PARIS, Feb 2: Scientists on Friday delivered their starkest warning yet about global warming, saying fossil fuel pollution would raise temperatures this century, worsen floods, droughts and hurricanes, melt polar sea ice and damage the climate system for a thousand years to come.
In its first assessment in six years, the United Nations Inter-governmental Panel on Climate Change (IPCC) dealt a crippling blow to the shrinking body of opinion that claims higher temperatures in past decades have been driven by natural, and not man-made, causes.
The United Nations’ paramount scientific authority on global warming highlighted a range of changes that had taken place in Earth’s ice cover, rainfall patterns and permafrost and declared that most of the temperature rise over the past 50 years had `very likely’ been caused by human activity.
This term means a certitude of more than 90 per cent and signals an increase on the IPCC’s previous assessment in 2001, which gave a probability of more than 66 per cent.
By 2100 global average surface temperatures could rise by between 1.1 and 6.4 degrees Celsius compared to 1980-99 levels, depending on how much carbon dioxide, the principal greenhouse gas, is in the air.
Within this broad temperature range – which runs from the best-case scenario to the worst-case one – the `best estimate’ is that the Earth’s surface temperatures will rise between 1.8 and four degrees C, the IPCC said. In 2001, it had forecast a broad range of 1.4 to 5.8 C.
These figures are contained in a `summary for policymakers’ in the IPCC’s fourth review of the scientific evidence for global warming. They are derived from computer models based on how much carbon dioxide enters the atmosphere.
Greenhouse gases disgorged into the atmosphere this century will cause climate disruptions `for more than a millennium’ to come because of the long time it takes for these molecules to break down, the summary warned.
France and Britain swiftly declared that time was running out for tackling climate change.
“We are on the verge of the irreversible,” French President Jacques Chirac told an environmental conference in Paris.
“Faced with this emergency, the time is not for half measures. The time is for a revolution – a revolution of our awareness, a revolution of the economy. A revolution of political action.”
