Earth is warming faster due to a growing energy imbalance. Learn how new research pinpoints cloud changes, not aerosols, as the primary cause of worsening global warming.
Earth is warming faster than before, and new research suggests that changes in clouds, rather than air pollution, are the main reason for this increase in heat. Scientists have found that the planet is absorbing more energy from the Sun than it is sending back into space, creating what is known as an “energy imbalance.” This imbalance is a significant factor in the planet’s rising temperatures. Although air pollution has often been linked to climate changes, a new study argues that it is not the main cause of this energy imbalance.
Researchers from the University of Miami published their findings in the journal Science Advances. Their study shows that changes in clouds are now the largest contributor to the increase in heat being trapped on Earth.
Aerosols Affecting Cloud Formation
Air pollution produces tiny particles called aerosols, which come from sources like factories, cars, wildfires, and volcanic eruptions. These aerosols can influence cloud formation and their brightness. Brighter clouds reflect more sunlight back into space, which can have a cooling effect on the planet. For many years, scientists believed that changes in aerosol levels played a major role in recent warming trends.
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However, by analyzing nearly 20 years of satellite data and using advanced climate models, the researchers found that aerosols have had a minimal overall impact on Earth’s energy balance in recent decades. This is because aerosols behave differently in the Northern and Southern Hemispheres.
Impact on Northern and Southern Hemisphere
In the Northern Hemisphere, where most industrial activity is located, air quality has improved. This means there are fewer pollution particles in the atmosphere. With fewer particles to make clouds reflect sunlight, more solar energy now reaches the Earth's surface, contributing to warming in that region.
On the other hand, the Southern Hemisphere has seen a different trend. Large natural events, such as the Australian bushfires in 2019-2020 and a major volcanic eruption in Tonga in 2022, released a significant amount of particles into the atmosphere. These aerosols made clouds more reflective, sending more sunlight back into space and having a cooling effect.
Earth’s Energy Imbalance
When scientists considered the planet as a whole, these opposing effects largely cancelled each other out. As a result, aerosols have had little effect on the global increase in trapped heat.
The study also found that Earth’s energy imbalance has increased mainly because the planet is reflecting less sunlight than before, not because less heat is escaping into space. Between 2003 and 2023, the Earth gained extra heat at a steady rate, equivalent to about half a watt per square metre every ten years.
To accurately track changes in aerosols, researchers used two separate methods. One method involved satellite data showing how particles affect sunlight as it passes through the atmosphere. The other method used climate models to estimate pollution and natural particles from sources like volcanoes and fires. Both methods showed the same patterns across the hemispheres.
Why Is It Important
These findings are important because they help scientists better understand the real causes of global warming. While cleaner air may lead to some regional warming in industrialized areas, it does not explain the overall increase in heat worldwide.
Looking ahead, the scientists say more attention needs to be given to how clouds change as the planet warms, as well as to natural climate cycles. Earth’s energy imbalance is one of the clearest signs of how quickly heat is accumulating, and understanding it is essential for accurate climate predictions and better decision-making.
