Download - Climate Change
Climate ChangeWhat Does the Science Really Tell Us?
Craig CoggerWSU Puyallup
Simplified Greenhouse Effect
Solar energy passes through atmosphere and is absorbed by the earth
Energy radiates back toward space as lower-energy infrared waves
Greenhouse gases absorb and re-radiate some of the infrared energy, trapping heat in the atmosphere.
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Greenhouse Gases• CO2, H2O, N2O, CH4:
Absorb infrared energyAct like a blanket
• Without the greenhouse effect, earth’s mean temperature would be 0o F, nearly 60o lower than it is now
Carbon Dioxide
Water
The Problem:We are increasing atmospheric CO2, adding to the greenhouse effect, and warming the planet
NASA
G. Holloway, Instituteof Ocean Sciences,
Sidney, BCUCAR USDOE PNNL
Ocean Circulation moves and stores heat and CO2
Atmospheric Circulation moves heat
Carbon Cycle moves, transforms, and stores CO2
Aerosols interact with solar energy
Some of the Complicating Details
Definitions:Weather and Climate
• Weather: The current state of the atmosphere (hours, days, weeks, months)
• Climate: Average weather over time (30 years or more)
• Climate is what you expect, weather is what you get
San Antonio DailySan Antonio Daily
Weather:
Climate:
http://data.giss.nasa.gov/gistemp/graphs/
Climate Forcing• Climate forcing:
Affects global energy balance, forcing a change in climate
• Examples:o Changes in solar energy
(sunspot cycles, orbital changes – small over short time scales)
o Changes in greenhouse gas concentrations (CO2, CH4, N2O, others)
o Aerosols
NOAA
Minnesota public radioUSGSUSGS
Climate FeedbackAmplifies or dampens climate forcing
• H2O in atmosphere: Positive feedback, increases warming
• Snow and ice melting: Positive feedback – more melting, less reflection of heat, more warming
• Melting permafrost and thawing soil releasing greenhouse gases: Positive feedback
• Changes in cloud cover: Both positive and negative
NASA
UNEP
Katey Walter, UAF
Jon Sullivan
http://data.giss.nasa.gov/gistemp/graphs/
Evidence for Current Climate Change:Temperature Anomalies
Evidence for Current Climate Change:Temperature Extremes – US 48 states
www.ucar.edu
Evidence for Current Climate Change:Sea Ice Extent
USGS
Evidence for Current Climate Change:Accelerating Glacier Loss
Evidence for Current Climate Change:Ecosystem Changes
• Bleached coral reefo Coral death and decline appear
linked to increased water temperatures
• Pine bark beetle damageo Extreme cold keeps beetle
populations in check. Recent severe infestations appear related to moderating winter temperatures
US Forest Service
NOAA
Evidence for Current Climate Change:Sea Level Rise
http://sealevel.colorado.edu/
Evidence for Current Climate Change:
http://www1.ncdc.noaa.gov/pub/data/cmb/bams-sotc/2009/bams-sotc-2009-brochure-lo-rez.pdf
IPCC 4th Assessment
IPCC Regional Temperature ProjectionsChange compared with 1980-1999 baseline
IPCC 4th Assessment
IPCC Regional Precipitation Projections for 2090-2099Compared with 1980-1999 baseline
Saiful Huq Omi/Polaris, for The New York Times
Land at risk from 1m sea level rise
Watts Up With That? Commentary on puzzling things in life, nature, science, weather, climate change, technology, and recent news by Anthony Watts
Isn’t there another point of view?
Not one with a credible scientific basis.
The Global Challenge
• 86% of world’s energy comes from fossil fuel• Deforestation is #2 human source of CO2
• Target 80% reduction in CO2 emissions by 2050 to avoid worst outcomes of climate change
• Individual and government action needed
Responding to the climate change challenge
We basically have three choices: mitigation, adaptation and suffering. We’re going to do some of each. The question is what the mix is going to be. The more mitigation we do, the less adaptation will be required and the less suffering there will be. John Holdren
The “Wedge Strategy” for Mitigation
• Each wedge plays a role in reducing greenhouse gas emissions
• Think of how our industry can contribute to these wedges.
NRDC
Getting Involved• Reduce emissions at home and
work• Learn more about climate
science• Talk to your friends, neighbors,
and co-workers • Write to decision makers• Support organizations who
work for those in greatest need
Take-home message• Greenhouse effect
– Science is unassailable: Added greenhouse gases warm the earth
• Multiple lines of evidence show effects of warming across the globe
• We need to act now to avoid the most severe harm to people and the environment.
Looking to the future:Many of the youngest among us will still be alive in the closing decades of this
century. How can we shape the world will they be living in?
Recommended Reading
IPCC synthesis of the best science, 2007(already a little out-of-date)
Well written by a physicist/historian, 2008
Readable, robust science, 2009
Trustworthy climate science blogs