“Six Degrees: Our Future on a Hotter Planet,” Mark Lynas

Caspar Henderson
25 March 2007


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"Six Degrees: Our Future on a Hotter Planet"

Mark Lynas

Fourth Estate | March 2007 | ISBN 0007209045


What we are seeing now, in regard to climate change, are the consequences of what we did some time ago. We cannot see directly the impact of what we are doing right now.

What the scientists are saying is complicated, of course, but generally it boils down to this: Anything more than a rise of something like 2 degrees Centigrade (3.6° Fahrenheit) in average global temperature is bad news. (For graphics that say it all, go to the fifth page of this document or the second page of this one.)

The good news is that many sane people and some large institutions recognise this. The European Union, for example, has championed 2°C for some time. Empty words from politicians or part of a basic charter for the twenty-first century? As long as everyone else gets serious about reducing the probability of a temperature rise exceeding about 2°C, there's a chance that climate change will be manageable.

So much for the theory. In practice, what to do?

One of the things that can help change minds and society is a good book. Silent Spring by Rachel Carson is probably the best-known example. Writing in 1962, Carson warned that the reckless use of artificial pesticides and herbicides over the previous twenty years risked devastation for life on Earth. Today the greatest environmental threat stems not from complex artificial chemicals but from an excess of a naturally occurring, simple compound - carbon dioxide.

Shelf-loads of books warn of the dangers of CO2 and how to deal with it. Six Degrees by Mark Lynas is one of the better recent efforts. Lynas, whose earlier High Tide was noted on openDemocracy here, structures his new book around what could be the impacts of increases in average global temperature of one degree through six degrees. It is a clever presentational device, and will help general readers get to grips with the issues.

Easing in, Lynas explains: "...most people have [no idea] what two, four or six degrees average warming actually means in reality. These sound like very small changes when the mercury swings by fifteen degrees between day and night ... it doesn't mean the end of the world, it means we can leave the overcoat at home ... But six degrees of global average change is an entirely different prospect.

"Consider this: 18,000 years ago, during the deepest freeze of the last ice age, global temperatures were about six degrees colder than today ... Where I sit writing, in [southern England], would have been just a dozen miles from the southern edge of the ice sheet, a freezing polar desert blasted by dust-laden winds and suffering winter temperatures as low as -40°C."

Six Degrees is a handy and pretty heroic summary, in accessible language, of several hundred peer-reviewed scientific papers relevant to rapid climate change. In describing vividly, and in one place, the likely and the possible consequences of our actions, the book helps to concentrate the mind. Although the prose isn't helped by some clichéd writing - "The choice is ours ... the clock is ticking" - I recommend Six Degrees, with caveats that include the following six.

First, the cover illustration is unhelpful. It would take sea-level rise of about 60 metres (190 feet) to submerge St Paul's Cathedral in London to its dome. As far as I know, no serious scientist is suggesting this will happen over the next few years or decades, which is how the cover is likely to be interpreted. (Some modelling indicates that if global average temperatures stabilise two degrees higher than those of the pre-industrial era, sea levels could rise by more than 50 metres, but that rise would take many thousands of years.)

Caspar Henderson is contributing a background paper to the 2007 United Nations Human Development Report, which will focus on climate change. His most recent article on openDemocracy is a review of Coral by Steve Jones

The melting of the Greenland ice sheet - which many scientists consider one of the more likely climate-change tipping points - could raise sea levels by five to seven metres. Until recently it has been thought this could take millennia; now, however, some scientists argue that it could take much less time. A five-metre sea-level rise would be enough to devastate large areas of London and many other major cities, but not to wipe them out completely.

Second, to say a "degree by degree guide to the planet's future" is "unique" is not right. A version goes back at least to the "burning embers" graph in the Intergovernmental Panel on Climate Change's (IPCC) Third Assessment Report of 2001. The environmental group WWF has used a similar approach, and did the British government's 2006 Stern Review on the economics of climate change, which includes the two graphics mentioned at the top of this article. Six Degrees does, however, give a compelling narrative form to the whole.

