MITers and "roulette wheel" of temperature increases

Total warming of 10F means a very different world, one in which the natural world is decimated and feeding current and projected populations is impossible.

The report, which was the subject of stories earlier this year, has just been published in the prestigious Journal of Climate. If the report is correct, the survival of most people on Earth is at risk. A 10F warmer planet will support many billions fewer people, and with a transition period quite possibly marked by massive war and conflict. Any steps that save many lives are likely to be so draconian as to feel like wartime, even if implemented as benignly as possible.

The natural environment would become unrecognizable and sparse, with no time available for migrations and evolution to preserve anything resembling current diversity.

The projected increase is much higher than projected in a 2003 study by the same group, which projected roughly half the warming. (Even the 2003 MIT results were higher than those used in the IPCC 2007 reports and Al Gore’s An Inconvenient Truth.)

What’s changed is a better understanding of how much CO2 growing economies are likely to emit (backed up by big recent increases from India and China), more knowledge of how some 20th century warming was actually masked by volcanoes – demonstrating high temperature sensitivity to greenhouse gas emissions – and a lowered projection of the rate of heat transfer to the deep oceans.

The warming predicted by the report is also likely to be an underestimate. That’s because the report doesn’t take into account many likely feedbacks from climate change, such as increased emissions of CO2 and methane from melting permafrost in the north. These emissions would likely increase temperatures several degrees further, as unimaginable as that is.

How will the world know whether the MIT report is an outlier, or a new basis for planning in reacting to climate change? Confirmation will require additional work, and new publications, from others. Fortunately, the report comes out in plenty of time to be included in the upcoming 2014 IPCC report, which represents the agreed view of the world’s governments. (Not the world’s scientists, as commonly believed.)

Though strongly conservative, and usually containing underestimates of both current emissions and near-future changes, the IPCC report at least brings together a range of views. In the next report, the MIT results should either be sharply criticized, or substantially confirmed.

If one has to start making bets today, though, the MIT projections are hard to contradict. The report takes into account a wide range of historical data and predictions of current effects that have been tested against emerging realities in recent years. Most climate feedbacks are turning out to be more strongly positive and faster-acting than previously predicted.

For instance, the North Pole’s ice cap was recently predicted to disappear at the end of the century. Scientists have been stunned by its recent collapse, with its disappearance in summertime now projected for perhaps 2030, or earlier. While it’s easy to identify carbon sources, damage to carbon sinks, and interactions that might make things worse, there’s very little that’s obvious out there that would lessen warming – no new carbon sinks that seem to be on the verge of activation, for instance.

In upcoming posts, I’ll discuss the range of policy actions still available and how they might possibly slow – not stop – warming, and how communicators and others should treat this report.

• The environment absorbs less CO2. About 50% of our current emissions are absorbed by the environment – roughly half of that by the oceans, the other half by plants on land. This uptake of CO2 by the environment may already be in decline.
• Reflection of sunlight drops. As snow and ice cover retreat – as cover is smaller in geographic extent, or seasonal cover lasts for less of the year – dark ground and even darker water are exposed, which absorb sunlight, further warming the earth.
• More CO2 and methane are emitted from nature. Soils, forests, peat, the seas, organic deposits in permafrost, and methane clathrates all emit some CO2 and methane. As the environment warms, “natural” emissions increase.

Less uptake of CO2, plus less reflecting of sunlight, plus more CO2 from nature, can add up to a self-sustaining cycle. Once begun, it might well not end until the uptake of CO2 by nature has largely stopped, there’s very little snow and ice left to reflect sunlight, and stored deposits of CO2 and methane are largely depleted.

When this has occurred, our planet would be a very different place. It might be 5-10C (9-18F) warmer, bereft of most of its living species, and substantially desertified, for a very long time to come.

In its 2007 Report, the Intergovernmental Panel on Climate Change, or IPCC, warned that global warming must be kept at less than 2C (3.6F) to give humanity a 50/50 chance of avoiding runaway climate change. This raises three questions:

• Is 50/50 a chance we want to take?
• Might the climate be more resistant to warming, perhaps giving us more breathing room?
• Might the climate be less resistant to warming? In particular, might runaway climate change have already begun?

This blog’s job is to help investigate these questions, from a science and technology journalist’s point of view. That is, not to do the scientific work to answer the question – no one person could do that – but to review the work that has been done, and new work as it comes along, with a view to answering this question.

I’ve already done a preliminary survey, and made some initial calculations, in my book, Runaway. My current hypothesis – and my personal belief – is that runaway climate change is inevitable, even if emissions from humanity stopped today.

I believe even more firmly that humanity will not do anything resembling halting emissions today, but will emit much more. Even if I’m wrong, and we still have a margin before runaway warming begins, we’re certain to bust right through it before we get a handle on our emissions. If and when we do so, we’ll then have to stop the mightiest genie ever let loose from any bottle, before it permanently changes the earth, and eliminates most or all of us in the process.