Sunday, June 23, 2013

Question: If the blogosphere had existed in 1988, would we have avoided decades of mainstream global warming hysteria?

Twenty-five years later, a look back at James Hansen's critical Senate testimony reveals the absolutely stunning flimsiness of his argument. 

It was allegedly .4 C warmer in 1987 than the 1950-1980 mean; the probability of "a chance warming of that magnitude" was allegedly 1 percent; after the fact, Hansen claimed that he had expected about .4C of CO2-induced warming over that period; therefore, CO2 was overheating the planet.  In addition, it was warm in the room because of stagecraft.

That's it?  If maybe a decade of pre-1988 warming convinced people to buy the hypothesis then, why shouldn't nearly two decades of non-warming now convince them to give it up?

James Hansen's June 23, 1988 Senate testimony is here [PDF] .

A text version of his testimony is available here
Now let me turn to my second point which is causal association of the greenhouse effect and the global warming. Causal association requires that the warming be larger than natural climate variability and, second, that the magnitude and nature of the warming be consistent with the greenhouse mechanism. These points are both addressed on my second viewgraph. The observed warming during the past 80 years, which is the period when we have accurate measurements of atmospheric composition, is shown by the heavy black line in this graph. The warming is almost 0.4 degrees Centigrade by 1987 relative to climatology, which is defined as the 30 year mean, 1950 to 1980 and, in fact, the warming is more than 0.4 degrees Centigrade in 1988. The probability of a chance warming of that magnitude is about 1 percent. So, with 99 percent confidence we can state that the warming during this time period is a real warming trend.
The main point to be made here is that the expected global warming is of the same magnitude as the observed warming. Since there is only a 1 percent chance of an accidental warming of this magnitude, the agreement with the expected greenhouse effect is of considerable significance. Moreover, if you look at the next level of detail in the global temperature change, there are clear signs of the greenhouse effect. Observational data suggests a cooling in the stratosphere while the ground is warming. The data suggest somewhat more warming over land and sea ice regions than over open ocean, more warming at high latitudes than at low latitudes, and more warming in the winter than in the summer. In all of these cases, the signal is at best just beginning to emerge, and we need more data. Some of these details, such as the northern hemisphere high latitude temperature trends, do not look exactly like the greenhouse effect, but that is expected. There are certainly other climate change factors involved in addition to the greenhouse effect.

Altogether the evidence that the earth is warming by an amount which is too large to be a chance fluctuation and the similarity of the warming to that expected from the greenhouse effect represents a very strong case. In my opinion, that the greenhouse effect has been detected, and it is changing our climate now.
A climate change turning point: The 20th Anniversary of the "Hansen Hearing" | Worldwatch Institute
Dr. Hansen's testimony echoed around the world and he has turned out to be the Paul Revere of climate change. Mainstream scientific thinking has swung behind his 1988 testimony, and climate change now looms as a more immediate and serious threat than ever before.

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