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Rising sea levels, melting glaciers and ocean heatwaves — 2023 has brought alarming new warming records in nearly every measurable category. One of the most alarming was rising
Rising sea levels, melting glaciers and ocean heatwaves — 2023 has brought alarming new warming records in nearly every measurable category. One of the most alarming was rising global average temperatures, reaching nearly 1.5 degrees Celsius (2.7 Fahrenheit) above pre-industrial levels. Scientists are working to determine what is driving this sudden increase in global warming. They took into account anthropogenic effects such as greenhouse gases, the El Niño effect, and natural events such as volcanic eruptions. Still, these factors leave an unexplained warming range of 0.2 degrees Celsius.
A research team from the Alfred Wegener Institute (AWI) suggests that changes in Earth’s cloud cover may explain this gap in warming.
Dr. “In addition to the impact of El Niño and the expected long-term warming due to anthropogenic greenhouse gases, several other factors that could contribute to surprisingly high global average temperatures from 2023 have already been discussed,” said Helge Hessling. Writer from AWI.
Dr. Hessling cited factors such as increased solar activity, excess water vapor from volcanic eruptions and fewer aerosol particles in the atmosphere. But adding these elements leaves 0.2 degrees Celsius (0.36 degrees Fahrenheit) unexplained.
Dr. “The 0.2 degree Celsius disclosure gap for 2023 is currently one of the most debated topics in climate research,” Hessling said.
To investigate further, climate modelers from AWI and the European Center for Medium-Range Weather Forecasts (ECMWF) analyzed NASA satellite data. They also used data from the ECMWF reanalysis, which combines observational data with weather models. The data revealed a worrying trend: 2023 will see the lowest planetary albedo since at least 1940.
Planetary albedo depends on how much sunlight a planet reflects into space. Think of this as the planet’s “brightness factor.” For example, the Earth reflects about 30% of the sunlight that hits it, giving it an albedo of 0.3 (on a scale of 0 to 1). Different surfaces on the planet contribute to this reflection. Bright areas like glaciers and clouds reflect a lot of light, while darker areas like oceans and forests absorb more sunlight.
The balance of reflected and absorbed sunlight plays a major role in shaping the planet’s climate and energy budget. On Earth, changes in albedo can have a big impact. As ice melts due to warming, it reveals darker water or soil, which absorbs more sunlight and accelerates the warming process; This is a feedback loop known as the albedo effect.
Study co-author Dr. “It caught our attention that 2023 stands out as the year with the lowest planet albedo in the NASA and ECMWF datasets,” said Thomas Rakow. A lower albedo means less reflected sunlight, which contributes to higher global temperatures. So what caused this decrease in albedo?
The answer is a reduction in low-altitude cloudiness, especially in the northern mid-latitudes and the tropics. This trend was most pronounced in the Atlantic, which coincidentally saw unusual temperature records in 2023.
“In particular, the eastern North Atlantic, which has been one of the main drivers of the recent increase in global average temperature, was characterized by a significant reduction in low-altitude cloudiness,” Dr Hessling said. he said.
A decrease in low cloud cover means a decrease in the Earth’s albedo, which increases global warming.
Clouds play a very important role in reducing the temperature of the Earth. They create a cooling effect by reflecting sunlight. Low clouds are particularly important because they do not have the heat-trapping greenhouse effect seen in higher clouds. As cloud cover decreases, the cooling effect decreases, causing the temperature to increase. “If there are fewer low clouds, we lose the cooling effect, it gets hotter,” Hessling explained.
So what causes fewer clouds to form at lower altitudes? A combination of factors is possible. Tighter marine fuel regulations have reduced the amount of atmospheric aerosols, tiny particles that act as condensation nuclei for cloud formation. Aerosols also reflect sunlight, and fewer aerosols mean less cloud formation and less reflected sunlight. Natural climate fluctuations and ocean feedbacks may also contribute, but Gessling believes that’s not the whole story. “Global warming itself may reduce low cloud cover,” he said.
This feedback loop between warming and cloud loss could be a sign of a worrying trend.
Dr. “If much of the decrease in albedo is indeed due to feedback between global warming and low cloudiness, as some climate models suggest, we should expect fairly intense warming in the future,” Hessling said.
This means we may pass the critical threshold of global warming of 1.5 degrees earlier than expected. In such a case, the remaining carbon budgets within the scope of the Paris Agreement will decrease and adaptation measures will become even more urgent.
The study sheds light on why temperatures jumped so suddenly and highlights the importance of Earth’s cloud cover in regulating the climate. Reducing cloud cover, especially at lower altitudes, reduces the Earth’s ability to reflect solar radiation, contributing to the warming already caused by greenhouse gases.
As climate models point to this feedback being an important factor, urgent action to manage future warming and minimize extreme weather events becomes even more important. The study was published in the journal Science.
Source: Port Altele
As an experienced journalist and author, Mary has been reporting on the latest news and trends for over 5 years. With a passion for uncovering the stories behind the headlines, Mary has earned a reputation as a trusted voice in the world of journalism. Her writing style is insightful, engaging and thought-provoking, as she takes a deep dive into the most pressing issues of our time.
