Ask A Scientist© Environmental Science Archive

Author:     wayers
Text:       How fast is the warming due to the greenhouse effect? How do we 
measure the rate of warming and how long will it take to confirm the effect?

Response #: 1 of 1
Author:     Don Libby
Text:       This is a difficult question. There is general agreement among 
atmospheric scientists that a rise of 4 degrees Celsius in the average global 
temperature might result from the greenhouse effect bythe year 2050, or 
roughly one degree Celsius every 15 to 20 years. However, there are also many 
reputable scientists who dissent from this view because they do not agree with 
the theoretical assumptions underlying the forecast. In fact, some believe a 
global cooling is more likely. It will require years of global temperature 
monitoring to establish reliable baseline data from which to measure 
departures or trends. In the mean time, it would be prudent to restrain the 
rate of growth in air pollution to avoid making the problem worse (if indeed 
there IS a problem), and the United Nations have agreed in principle to do 
this, though it is not likely that much economic activity will actually be 
restrained. In my own research on this subject, I skipped over the intervening 
step of trying to predict how much warming would take place (which is the 
major concern of atmospheric scientists) and went directly to the political 
and economic consequences of a drastic global warming. Given crude predictions 
of future population and future food supply under a global warming scenario, 
there will likely be enough food to go around, but it will be very important 
to distribute the food efficiently from productive regions to regions where 
agriculture will be hard hit (such as Africa). Global warming would make 
global trade a vitally important issue.