Planet at risk of heading towards irreversible “Hothouse Earth” state

06/08/2018 - Keeping global warming to within 1.5-2°C may be more difficult than previously assessed. An international team of scientists has published a study in Proceedings of the National Academy of Sciences (PNAS) showing that even if the carbon emission reductions called for in the Paris Agreement are met, there is a risk of the planet entering what the scientists call “Hothouse Earth” conditions. A “Hothouse Earth” climate will in the long term stabilize at a global average of 4-5°C higher than pre-industrial temperatures with sea level 10-60 m higher than today, the paper says. The authors conclude it is now urgent to greatly accelerate the transition towards an emission-free world economy.
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What saved the West Antarctic Ice Sheet 10,000 years ago will not save it today

06/14/2018 - The retreat of the West Antarctic ice masses after the last Ice Age was reversed surprisingly about 10,000 years ago, scientists found. This is in stark contrast to previous assumptions. In fact, it was the shrinking itself that stopped the shrinking: relieved from the weight of the ice, the Earth crust lifted and triggered the re-advance of the ice sheet. However, this mechanism is much too slow to prevent dangerous sea-level rise caused by West Antarctica’s ice-loss in the present and near future. Only rapid greenhouse-gas emission reductions can.
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Better be safe than sorry: economic optimization risks tipping of important Earth system elements

06/15/2018 - Optimizing economic welfare without constraints might put human well-being at risk, a new climate study argues. While being successful in bringing down costs of greenhouse gas reductions for instance, the concept of profit maximization alone does not suffice to avoid the tipping of critical elements in the Earth system which could lead to dramatic changes of our livelihood. The scientists use mathematical experiments to compare economic optimization to the governance concepts of sustainability and the more recent approach of a safe operating space for humanity. All of these turn out to have their benefits and deficits, yet the profit-maximizing approach shows the greatest likelihood of producing outcomes that harm people or the environment.
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China floods to hit US economy: climate effects through trade chains

05/28/2018 - Intensifying river floods could lead to regional production losses worldwide caused by global warming. This might not only hamper local economies around the globe – the effects might also propagate through the global network of trade and supply chains, a study now published in Nature Climate Change shows. It is the first to assess this effect for flooding on a global scale, using a newly developed dynamic economic model. It finds that economic flood damages in China, which could, without further adaption, increase by 80 percent within the next 20 years, might also affect EU and US industries. The US economy might be specifically vulnerable due to its unbalanced trade relation with China. Contrary to US president Trump’s current tariff sanctions, the study suggests that building stronger and thus more balanced trade relations might be a useful strategy to mitigate economic losses caused by intensifying weather extremes.
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Sea-level legacy: 20cm more rise by 2300 for each 5-year delay in peaking emissions

02/20/2018 - Peaking global CO2 emissions as soon as possible is crucial for limiting the risks of sea-level rise, even if global warming is limited to well below 2°C. A study now published in the journal Nature Communications analyzes for the first time the sea-level legacy until 2300 within the constraints of the Paris Agreement. Their central projections indicate global sea-level rise between 0.7m and 1.2m until 2300 with Paris put fully into practice. As emissions in the second half of this century are already outlined by the Paris goals, the variations in greenhouse-gas emissions before 2050 will be the major leverage for future sea levels. The researchers find that each five year delay in peaking global CO2 emissions will likely increase median sea-level rise estimates for 2300 by 20 centimeters.
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