Saturday, January 21, 2017

‘A Cat in Hell’s Chance’ – Why We’re Losing the Battle to Keep Global Warming Below 2C

It all seemed so simple in 2008. All we had was financial collapse, a cripplingly high oil price and global crop failures due to extreme weather events. In addition, my climate scientist colleague Dr Viki Johnson and I worked out that we had about 100 months before it would no longer be “likely” that global average surface temperatures could be held below a 2C rise, compared with pre-industrial times.

What’s so special about 2C? The simple answer is that it is a target that could be politically agreed on the international stage. It was first suggested in 1975 by the environmental economist William Nordhaus as an upper threshold beyond which we would arrive at a climate unrecognisable to humans. In 1990, the Stockholm Environment Institute recommended 2C as the maximum that should be tolerated, but noted: “Temperature increases beyond 1C may elicit rapid, unpredictable and non-linear responses that could lead to extensive ecosystem damage.”

To date, temperatures have risen by almost 1C since 1880. The effects of this warming are already being observed in melting ice, ocean levels rising, worse heat waves and other extreme weather events. There are negative impacts on farming, the disruption of plant and animal species on land and in the sea, extinctions, the disturbance of water supplies and food production and increased vulnerability, especially among people in poverty in low-income countries. But effects are global. So 2C was never seen as necessarily safe, just a guardrail between dangerous and very dangerous change.

To get a sense of what a 2C shift can do, just look in Earth’s rear-view mirror. When the planet was 2C colder than during the industrial revolution, we were in the grip of an ice age and a mile-thick North American ice sheet reached as far south as New York. The same warming again will intensify and accelerate human-driven changes already under way and has been described by James Hansen, one of the first scientists to call global attention to climate change, as a “prescription for long-term disaster”, including an ice-free Arctic. (...)

Is it still likely that we will stay below even 2C? In the 100 months since August 2008, I have been writing a climate-change diary for the Guardian to raise questions and monitor progress, or the lack of it, on climate action. To see how well we have fared, I asked a number of leading climate scientists and analysts for their views. The responses were as bracing as a bath in a pool of glacial meltwater.

by Andrew Simms, The Guardian |  Read more: