Jean-Marc Jancovici

OA - Liste

2025

Global temperature leaped more than 0.4°C (0.7°F) during the past two years, the 12-month average peaking in August 2024 at +1.6°C relative to the temperature at the beginning of last century (the 1880-1920 average). This temperature jump was spurred by one of the periodic tropical El Niño warming events, but many Earth scientists were baffled by the magnitude of the global warming, which was twice as large as expected for the weak 2023-2024 El Niño.
... An “acid” test of our interpretation will be provided by the 2025 global temperature: unlike the 1997-98 and 2015-16 El Ninos, which were followed by global cooling of more than 0.3°C and 0.2°C, respectively, we expect global temperature in 2025 to remain near or above the 1.5°C level. Indeed, the 2025 might even set a new record despite the present weak La Nina. There are two independent reasons. First, the “new” climate forcing due to reduction of sulfate aerosols over the ocean remains in place, and, second, high climate sensitivity (~4.5°C for doubled CO2) implies that the warming from recently added forcings is still growing significantly.
Human-driven ocean warming is increasingly overwhelming El Niño, La Niña, and other natural climate patterns.
An international group of scientists, led by King's College London, has revealed how continued global warming will lead to more parts of the planet becoming too hot for the human body over the coming decades. the amount of landmass on our planet that would be too hot for even healthy young humans (18 to 60-year-olds) to keep a safe core body temperature will approximately triple (to 6%)—an area almost the size of the US—if global warming reaches 2°C above the preindustrial average.
An engaging discussion on groundbreaking research that reveals the unexpected drivers behind the recent unprecedented rise in global temperatures. Moderated by SDSN President Professor Jeffrey Sachs, this virtual event explored Dr. James Hansen and colleagues' findings in the latest publication, “Global Warming Has Accelerated,” their implications for climate sensitivity, and the urgent need for alternative approaches to mitigate the looming "point of no return."
Some scientists fear the risk of a collapse to warm Atlantic currents has not been taken seriously.
Human-caused climate change increased the likelihood and intensity of the hot, dry and windy conditions that fanned the flames of the recent devastating Southern California wildfires, a scientific study found. But the myriad of causes that go into the still smoldering fires are complex, so the level of global warming's fingerprints on weeks of burning appears relatively small compared to previous studies of killer heat waves, floods and droughts by the international team at World Weather Attribution. Tuesday's report, too rapid for peer-review yet, found global warming boosted the likelihood of high fire weather conditions in this month's fires by 35% and its intensity by 6%.

2024

Surpassing 1.5°C of warming can be undone at a later date – using tech, land and resources that don’t exist.
Carbon Brief provides an updated analysis of when the world will likely exceed the Paris 1.5C limit
Global temperature (12-month mean) is still rising at 1.56°C relative to 1880-1920 in the GISS analysis through April (Fig. 1). [Robert Rohde reports that it is 1.65°C relative to 1850-1900 in the BerkeleyEarth analysis.[3]] Global temperature is likely to continue to rise a bit for at least a month, peak this summer, and then decline as the El Nino fades toward La Nina. Acceleration of global warming is now hard to deny. The GISS 12-month temperature is now 0.36°C above the 0.18°C/decade trend line, which is 3.6 times the standard deviation (0.1°C). Confidence in global warming acceleration thus exceeds 99%, but we need to see how far temperature falls with the next La Nina before evaluating the post-2010 global warming rate.