused levels of CO2 to increase?


Time history of atmospheric CO2 from 800,000 years BP to January 2012.




Other greenhouse gasses add to warming


US emissions of major greenhouse gasses



Feedback complicates our predictions



Most aerosols exert a cooling effect


Radiative forcing expresses change in energy



Milankovitch cycles influence climate


Orbital Variations





Solar output and ocean absorption influence climate


Ocean circulation influences climate


Direct measurements tell us about the present


Proxy indicators tell us about the past


Ice cores from Antarctica



More proxy indicators


Models help us predict the future

Models simulate climate processes to accurately predict climate change

Java-based Climate Model



Results from three simulations



The IPCC's fourth assessment report (2007)


The IPCC's fourth assessment report (2007)



Temperatures continue to rise



The future will be hotter



Temperatures will rise globally

Projected increases in surface temperature
for 2090-2099 relative to 1990-1999



Precipitation is changing too

Projected changes in precipitation

Precipitation will increase at high latitudes
and decrease at low and middle latitudes



Melting snow and ice


Worldwide, glaciers are melting rapidly




Rising sea levels



Coastal areas will flood



Rising sea levels will devastate coasts


Coral reefs are threatened


Climate change affects organisms and ecosystems



Climate change affects people



Heat waves will increase




Climate change affects economies


Impacts will vary regionally


Impacts of climate change




Impacts of climate change will vary




Predictions from two climate models

By 2050, Illinois will have a climate like
Missouri's and by 2090, it will have a
climate like Louisiana



Are we responsible for climate change?



The debate over climate change is over





Shall we pursue mitigation or adaptation?



We need both adaptation and mitigation

The faster we reduce our emissions,
the less we will alter the climate




Electricity generation



Sources of electricity


Market mechanisms address climate change




Cap-and-trade emissions trading programs


Carbon taxes are another option


Carbon offsets are popular