Third, a little too much of the uncertainty in the science and the complexity of the context in which climate change is taking place is sometimes ironed out in the interests of a good story. Take the account of Amazon "dieback", a finding that if the global temperature rises by more than about 3°C, then the remaining rainforest dies, releasing more CO2 and driving global temperatures another 1.5°C higher.

Scientists consider some dieback to be more likely than not if present trends continue. But my impression - based on what some researchers are saying, and on observing and talking to delegates at a recent major conference on the future of Amazon (see here and here) - is that a lot, including aspects of the modelling, is still uncertain.

This is not to say the future of Amazon basin looks bright. Direct human impacts, including those associated with expanded ranching and ethanol production, may be even greater threats. But if these challenges are tackled effectively, the forest may be more resilient, under certain circumstances, to climate change. This slightly more subtle message is unlikely to be one the general reader will take away from this book.

Fourth, Six Degrees lays itself open to being read as if a 6°C rise over the twenty-first century is inevitable if emissions increase at the rates that currently seem likely. Lynas acknowledges this pitfall in his introduction: "...a temperature-based approach makes giving dates very hazardous. The world could become two degrees warmer by 2100, or it could already have hit that level as soon as 2030". But he is bound by the straightjacket of the book's structure. On page 102, a temperature rise of 0.4°C per decade is described as a "likely scenario"; page 127 points to a 3°C rise by 2050; on page 223, 5°C is "a few decades from now"; and chapter 6 outlines a scenario for 6°C by 2100.

Such a rate of change is possible. The summary of the IPCC's Fourth Assessment Report, for example, indicates a rise by 2100 in the range of 1.1 to 6.4°C, depending on various factors. The IPCC says that with a doubling of atmospheric CO2, the most likely rise is between 2° C and 4.5°C, with a best estimate of about 3°C. Warming over the next two decades, the climate panel says, is likely to be about 0.2°C per decade.

But even if climate sensitivity is at the higher end of the predicted range, that does not necessarily mean the consequences will play out over the next ninety to one hundred years. And climate change doesn't have to happen before 2100 to be bad news. Climate tipping-point guru John Schellnhuber gives the example of an unstoppable mobilisation of methane clathrate. It could, he says, be set in motion this century, but could about take a thousand years to fully play out.

Fifth, Six Degrees makes only a brief contribution on perhaps the biggest of all questions: what humanity needs to do. It notes, correctly, that some official statements by the British government regarding emissions reduction have been excessively cautious.

There was, for example, an inconsistency between some work commissioned for the landmark 2005 conference Avoiding Dangerous Climate Change - which suggested that a target for atmospheric concentrations of greenhouse gases of 450 parts per million C02 equivalent would be prudent - and statements in 2006 by the British government's chief scientist, David King, that stabilisation at 550 ppm would be acceptable. Six Degrees does not mention that the influential Stern Review also finessed this issue.

The book makes the familiar and, in my view, correct criticisms of biofuels as likely to provide only a small contribution to a solution, and with significant downsides. It concludes that individual carbon rationing is the key to progress. Rationing is a fashionable idea, and may have some merit, but is not itself a solution. An individual rationing system can only make a useful difference once substantial emission reductions, and the means to achieve them, are agreed.

The sixth and final caveat concerns how this book and other alarming projections may shape feeling and action. The author writes that it does not occur to him to get depressed. He compares the situation to finding a fire in your kitchen: you don't just sit there getting depressed as the fire spreads; you do something about it. The analogy is beguiling, but not adequate. Climate change is bigger and more complicated, and can drive some very good minds to extreme statements.

Feeling overwhelmed and pessimistic is a rational first reaction following any thorough review of evidence and trends. This is why it is not always helpful to frame psychological reactions through the lens of denial: for many people, acceptance and fatalism would be more like it. It is also important to acknowledge fear and grief at what looks likely to the continuing loss of countless living forms.

It is probably necessary to work through all of these feelings to find hope that is well grounded, if there is any. Being solipsistic may help: having perceived and experienced even a fraction of wonderful existence is a good start. At least that experience has been real, something to give thanks for, and a place to start looking for hope.


A longer version of this review appears on Grains of Sand



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