We’re sweating, and it’s not over yet; the worst is still to come! This could summarize the fourth edition of the key indicators for global climate change, published Thursday, June 11, in Earth System Science Data. Conducted by 73 scientists from 56 institutes and 17 countries, some of whom are also authors of IPCC (Intergovernmental Panel on Climate Change) reports, this study aims to use the latest Earth observations to update warming forecasts between two sets of IPCC reports, the most recent of which were published in 2022 (with 2020 data), and the next ones are expected from 2027 onwards (the first document will focus on cities facing heat waves).
An unprecedented warming rate of +0.27°C per decade
Global warming is projected to have already reached +1.37°C by 2025 compared to the pre-industrial era, and the latest observations paint an even bleaker picture than anticipated. This report indicates that « the rate of warming is increasing by +0.27°C per decade, an unprecedented level , » which suggests a warming of « +1.5°C around 2030 » compared to the end of the 19th century, explains Aurélien Ribes, a researcher at Météo-France and the CNRM (National Center for Meteorological Research, which also reports to the CNRS) in Toulouse, and co-author of the latest publication. Average temperatures are rising faster than predicted by the IPCC scenarios. But « instead of an expected rise of +1.55°C over land, the latest leading indicators estimate the updated warming at +1.92°C over the continents, on average for the period 2016-2025 » , explains Christophe Cassou, research director at the CNRS at the LMD (Laboratory of Dynamic Meteorology).
This situation is explained by the continued rise in greenhouse gas emissions and the reduction in emissions of certain fine particles, which had a masking effect on solar radiation. Even over the seas, the rise in maximum surface temperature has been revised to +1.26°C, nearly two-tenths of a degree higher than anticipated by previous IPCC reports. This publication on key climate change indicators assesses, for the first time, the average duration of marine heatwaves, which have been accelerating since 2015. They lasted an average of 58 days per year over the period 2016-2025 across the various ocean basins, compared to 36 days for the period 2007-2016.
Greenhouse gas emissions have reached a record 56.8 billion tons of CO2 equivalent (including methane and nitrous oxide emissions). The concentration of carbon dioxide in the atmosphere « is 52% higher than its pre-industrial level, » notes Pierre Friedlingstein, research director at the CNRS and lead author of the Global Carbon Budget, which assesses global emissions annually. As for the methane concentration, it is more than two and a half times higher! At the current rate of greenhouse gas emissions, global warming will exceed the threshold of +1.5°C before 2030, +1.7°C in 2038, and +2°C around 2050. It is therefore imperative to reduce them as quickly as possible » to bring them down to zero , » the scientist emphasizes.
D’autant que ces perturbations du système climatique se traduisent déjà « par une accélération de la hausse du niveau de la mer (…) évaluée à 3,7 mm par an pour la période 2006-2025 », ajoute Valérie Masson-Delmotte, directrice de recherche au CEA au LSCE, à Gif-sur-Yvette. La précédente estimation du GIEC évaluait la hausse moyenne à 1,73 mm par an.
source : msn
