Monday, June 23, 2014

Prof Kerry Emanuel - What We KNOW About Climate Change

Recently Professor Kerry Emanuel PhD gave a talk for the MIT Club of Northern California were he did a nice job of reviewing the many lines of evidence that make clear that we and our society are changing our global climate in threatening ways.  I liked the talk enough to think it deserved the time and effort to make short notes with time signatures for easy reference.  

Feel free to copy and share.

Kerry Emanuel - Lorenz Center, Department of Earth, Atmosphere, and Planetary Sciences, MIT


3:25 - The something that get's lost is how intellectually exciting climate is.

5:15 - Important points about climate and climate science...
* Earth's climate is not terribly stable
* Climate science has a long and illustrious history
* Human activities can and do have a strong effect on climate
* The idea that we are altering climate is based on much more than complex global models
* Anthropogenic climate change is not controversial among climate scientists

7:30 - Post-Glacial Sea Level Rise
9:10 - Last 450 Thousand Year of Ice Age Temperature Changes based on ice cores.
10:20 - Snowball Earth, 650-750 MYA (million year ago)
11:40 - climate science history beginning early 1800s - Jean Baptiste Joseph Fourier, John Tyndall
12:40 - Milutin Milankovic' and his cycles cycles
14:20 - how do we know Milankovic' cycles cause climate changes?
16:40 - Guy Steward Callendar "The Artificial Production of Carbon Dioxide and its Influence on Temperature" 1938
16:50 - Jule G. Charney - "Carbon Dioxide and Climate: A Scientific Assessment" 1979
(K. Emanuel's thesis advisor)
17:05 - based on simple models they estimated 2°C-3.5°C for doubling CO2
17:20 - How can humans have such a strong effect on climate?
18:10 - Tyndall's Essential Results... {trace gases do make a world of difference}
20:10 - Atmospheric Composition
21:00 - about water vapor (0.25%)... cycles out of atmosphere; 2 weeks... temp regulated... feedback... 

21:55 - Physics Tutorial - "... Atmosphere is absorbing infrared radiation leaving the Earth's surface and it is reradiating that infrared energy both up and down.  So, if you sit at some point on the Earth's surface and you measure sunlight coming down and you measure infrared radiation coming down from the atmosphere and the clouds, remarkably over the course of a year, on average over the world, we get more than twice as much energy, actually almost three times as much energy from the atmosphere and the clouds as directly from the sun.  That's how powerful the greenhouse effect is."

22:30 - the long lived trace gases (0.04%) ... makes the difference between and average temp of 0°F and 60°F for our planet...
43% increase since dawn of industrial revolution...
23:40 - explaining what Svante Arrhenius did/learned around the turn of the previous century... transmissivity of CO2... estimated 4° increase for doubling CO2... his prediction has been verified...
26:15 - the idea of climate change is based on much more than complex global climate models...
27:10 - Paleoclimate - the atmospheric carbon dioxide
27:30 - Carbon Dioxide from Ice Cores and Direct Measurements 1700-2005
29:00 - adding Antarctic ice core - graph of 900-2005
29:10 - going back 20,000 years, peak of last ice age... there is no doubt about this.
30:10 - paleo reconstruction... {the hockey sticks, aka the "spaghetti graph"}
31:10 - Arctic air temperature change reconstruction and observed record (2000 yr.)
31:35 - Actual thermometer measurements going back to 1750 {the graph looks like the contrail on a rocket lauch}
32:10 - Surface and Satellite Temperatures - 1975
32:50 - Global Distribution of temperature change, 1901-2005
33:30 - 0-2000m Global Ocean Heat Content 1960-2013
34:05 - Changes in Earth's Total Heat Content 1961-2011... it's the oceans

