This is about new research presented originally at Nature.com and elaborated on at Yale Environment 360. New research warns that the earth may be approaching key tipping points, including the runaway loss of ice sheets, that could fundamentally disrupt the global climate system. A growing concern is a change in ocean circulation, which could alter climate patterns in a profound way (Yale Environment360) https://e360.yale.edu/features/as-climate-changes-worsens-a-cascade-of-tipping-points-looms https://www.nature.com/articles/d41586-019-03595-0 IPCC reports from 2001 to 2018 show a trend towards a lowering of the GMT threshold above pre-industrial levels for tipping points to occur. Even if this research turns out to be wrong that any tipping point thresholds will occur at a GMT increase of 2 degrees C. above pre-industrial levels, the GMT could be somewhere around 3 degrees C by the end of the 21st century. Below is from Nature.com: If current national pledges to reduce greenhouse-gas emissions are implemented — and that’s a big ‘if’ — they are likely to result in at least 3 °C of global warming. This is despite the goal of the 2015 Paris agreement to limit warming to well below 2 °C. Some economists, assuming that climate tipping points are of very low probability (even if they would be catastrophic), have suggested that 3 °C warming is optimal from a cost–benefit perspective. However, if tipping points are looking more likely, then the ‘optimal policy’ recommendation of simple cost–benefit climate-economy models4 aligns with those of the recent IPCC report2. In other words, warming must be limited to 1.5 °C. This requires an emergency response. The 2 paragraphs below are from the Yale Education 360 article: The potential tipping points come in three forms: runaway loss of ice sheets that accelerate sea level rise; forests and other natural carbon stores such as permafrost releasing those stores into the atmosphere as carbon dioxide (CO2), accelerating warming; and the disabling of the ocean circulation system. Their biggest fear is for the future of the global ocean circulation system, which moves heat around the world and may dictate global climate. They say melting Greenland ice in a warmer Arctic has driven a key component of ocean circulation to a thousand-year low. Further decline, which would lead to a shift in heat distribution around the planet, could trigger forest collapse in the Amazon; cause near-permanent drought in Africa’s Sahel region; disrupt Asian monsoons; rapidly warm the Southern Ocean, which would cause a surge in global sea levels as the West Antarctic Ice Sheet disintegrates; and potentially shift the planet to a new climate regime they call “hothouse Earth.” The Portions below are from the Nature.com article: We think that several cryosphere tipping points are dangerously close, but mitigating greenhouse-gas emissions could still slow down the inevitable accumulation of impacts and help us to adapt. Research in the past decade has shown that the Amundsen Sea embayment of West Antarctica might have passed a tipping point3: the ‘grounding line’ where ice, ocean and bedrock meet is retreating irreversibly. A model study shows5 that when this sector collapses, it could destabilize the rest of the West Antarctic ice sheet like toppling dominoes — leading to about 3 metres of sea-level rise on a timescale of centuries to millennia. Palaeo-evidence shows that such widespread collapse of the West Antarctic ice sheet has occurred repeatedly in the past. The latest data show that part of the East Antarctic ice sheet — the Wilkes Basin — might be similarly unstable3. Modelling work suggests that it could add another 3–4 m to sea level on timescales beyond a century. The Greenland ice sheet is melting at an accelerating rate3. It could add a further 7 m to sea level over thousands of years if it passes a particular threshold. Beyond that, as the elevation of the ice sheet lowers, it melts further, exposing the surface to ever-warmer air. Models suggest that the Greenland ice sheet could be doomed at 1.5 °C of warming3, which could happen as soon as 2030.