Researchers from the Alfred Wegener Institute (AWI) have highlighted a significant decline in the Earth's planetary albedo as a possible cause of the sharp rise in global temperatures in 2023. This decline, tied to a reduction in low-altitude clouds, has been identified as a key factor contributing to the global mean temperature increase of nearly 1.5 degrees Celsius above pre-industrial levels—a record-breaking figure. According to Dr Helge Goessling, climate modeller at AWI and lead author of the study, in a statement, this phenomenon has created an "explanation gap" of 0.2 degree Celsius in the recorded temperature rise that existing factors like greenhouse gases, El Niño, and volcanic activity fail to address.
Low Cloud Decline and Reflectivity Loss
The study was published in Science. The research has pointed to a marked reduction in low-altitude cloud cover, particularly in the northern mid-latitudes and tropics, as a primary driver of reduced planetary albedo. Dr Thomas Rackow, a co-author of the study, noted in a statement that in AWI's release, 2023 saw the lowest levels of planetary albedo since at least 1940, according to data from NASA and the European Centre for Medium-Range Weather Forecasts (ECMWF). Albedo is a measure of the Earth's reflectivity, with less sunlight being reflected back into space, contributing to further warming.
Implications of the Findings
The decline in low-altitude clouds, which offer a cooling effect by reflecting sunlight, contrasts with higher clouds that trap heat, intensifying the warming effect. Stricter marine fuel regulations, reducing aerosol concentrations that aid cloud formation, and oceanic changes have been proposed as contributing factors. However, Dr Goessling has suggested that feedback loops between global warming and low cloud reduction may play a significant role.
The findings underscore the urgency of revising global carbon budgets and implementing adaptation measures, as warming beyond the 1.5 degree Celsius threshold outlined in the Paris Agreement may occur sooner than anticipated, as per reports. Climate researchers continue to stress the critical need for immediate action to address these compounding challenges.
