Dr. James Hansen, who is the head of NASA's Goddard Institute of Space Studies (GISS) recently spoke to House Select Committee back in June, which was exactly 20 years after he first testified to Congress about the dangers of global warming. I blogged about that story on June 25th. As I expected, there was a fair amount of sharp criticism about his speech in the commentary section of this blog.

In a recent post (pages 11-18) (Aug 4th) on his Columbia University website James Hansen discusses how he was bombarded with critical emails after that speech. I wonder if any of those came from some of our regular commentators?

Anyway, Hansen explains that a majority of the critical emails insisted that the sun, not man, was the primary cause of climate change.

In his response, Hansen explains why these ideas about sun and climate change are wrong and that speculation that we may have entered a solar driven long-term cooling trend must be dismissed as a pipedream as the solar signal in shorter term global temperature is too weak. See next paragraph.

The text below is directly taken from Hansen's post:

Solar irradiance seems to be slightly less at its current minimum than in earlier minima (Figure 6), but, at most, the decrease from the mean irradiance of recent decades is ~0.1% yielding a climate forcing of about -0.2 W/m2. The current rate of atmospheric CO2 increase is ~2 ppm/year, yielding an annual increase of climate forcing of about +0.03 W/m2 per year. Thus if the sun remains "out", i.e., stuck for a long period in the current solar minimum, it can offset only about 7 years of CO2 increase. The human-made greenhouse gas climate forcing is now relentlessly, monotonically, increasing at a rate that overwhelms variability of natural climate forcings.

Hansen also tries to explain how science really works and admits that scientists may not fare very well against contrarians in you-tube style debates. Now you know why he may not be too keen about debating.

Hansen includes a few of the critical emails within the sources section at the bottom of the last page. I just touched upon his response, once again, there is a lot more detail between pages 11-18 in his post if you are interested.