PARIS -- Global warming Two studies, both published in Nature, are among the first
Computer models have long predicted that the observed rise in atmospheric greenhouse gases would magnify episodes of diluvian rainfall.
Since wamer air holds more water.
But up to now, the link has been largely theoretical.
Data gathered between 1951 and 2000 from across Europe, Asia and North America showed that, on average, the most extreme 24-hour precipitation event in a given year - whether rain, snow or sleet - increased in intensity over the last 50 years of the 20th century.
Compared to what? The first 50 years? November 11, 1918? July 4, 1776?
When this measurable spike was compared with changes simulated by climate models, the fingerprint of human influence on Earth's weather patterns was unmistakable, Zwiers said.
"The observed change cannot be explained by natural, internal fluctuations of the climate system alone."
In the second study - which sought to tease out the impact of global warming on England's wettest autumn on record, in 2000 scientists led by Myles Allen of the University of Oxford tapped into the power of Internet-based social networks to overcome this last constraint.
They took a poll on Facebook, I suppose.
The researchers compared two climate models, one based on detailed historical weather data and the other on a "parallel" autumn 2000 simulating conditions had no greenhouse gases been emitted in the 20th century.
Ah, the old computer model trick! Define the outcome and anybody can make the model!
Global warming likely doubled the odds that such an event would occur, they found.
"To really pin down the difference between these two worlds, we needed to repeat the simulation thousands of times," explained lead author Pardeep Pall, who initiated the project as a graduate student in 2003.
With a computer? With one model? Wouldn't the results be the same each time? That's how my computer works!