A recent claim circulating online asserts that global warming is caused by natural changes in the Earth's cloud cover and albedo, rather than human actions. This assertion is false, according to PesaCheck. The claim cites data from NASA's Clouds and the Earth's Radiant Energy System (CERES) project, but this data does not support the conclusion. Global temperatures have been rising steadily, with last year ranking as one of the hottest on record. This trend has continued in 2026, with May being the second hottest month ever recorded for both land and ocean temperatures.
The rise in global temperatures is well-documented. PesaCheck has previously reported on the dramatic increase in global temperatures on multiple occasions. Water vapour in the atmosphere is not responsible for the increase in temperatures, as it condenses into rain or snow before it can trap heat from the sun. Clouds play a complex role in regulating the planet's temperature. While they help cool the planet, their effect depends on the type of cloud. Some clouds may cause a slight heating, but human pollution has led to more cloud formation, resulting in a slight cooling effect.
Research has shown that global warming is affecting clouds, leading to a decrease in cloud cover and amplifying global warming. A feedback loop exists between global warming and clouds, where warming alters wind patterns, decreasing reflective clouds and leading to more warming. Low-level clouds in the tropics have been found to amplify global warming more than previously thought. However, there is substantial uncertainty about how clouds will respond to global warming, which affects climate models.
Albedo, the ability of a surface to reflect light, also plays a role in regulating the planet's temperature. Ice and snow reflect more light than darker surfaces, while darker surfaces absorb more sunlight and increase temperatures. A study in Nature found that a decrease in albedo due to urbanization caused a negligible warming of 0.00014°C between 2001 and 2018. This is much less than the observed global warming during the same period.
The interaction between albedo and climate is complex. When ice melts, albedo decreases, revealing darker areas that absorb more sunlight and increase temperatures. This is known as the ice-albedo feedback. Sea ice covered with snow reflects up to 85% of the light that falls on it, while water only reflects 7%. About a third of the solar energy that reaches the planet is reflected back by Earth's albedo.
The relationship between clouds, albedo, and global warming is intricate. While clouds and albedo changes do play a role in regulating the planet's temperature, they are not the primary cause of modern warming. Human activities, such as pollution and greenhouse gas emissions, are significant contributors to global warming. Understanding the complex interactions between clouds, albedo, and climate is crucial for developing accurate climate models.
In conclusion, the claim that clouds and changes in Earth's albedo are the reason for global warming is false. The evidence suggests that human activities are a significant contributor to the rising temperatures. Further research is needed to understand the complex interactions between clouds, albedo, and climate, but it is clear that these factors are not the primary cause of modern warming.
Key points
- A claim that clouds and changes in Earth's albedo are the reason for global warming is false.
- Human activities, such as pollution and greenhouse gas emissions, contribute significantly to global warming.
- Clouds and albedo changes play a complex role in regulating the planet's temperature, but are not the primary cause of modern warming.
