Six Degrees

This posting is based on a Waikato Times column written in July.

The Royal Society in the UK awarded its 2008 science writing prize to Mark Lynas for his global warming book Six Degrees: Our Future on a Warming Planet. I found the book telling when I read it last year, and it was good to see it receive this confirmation.

Lynas’s first book High Tide, published in 2004, grew out of three years visiting parts of the globe where the signs of global warming were becoming evident – Alaska, Tuvalu, Mongolia, Peru, the US.  Six Degrees had a different genesis. It is the result of many months in the Radcliffe Science Library at Oxford trawling through scientific journals to find the peer-reviewed papers on which the book is entirely based.  The source material ranges from computer model projections to studies of climate in the past. Lynas is not a scientist, but he makes it his business to adequately understand and interpret what the scientists have written in their specialist fields.

Sceptics often scoff at computer models as somehow fiddled in advance, but Lynas points out that they are based not on subjective judgements by their constructors but on the fundamental laws of physics.  They have grown increasingly sophisticated and the insight they offer into likely future conditions on the planet is something humanity has never had access to before.  One check on their accuracy is ‘hindcasting’ the 20th century, and some of the most powerful recent models have done this with almost unerring accuracy.  Not that Lynas suggests that they are infallible in their forecasts.

Six Degrees is a highly readable narrative for the general reader, tracking through what changes can likely be expected from each degree of global warming from one degree through to six degrees, the upper limit for worst case scenarios.

Even at what may seem comparatively low rises of one or two degrees centigrade he finds plenty to cause alarm. A few of his examples:  possible desertification and abandonment of agriculture over millions of square kilometres in the US, an extremely hot and drought-ridden Mediterranean Europe, an ice-free Arctic ocean with implications still difficult to understand, the bleaching and likely death of many coral reefs, major loss of food production in India, serious population displacement in Bangladesh. On through three and four degrees the book points to desertification intensifying in many places, water supply severely declining in Pakistan, the Amazon rainforest dying, far more of Australia burning and suffering serious drought, the West Antarctic ice sheet facing collapse, sea levels rising threateningly. Five and six degrees hardly bear contemplating as the possibility is faced of methane hydrates on subsea continental shelves becoming destabilised and venting into the atmosphere, adding an enormous feedback to global warming.

As a writer for the general public Lynas doesn’t shrink from putting emotional depth into his analysis.  He explains in a Guardian column: “If I’ve read a paper about coral bleaching or precipitation trends in the Sahel, I need to be able to describe what this means in the real world – grey weed creeping over once-vibrant coral reefs, and Sudanese herders struggling to feed their children as their livestock starves around them and a dust-storm looms on the horizon.”   However he sees his first duty as accurately representing what he has read in the scientific literature.   The Royal Society judges are clear that he has met this test. They state that the book provides a good overview of the latest science on the issue. An interesting response came from  Eric Steig, one of the contributing scientists to the Real Climate website, when he reviewed the book in Conservation Magazine. Initially he had assumed from news reports that the book was alarmist and probably not worth reading; however, after reading it he reported it firmly based on published scientific literature and nowhere exceeding those bounds. Alarming, yes, but not alarmist.

There is no escaping that the science is alarming. That is why this issue is of such overwhelming importance. Yet like most writers on the subject Lynas hopes that we can yet avoid the worst prospects. There is already unavoidable further warming ahead of between 0.5 and 1 degree Celsius, but it is possible that we might manage a ‘safe landing’ within the 1-2 degree corridor if appropriate action is begun now to drastically reduce greenhouse gas emissions.

This is the point at which the question moves from science into the realm of the political. We largely know how the needed reductions could be achieved.  The question is whether we find the collective will to do it.  The fact that that is still an open question indicates the full reality of the science has not dawned for enough of us.   Books like Six Degrees need wide readership. Hopefully the Royal Society prize will assist that.

It is worth noting that Six Degrees was published in America by National Geographic, which has also made a television documentary based on the book and broadcast on the National Geographic channel internationally. On a lighter note Lynas also achieved minor fame as a somewhat younger man in 2001 by throwing a cream pie at Bjorn Lomborg, the ‘sceptical environmentalist’. “I wanted to put a Baked Alaska in his smug face in solidarity with the native Indian and Eskimo people in Alaska who are reporting rising temperatures, shrinking sea ice and worsening effects on animal and bird life.”

Going, going, gone (by 2015)

One for the furry blogger with sharp teeth: the Winnipeg Free Press reports that University of Manitoba geoscientist David Barber is predicting that the Arctic will be ice free in summer in the next seven years.

“We’ll always have ice in the winter time in the Arctic, but it will always be first-year ice,” Barber said on Friday. He said he estimates the Arctic sea should see its first ice-free summer around 2015. “That has got industry very interested in the Arctic,” he said. “That will put more pressure there. The change is happening so quickly.”

Barber, who will be officially presenting his preliminary findings at the International Arctic Change 2008 conference in Quebec City next week, was the scientist in charge of the Circumpolar Flaw Lead System Study (CFL), a $40-million Arctic research project.

