Guest essay by Eric Worrall
Christopher Reyer of the Potsdam Institute for Climate Impact Research, one of the authors of a 2014 world bank publication “Turning down the heat: Confronting the new Climate Normal”, has claimed in an interview that economic collapse will ensure we never achieve global temperature rises of 6-8c – he expects the global economy to start to falter, after we pass 2c of warming.
According to Reyer (talking about the climate in the year 2100):
I guess it should be between three and four degrees hotter. We used to think that we were headed for +8°C, but that will never happen. We are not even on track for +6°C because economies will be collapsing long before we get there. We know that after +2°C, dangerous things start happening, and we start passing crucial tipping points, like the West Antarctica ice sheet collapse, which has reportedly already begun.
Reyer also has some doom laden predictions for the year 2050:
What will a two degrees warmer world, which we seem likely to inhabit by 2050, look like?
“Two degrees is not a picnic either. Imagine events like the 2003 European heat wave, the 2010 Russian heat wave which had repercussions on the global wheat market, and Hurricane Katrina, all of them happening simultaneously everywhere in the world.”
CO2 levels were around 1700ppm in the Cretaceous, 4x higher than today.
The Cretaceous lasted for 80 million years, so the 4c warmer, 1700ppm CO2 climate was a stable climate, by any reasonable measure. The ecosystem which gave birth to all those textbook pictures of tropical jungles and dinosaurs tramping about – that simply couldn’t have happened, in a world whose life support systems were on the brink of failure. In fact, the age of the dinosaurs didn’t fall, until a huge meteor struck the earth around 66 million years ago, and killed 3/4 of all living species.
The most productive regions of the world, food wise, are the tropics. Indonesia, with a land area of 1.9 million square kilometres, 1/5 the size of the USA, supports a population of 237 million people – many of whom survive by subsistence agriculture. If the USA had a similar climate to tropical Indonesia, it could potentially support a population of 1.8 billion people – even using the subsistence agriculture employed by many Indonesians.
Suggesting that a 4c warmer world would be a dying world of broken eco-systems and failed nations seems utterly implausible. As the Cretaceous period proves beyond reasonable doubt, as the global experience of tropical agriculture demonstrates, warm climates are incredibly abundant and supportive of living ecosystems, and humans, who evolved in the hottest climate on Earth, are well able to thrive in such environments.
Would returning CO2 to 1700ppm even cause a 4c rise in temperature? This seems doubtful to me, because the geography and geology of the modern world is different to the Cretaceous. The rise of the Himalayas, and the formation of the Antarctic circumpolar current, have consolidated our brutally cold Quaternary climate of frequent glaciations. I suspect it would take a lot more than 1700ppm to overcome these geological disadvantages, and restore a more benevolent climate, than our current ice age prone Quaternary.