Where I ended up after a series of happenings as described below, is concluding that we need a paradigm shift in our climate change aspirations. Instead of trying to limit warming to a point where we can avoid dangerous climate change, we need to recognize that we’ve already gone too far, that the climate is already dangerous, so we should aim to ratchet down GHG concentrations in the atmosphere to attain a safe climate.
1. Germans look to 7.4 trillion tons of fake snow to save the West Antarctic Ice Sheet
The target should not be 1.5°C; rather we should aim for a safe climate. James Hansen told us in 2007 that to achieve a safe climate we need to bring GHG concentrations down to 350 ppm as soon as possible. That’s CO2 equivalent, not CO2. Current CO2e is not often quoted, but would be around 500 ppm on the basis that CO2 is about 80% of total GHGs. Also we need to focus on what we are doing to the planet over centuries and millennia, not just the next 50 to 100 years.
However, the IPCC team putting the report together were not asked what the goal should be. They were asked to build a scenario for achieving the 1.5°C warming limit specified as desirable in the Paris Agreement of 2015, and to look at the impacts of a 1.5°C world as against a 2°C world. Two Degrees came out of Europe in the 1990s, achieved a general currency, then became the official goal of at the Conference of Parties of the UNFCCC in Cancun in 2010. At that time there was a move mainly by many of the island states vulnerable it inundation for a more ambitious target. Essentially the whole group at Paris agreed to try.
However, while two degrees was commonly seen as a guardrail for a safe climate even by many scientist, it was never a scientifically derived goal for a safe climate.
The report predicts that half of the world’s identified tipping points – such as the collapse of polar ice sheets and the drying out of the Amazon rainforest – would be crossed under 2C warming, compared with 20% of them at 1.5℃.
Not just the hottest July, we’ve just had the hottest single month since records began in 1880. It’s also been the hottest first seven months of any year, so we are heading into new territory. Continue reading Climate clippings 153→
Back in 2011 David Spratt took a look at where we were in relation to temperature rise and the Holocene. At 2000 we were at 0.7°C above the pre-industrial temperature. This happens to coincide with the Holocene maximum:
Spratt says James Hansen warns that at 0.7°C the ice sheets start to become unstable, so in terms of sea level rise alone we are entering a danger zone. Since then the temperature has risen ~ 0.15°C.
The bottom line is that “aiming for the 2°C pathway would be foolhardy” because it “would have consequences that can be described as disastrous”. The authors believe that humanity and nature, the modern world as we know it, is adapted to the Holocene climate that has existed more than 10,000 years. Departing from this climate by more than 1°C would have intrinsically harmful effects. At 2°C these effects become unacceptably severe. Moreover we enter a zone where further feedbacks, such as ice sheet response, methane release and vegetation change, are likely to push the climate towards further warming, of probably at least 3°C.