Regional climate thresholds reached sooner than expected

The latest research indicates the fatal wet bulb temperature (WBT) limit is more like 31 degC. The North China Plain is at great risk. Southeast Asia is at risk too, esp for outdoor workers in cities with an urban heat island effect. "For a 2°C (3.6°F) global average temperature rise, which – given inaction on emissions reductions – is almost certain, dangerous humid heatwaves will become prevalent in many parts of the world. Most at risk will be those living in northern India, Pakistan, Bangladesh, the Arabian Gulf, the Sahel region of Africa and East Asia. Because of the so-called ‘heat island effect’, whereby urban centres dominated by concrete and tarmac are hotter than their surroundings, those in cities will be most at risk. WBTs approaching 31°C (87.8°F), at which working outdoors would be all but impossible, are forecast to occur in excess of 200 hours a year in Aden (Yemen), more than 150 hours in Lahore (Pakistan), and 30–40 hours in the Indian cities of Delhi and Kolkata. A global temperature rise of 3°C (5.4°F) would see an extension of these conditions, which would begin to be encountered in Tokyo (Japan), Lagos (Nigeria), Shenzhen (China), Chicago and New York (USA)." "A 2018 study highlighted a particular threat to the North China Plain: the country’s breadbasket, criss-crossed by a dense network of irrigation courses. Not only does all this water push up humidity levels, it's predicted to raise the temperature across the region by 0.5°C (0.9°F). While I suspect there are other candidates, the authors of the study warn that the region faces “the greatest risk to human life from rising temperatures of any location on Earth.” Bearing in mind that this is one of the most densely populated parts of the planet – home to more than 400 million people, mostly farmers – this is not a surprise." "Individual events will, of course, happen much sooner, along with an increasing frequency of WBTs of 31°C (87.8°F), which, at the very least, will bring working outside to a grinding halt. It’s even questionable whether places like the North China Plain will continue to be habitable." "Productivity will inevitably take a massive hit. In the decades to come, working outside during the summer in places as far apart as southern Europe, North America, South and South East Asia, and large parts of Africa, is going to be at best excessively unpleasant and, at worst, fatal." The harsh reality is that the only way of coping with the new conditions on our hothouse planet will be to abandon those parts of it that no longer support human life year-round without artificial aid." https://lnkd.in/gRJkzeKk

December 10, 2024 - By Kate Giles -IOP Publishing, "Three leading climate scientists have combined insights from 10 global climate models and, with the help of artificial intelligence (AI), conclude that regional warming thresholds are likely to be reached faster than previously estimated. The study, published (https://lnkd.in/dxnPR-fx) in Environmental Research Letters by IOP Publishing, projects that most land regions as defined by the Intergovernmental Panel on Climate Change (#IPCC) will likely surpass the critical 1.5°C threshold by 2040 or earlier. Similarly, several regions are on track to exceed the 3°C threshold by 2060—sooner than anticipated in earlier studies. Regions including #SouthAsia, the #Mediterranean, #CentralEurope and parts of #subSaharanAfrica are expected to reach these thresholds faster, compounding risks for vulnerable ecosystems and communities. The research, conducted by Elizabeth Barnes, professor at Colorado State University, Noah Diffenbaugh, professor at Stanford University, and Sonia Seneviratne, professor at the ETH-Zurich, used a cutting-edge AI transfer-learning approach, which integrates knowledge from multiple #climatemodels and observations to refine previous estimates and deliver more accurate regional predictions. Key Findings Using AI-based transfer learning, the researchers analysed data from 10 different climate models to predict temperature increases and found: >> 34 regions are likely to exceed 1.5°C of warming by 2040. >> 31 of these 34 regions are expected to reach 2°C of warming by 2040. >> 26 of these 34 regions are projected to surpass 3°C of warming by 2060. Elizabeth Barnes says: “Our research underscores the importance of incorporating innovative AI techniques like transfer learning into #climatemodelling to potentially improve and constrain regional forecasts and provide actionable insights for policymakers, scientists, and communities worldwide.” Noah Diffenbaugh, co-author and professor at Stanford University, added: “It is important to focus not only on global temperature increases but also on specific changes happening in local and regional areas. By constraining when regional warming thresholds will be reached, we can more clearly anticipate the timing of specific impacts on society and ecosystems. The challenge is that regional #climatechange can be more uncertain, both because the climate system is inherently more noisy at smaller spatial scales and because processes in the atmosphere, ocean and land surface create uncertainty about exactly how a given region will respond to global-scale warming.” #climatecrisis #globalwarming #regionalwarming #transferlearning #regionalclimatechange

This could be one of the most important papers to be published since James Hansen’s Pipeline paper a year ago. Climate change will continue to get worse for centuries after net-zero is achieved. It had been assumed that net-zero would halt further temperature rise and with it climate impacts, since the relationship between CO2 loading and temperature was thought to be near-linear. The models used to support the IPCC 1.5 special report were based on transient climate states, assumed scenarios and time sampling. They looked at global averages rather than regional effects and stop at 2100. Critically they tended also not to include triggered tipping points. The new paper from Andrew King et al from University of Melbourne but with co-authors from Reading, Seoul and 4 other Australian centres, ran coupled climate models for 1000 years into the future with different net-zero achievement points from 2030 to 2060. SSP5-8.5 was used up to the net-zero point to simplify the experiment but also to clearly illustrate the criticality of reaching net-zero as soon as possible, with as low a starting temperature as possible. In all cases mean surface temperature continued to rise after net-zero, but the later net-zero was achieved, the higher the temperature at the start, the faster the continued rise. All showed considerable slowdown of rise rate, but not uniformity or overall stability. Regional climate change continued, especially in the southern hemisphere with Australia continuing to rise by a further +1C if net-zero is delayed to 2060. The Southern Ocean temperature would also continue to rise significantly with continued reduction in Antarctic Sea Ice. This combination would likely lead to the continued melting of the West Antarctic Ice Shelf. Meanwhile the Arctic sea-ice would stabilise but likely see years of ice-free summer conditions. Rainfall patterns and ENSO change during stabilisation. Weather extremes are locked in, but the relative difference in levels greatly increases with net-zero delay. Even a 5 year delay still has influence 1,000 years into the future. The key takeaway for me is the graph below. Things may continue to get slowly worse even after net-zero, but the point at which it is achieved is critical. We can’t get back to the climate of my youth, but we can control how bad it gets for people born today. The faster we decarbonise, the least bad the future will be, for humanity and nature alike. Story: https://lnkd.in/ev5QK5bg Paper: https://lnkd.in/eaKkeHN7 #climatechange #netzero