Rob Lyons: Apocalypse Postponed (Again)
Even scientists at the forefront of climate-change alarmism accept the world isn’t warming as quickly as once thought.
‘Looking back, I underestimated the risks. The planet and the atmosphere seem to be absorbing less carbon than we expected, and emissions are rising pretty strongly. Some of the effects are coming through more quickly than we thought then.’ So said Lord Nicholas Stern, author of the Stern Review on climate change, in an interview at the Davos World Economic Forum last month. Well, Nick, if you’re having trouble sleeping at night, you should talk to some scientists – you might get a surprise.
One area that has attracted considerable attention is the lack of rising temperatures in the past decade or so. Climate sceptics have been loudly pointing at this fact for some time, but have been dismissed by what might be called the climate-change establishment. However, in recent months, there has been a quiet recognition that temperatures are not rising anything like as fast as expected, despite greenhouse-gas emissions galloping upwards.
For example, in December, the UK Met Office released a new forecast which suggests that not only have global temperatures not risen for over a decade but that they are unlikely to rise significantly in the period up to 2017. In a recent paper, the man most responsible for kickstarting the current climate alert, NASA’s James Hansen, and his colleagues note that the ‘five-year-mean global temperature has been flat for the last decade, which we interpret as a combination of natural variability and a slowdown in the growth rate of net climate forcing’.
None of this should be interpreted as meaning that either the Met Office or Hansen think global warming is over – far from it. But it does mean there is a recognition that the idea that there is a complete or near-complete understanding of the science is wide of the mark. This hiatus – if it is indeed just a pause – needs to be explained somehow.
More generally, there has been a scaling down of expectations on global warming, a fact well illustrated by the New York Timesenvironment writer, Andrew Revkin, in a recent blog post. Revkin observes that ‘there is an accumulating body of reviewed, published research shaving away the high end of the range of possible warming estimates from doubled carbon dioxide levels’.
Revkin quotes the well-known climate modeller James Annan, who in a recent blog post wrote about this issue of climate sensitivity – that is, how much the planet will warm if CO2 levels double: ‘[T]here have now been several recent papers showing much the same – numerous factors including: the increase in positive forcing (CO2 and the recent work on black carbon), decrease in estimated negative forcing (aerosols), combined with the stubborn refusal of the planet to warm as had been predicted over the last decade, all makes a high climate sensitivity increasingly untenable. A value (slightly) under 2 [degrees Celsius] is certainly looking a whole lot more plausible than anything above 4.5 [degrees].’ Most interestingly, Revkin quotes two of the noisier, anti-sceptic bloggers – Gavin Schmidt and William Connolley – agreeing with this assessment.
As far as Revkin is concerned, this doesn’t change the overall picture all that much: ‘the odds of substantial, prolonged and disruptive climate change (and changes in ocean chemistry) are still plenty high enough to justify a sustained push toward an energy menu that works for the long haul’, but the weaker pace of warming ‘could substantially expand the timescale on which decarbonisation of humanity’s energy menu would need to take place to blunt climate change’.
At a time when governments are still pushing expensive plans to cut emissions drastically, the fact that mainstream scientific opinion now thinks that a doubling of carbon-dioxide concentrations will produce a world which is significantly warmer than now, but by no means devastatingly warmer, is deserving of wider attention. To fail to recognise this point would be to skew energy policy towards drastic, costly and probably unnecessarily rapid emission reductions.