A relatively new reader of this blog (see comments under “Meat Eater” post) requested that I state my views on climate science and I am happy to do so.
For people new to climate science, the Intergovernmental Panel on Climate Change (IPCC) is an agency of the United Nations charged with making recommendations about what to do about climate change. Climate change is a given in their charter and mission statement. Because this is the “official” climate change body, I’m using their predictions to represent the pro-GW warming case. The IPCC shared the Nobel Peace Prize with former Vice President Al Gore.
As background, temperatures were at least as warm as they are today both 1,000 and 2,000 years ago during the Medieval and Roman warm periods, respectively. There is nothing unprecedented in today’s temperatures.
Based on the best scientific evidence I have reviewed, human beings – on balance – warm the planet. The magnitude of the warming is less than the IPCC believes.
Yes, there is a “greenhouse effect” where additional concentrations of CO2 and other greenhouse gasses trap earth’s outgoing radiation and, through a physical process, heat the planet. However, the effect is logarithmic as indicated in the graph below:
|click to enlarge, from WattsUpWithThat
To better visualize a logarithmic effect, consider a hot tub. If you wished to trap the heat of the water, you might put a cover with an inch of insulation over it. That would trap the heat. If you wanted to trap more and more heat, you might but a second and third inch of insulation over the water. However, by the time you put a 20th inch of insulation, there would be little additional heat trapping. The same is true with CO2 as indicated on the graph. Additional CO2 concentrations produce less additional warming.
Using this graph, we would expect an additional 1.1°C of warming as CO2 concentrations continue to double from their 1950’s values. Almost no one believes that would be a major problem. Indeed, it is likely that a small amount of additional warming is a net benefit to mankind. Even the IPCC acknowledges this.
“The message I have for climate deniers is this: you are endangering humankind,” Boxer said during a press conference in the Capitol.
– Senator Barbara Boxer, D-Calif., Dec. 6, 2011
So, from where does the concern about catastrophic global warming, such as the comment above, originate?
The IPCC, in its reports to date, chooses not to quantify the known cooling effect of volcanoes. They do not attempt to quantify the potential cooling effect of cosmic rays. They assume (without much evidence) the sun will not bring about cooling temperatures. Finally, they assume that the net effects of clouds, atmospheric particles, and all other effects cause additional warming, a process they call “positive feedback.” From these assumptions, they predict much larger temperature rises than 1.1°C. Obviously, I disagree with these assumptions.
During the 1990’s these larger warming estimates looked good. You frequently saw graphs like this in newspapers. The IPCC predicted continued rapid warming. It took a great deal of courage to be a “skeptic.”
However, since 2000, you rarely see the temperature graph because it has certainly not turned out the way the IPCC forecast.
There is a more important metric of earth’s temperature which is ocean heat content (water can hold much more heat than air). Ocean heat content has been flat along with temperatures over the last ten years. This clearly indicates the computer models used by the IPCC are too warm and/or the omission of these other factors (volcanoes, etc.) are critical errors.
The bottom line: If solar and cosmic ray effects stay constant, we will have about 1°C of additional warming. That is a small net problem and does not justify either major or urgent efforts.
My bigger concern than global warming is that there are indications there could be significant cooling due to what appears to be a cooling sun. That would be a major problem for mankind due to shorter growing seasons and less agricultural productivity. Ironically, if the sun is indeed cooling, then the additional CO2 in the atmosphere would be of great benefit as it would both lessen the amount of cooling and it enhances agricultural productivity.
Finally, there is no persuasive scientific evidence that storms+droughts+cold+heat+hurricanes, etc., etc., are getting worse due to global warming.
An excellent global warming FAQ written by a meteorologist and statistician is here