Global warming underestimated, say scientists

May 23, 2006 Some scientists say current climate change estimates may be significantly underestimating the potential scale of global warming. The team of researchers report that the actual warming due to human fossil fuel emissions could be 15 percent to 78 percent higher than estimates that fail to take into account the feedback mechanism which involves carbon dioxide and Earth temperature.

Greenhouse gases are believed to contribute to global warming, yet scientists have said that global warming itself triggers greenhouse gas emissions - meaning that the Earth may get hotter faster than climate models predict.

Another team of researchers in California, has reported a similar conclusion: "when the Earth has warmed up in the past, due to the sun's natural cycles, more greenhouse gases have been spewed into the atmosphere. As greenhouse gas levels rose, so did the Earth's temperature," the scientists reported.

Dr Margaret Torn of Lawrence Berkeley National Laboratory said: "It means the warming is happening faster, each decade is actually warming faster than it would have," Dr Torn said. "It's the pace of change that will be one of the big problems. It's how humans adapt and the cost that will depend on the rate of change of climate."

Over the past 30 years, the Earth has warmed by 0.6 degrees Celsius, NASA has reported. Over the past 100 years, it has warmed by 0.8 degrees C, indicating a recent acceleration in warmth. Current climate models predict temperature increases of 1.5 to 4.5 degrees Celsius, but the California team realised that additional carbon dioxide caused by the natural solar cycle may elevate these estimates.

Taking this information on board could mean temperature increases of 1.6 to 6 degrees Celsius - and the higher temperatures are more likely, they said in a statement.

Meanwhile, another group of leading US scientists has linked global warming to the recent increase in hurricane intensity. They warn that humans must develop cleaner energy and transportation immediately - or bear the risk of more extreme storms.

"One is faced with repeating history, of putting up with $200 billion worth of damage every so often," said Dr. Peter Webster, a professor at the Georgia Institute of Technology and author of a 2005 study that found the strength and duration of hurricanes has doubled in the last 50 years. "I’m not sure how many $200 billion the country can afford," he told journalists.

Lawrence Berkeley's Dr Torn said humans are the biggest unknown: "To predict the future, you have to guess how much CO2 levels will go up. That depends on the biggest uncertainty of all - what humans decide to do. Do we get smart and prevent CO2 emissions? Do we continue with business as usual? Or will we end up somewhere in between?"