4 degrees and counting
I don’t often use this blog to summarise single articles, but a recent New Scientist has an article in it which is in urgent need of summary (the full article is behind the NS paywall).
The piece, called Global Warning, written by Michael le Page, observes that if the 2007 prognosis of the IPCC was gloomy, the next one ought to be even grimmer. Le Page offers seven reasons why: in a nutshell, our earlier climate change models didn’t have sufficiently strong system-wide feedback loops in them, and despite our knowledge of climate change science we’ve done nothing meaningful to change our behaviour. Here’s a summary of the seven reasons.
1. The Arctic is warming faster then predicted.
The Arctic winter refreeze has already stopped compensating for the summer melt, and white ice (which reflects heat) has given way to heat absorbing dark water. For this and other reasons, the Arctic is warming twice as fast as anywhere else on the planet. At the end of this summer only a quarter of the Arctic ice was still covered with ice – a record low. This may be a blip, but the trend is clear. We will see ice-free summers in the Arctic far sooner than the end of the century projected by the IPCC – and possibly as soon as the end of the decade.
2. Extreme weather is getting more extreme.
40 degree heatwaves in Russia, extraordinary blizzards in the US, torrential summer rainfall in the UK. Of course it’s impossible to know how much of any single weather event is down to climate change, but the pattern is clear; there is more extreme weather about, and it is more extreme than it was predicted to be. As with Arctic melt, heatwaves as strong as those in Europe in 2003 and 2010 were predicted to occur only towards the end of the century.
3. Food production is taking a hit.
The 2007 IPCC report predicted that some warming ([correction] 1.5-3.5 degrees) would increase food production, at least in temperate areas. But with warming still well below this level, it seems that climate change is having the opposite effect. Stanford University research suggests that average yields in a range of staples are 1% below than they would have been without warming. Expect to see some innovation in heat-resistant crops, and larger changes in what is grown where, and how it is grown.
4. Sea levels will rise faster than expected.
At the heart of Greenland’s vast ice sheet summer temperatures normally stay comfortably below freezing. Not this year: in July temperatures rose above zero. At one point 97% of the sheet’s surface was melting, causing flooding. The latest modelling suggests that the planet will warm enough to remove Greenland’s ice sheet, although there is uncertainty as to when. At the same time projections that the Antarctic ice sheet would grow seem to have been wrong. Glaciologists now expect at least sea level rises of a metre by 2100, possibly even two metres. Enough, in other words to flood coastal cities, or make them vulnerable to storm surges.
5. Greenhouse gas levels could keep rising even if emissions stop.
Only half of the CO2 we emit ends up in the atmosphere. the other half is absorbed by land and sea. But as levels rise they absorb less, and eventually start to emit CO2 themselves. It gets worse. Although the 2007 IPCC report included increasing carbon feedback from soil and sea, it didn’t include the possibility of carbon being released from permafrost or the seabed’s methane hydrates. This could add anything from 0.25-1.00 degrees to exisitng projections. One of the few balancing features of the carbon cycle is that warming stimulates plant and tree growth, and these then absorb more CO2. But the latest research suggests that these have been over-estimated. And these models also suggest that under some circumstances carbon feedback loops could create a self-perpetuating cycle of carbon release.
6. We’re emitting more than ever.
Of course, if we stopped emitting tomorrow, we might still avoid the worst temperature increases. But apart from a small reduction in 2008, the year of the financial crisis, emissions keep on rising. They are near the worst end of the IPCC’s 2007 scenarios, and therefore on course – even on the IPCC’s existing models – for 4 degrees rather than 2.
7. Heat stress means big trouble.
Recent research suggests that the effects of climate change on human health and productivity have been under-estimated. The critical data point is the so-called ‘wet-bulb’ temperature which gives a good gauge of both heat and humidity. Humans can’t survive wet-bulb temperatures of more than 35 degrees for long. At the moment the hottest areas reach 31 degrees, but warming could change this in swathes of Asia, Africa, Australia, Brazil, India and the US.
In other words, as Le Page observes:
“The ‘best estimates’ are now between 5 degrees C and 6 degrees C by 2100, with roughly a 10% chance of a rise to 7 degrees C. This means many of us are likely to live long enough to live long enough to experience severe global warming.”
I could offer an eighth reason as well: that if the IEA’s latest Energy Outlook is to be believed, our addiction to oil is such that we are ready to drill for every last carbon-intensive drop of the stuff that we can find, in tar sands, shale and so on.
If America is really going to be a larger oil producer than Saudi Arabia in 2020, the climate consequences are horrific. Fortunately more sceptical analysts have good reasons to believe that the IEA’s case is over-stated. But it’s the tiniest of glimmers on a grim horizon, and – of course – all the finance that goes into the identification and production of this high carbon, energy intensive oil is money that could have been spent on developing renewable energy resources. In the parallel universe where fracking is banned as being environmentally dangerous, where people have more regard for inter-generational consequences, and policy makers read New Scientist, it is.
The image at the top of the post shows NASA images of the rapid melting of Greenland’s ice in July this year.