The United Nations' Intergovernmental Panel on Climate Change (IPCC) was expected to delivery its fifth Assessment Report (AR5) next month, but over the past weekend, a draft of that report was leaked to Reuters, which reported the early details:
Drafts seen by Reuters of the study by the UN panel of experts, due to be published next month, say it is at least 95 percent likely that human activities – chiefly the burning of fossil fuels – are the main cause of warming since the 1950s.
That is up from at least 90 percent in the last report in 2007, 66 percent in 2001, and just over 50 in 1995, steadily squeezing out the arguments by a small minority of scientists that natural variations in the climate might be to blame.
That shifts the debate onto the extent of temperature rises and the likely impacts, from manageable to catastrophic.
For those familiar with global warming science, there isn't much new here. We've long known that manmade activity was likely the leading cause of our current warming and climate change. But the AR5 is newsworthy because of the new level of agreement among experts: 95 percent certainty.
The AR5 also concludes that we're on track for dangerous levels of warming, however Joe Romm at ClimateProgress notes that in some areas the assessment report gets the forecasts wrong:
I say the AR5 is a “partial” review that is “hopefully” the last because, like every IPCC report, it is an instantly out-of-date snapshot that lowballs future warming because it continues to ignore large parts of the recent literature and omit what it can’t model. For instance, we have known for years that perhaps the single most important carbon-cycle feedback is the thawing of the northern permafrost. The IPCC’s Fifth Assessment climate models completely ignore it, thereby lowballing likely warming this century.
Romm concludes it won't change much:
I very much doubt the IPCC’s Fifth Assessment Report will move the needle on climate action because of its inadequacies; because the media has scaled back climate coverage and let go of its best climate reporters; and because the fossil fuel funded disinformation campaign will try to exploit those first two problems to make it seem like this report gives us less to worry about, when it simply underscores what we have known for a quarter-century. Continued inaction on climate change risks the end of modern civilization as we know it.
John Abraham at The Guardian says the leaks of the draft are meant to disrupt the process, and suggests looking to the body of science from which the report is compiled to make predictions about what it will contain:
The new report will describe how climate changes are continuing without abatement. In particular, temperatures are rising, oceans are heating, waters are rising, ice is melting, the oceans are acidifying, heat is even moving to the deepest parts of the oceans. Just as importantly, the report will show that these changes are largely human-caused.
Some items are worse than we thought. In the last report, ice loss, particularly from Greenland, was a minor issue. Now, it is clear that not only Greenland, but also Antarctica are melting and this melt is raising sea levels. Furthermore, Arctic sea ice is being lost faster than previously reported.
He concludes by wondering how many warnings like this we need before humanity takes action:
the IPCC has done its job. For this fifth report, they have synthesized the science and provided enough evidence that action is warranted. How many more reports of this type do we need? Will a sixth report that confirms what we already know make much of a difference? Will a seventh? Do these reports need to be written every 5-6 years? Perhaps one a decade would be sufficient? These reports require enormous amounts of time and energy. Scientists who take authorship roles put their own research on hold, sometimes for years.
Whatever the future holds for the IPCC, the history books will tell us we were warned.
Indeed we have been. Will it be enough to inspire the global community to act?
IMAGE: It's not a hockey stick, it's a scythe. Chart shows that finds that Earth is on track to become warmer than it has been in 11.3 millennia.