références en Anglais

Global temperature for 2025 should decline little, if at all, from the record 2024 level. Absence of a large temperature decline after the huge El Nino-spurred temperature increase in 2023-24 will provide further confirmation that IPCC’s best estimates for climate sensitivity and aerosol climate forcing were both underestimates. Specifically, 2025 global temperature should remain near or above +1.5C relative to 1880-1920, and, if the tropics remain ENSO-neutral, there is good chance that 2025 may even exceed the 2024 record high global temperature.

The world is warming despite natural fluctuations from the El Niño cycle.

... 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.

The floods displaced more than 80,000 people, led to over 150,000 being injured and, on the 29th of May, to 169 fatalities with 44 people still missing (Governo do Estado de Rio Grande do Sul, 2024). Essential services were also disrupted, leaving 418,200 households without electricity and over a million consumer units without water. Dozens of municipalities lost telephone and internet services.

A long-term sea level dataset shows ocean surface heights continuing to rise at faster and faster rates over decades of observations. Global average sea level rose by about 0.3 inches (0.76 centimeters) from 2022 to 2023, a relatively large jump due mostly to a warming climate and the development of a strong El Niño. The total rise is equivalent to draining a quarter of Lake Superior into the ocean over the course of a year.

Global warming is accelerating because the drive for warming, Earth’s energy imbalance, has doubled in the past decade. Measurement of the acceleration is hampered by unforced tropical (El Nino/La Nina) variability, but a good measuring stick is provided by warming between successive large El Ninos. Strengthening of the current (2023-24) El Nino has raised it to a level similar to the 1997-98 and 2015-16 El Ninos. The first six months of the current El Nino are 0.39°C warmer than the same six months of the 2015-16 El Nino, a global warming rate of 0.49°C/decade, consistent with expectation of a large acceleration of global warming. We expect the 12-month mean temperature by May 2024 to eliminate any doubt about global warming acceleration. Subsequent decline of the 12-month temperature below 1.5°C will likely be limited, confirming that the 1.5°C limit has already been passed.

September 2023 smashed the prior global temperature record. Hand-wringing about the magnitude of the temperature jump in September is not inappropriate, but it is more important to investigate the role of aerosol climate forcing – which we chose to leave unmeasured – in global climate change. Global temperature during the current El Nino provides a potential indirect assessment of change of the aerosol forcing. Global temperature in the current El Nino, to date, implies a strong acceleration of global warming for which the most likely explanation is a decrease of human-made aerosols as a result of reductions in China and from ship emissions. The current El Nino will probably be weaker than the 1997-98 and 2015-16 El Ninos, making current warming even more significant. The current near-maximum solar irradiance adds a small amount to the major “forcing” mechanisms (GHGs, aerosols, and El Nino), but with no long-term effect. More important, the long dormant Southern Hemisphere polar amplification is probably com

Human-caused climate disruption and El Niño push temperature in mountains to 37C

Australian scientists have challenged the latest UN-backed global warming report, saying it underestimated the likelihood major weather events driven by processes in the Pacific will become more extreme as the planet heats.