The climate change challenge
January 9, 2010
BY DR. RAY WEYMANN
In a recent essay on this web site, (“The Climate Change Hoax”), Matt Kokkonen correctly calls attention to three facts regarding climate change and global warming and manages to draw erroneous conclusions from each of them:
1) “Dissenting experts” claim that global warming is cyclical
2) “Dissenting experts” also point out that the increase in carbon dioxide has always followed periods of warming rather than being caused by the warming.
These two statements are true, but totally irrelevant to the problem of present-day climate change. There have been several periods of glaciation between which shorter warmer periods have occurred, with intervals of roughly 100,000 years between ice ages.
Over 70 years ago, the Serbian engineer & mathematician Milutin Milankovitch proposed that the “pace-maker” for these recurring events was very slow and subtle changes in the properties of the earth’s orbit over tens of thousands of years. They cause the amount of solar energy reaching various portions of the earth, especially the north polar region of the earth, which is especially climates-sensitive, to change.
Most, but not all, climate scientists, accept this basic proposition though the details are certainly not clear–after all the armada of satellites now gathering amazingly precise and voluminous amounts of data on our present climate were not orbiting the earth 150,000 years ago. What is agreed is that regardless of the details of the “pace-maker”, it initiated a chain of events (“feedbacks”) leading to an emergence from an ice age. It is further agreed that a key link in this chain was the release of large amounts of carbon dioxide from warming oceans which strongly amplified the warming and spread the warming over the entire globe. (A similar sequence occurs for the onset of an ice age).
Without the strong amplifying effect of the carbon dioxide these extreme changes would not occur: the climate is sensitive to the amount of carbon dioxide in the atmosphere. The fact that in this chain of events the amount of carbon dioxide released lags behind the initial warming is exactly what is expected.
The fundamental fallacy in the two points made by the “dissenting experts” is that changes in the earth’s climate are always initiated by the same cause. That makes no more sense than saying that since lightning has historically caused forest fires, all forest fires are “natural” and never caused by humans.
The present warming, which has been most dramatic in the last few decades, has nothing to do with the Milankovitch effects which are much too slow and too small to cause this rapid warming and are not even in the right direction to cause warming. The present warming is due to the sudden and tremendous increase in the carbon dioxide content of the atmosphere, which is already at a level never even approached during the past million years and is entirely due to human use of fossil fuels and deforestation.
“In order to substantiate the claim for global warming, accurate historical data must be available.”
Mr. Kokkonen claims that existing data is invalid because many of the weather stations maintained by the U.S. Historical Climatology Network are located in areas affected by local man-made heat sources. This “urban heat island” effect is well known for many years and has been thoroughly studied and corrected for. The effect on the U.S. average temperature trend (let alone the global temperature trend ) is undetectable. A study by the NOAA of exactly this effect compared properly located stations with a group of stations regardless of appropriate location and found no discernable difference in the temperature trend.
But the misunderstanding propagated by Mr. Kokkonen goes much deeper than this:
* The temperature records used to document global warming are trends, not absolute measures–that is, it is the long term change in the temperature of each location that is being referred to.
* Any remaining biases in the global temperature record maintained by NASA due to “urban heat island effects” are removed by comparing urban with nearby rural trends. Far from introducing errors, this procedure removes any residual errors.
* The global temperature trend records mean just that: they are averages in the trend over the entire surface of the earth–the area of the continental U.S. is about 1.5% of the earth’s surface area, of which about 70% is ocean. There are rather few heat island effects in the middle of the ocean.
* Comparison of the total global temperature trends with the trends from just the ocean surface temperatures show the same overall pattern.
* There are numerous other indications that the earth’s climate system is out of energy balance and is warming: measurements of the deeper layers of the ocean down to several thousand feet show that they have accumulated a huge amount of heat energy since 1970; glaciers worldwide as well as the Greenland and West Antarctic ice caps are melting at accelerating rates and summer sea ice in the Arctic is shrinking; the globally-averaged sea level is rising as the ocean warms and the ice sheets melt.
All of the foregoing is well-known and documented. What is most disturbing about Mr. Kokkonen’s statements and those of fellow “climate change deniers” is their eagerness to accept whatever statements they come across on talk radio shows or the Internet without putting in the effort to investigate whether they have any scientific validity. If this is typical of the level of scientific understanding of some present or would-be office holders, then our country is headed for serious trouble.
Ray Weymann is a graduate of Cal Tech and holds a Ph.D. in astrophysics from Princeton. He lives in Atascadero.