CE 401

Climate Change Science and Engineeringgeologic past and evolution of climatechange since the industrial revolution

3 February 2011

http://www.skepticalscience.com/solar-activity-sunspots-global-warming.htm

http://solar-center.stanford.edu/sun-on-earth/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 8and figure out what their arguments are, and then look around for support or nonsupport

http://hockeyschtick.blogspot.com/2010/09/is-sun-causing-global-warming.html

www.realclimate.org

http://www.pbs.org/wgbh/warming/debate/singer.html

http://www.independent.org/newsroom/article.asp?id=1945

http://www.hillsdale.edu/news/imprimis/archive/issue.asp?year=2007&month=08

http://www.skepticalscience.com/global-cooling-mid-20th-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: http://carbontracker.noaa.gov.

climate change in the geologic past

no human influence

The atmospheric concentration of CO2, N2O, and CH4 now exceeds by far the natural range of the last 650,000 years - currentchanges have occurred all in a few hundreds of years

CO2

CH4

N2O

600 0time (thousands of years before present)

360

200

note

Current level ishigher than anytime in past 600,000 years.

150,000 years ago to present

this graph dramatic evidence that CO2 drives climate: more CO2 higher temperatures. YES?

Here is Al Gore on this graph: “Here is an important point. If my classmate from 6th grade were to seethis, he would ask, “Did they ever fit together?”. The answer from the scientist would be, “Yes, they dofit together.” It’s a complicated relationship, but the most important part of it is this: When there ismore CO2 in the atmosphere, the temperature increases because more heat from the sun is trappedinside. There is not a single part of this graph – no fact, no date, or number – that is controversialin any way or is disputed by anyone.”

What is cause and effect? The implication here, honestly stated by Gore, but implied, is more CO2 , higher T

Yet, many scientists think the opposite: large changes in CO2 were a result of the warming, not the cause. Changes in temperature in this graph weredriven not primarily by CO2 changes, but by changes in the orbit and axis of the Earth.

Caillon et al, 2003, Science 299, 1728 CO2 lags behind temperature changes by about800 years + 200 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 CO2 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 CO2 increase, but not clear for the dramatic temperature variations of ancient data shown in the plot”

source: Jouzel et al. 1994

10°C

10°C

5°C

age (thousands of years ago)0150

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

CO2 concentrations are increasing due to industrial activity

CO2 Concentrations (ppm) 1860 - 1995

Conclusions from the Climate Record preindustrial to 650k years ago (no human influence)

• temperatures have varied by approximately 7°C

• highest observed CO2 is about 300 ppmv (current 385 ppmv)

• highest observed methane is about 0.7 ppmv (current 1.7 ppmv)

• temperature, CO2 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 COGlobal CO2 2 distribution in ppmdistribution in ppm

380 parts / million380 parts / million

372 ppm372 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 1000-1900 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 CO2 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• 14th 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 representswestern 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 meanSmoothed series5-95 decadal error bars

source: IPCC = source: IPCC = Intergovernmental Panel on Climate Change, 2007Intergovernmental Panel on Climate Change, 2007

11 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? – CO2 record

is very smooth – no big bumps and wiggles

NASA Global Temperature Record 1880 - 2008

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/answersonto the class website today

IPCC 2007