The Basic Science of Climate Change

1. The Basic Science of Climate Change Janina Moretti September 6, 2012

2. Overview • Basic science of climate change: • What is climate change? What is causing it? • Global and local impacts of climate change • Climate change tipping points • Climate change solutions

3. There is a scientific consensus: greenhouse gas emissions are causing climate change 928 Number of scientific studies dealing with “climate change” published in scientific journals between 1993 and 2003: 0 Number disagreeing with the global consensus that greenhouse gas pollution has caused most of the warming of the last 50 years: Science, December 3, 2004 Vol. 306, Issue 5702,1686

4. The greenhouse effect http://www.ecy.wa.gov/climatechange/whatis.htm

5. In the past 100 years we have been burning a lot of fossil fuels. . . CO2 CO2 CO2 +0.8°C (1.4°F) CO2 CO2 CO2 CO2

6. Burning fossil fuels increases the concentration of carbon dioxide in the atmosphere CO2 CO2 CO2 +0.8°C (1.4°F) CO2 CO2 CO2 CO2

7. More carbon dioxide in the atmosphere warms the planet CO2 CO2 CO2 +0.8°C (1.4°F) CO2 CO2 CO2 CO2

8. What is 350ppm? 550ppm??! 275ppm Now: 392ppm

9. We are already experiencing climate change impacts • Temperature rise • Sea level rise • Loss of glaciers • More frequent extreme weather events (droughts, floods, hurricanes, wildfires) • Ocean acidification

10. Temperature is rising • 9 of the 10 warmest years in the modern meteorological record have occurred since the year 2000 • July was the hottest on record for the United States (27,000 high temperature records were broken or tied.) http://www.nasa.gov/home/hqnews/2012/jan/HQ_12-020_2011_Global_Temp.html

11. The Arctic is currently warming at twice the rate of the rest of the world 1979 2007 Between 1979 and 2007, the Arctic lost over 40% of its ice

12. The Arctic is currently warming at twice the rate of the rest of the world

13. More frequent droughts This summer over half the United States is in extreme or moderate drought. Decreased crop yields have caused a 10% spike in food prices.

14. Climate change impacts San Diego County More intense and frequent wildfires • Water • Shortages Beach erosion and coastal flooding http://www.sdfoundation.org/

15. We need to act fast to avoid triggering feedback loops

16. We need to act fast to avoid triggering feedback loops More examples: • Desertification of the Amazon rainforest • Melting of the Greenland ice sheet • Melting of the West Antarctic ice sheet • Methane release from permafrost melt • Monsoon shift in India

17. How do to avoid tipping points? The Three Simple Numbers 1) 2°C (3.6°F) 2,795 GT CO2 2) 565 GT CO2 3) 2,795 GT CO2 565 GT CO2

18. Can we stabilize at 2°C? 95% reduction by 2020: Business as Usual: http://climateinteractive.org/simulations/climate-momentum-simulation/climate-momentum

19. Global major contributors to climate change World Resources Institute, http://earthtrends.wri.org/images/GHG_emissions_by_sector2.jpg

20. Local major contributors to climate change In San Diego County, on-road transportation and electricity are the largest contributors to greenhouse gas emissions. http://www.fypower.org/pdf/SanDiegoCounty_GHGinventory.pdf

21. Solutions • There are many well-understood solutions • Inventory, identify potential solutions, create & implement plan Change land use & transportation to reduce miles traveled Replace fossil fuels with clean renewable sources Stop deforestation Consume less and waste less Conserve electricity, water & gas Move diets lower on the food chain Increase energy efficiency of existing and new buildings Increase gas mileage for cars Carbon tax & dividend • Solutions require both collective action as citizens… as well as individual actions as consumers

22. Climate Facts • There is a scientific consensus that the earth is warming due to human caused greenhouse gas emissions. • The current atmospheric concentration of carbon dioxide is 392ppm. Before the industrial revolution is was 275ppm. 350ppm is a safe upper limit. • The impacts of climate change are happening now and faster than previously though. • Nine of the 10 warmest years in the modern meteorological record have occurred since the year 2000. • 2°C of global warming is a safe upper limit. We can only emit 565 gigatons CO2to stay below this limit. Fossil fuel industries have 2,795 gigatons CO2 in reserve. • In San Diego county, the largest contributors to greenhouse gas emissions are transportation (46%) and electricity (25%). • In San Diego county, the impacts of climate change are rising temperatures, water shortage, sea level rise, and more frequent and intense wild fires. • There are known solutions to climate change, but we need to implement them quickly, on a large scale.

23. Useful References • Climate Progress: http://thinkprogress.org/climate/issue/ The latest news on climate change science, solutions, and politics • Skeptical Science: http://www.skepticalscience.com/ Climate science summarized for a general audience. Includes an extensive list of climate myths debunked. • Just the Facts-CA: http://www.opr.ca.gov/s_climatechangefacts.php Basic facts and science of climate change