Global warming deniers often suggest that the Intergovernmental Panel on Climate Change Fourth Assessment Report is a political document, and they’re partially right — but not in the way that they might think. The report is conservative by nature, relying on studies that were largely published before 2005, and the picture it paints is far rosier than it should be.
Over the last five years, study after peer-reviewed study has suggested that the Fourth Assessment Report is already out-of-date, and global warming is barreling along.
So it’s worthwhile to reconsider the science on this, Blog Action Day. Luckily for me, I don’t have to do the heavy lifting. Leading experts have made good on a promise to update the climate change science in advance of Copenhagen, and they’re telling politicians that humanity is risking “abrupt and irreversible climatic shifts” from the accelerating pace of global warming. Rising global surface and ocean temperatures, surging sea levels, extreme weather events, and the retreat of Arctic sea ice* are all coming harder and faster than research suggested five or 10 years ago. The takeaway message is that politicians had better find a way to work together at the next international climate summit in December — or shortly after — or the results will be devastating.
The 36-page document summarizes more than 1,400 studies presented at an emergency climate conference held last in March in Copenhagen. The report said that greenhouse gas emissions are growing faster than expected, and evidence accumulates that the planet itself is becoming a factor. Some carbon sinks like the oceans and Canadian boreal forests are diminishing, and many places in the far north show signs of liberating methane into the atmosphere.
“Rapid, sustained, and effective mitigation … is required to avoid ‘dangerous climate change’ regardless of how it is defined,” according to the report. “Temperature rises above 2°C will be difficult for contemporary societies to cope with, and are likely to cause major societal and environmental disruptions through the rest of the century and beyond.” And a business-as-usual approach will take us well beyond the 2°C threshold in less than 50 years.
The report suggests that deep emission cuts are essential, and the sooner the better. “Weaker targets for 2020 increase the risk of serious impacts, including the crossing of tipping points” beyond which irreversible natural forces could push temperatures to unthinkable levels.
First Nations in North America have a wonderful — and pointed — expression: We don’t inherit the Earth from our ancestors, we borrow it from our children.
I hope our leaders are listening.
* Among the predictions made, and summarized in this 36-page document: The coming decade will be the warmest ever, and summer arctic sea ice will largely melt by 2020. Droughts will intensify, and hurricanes will become ever more potent. By 2100, we should expect sea levels to rise by between 5 and 7 feet; that more than 70 percent of the Amazon rainforest will die (if it isn’t already cut down); that 50 to 70 percent of species will go extinct; that agriculture will fail in California; that the American Southwest will be turned into a permanent dust bowl; and that a few billion people in Asia to have no water for life. And that’s but a sampling of dozens of apocalyptic predictions.