I thought I'd ask you for help in an online debate with some sharp folks who don't believe we are warming the earth. What's the most convincing science you know of on this? --Bob W, Pepe'ekeo, Hawaii
Bob, In an earlier Q&A, I advised that many of us "older" clean energy advocates had been promoting energy efficiency and renewable energy, recycling and resource conservation, and maximum reduction of fossil fuels for security and pollution (including mercury and carcinogen emissions) long before climate change was even acknowledged by those within the scientific community.
That said, my suggested reading list is the National Academy of Science review on climate change that covers Human Caused Climate Forcings, which addresses these questions:
• Are concentrations of greenhouse gases and other emissions that contribute to climate change increasing at an accelerating rate, and are different greenhouse gases and other emissions increasing at different rates?
• Is human activity the cause of increased concentrations of greenhouse gases and other emissions that contribute to climate change?
• What other emissions are contributing factors to climate change (e.g., aerosols, CO, black carbon soot), and what is their relative contribution to climate change?
• How long does it take to reduce the buildup of greenhouse gases and other emissions that contribute to climate change?
• Do different greenhouse gases and other emissions have different draw-down periods?
• Are greenhouse gases causing climate change?
This is the most balanced review I have read. And the National Academy of Science states: "Carbon dioxide (CO2) is probably the most important climate forcing agent today, causing an increased forcing of about 1.4 W/m2. CO2 climate forcing is likely to become more dominant in the future as fossil fuel use continues. If fossil fuels continue to be used at the current rate, the added CO2 forcing in 50 years will be about 1 W/m2. If fossil fuel use increases by 1-1.5% per year for 50 years, the added CO2 forcing instead will be about 2 W/m2. These estimates account for the non-linearity caused by partial saturation in some greenhouse gas infrared absorption bands, yet they are only approximate because of uncertainty about how efficiently the ocean and terrestrial biosphere will sequester atmospheric CO2. The estimates also presume that during the next 50 years humans will not, on a large scale, capture and sequester the CO2 released during fossil-fuel burning."
The Academy also states, "Although warming at Earth's surface has been quite pronounced during the past few decades, satellite measurements beginning in 1979 indicate relatively little warming of air temperature in the troposphere. The committee concurs with the findings of a recent National Research Council report, which concluded that the observed difference between surface and tropospheric temperature trends during the past 20 years is probably real."
Former USDOE and Rocky Mountain Institute Scientist Joseph Romm just wrote his bellwether book "Hell and High Water: Global Warming - the Solution and the Politics - and What We Should Do." Combined with former VP Al Gore's film "Earth In the Balance," these articulate the more strident views, and both works draw upon a myriad of scientific studies.
My final climate reading suggestion is the paper by Hansen and other climate authorities for the National Academy of Sciences: Hansen, J., M. Sato, R. Ruedy, A. Lacis, and V. Oinas, Global warming in the twenty-first century: an alternative scenario, Proceedings of the National Academy of Sciences, 97: 9875-9880, 2000.
As I started this response, I addressed that accelerated and enhanced use of efficiency and renewables is the ultimate "no regrets" answer addressing changes in climate. Two papers written by former Union of Concerned Scientist Dr. Don Aiken and a companion article with Dr. Bull and Dr. Billman, both of the National Renewable Energy Laboratory, are worth reading:
• The Renewable Energy Transition: Can It Really Happen? by Donald W. Aitken, Solar Today, January-February 2005
• The climate stabilization challenge: Can renewable energy sources meet the target? by Donald W. Aitken, Lynn L. Billman and Stanley R. Bull, Renewable Energy World, November-December 2004
I have been in many dialogues with global policymakers, scientists, military leaders, and government officials concerning climate change and responses. My advice is that the scientific community does agree that greenhouse gas (of which carbon is of the largest proportion) is changing our climate.
We also know that while this has happened before, it has not happened while we humans were on earth. And while we do not know every aspect of this change, it would probably be judicious not to allow this grand climate experiment to continue unabated, but rather address it in ways that increase economic growth, protect global security, and decarbonize our economy -- all at the same time.
Good luck with your online debates.
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