IPCC Countdown Begins. Scientists Ever More Certain on Climate Change
August 21, 2013
The hinge of history is turning. The climate communication community is gearing up for the assault on the new IPCC 5th Assessment Report, AR5, that will be released starting on September 27th. This time, it looks like the mass media, recognizing how it’s been punked by deniers over the past few years, will give much shorter shrift to the disinformers.
We did it.
And now we have to fix it.
It’s hard to imagine drawing any other conclusion from the latest news on global warming, this time from the preeminent body on the topic:
The odds are at least 95 percent that human activity is the cause of warming of the planet since the 1950s, a United Nations panel of experts has concluded in a draft report leaked to Reuters and the New York Times. The report, which may change slightly in its details but isn’t expected to deviate from its broad conclusions, will be finalized in late September.
That 95 percent figure is up from 90 percent in 2007, 66 percent in 2001 and about 50 percent in 1995. The report comes from the Nobel Peace Prize-winning Intergovernmental Panel on Climate Change, a group of several hundred scientists that survey and summarize scientific findings on climate change.
But as the latest — and most definitive — assessment on global warming makes clear, manmade global warming is here and already damaging local economies, livelihoods and the natural world we cherish. The only question now is how severe do we want that damage to be — for us today and the generations that will be forced to inhabit a hotter and less hospitable planet.
The coming report will be the fifth major assessment from the group, created in 1988. Each report has found greater certainty that the planet is warming and greater likelihood that humans are the primary cause.
The 2007 report found “unequivocal” evidence of warming, but hedged a little on responsibility, saying the chances were at least 90 percent that human activities were the cause. The language in the new draft is stronger, saying the odds are at least 95 percent that humans are the principal cause.
On sea level, which is one of the biggest single worries about climate change, the new report goes well beyond the assessment published in 2007, which largely sidestepped the question of how much the ocean could rise this century.
The new report also reiterates a core difficulty that has plagued climate science for decades: While averages for such measures as temperature can be predicted with some confidence on a global scale, the coming changes still cannot be forecast reliably on a local scale. That leaves governments and businesses fumbling in the dark as they try to plan ahead.
On another closely watched issue, the scientists retreated slightly from their 2007 position.
Regarding the question of how much the planet could warm if carbon dioxide levels in the atmosphere doubled, the previous report largely ruled out any number below 3.6 degrees Fahrenheit. The new draft says the rise could be as low as 2.7 degrees, essentially restoring a scientific consensus that prevailed from 1979 to 2007.
But the draft says only that the low number is possible, not that it is likely. Many climate scientists see only a remote chance that the warming will be that low, with the published evidence suggesting that an increase above 5 degrees Fahrenheit is more likely if carbon dioxide doubles.