35:00 - "How do we know that this recent increase in temperature is because of CO2?
Lower Tropospheric temperature trend from 1979-2012 based on satellite only measurements (RSS)
35:50 - then Top of the Stratosphere (TTS) 1979-2006 temperature trend - cooling
as expected from the calculations.
36:50 - Mountain Glacier Changes Since 1970
37:10 - September Arctic Sea Ice Extent 1800-2080, projections vs. actual
37:55 - Hurricane power and Tropical Atlantic SST August-October (Emanuel, et al.)
38:40 - reevaluating low impact projections
39:00 - Ocean acidification
39:45 - laboratory test on marine life
{now being observed in the oceans, see

40:20 - simple models
41:15 - a sociological message, the contrast with what the American public believes scientist thing and what scientists think they are thinking. - Leiserowitz et al. 2013

42:25 - Why worry?  Known Risks
what are the odds
* increasing sea level
* increasing hydrological events... droughts and floods
* increasing incidence of high category hurricanes and associated storm surges and freshwater flooding
* more heat stress

46:00 - social unrest, national security threat
46:45 - historic examples... {cascading consequences}
48:00 - what about the future
48:45 - have to think of the complete risk curve
51:10 - CO2 Will Go Well Beyond Doubling
52:05 - life time of atmospheric CO2
53:00 - realistic solutions
* Carbon capture and sequestration
* Nuclear energy

57:20 - Summary
* Several aspects of climate science are well established
* Projections entail uncertainty, particularly at the regional scale
* Ill effects felt mostly through sea level rise, weather extremes and through indirect fallout, such as global armed conflict.
* Highly asymmetric risk function
* Rational response to risk impeded by well-funded and highly effective marketing campaign by fossil fuels interests
* Rational measures possible when many begin to notice tangible climate change

Q and A
59:00 - What are the most material unknown in the climate system?
1:00:00 - Cosmic Rays? - tiny effect and ray flux is going the wrong way.
1:01:45 - IPCC misrepresentation vs. media misrepresentation?
"IPCC does not emphasis the tail risk... scientists conservative bunch... historically has underrated risk... probability distribution...
About the media, where do I begin…"

1:04:10 - "Yes the consensus is very important!  No body in their right mind, if they were sick would do anything but take a consensus of good doctors and not just go with the one that gives a the rosy, nicest sounding diagnose.  Science does not advance by consensus, but anybody trying to formulate policy had better jolly well use the consensus."

1:04:55 - Cloud cover? clouds work on both the solar and infrared parts of the spectrum... most important uncertainty... 
1:06:50 - What are the carbon sinks?
1:09:05 - The AAAS What We Know initiative?
1:10:25 - Disparity of between what people believe and what scientists believe - How much money is in the well funded denialist campaign?
1:11:40 - Dangers of wind power?
1:12:30 - Aware of human efforts to modify weather?
1:13:25 - Rise in temp is not all bad?
1:15:40 - Cool effects from pollutants? burning coal... sulfates...
1:17:40 - Where would climate be going if humans weren't impacting it?
1:19:40 - Feedbacks
1:22:00 - Clathrates?
~ ~ ~ ~ ~ ~ ~ 

~ ~ ~

History of the greenhouse effect and global warming

By S.M. Enzler MSc

~ ~ ~ 

The Discovery of Global Warming: The Carbon Dioxide Greenhouse Effect.
American Institute of Physics

~ ~ ~

The Callendar Effect. The life and work of Guy Stewart Callendar (1898-1964), 
the scientist who established the carbon dioxide theory of climate change
Fleming, James Rodger. 2007. 
Boston: American Meteorological Society.

~ ~ ~

On the Influence of Carbonic Acid in the Air upon the Temperature of the GroundSvante Arrhenius
Philosophical Magazine and Journal of Science, 
April 1896

~ ~ ~

Carbon Dioxide and Climate A Scientific Assessment - 1979
Report of an Ad Hoc Study Group on Carbon Dioxide and Climate
aka "The Charney Report"

~ ~ ~ 

Guide to Charney's Papers

No comments: