1. 1. How has the climate changed during the very recent past? 2. What can we say about current climate change? 3. How do climate models work and what are their predictions for the future? What we wish to learn Today:

2. Possible Causes of Climate Change Power: 4 x 10 26 W 2 x 10 17 W Long-Term 1.Solar Luminosity 2.Shifting Continents 3.Greenhouse gases Medium-Term 1.Orbital parameters 2.Greenhouse gases Short-Term 1.Oceans 2.Sunspots 3.Volcanoes 4.Greenhouse gases

3. In May, 2010, the National Academies of Science reported to Congress that “the U.S. should act now to reduce greenhouse gas emissions and develop a national strategy to adapt to the inevitable impacts of climate change” because global warming is “caused largely by human activities, and poses significant risks for — and in many cases is already affecting — a broad range of human and natural systems.” Rep. John Boozman (Arkansas): “Is man causing it, or, you know, is this a cycle that happens throughout the years, throughout the ages. And you can look back some of the previous times when there was no industrialization, you had these different ages, ice ages, and things warming and things. That’s the question.” [KTHV Little Rock, 3/10]3/10 Rep. Roy Blunt (Missouri): “There isn’t any real science to say we are altering the climate path of the earth.” [Human Events, 4/29/09]4/29/09 Sen. Tom Coburn (Oklahoma): “I am not the smartest man in the world … But I have been trained to read scientific documents, and it’s malarkey.” [Sooner Tea Party, 8/25/09]8/25/09 Ron Johnson (Wisconsin): “I absolutely do not believe that the science of man-caused climate change is proven. Not by any stretch of the imagination. It’s far more likely that it’s just sunspot activity, or something just in the geologic eons of time where we have changes in the climate.” [Milwaukee Journal-Sentinel, 8/19/10]8/19/10 John Raese (W. Virginia): “And if you have one volcano in the world that one volcano puts out more carbon dioxide than everything that man puts out.” [Charleston Gazette, 7/22/10]7/22/10

4. The threat to our society from failure to recognize, slow down, and adapt to climate change is just one facet of the subset of threats that we face from the denial of science, the rise of opinions over facts, and the forced restraint of our ability and freedom to develop and use our minds. Rep. Paul Broun (Georgia): "All that stuff I was taught about evolution and embryology and the Big Bang Theory, all that is lies straight from the pit of Hell“. "You see, there are a lot of scientific data that I've found out as a scientist that actually show that this is really a young Earth… about 9,000 years old.“ Broun is on the House Congressional Science Committee. [6 October 2012, and captured on video at a Sportsmans Banquet, September 2012 – video http://www.youtube.com/watch?v=Ge64kMFoQEo ]http://www.youtube.com/watch?v=Ge64kMFoQEo Neil Newhouse, political pollster, “We’re not going to let our campaign be dictated by fact checkers.” [NY Times, Kevin M. Kruse, published 5 Nov 2012] 2012 Texas Party platform opposes “the teaching of … critical thinking skills and similar programs that … have the purpose of challenging the student's fixed beliefs and undermining parental authority.” [NY Times, Kevin M. Kruse, published 5 Nov 2012] North Carolina's Senate legislation (HB 819) that would have required the state's Coastal Resources Commission to base predictions of future sea level rise along the state's coast on a steady, linear rate of increase. {That is, to deliberately ignore the science indicating that sea- level rise has been and will be non-linear, rising more quickly over time as ice sheets melt} [Science Insider, by Jane J. Lee on 3 July 2012, http://news.sciencemag.org/scienceinsider/2012/07/update-revised-north- carolina-se.html ]http://news.sciencemag.org/scienceinsider/2012/07/update-revised-north- carolina-se.html

5. Recent Trends in Temperature Departures in temp (deg C) from 1961-1990 mean Global Temperature Data from thermometers Year

6. Solar Activity and Climate Very few sunspots seen between 1645 and 1715 Corresponds to the time of the “Little Ace Age” Sunspot number Little Ice Age

7. http://solarscience.msfc.nasa.gov/SunspotCycle.shtml Year Number of sunspots Sunspot number Sunspots increased at the same time that global temperatures increased Multicollinearity!

