As an atmospheric scientist, I laid out in my Aug. 1, 2007, and Nov. 14, 2007, Other Voices pieces some scientific evidence that the current wave of climate hysteria is overblown. I recently returned from the Annual Meeting of the American Meteorological Society in New Orleans and I wanted to update readers on some of the interesting developments in climate science presented.

Alarmists have been saying since Hurricane Katrina that climate change is causing more and more severe hurricanes. Some recent findings presented at the meeting in fact tend to disprove that assertion. Several papers noted that there has been no discernible change in the frequency or severity of hurricanes and tropical storms in the Atlantic and Gulf once the data have been corrected for the improvements in storm detection since the advent of satellites. In other words, the data make it clear that we are seeing more tropical storms now than 50 years ago because we can see more, not because there are more.

Additionally, recent research has shown that the storms that do occur are not more destructive. Rather, we have been building more structures and more expensive structures in hurricane-prone areas. Recent storms have indeed caused more dollar loses, but it's not the intensity of the storms that has changed. It's the value of what we put in their way that's changed.

Further, recent studies show that even if substantial global warming were to occur, the net effect is likely to be a decrease in frequency and intensity of storms. This is due to an increase in wind shear aloft that inhibits tropical storms' development. So the evidence is that there is no discernible trend toward more severe hurricanes. Any substantial global warming that might occur in the future would likely act to inhibit tropical storm formation and intensity.

Likewise, there has been some interesting news on temperature. In 2007, the mean global surface temperature was about one degree Fahrenheit above the 20th-century mean, ranking it as the fifth-warmest since modern records started about 1900. The most interesting point is that there has been no apparent trend toward increasing global mean temperature since the late 1990s. Even while atmospheric carbon dioxide continued to increase over the past 10 years (it is still only a few hundred parts per million of the atmosphere), there has been no corresponding increase in mean global surface temperature. The temperature trend has been essentially flat. So, in contrast to the increasing trend in mean temperatures that climate models say should be happening, we are in a period of about 10 years of no apparent trend.

In summary, some recent work shows that there is still no smoking gun that clearly links atmospheric carbon dioxide as the chief cause of global mean temperature change. What's going on? It looks like the computer models used to predict the future climate may be overestimating the role CO2 plays in the very complex ocean-atmosphere system. It's also possible that the models haven't properly considered the role that that the sun's energy output contributes over both the visible and non-visible spectrum. It is the sun, after all, that ultimately controls what the climate on Earth will be like.

The answers to these questions are unknown now and likely not knowable for some years yet. As I've counseled before, look skeptically at anyone who tells you that they know what the climate will be like in 50 years. The state of the science does not support a high confidence in such projections.

Pfeffer, of Colorado Springs, is former director of weather for NORAD, United States Space Command and Air Force Space Command and former deputy director of the Air Force Weather Service.