The Island of Doubt

No, there's no revolutionary finding that maybe the world isn't warming. At least, not yet. But a group of researchers has at least come across evidence that one of the dreaded feedback mechanisms that could accelerate the temperature rise beyond our ability to cope may not be such a threat after all. And just in time -- after all the fuss about record sea ice minima in the Arctic, we could use some good news.

The ecosystems in question are also in the Arctic. It's the not-so-permanent permafrost of the northern peatlands, terrain that has over the milennia sequestered oodles carbon, that has so many climatologists worried. If the permafrost melts, goes the nightmare scenario, the released methane and carbon dioxide will only cause more warming, producing a positive feedback loop that only ends when the atmosphere reaches a new equilibrium far too many degrees warmer than our species, and most others, have evolved to exploit.

James "Gaia" Lovelock and others who have already given up hope of mitigating our assault on the climate through the logical route of cutting fossil-fuel emissions, cite such scenarios to justify more drastic responses. In the current Nature, Lovelock writes:

Such feedbacks, as well as the inertia of the Earth system -- and that of our response -- make it doubtful that any of the well-intentioned technical or social schemes for carbon dieting will restore the status quo.

Lovelock argues that things are so bad that we should start investing in geo-engineering schemes to reverse the warming. He proposes "ocean pipes" to bring nutrient-rich deep waters to there surface where they would enhance algal growth that would drawn down CO₂.

We may yet come to such a point -- a point where we'll have no choice but to embrace strategies that even Lovelock concedes "may fail, perhaps on engineering or economic grounds. And the impact on ocean acidification will need to be taken into account."

Just last week, a Russian veteran of 30 years of permafrost studies reported that "as this organic matter becomes exposed to the air it will accelerate global warming faster than even some of the most pessimistic forecasts."

And try reading this excerpt from a Queen's University press release on Canadian Arctic research without raising your eyebrows:

From their camp on Melville Island last July, where they recorded air temperatures over 20°C (in an area with July temperatures that average 5°C), the team watched in amazement as water from melting permafrost a metre below ground lubricated the topsoil, causing it to slide down slopes, clearing everything in its path and thrusting up ridges at the valley bottom "that piled up like a rug," says Dr. [Linda] Lamoureux, an expert in hydro-climatic variability and landscape processes. "The landscape was being torn to pieces, literally before our eyes. A major river was dammed by a slide along a 200-metre length of the channel. River flow will be changed for years, if not decades to come."

But now comes a welcome contrarian prediction that at least on the subject of melting permafrost, things might not be so bad after all. Writing in Global Change Biology, ecologist Merritt Turetsky of Michigan State University and colleagues find evidence for a negative feedback mechanism, one that Science magazine cleverly describes as "A Climate Bomb Defused?"

Instead of producing more warming, changes in the peatlands due to climate change could actually foster increased plant growth that could draw down more carbon that the melt releases.

Net organic matter accumulation generally was greater in unfrozen bogs and internal lawns than in the permafrost landforms, suggesting that surface permafrost inhibits peat accumulation and that degradation of surface permafrost stimulates net carbon storage in peatlands.

Of course, eventually, the situation could reverse and the peatlands could become a net carbon source. The authors warn:

... in terms of radiative forcing, increased CH4 emissions to the atmosphere will partially or even completely offset this enhanced peatland carbon sink for at least 70 years following permafrost degradation.

And Science's Noreen Parks ends her coverage of the study with on an ominous note:

The study does a "stellar job at pulling together the links among carbon, water, and plant ecology," says arctic biologist Jennifer Harden of the U.S. Geological Survey in Menlo Park, California. But the benefit of thawing peatlands could be even more ephemeral in the future. Increasing fire activity in boreal and subarctic regions--almost certainly a direct result of enhanced summer drought over the past 50 years--"doesn't bode well for peatlands," she says, noting that if peatlands dry out rapidly and burn, they could release loads of carbon dioxide.

Oh well, at the very least, the conflicting science of the future of the Canadian and Siberian tundra leaves us with considerable doubt on one facet of the problem. And these days, a little doubt is about all we can hope for.