A new report by the United Nations’ Intergovernmental Panel on Climate Change states what has been obvious to most scientists for decades about the effect of greenhouse gas emissions on rising global temperatures, and how they contribute to the world’s mounting environmental challenges.
When the panel issued its last report in 2007, the consensus among climate scientists — that human activity was a culprit in global warming — was as high as 90 percent. Since then, the percentage of like-minded scientists has risen to 95 percent, from 66 percent in 2001.
“This report confirms with even more certainty than in the past that it is extremely likely that the changes in our climate system for the past half a century are due to human influence,” said Michel Jarraud, secretary general of the World Meteorological Organization.
The new report predicts sea levels will rise by 9 feet, 10 inches by 2300, thanks to ice and glacier melts that are under way. Coastal cities will be inundated. Some 15 to 40 percent of carbon dioxide will be trapped in the atmosphere for 1,000 years, compounding whatever other misery humanity faces because of the global addiction to fossil fuels.
The long-term negative effects of global warming won’t inconvenience just a generation or two. Earth’s inhabitants will deal with drought, rising sea levels, heat waves, and floods — the fallout from a lack of environmental stewardship — for centuries, the report concludes.
The document is a plea to governments to commit to addressing the challenge of climate change by reaching a U.N. accord by 2015. This clarion call to meaningful action has opponents in the industrialized and rapidly industrializing world who have an interest in denying science for economic and political reasons.
Climate-change deniers trumpet the fact that temperatures have not risen as quickly in the past 15 years as some had predicted, despite record levels of emissions — now 10 billion tons annually and rising. But ocean temperatures are rising, the report noted, which will bring harmful consequences.
Even after the glaciers retreat and big cities endure routinely rising water, some people likely will continue to deny that human activity played a role in these disasters. The report makes clear that the time for accommodating such unscientific opinions is past. Action to avert catastrophe is needed now.