This week’s Nature has an extended climate special made of original research papers, features, commentaries, editorials, essays and book reviews. Here’s the content at a glance.
An uplifting read the package is not, but this will hardly surprise devoted readers of these pages. What’s it all about then? Well, Gavin Schmidt and David Archer, in their news and views piece, get to the heart of it: “Dangerous climate change, even loosely defined, is going to be hard to avoid.”
Malte Meinshausen and colleagues find that cumulative emissions from 2000 to 2050 of about 1,400 billion tonnes of CO2 yield a 50% probability of exceeding 2 °C warming – the somewhat randomly defined threshold of dangerous climate change – by the end of the twenty-first century Here’s an editor’s summary of the paper. Just to be clear: Known 2000-2006 emissions were almost 250 billion tonnes.
Myles Allen and colleagues take a slightly different approach to calculating the climate response to anthropogenic emissions. They show that cumulative emissions of one trillion tonnes of carbon (3,670 billion tonnes CO2) over the entire 1750-2050 period yield a 90% probability of warming between 1.3 and 3.9 °C above pre-industrial temperatures, with 2 °C of warming being the best estimate. About half a trillion tonne has been emitted since the onset of industrialization. Here’s an editor’s summary.
In clear, if we want a reasonably good chance of staying beyond 2°C warming, we cannot afford burning all the oil, gas and coal buried in the ground. We can’t actually afford burning more than half the proven reserves. If we continue burning fossil fuels at current rates we will leave the ‘safety zone’ in less than 20 years. Let’s face it: We have a bad hand – and we can’t bluff the planet.
The authors of the paper duo jointly discuss the implications of their dire findings in a Commentary which will appear today in Nature Reports Climate Change. They make a case for placing emission targets in the context of a cumulative carbon budget, rather than aiming at stabilizing atmospheric greenhouse gas concentrations at values which might prove ineffectual. Nature Reports Climate Change also has a feature by Mason Inman discussing uncertainties around the true value for climate sensitivity – the temperature response to doubling atmospheric CO2 – the alpha and omega of climate science, if you will.
Stephen Schneider ponders in his essay (subscription required) what the greenhouse world our grand children may be living in if our mitigation policies and technologies fail will look like. Suffice to say it could be a pretty bleak and barren place, particularly for the poor.
As things stand, picking ourselves up and dusting ourselves off won’t quite do. What we need is a plan to adapt to climate change, and we should be planning to adapt to at least 4 °C of warming, suggest Martin Parry, Jason Lowe and Clair Hanson in a commentary entitled ‘Overshoot, adapt and recover’ (subscription needed). Effectual adaptation measures, from improvements in water management to coastal protecting, will cost hundreds of billions per year, but they might be worth every single dollar, the trio argues.