CE 401 Climate Change Science and Engineering geologic past and evolution of climate change since the industrial revolution 3 February m/solar-activity-sunspots-global-wa rming.htm h/glob-warm.html HW6 Robinson paper for HW6 couple of pdf’s on the HW website on solar stuff – read the Robinson article to page 8 and figure out what their arguments are, and then look around for support or nonsupport com /2010/09/is-sun-causing- global-warming.html ?year=2007&month=08 century-advanced.htm

HW 6 now due next Thursday quiz from last time: nearly everyone like the ppt style; more emphasis on the myriad of graphs of what is really important; I have been replacing the ppt on the web with the actual class one HW: some of the problems have not been clear as to what is expected and that has caused frustration ; do examples in class class interaction – I need to just keep pushing for more general thoughts – class will be graded on a curve; go over math more before HW; TA office hours to twice/week; other resources – use web

where are we in the syllabus: latest version always on website 

interesting new web site:

climate change in the geologic past no human influence

The atmospheric concentration of CO 2, N 2 O, and CH 4 now exceeds by far the natural range of the last 650,000 years - current changes have occurred all in a few hundreds of years CO 2 CH 4 N2ON2O time (thousands of years before present) note

Current level is higher than any time in past 600,000 years. 150,000 years ago to present

this graph  dramatic evidence that CO 2 drives climate: more CO 2  higher temperatures. YES? Here is Al Gore on this graph: “Here is an important point. If my classmate from 6 th grade were to see this, he would ask, “Did they ever fit together?”. The answer from the scientist would be, “Yes, they do fit together.” It’s a complicated relationship, but the most important part of it is this: When there is more CO 2 in the atmosphere, the temperature increases because more heat from the sun is trapped inside. There is not a single part of this graph – no fact, no date, or number – that is controversial in any way or is disputed by anyone.” What is cause and effect? The implication here, honestly stated by Gore, but implied, is more CO 2, higher T Yet, many scientists think the opposite: large changes in CO 2 were a result of the warming, not the cause. Changes in temperature in this graph were driven not primarily by CO 2 changes, but by changes in the orbit and axis of the Earth. Caillon et al, 2003, Science 299, 1728  CO 2 lags behind temperature changes by about 800 years years (why 800 years?) Some climate scientists now doubt the order. Richard Muller (Physics for Future Presidents, 2008)  “The fairest statement that can be made is that the issue is unsettled”. “Many people see the plot and come away believing that CO 2 has been established as the main driver for past climate change. That is very likely a correct conclusion for small (1°C) changes attributed to the present CO 2 increase, but not clear for the dramatic temperature variations of ancient data shown in the plot”

source: Jouzel et al °C 5°C age (thousands of years ago) Antarctica Greenland North Atlantic Antarctic and Greenland Ice Core and N. Atlantic Sed. Temp. Data note how stable temperature has been for the last 10,000 yrs

Mann et al, 1998

CO 2 concentrations are increasing due to industrial activity CO 2 Concentrations (ppm)

Conclusions from the Climate Record preindustrial to 650k years ago (no human influence) temperatures have varied by approximately 7°C highest observed CO 2 is about 300 ppmv (current 385 ppmv) highest observed methane is about 0.7 ppmv (current 1.7 ppmv) temperature, CO 2 and methane follow each other closely in time changes have generally occurred over long time periods past 10K years have been remarkably stable in temperature this period marked the development of civilization most “equable” climate of the past many millions of years rapid (decadal) changes in surface temps of 5-6°C have occurred in the past

Global CO 2 distribution in ppm 380 parts / million 372 ppm WHY

hockey stick plot continuing now to the present – the rest of the diagram shown earlier

hockey stick: published in 1998 NH remarkably constant showing cool years with significant global warming occurred 2001 IPCC report included it – 5 times in the summary volume alone prominently featured in Al Gore’s film showed the modern fossil fuel era was unprecedented in increased temperature just like the CO 2 rise plot  patently obvious that humans were causing warming Canadian gov’t sent a copy to every household in Canada every politician in DC was familiar with it 14 th century COLD period appears nowhere in the plot (it was European only?), but that cold period is well established the graph is wrong – the analysis has proved to be faulty and really only represents western US, not the northern hemisphere US National Academy of Sciences was asked by Congress to review  confirmation of error does it matter that the hockey stick plot was wrong? yes, it reinforces misconceptions to a scientist, it is wrong, but it is just another step in the process IPCC consensus did not depend on the hockey stick graph of temperature vs time it is embarrassing for sure scientists usually reach the truth, but sometimes it takes a while

US surface temperature record

Global Mean Temperatures Annual mean Smoothed series 5-95 decadal error bars source: IPCC = Intergovernmental Panel on Climate Change, of the past 12 years are the hottest on record

last decade is the warmest decade on record increase in past 25 years is ~ 0.2°C/decade why the leveling off/cooling in the 50’s? – CO 2 record is very smooth – no big bumps and wiggles NASA Global Temperature Record source: GISS, 2010

During the 1950s and 1960s, average global temperatures leveled off, as increases in aerosols from fossil fuels and other sources cooled the planet. I will put the IPCC technical summary and frequently asked questions/answers onto the class website today IPCC 2007 