In 1999 NASA lost its $125-million Mars Climate Orbiter because spacecraft engineers failed to convert from Imperial to metric measurements when exchanging vital data before the craft was launched. Numbers are important!
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.
Hansen told the politicians that our production of greenhouse gases, principally CO2, N2O, CH4 and CFC, were warming the climate. He said temperatures would go up in the coming years: Continue reading Hansen got it right→
James Hansen said in his book Storms for my Grandchildren that if we burnt all the available coal, tars, and oil then the ‘Venus Syndrome’ would be a dead certainty, extinguishing life as we know it on the planet. He has now thought further and says that is not going to happen, the time-scales make it impossible. It would take 100 million years to get enough carbon into the atmosphere, and by that time much of it would be back on the sea floor.
However we are on a path to make living at low latitudes impossible, plus more than half the major cities in the world cling to the coastline and are subject to sea level rise. The world, he says, would become ungovernable.
A bit longer than 250 million years is when we had the Great Dying, the Permian–Triassic extinction event, when up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct. A mere 65 million years ago saw the extinction of the dinosaurs and the dawn of the Cainozoic Era. From a screenshot of this YouTube, this is how the continents were placed around the globe:
I can’t comment on his blog, because the Askimet software has got me marked as a pest, and my comments go straight to spam. There is no facility for telling Askimet I’m OK, so there it is, I’m as good as banned. So I’ll make my comments here, which are in any case longer than is form for comments there.
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℃.