Climate Change What Does the Science Really Tell Us? Craig Cogger WSU 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

Greenhouse Gases CO 2, H 2 O, N 2 O, CH 4 : Absorb infrared energy Act like a blanket Without the greenhouse effect, earth’s mean temperature would be 0 o F, nearly 60 o lower than it is now Carbon Dioxide Water

The Problem: We are increasing atmospheric CO 2, adding to the greenhouse effect, and warming the planet

NASA G. Holloway, Institute of Ocean Sciences, Sidney, BC UCAR USDOE PNNL Ocean Circulation moves and stores heat and CO 2 Atmospheric Circulation moves heat Carbon Cycle moves, transforms, and stores CO 2 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 Daily

Weather: Climate:

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 (CO 2, CH 4, N 2 O, others) o Aerosols NOAA Minnesota public radio USGS

Climate Feedback Amplifies or dampens climate forcing H 2 O 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

Evidence for Current Climate Change: Temperature Anomalies

Evidence for Current Climate Change: Temperature Extremes – US 48 states

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 reef o Coral death and decline appear linked to increased water temperatures Pine bark beetle damage o 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

Evidence for Current Climate Change:

IPCC 4 th Assessment IPCC Regional Temperature Projections Change compared with baseline

IPCC 4 th Assessment IPCC Regional Precipitation Projections for Compared with 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 CO 2 Target 80% reduction in CO 2 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