Johan Rockström: ‘We need bankers as well as activists… we have 10 years to cut emissions by half’ | Climate change | The Guardianhttps://www.theguardian.com/environment/2021/may/29/johan-rockstrom-interview-breaking-boundaries-attenborough-bidenAn emergency is calculated by risk divided by time. Risk is probability multiplied by impact. Scientifically, we now have a very unfortunate set of data in front of us. We know that the likely impact on humans of climate disruption, mass extinction and air pollution is very, very high indeed. The probability is also uncomfortably high. This adds up to a very high risk. Now divide that by time. We have unequivocal evidence that we have entered a decisive decade. If we have any chance to prevent the loss of more than a million species, we must halt biodiversity loss now, not in 20 or 30 years. If we want to have any chance of keeping global warming to 1.5C, we need to cut emissions by half over the next nine years. That is what the Nobel laureates and other scientists are speaking out about. This isn’t just a matter of raising the volume on the same old data - it is a new juncture. We are running out of time.
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we have passed three important tipping points: Arctic summer ice, tropical coral reef systems and parts of the west Antarctic have, as far as the latest science shows, reached the point of no return.We are also seeing more evidence of a weakening of the Atlantic meridional overturning circulation (AMOC) an effect of ice melt from Greenland and the Arctic that reduces the salinity and temperature gradient between warmer salty water flowing north from the equator and colder less salty water in the north atlantic, which in turn slows ocean and atmospheric currents, with impacts on regional climate systems such as the Amazon monsoon. Slower flow of warm waters from south to north, can also explain why the southern ocean is warming so fast, which in turn has led to accelerated melting of the west Antarctic ice sheets. These cascades are a core feature of a potential drift to a hothouse Earth.
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the forthcoming IPCC 6 (Intergovernmental Panel on Climate Change) assessment, which for the first time will show a change in the climate sensitivity range (the amount of warming projected by computer models if humanity doubles the amount of carbon dioxide in the atmosphere). In the five previous assessments, the IPCC estimated this range would be between 1.5C and 4.5C. In the sixth assessment that will be compacted. The higher point of 4.5C will remain, while the lower point will climb to 2.3C. This means
we no longer have a range that goes from a manageable 1.5C to disastrous over 4C. Now the range is from very dangerous (above 2C, which can lead to a hothouse Earth) to catastrophic (over 4C). If we continue as we are, we are very unlikely to remain under 2C in 30 or 40 years....
What we see in several of the model inter-comparisons coordinated by the World Climate Research programme is that if we completely halt all greenhouse gas emissions, then the ocean will mop up the damage done to the climate system. That is under the assumption that ocean currents continue operating as now and that there are no further nasty surprises. It would come with very negative secondary effects: long-term ocean acidification, damage to marine life and perturbations of the heat conveyor belt in the ocean. Despite that, overall,
I must admit I find it reassuring that the ocean might be able to continue buffering and ultimately clean up.
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Even after a period of overshoot, of challenging decades of air pollutants and climate extremes, if we can completely phase out greenhouse emissions and go to zero carbon in an absolute sense, then we still have a chance to return within a Holocene-like state....
All the cards need to be put on the table. The patient is sick and we must do a transparent diagnosis. We are clearly close to the point that can lead to disaster. A science based fear element is justified and important.
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In 2018, when Fridays for Future held its first international demonstration in Berlin, I invited Greta to come to the Potsdam Institute to meet our scientists and have a closed-door seminar on the latest climate research. She immediately said yes and I sent an electric car to pick up her and Luisa. Since then, many in the scientific community are informally offering our knowledge to Fridays for Future. They are hungry to learn.
I am in relatively frequent contact with Greta. I spoke to her this month. She had a session with the Swedish prime minister about a European green deal follow-up and wanted assessments. These are clever young people. Our exchanges are very informal. I do them because I think they are so fantastic and that they can make a real difference.
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I am also encouraged by the race to decarbonise in the global car industry, which is nothing less than remarkable. Here in Germany, I sit on the sustainability advisory boards both for Daimler lorries and Mercedes-Benz cars. A few years ago, a chief executive would never participate in such meetings now he is here frequently because the key discussion in the company is how to accelerate to net zero. That is what we are seeing across industry. Agriculture is lagging behind, but the debate there is becoming more mature. I am not as optimistic as Mann, but we have shifted the narrative and it is much more aligned with what is needed, namely, that the sustainability across different industries, now is understood as the path to profits and business survival.
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There is no plausible chance of an absolute zero landing by 2050. There will be a residual of at least 5 gigatonnes of CO2 equivalent a year by 2050, due to methane fluxes, difficult-to-debate sectors, slow transitions in many developing countries and invested assets that cannot be completely stranded.
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What is disturbing is when a company such as Shell puts out a scenario that it says is compatible with 1.5C and will reach net zero a few years after 2050. At first sight, Shell’s “Sky” scenario looks good, but scratch the surface and you see it is a seductive but completely incorrect analysis. It plans a very slow phase out of emissions, considerable overshoot and then a landing at zero emissions by 2070. It pushes this forward to 2058 by planting trees. That is an example of kicking the can down the road. This is not allowed. We have a responsibility to call out those who use “net” or “magic bullet” technological fixes such as carbon capture and storage and geoengineering to push emission reductions into the future. This has plagued discussion for too long. There has to be more independent and institutionalised ways of scrutinising this and holding commitments to account