A newcomer to the form book, Barber’s track record is yet to be established. But he’s clearly a runner. And that sounds like a conference to watch…

(See also Spiegel Online – h/t S Bloom Esq)

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The cracks are showing #2 (polar notes)

wilkins26nov480.jpg

Summer’s arriving on the Wilkins ice shelf, and its disintegration continues. New cracks are threatening to destroy the ice “bridge” that’s been holding the ice shelf pinned between Charcot Island (top left) and the Antarctic peninsula. This picture, captured by the European Space Agency’s ENVISAT satellite on November 26, shows the new cracks (coloured lines) and the dates they first appeared (NASA version here). If the chunk of ice under “21 July” breaks away, the long thin bridge will lose support and follow suit, the ESA analysts say.

Meanwhile, a team lead by Richard Alley at Penn State has worked out that ice shelf calving – where icebergs break away at the edge of an ice shelf – is critically influenced by the rate at which the ice shelf is spreading out. The PSU release notes:

For iceberg calving, the important variable — the one that accounts for the largest portion of when the iceberg breaks — is the rate at which ice shelves spread, the team reports in the Nov. 28 issue of Science. When ice shelves spread, they crack because of the stresses of spreading. If they spread slowly, those cracks do not propagate through the entire shelf and the shelf remains intact. If the shelf spreads rapidly, the cracks propagate through the shelf and pieces break off.

When ice shelves break up, the glaciers that feed them can speed up noticeably, dumping more ice into the ocean. Over recent years, the role of water as a lubricant for glacier flow has been receiving a lot of attention (rubber ducks were recruited as under ice research tools in Greenland this year), and the BBC reports that a sub-glacial “flood” under the Byrd Glacier which feeds ice at the rate of about 20 billion tonnes a year into the Ross ice shelf caused that to increase to 22 billion tonnes over 2006. It has since returned to normal.

Up north, the NSIDC reports (Dec 3) that it continues to be warmer than average, even though the sea ice is now covering the whole Arctic ocean.

In the heat of the (Arctic) night

LWOct2008.gif Time for an Arctic update and a bit of “original” research. There’s been quite a bit of polar news around, and a rapid freeze-up is underway in the Arctic – so rapid that some are declaring that the sea ice is “back to normal” for the time of year, based on this graph from the Arctic Regional Ocean Observing System in Norway, which shows sea ice area climbing up towards to the average for 1979-2007, within one standard deviation (the grey area). On the other hand, if you look at the equivalent graph at Cryosphere Today, you’ll see that ice area is 1.25m km2 below the average – which in CT’s case is 1979-2000. So the ice is approaching normal, only if you define “normal” as including the significant ice reductions over the last seven years. How encouraging. But this autumn’s freeze-up has been pretty rapid. Does that mean that it’s been unusually cold up there? I thought I’d take a look…

Continue reading “In the heat of the (Arctic) night”

Something in the air (methane mystery)

arcticmethane.jpgAtmospheric methane levels “shot up” in 2007, according to a paper in this week’s Geophysical Research Letters (MIT news release — Rigby, M., R. Prinn, et al (2008), Renewed growth of atmospheric methane, Geophys. Res. Lett., doi:10.1029/2008GL036037, in press. PDF here for AGU members.). This confirms NOAA’s announcement in April that methane levels were on the increase after a decade of stability, but adds a new twist to the data.

One surprising feature of this recent growth is that it occurred almost simultaneously at all measurement locations across the globe. However, the majority of methane emissions are in the Northern Hemisphere, and it takes more than one year for gases to be mixed from the Northern Hemisphere to the Southern Hemisphere. Hence, theoretical analysis of the measurements shows that if an increase in emissions is solely responsible, these emissions must have risen by a similar amount in both hemispheres at the same time.

A rise in Northern Hemispheric emissions may be due to the very warm conditions that were observed over Siberia throughout 2007, potentially leading to increased bacterial emissions from wetland areas. However, a potential cause for an increase in Southern Hemispheric emissions is less clear.

A possible explanation might be a global reduction in the amount of hydroxyl free radical (OH) in the atmosphere. OH “mops up” methane (and other stuff), and is sometimes called the atmosphere’s cleaner or “detergent”. Unfortunately, measuring atmospheric OH is difficult.

“The key thing is to better determine the relative roles of increased methane emission versus any decrease in the rate of removal,” Prinn said. “Apparently we have a mix of the two, but we want to know how much of each” is responsible for the overall increase.It is too early to tell whether this increase represents a return to sustained methane growth, or the beginning of a relatively short-lived anomaly, according to Rigby and Prinn.

Any increase in atmospheric methane is not good news. A possible reduction in OH is also disturbing, because it might indicate that pollution (from all sources, methane, industry, coal burning etc) is beginning to overwhelm the atmosphere’s ability to cleanse itself. Both together would be very bad news indeed.

[Update: Comments from a CSIRO scientist and co-author here.]

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