Un média

Improved knowledge of glacial-to-interglacial global temperature change implies that fast- feedback equilibrium climate sensitivity is at least ~4°C for doubled CO2 (2×CO2), with likely range 3.5-5.5°C. Greenhouse gas (GHG) climate forcing is 4.1 W/m2 larger in 2021 than in 1750, equivalent to 2×CO2 forcing. Global warming in the pipeline is greater than prior estimates. Eventual global warming due to today’s GHG forcing alone – after slow feedbacks operate – is about 10°C. Human-made aerosols are a major climate forcing, mainly via their effect on clouds. We infer from paleoclimate data that aerosol cooling offset GHG warming for several millennia as civilization developed. A hinge-point in global warming occurred in 1970 as increased GHG warming outpaced aerosol cooling, leading to global warming of 0.18°C per decade. Aerosol cooling is larger than estimated in the current IPCC report, but it has declined since 2010 because of aerosol reductions in China and shipping. Without unprecedented global actions to

Ce mercredi 4 décembre, les 57 institutions de recherche participant au Global Carbon Project (GCP) publient le Global Carbon Budget 2018 dans les revues Nature, Earth System Science Data et Environmental Research Letters. Le budget examine en profondeur la quantité de combustibles fossiles que les pays du monde entier brûlent et ce qu’il advient des émissions de CO2 associées. Selon les projections du Global Carbon Project, les émissions de dioxyde de carbone (CO2) devraient augmenter de 2,7 % en 2018, principalement en raison de la croissance soutenue de la consommation de pétrole et de gaz. En 2017, les émissions de carbone étaient déjà à la hausse (+ 1,6 %) après une stagnation de trois ans.