8. Change in sunspot number is greater than change in solar radiation. The change in solar radiation is only about 0.1%, too small to account for the full temperature increase Sunspots, solar radiation, and temperature Global Surface Temperature 1978-2009

9. Pre-1991 Post-1991 VOLCANO ! Ash on cars

10. Volcanic eruptions cool global temperature Volcanoes spew out ~160x less CO 2 than humans do…

11. Satellite troposphere temperature data El Niño index El Niño effect on temperature Satellite data minus El Niño effect Volcano effect on temperature After removing El Niño and volcanoes Residual Trend: 0.11°C per decade Effects of El Niño and volcanoes on air temperatures Pinatubo ’97-98 El Niño

12. Summary of Climate Forcings in “energy” terms of Watts per m 2 Orbital variations ~ 0.5 W m -2 / century (occurs over long time scales) Solar variation ~ 0.29 W m -2 peak-to-peak over ~2 centuries Greenhouse Gases - past: ~ +0.0067 W m -2 / century CO 2, 4050 BC to ~1000 AD ~ +0.0016 W m -2 / century CH 4, 4050 BC to ~ 1500 AD ~ +0.0006 W m -2 / century N 2 O, 4050 BC to ~ 1000 BC Volcanic eruptions 0 down to -10 W m -2, but short lived (a few years). Estimated long-term mean forcing ~ -0.3 W m -2 * Current GHG emission – Doubling of CO 2 ~ 4 W m -2 !

13. Past and Modern Changes on Earth – CO 2, CH 4, and temperature are correlated CO 2 CH 4 Temp.

14. Atmospheric CO 2 concentration and temperature are correlated in the Vostok ice core Temperature variations (ºC) Atmospheric CO 2 concentration (ppm) Glaciations Deglaciations Modern

15. Paleoclimate provides perspective on where we are headed … IPCC Projections to 2100 100012001400160018002000 0 0.5 1 -0.5 2 4 3 5 6 1 0 N.H. Temperature (°C) Global Temperature (°C)

16. Types of Models: Physical Models (a desktop globe) Statistical Models (a regression, y=mx+b) Conceptual Models (a flow chart) Computer Models (Global Climate Models, GCMs) “Climate models are only sophisticated tools, not crystal balls” “A useful model is not the one which is true, but the one that is informative” “ …all models are wrong, some are useful” USING MODELS TO PREDICT CLIMATE

17. What goes into a climate model?

18. Climate models work pretty well… Rainfall [annual] Which is observed and which is modeled ?

19. … but there is some variation Prediction of the 1997-1998 El Nino by 6 different GCM models shows a similar pattern of climate changes

20. Models show that anthropogenic causes of temperature change explain what has already occurred. Courtesy W. Washington/NCAR

21. “Climate change” is more than an environmental issue, and is related to adaptation and societal choices INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC)

22. The models must use “scenarios” of future GHG emissions World CO 2 emissions Gigatons of Carbon There are many different “storylines”, or scenarios of how much CO 2 will be emitted by society in the future

23. Pick your future… Source: IPCC TAR 2001

24. Predictions of large climate changes even by the 2050s Hadley Centre for Climate Prediction and Research

25. But, we control our destiny -- Temperature from the present day to the 2080s Hadley Centre for Climate Prediction and Research c Unmitigated Emissions c c Stabilization of CO 2 at 550 ppm Stabilization of CO 2 at 750 ppm

26. Take Home Message: Prediction into the future is difficult, but necessary…

27. Summary 1.Recent changes in Earth's paleoclimate record are likely due to shifts in ocean circulation, and the effects of greenhouse gas increases. Volcanoes have had only a small effect, and the sun spot record cannot account for the heat input needed. 2.Temperature changes and greenhouse gas abundances are correlated. Rapid global warming is underway and models have been developed to predict the effects of these changes. 3.Global Climate Models (GCMs) are sophisticated tools that predict a much altered climate on Earth during the next century.