Current State of Scientific Understanding of Climate Change Bob Watson.
Climate Change, and the Scientific Process
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Transcript of Climate Change, and the Scientific Process
Climate Change, and the Scientific Process
Let’s review last week: sometimes Venus, Earth and Mars are called the Goldilocks planets
Compare these Three:Venus Earth Mars
Temp at surface 880 F 59 F -58 F
Pressure at surface ~ 90 atmospheres 1 atmosphere(14.7 lbs/sq in)
0.007 atmospheres
Atmosphere composition
CO2 and sulfuric acid clouds
Nitrogen, oxygen, water vapor clouds,
CO2, nitrogen
Dist. from sun 0.7 A.U. 1 A.U. 1.5 A.U.
One word description?
Let’s look at atmosphere more carefully:
Earth
Nitrogen: 78%
Oxygen: 21 %
Argon: 0.9%
Water: > 1%
Carbon Dioxide: 0.004% *
Mars
Carbon Dioxide: 95%
Nitrogen: 3%
Argon: 2%
Venus
Carbon Dioxide: 96%
Nitrogen: 3.5%
How did Venus get so hot?
Planetary surface
A planet with an atmosphere
Solar radiation comes in
Planetary radiation goes out, but gets absorbed
The greenhouse gases reradiate. Some of the energy goes towards the surface.
Greenhouse gases
In class, or lab exercise: Greenhouse effectGo to http://phet.colorado.edu/en/simulation/greenhouse
How do greenhouse gases naturally get into the atmosphere?
Water: evaporation
CO2: vaporization of rocks, release from volcanos, vaporization of biotic material (like fossil fuels), respiration
Methane: release from earth, biology (bacteria, cows, rice)
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1. Volcanos brought up gas trapped in rock
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2. Comets hitting the young earth brought water, water vapor and carbon dioxide.
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3. Earth developed an oxygen atmosphere from plant life
What is happening to the atmosphere today?
Report on Global Climate Change –IPCC 2013*
* Intergovernmental Panel on Climate Change: A total of 209 Lead Authors and 50 Review Editors from 39 countries and more than 600 Contributing Authors from 32 countries contributed to the preparation
“Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased .”
Articles published in peer review journals support idea that this is happening, and that it is caused by
humans
Peer review, or refereed: article has been anonymously approved by another expert in the field before publication
Global warming: a look at the data
These temperatures are derived from different methods
CO2 levels in ppm (parts per million)
Class exercise with Mauna Loa (top of volcano in Hawaii) data: Plotting some data on the CO2 concentration in the atmosphere
Each team will plot one year’s worth of CO2 data
Date CO2 (ppm)
July
2005
July
July
July
2006 2007 2008 2009 2010 2011 2012
July
July
July
375
377
376
378
380
386
392
391
390
389
388
387
384
383
395
382
379
381
394
385
393
CO
2 Con
cent
rati
on (
ppm
)
Group # ______
Various effects of climate change today
Shrinking ice sheets
Declining arctic ice
Melting glaciers
Sea level rise
Global temperature rise
Warming oceans
Summary of effects:
What can we do to reverse this?
Currently, 30% of both the US House and Senate are on record as denying climate change, or its importance.
Solution requires many nations to address the problem: China in particular
What can we do…
•Buy more fuel efficient cars and trucks, do less driving, do more car pooling, use CFL (compact fluorescent) light bulbs, use solar cooker…
•Develop Solar power on homes
•Burn less coal (which creates much of our electricity)
•Develop alternative energy: wind, nuclear
•What are your ideas?
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Take away message:
Lecture tutorial, Greenhouse effect
Earth’s temperature is increasing because carbon dioxide concentration is increasing.
All evidence is that this is caused by human activity.
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Index: Change in earth’s temperature