A FAREWELL TO ICE

Peter Wadhams was Professor of Ocean Physics from 1992 to 2015, and has devoted his entire career to the study of the Arctic, making more than 50 expeditions to both polar regions. As such, we should take his 'report from the Arctic' very seriously as it is based on research and first-hand experience, not just on extrapolating computer models. Readers can consult his own literally chilling summary in the Articles section. In contrast with the first pictures from 1969, photographs from space show the top of the world in northern summer as blue rather than white. I have been following the Arctic debate for a number of years, and think it is right to assert that the sea ice situation is the canary in the mine of planetary climate change.

The book begins by explaining the background of the Arctic, the nature of ice, the history of ice on planet Earth and the modern cycle of ice ages. It is striking that previous geological changes took place over thousands of years, while the current global warming to 404 ppm of CO2 in the atmosphere has occurred in less than 100 years. The average concentration of CO2 during interglacial periods is 280 ppm, falling off to 180 ppm during ice ages. Peter then explains the nature of the greenhouse effect and the direct correlation between adding carbon dioxide to the atmosphere and temperature rise (p. 52). Greenhouse gases produce 'radiative forcing' that upsets the natural thermal balance of the planet, while 'Arctic amplification' explains why changes due to global warming happen first in the Arctic.

Peter then moves on to the history of Arctic sea ice melt back, using his own data both in terms of extent and thickness. Even by the 1990s, the ice thinned by 43% relative to the 1970s and the overall pattern is inexorably downwards, as illustrated in a chart showing what he calls the death spiral of Arctic ice. A further factor precipitated by open water is that wind can further break up the ice. The history is illustrated with useful comparative charts. The key question is whether we have passed the tipping point in terms of the possibility of substantial multi-year ice cover to reform. Peter thinks we may well have, and is critical both of scientists who rely on models rather than data, and more seriously of the IPCC 2013 report, which relies on a linear rather than nonlinear analysis and contains some dubious statistics (p. 90).

His next chapter explains eight forms of positive feedback that are likely to accelerate the melting effects. The most serious of these are ice-albedo and snowline retreat feedbacks, whose combined effects amplify the radiative forcing effect of CO2 by 50%. Then we should not forget ocean acidification feedback, which has already had a catastrophic effect on marine life and coral reefs. Arctic methane is described as a catastrophe in the making that could potentially lead to a further temperature rise of 0.6°C by 2040. As Peter points out, this is surely a case where the precautionary principle and risk analysis is urgently required. It is also possible that this could be amplified by permafrost melt. Some of our disruptive weather patterns seem to be due to increased meandering of the jet stream, also related to Arctic warming. The mechanisms are by no means clear, and Peter cites a number of models and references. However, disruptive weather is likely to exacerbate volatility in food production, especially as population is forecast to increase to 9.5 bn by 2050 and 11.2 bn by 2100.

There is a very interesting chapter on the Antarctic, where Peter explains the very different situations and ways in which sea ice is formed. The advance of sea ice in that region is often cited by sceptics as a criticism of global warming, but the situation is in fact more complex with regional variations, and it is likely that changing wind patterns are a critical explanatory factor. The Pacific sector has in fact warmed twice as fast as the rest of the continent so that while the western sector is shrinking, the eastern sector is growing, resulting in a slow net growth. However, this does not alter the fact that it is the Arctic that will determine the rate of global warming.

Peter now turns to the state of the planet, arguing that CO2 at 404 ppm is already too high for non-destructive climate change, especially as carbon emissions are not even beginning to slow. He returns to the question of population, showing that the population of Africa is anticipated to quadruple between 2015 and 2100, even though it is already in a situation of not able to feed itself. Personally, I find these projections extraordinary, precisely for that reason. Peter rightly notes that our current financial and economic system cannot lead to a sustainable equilibrium society. The magnitude of the challenge is illustrated by asking how long it would take to reduce current CO2 levels from 404 ppm to 280 ppm if we stopped emitting CO2 altogether. Due to the survival time of the gas, it would take 45 years to bring the level down even to 350 ppm, so further increase looks inexorable, not least because carbon remains in the atmosphere for 100 years.

So what can be done about it? An important part of Peter's recommendations is the urgent need for a new Manhattan Project to clean up our atmosphere. He references the important 2009 geo-engineering report from the Royal Society explaining two possible approaches of solar radiation management and carbon dioxide removal. SRM in terms of stratospheric aerosol spraying is at best a sticking plaster, as he points out, since it does nothing about the causes of global warming nor does it affect ocean acidification. More seriously, it requires constant application and the toxic chemicals fall back down to earth, which may also have an effect on water and food. In my review of Experiment Earth in the last issue (p. 54), I cited evidence that this may already be occurring, and will ultimately result in white rather than blue skies. Peter also discusses carbon drawdown and the possibility of direct air capture, which is not yet been developed. He also mentions new forms of nuclear power using pebble bed and thorium reactors. The need for geo-engineering is a drastic prospect, but Peter feels this will need to start by 2020, especially as there is little or no prospect of any serious reduction in CO2 emissions. He points out that the Paris Agreement will still leave us with a warming of at least 2.7°C even if all national commitments are honoured, which is vanishingly improbable. There are no plans for immediate action, 'and no date set for achieving carbon balance sat between 2050 and 2100, when current politicians will either be retired or dead.

In his last chapter, A Call to Arms, Peter states that it is not enough to reduce carbon emissions, hence the need to remove dioxide from the atmosphere. Interestingly, he quotes a speech by Margaret Thatcher to the UN in 1989, for which he provided the text - even then, he was warning of runaway climate change through feedback amplification. As readers will be aware, the political situation is further complicated by well funded institutes denying global warming and attacking leading scientists like James Hansen. In the UK, Nigel Lawson's Global Warming Policy Foundation plays a leading public role, and Peter Lilley called Peter a 'well-known alarmist' after he himself had published a report funded by the above foundation recommending no action on climate change and ignoring the Stern review. Although there are small actions that we can take as individuals, I was persuaded by Peter's analysis that we should all be vocally supporting his proposed new Manhattan Project to undertake a colossal scientific and technical research programme on clean energy as well as technologies for carbon dioxide removal. As a citizen of planet Earth, this book is compulsory reading.