The United Nation’s Intergovernmental Panel on Climate Change has issued its fourth report (video, audio, and slides here) saying that worldwide carbon emissions must stop increasing within seven years and greenhouse gas emissions must be reduced by 50 to 85 percent in about four decades, The Washington Post reports. If not, as many as 25 percent of the planet’s species will be killed from global warming.
Reaching the goals would require a drastic reworking of construction, industry, transportation, and agricultural practices. By 2050, stabilizing emissions would slow the average annual global economic growth by less than 0.12 percent, AP reports.
Global warming is “unequivocal,” according to the study, as reported by AP. Temperatures have risen 1.3 degrees Fahrenheit in the last 100 years. Eleven of the last 12 years are among the warmest since 1850. Sea levels have gone up by an average seven-hundredths of an inch per year since 1961. The report also finds that human activity is largely responsible for warming. Global emissions of greenhouse gases grew 70 percent from 1970 to 2004. The concentration of carbon dioxide in the atmosphere is far higher than the natural range over the last 650,000 years.
Current emissions already are nearing the limit required in 2015 to limit the warming to 2 degrees Celsius, but even at that threshold, the seas will continue to swell for centuries from thermal expansion and meltwater from ice caps and glaciers; the oceans will turn more acidic; most coral reefs will become lifeless expanses; floods and storms will increase; and millions of people will be short of the water they need, the WaPo article says.
If the world misses that target and does not stabilize carbon dioxide emissions until 2030, for example, the planet’s temperature will increase by as much as 6.3 degrees Fahrenheit above 2000 temperatures.
“This is a wake up call for the whole world. Britain has led the way, the first climate change bill in history, now the rest of the world must follow,” British Prime Minister Gordon Brown said from London, according to Voice of America. “And at Bali in the next few weeks we need a climate change agreement that is global, that is comprehensive, that is radical and meets our ambitions that we have a 50 percent cut in carbon emissions around the world and we will do even better than that.”
The IPCC does not recommend specific policies, but an early Guardian story based on a draft summary says that report introduces an “effective carbon price signal.” It says a carbon price of between $20-$80 per tonne by 2030 should be enough to limit the expected temperature rise.
The latest report will form the basis for policy makers when they meet next month in Bali, Indonesia.
This IPCC final report summarizes and integrates the most significant findings of three sections of a climate-science review that were released between January and April, The New York Times reports. Because the data had not previously been reviewed as a whole, scientists said the synthesized report was more explicit, creating new emphasis and alarm.
The Guardian has a graphic (PDF) illustrating how the earth might heat up by 2099.