Global Warming May Be Causing Longer Growing Season

Spring is arriving earlier every year throughout the Northern Hemisphere - possibly due to global warming - with the result that the growing season in many countries today is a week longer than 20 years ago, scientists announced Wednesday.

It is the first time that such a widespread increase in the growing season has been reported, the scientists said.

Researchers at the Scripps Institution of Oceanography and the University of California at San Diego, who have monitored seasonal changes in the atmosphere for almost 40 years, say their finding suggests that plant life in North America, Europe and Siberia may be responding already to the effects of global warming.

Driven by steadily rising temperatures, the amount of vegetation in those regions appears to have increased by as much as a fifth since the mid-1970s, researchers determined.

“This may be the first evidence of climate change and how it affects the growth of plants on a huge spatial scale,” said Pieter Tans, an authority on greenhouse gases and the atmosphere at the National Oceanographic and Atmospheric Administration’s climate-monitoring laboratory in Boulder, Colo.

The research, published today in the journal Nature, became public as United Nations officials met in Geneva earlier this week with representatives of 150 countries in an effort to stave off global warming by reducing the amount of carbon dioxide being pumped into the atmosphere.

U.N. officials hope to secure an agreement to curtail emissions of waste industrial gases and the burning of fossil fuels such as oil and coal. Scientists say that human activities today add about 3 billion tons of carbon dioxide to the atmosphere every year, helping trap heat close to the planet’s surface and potentially disrupting the world’s climate.

In a key but controversial report last year, a U.N. panel concluded for the first time that greenhouse gases such as carbon dioxide probably are partly responsible for changing the global climate. If emissions are not reduced, the panel warned, temperatures could rise as much as 6 degrees Fahrenheit by the year 2100.

Despite the growing scientific evidence, the controversy over global warming and climate change shows no signs of abating.

At the Geneva meeting, more than 100 European and American scientists issued a joint statement condemning any major steps to reduce global warming, such as international controls or energy taxes, as “ill-advised, premature, wrought with economic danger and likely to be counterproductive.”

The Scripps researchers based their conclusions on a careful study of the interplay between rising temperatures and the increasing carbon dioxide in the atmosphere, which they have been monitoring from stations in Hawaii and Alaska since the late 1950s.

Watching the level of carbon dioxide in the atmosphere is an indirect way of monitoring the spread of vegetation around the world. Every year, the level of carbon dioxide in the atmosphere rises and falls in a predictable seasonal pattern caused by the life and death of plants.