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In a recent paper , Guy McPherson, Beril Sirmacek and Ricardo Vinuesa discuss Environmental thresholds for mass-extinction events. Authors point at an image by  Song et al. (2021) that shows how major mass extinctions over the past 541 million years (the Phanerozoic) are linked to temperature rises higher than 5.2°C and rates of change higher than 10°C/Myr. Earlier, a 2018 study by Strona & Bradshaw found that at 5°C rise, most life on Earth will be extinct (see box below on the right, from an earlier post) .   In the video below, authors Guy McPherson, Beril Sirmacek and Ricardo Vinuesa discuss their analysis 'Environmental thresholds for mass extinction events'. Authors point out that, next to temperature rise and rates of change, there are further variables such as rates of deforestation, ocean acidification and spreading of toxic substances that can additionally contribute to cause species to disappear. Accordingly,  many ...

Many people could face unbearable temperatures soon.  Temperature anomalies on land in the Northern Hemisphere (red) are spread out much wider and they are more than 0.5°C higher than global land+ocean anomalies (blue). The pale green and grey trends are both long-term trends based on January 1880-August 2020 NOAA data. The short-term red and blue trends, based on January 2013-August 2020 NOAA data, are added to show the potential for a rapid rise. How could temperatures possibly rise this fast?  A rapid temperature rise could eventuate by 2026 due to a number of contributing factors: • crossing of the latent heat and methane tipping points • moving toward an El Niño  • entering solar cycle 25 • changes in aerosols • feedbacks kicking in more strongly as further tipping points get crossed. Crossing the Latent Heat and Methane Hydrate Tipping Points The image below, updated from an earlier post , shows two such tipping points. The August 2020 ocean temperature anomaly on t...

by Andrew Glikson Precis 21–23ʳᵈ centuries’ transient ocean cooling events (stadials), triggered by ice melt flow from the Greenland and Antarctic ice sheets into the adjacent oceans, herald conditions analogous in part to those of the Younger Dryas stadial (12.9–11.7 kyr) which succeeded the pre-Holocene Bölling-Allerod thermal maximum. The subsequent Younger Dryas cooling event was associated with penetration of polar air masses and ocean currents, leading to storminess, analogous to recent breaching of the weakened polar jet stream boundary, ensuing in major snow storms in North America and Europe and cooling of parts of the North Atlantic Ocean and parts of the circum-Antarctic ocean triggered by the flow of ice melt water from melting glaciers. 21–23ʳᵈ Centuries’ Stadial freeze events IPCC climate change projections for 2100-2300 portray linear to curved temperature progressions (SPM-5). By contrast, examination of transient cooling events (stadials) which ensued from the flow of ...