Letter: Reid right about fires and global warming

Wednesday, Nov. 21, 2007 | 7:13 a.m.

The intensity of wildfires, i.e., the rate of spreading, is determined by four environmental factors. These are, in order of importance: wind velocity, air temperature, humidity and fuel moisture. The higher the temperature, the lower the humidity and the drier the fuel. Global warming increases three of the four factors affecting wildfire intensity. There is some evidence that global warming also increases wind velocities.

The velocities of Santa Ana winds have been measured for 100 years. If these data were compiled and analyzed, the correlation between global warming and wind velocity could be calculated. And there is another way to determine the effect of global warming on wildfire intensity.

The U.S. Forest Service integrated the four factors affecting wildfire intensity into numerical indexes that were grouped into four fire danger classes: extreme, high, moderate and low. The Fire Danger Index was calculated for every ranger district on every national forest in the West for every day of the fire season. If these data have been preserved, the correlation between fire danger and global warming could be calculated.

All the evidence supports Senate Majority Leader Harry Reid's remark on the effect of global warming on wildfire intensity. There is no evidence supporting his critics.

Vernon Bostick, Las Vegas

The writer is a former U.S. Forest Service employee.