Each year, the sun sends radiation to the Earth equivalent to more than 7,000 hours of human annual energy consumption. Much of it is visible in space (around 30%), recirculating the atmosphere; the rest is absorbed or re-exposed after reaching the Earth’s surface. Global warming occurs when the greenhouse gases released into the atmosphere act as a warm, waterproof blanket, capturing this energy instead of letting it escape.
For decades, scientists have relied on models to predict how fast the world is warming as a result of human activity. And they’ve gotten good at them. But scientists publish in the journal Geophysical Research Letters on 25 March they described the first direct global observation of the amount of aerosols and greenhouse gases emitted by climate change leaders. “It is direct evidence that human activities are causing changes in the Earth’s energy budget,” said Ryan Kramer, co-author of the paper and a researcher at NASA’s Goddard Space Flight Center and the University of Maryland, Baltimore County.
Since 1977, NASA has been continuously reviewing the Earth’s energy budget by flying instruments aboard satellites with the Clouds and the Earth’s Radiant Power System (CERES) project. These have made a precise estimate of the planet’s radiation budget: how much will go in, how much will escape, and how much will go into the oceans. The new study is the first to describe human activity – as well as natural factors such as water valves, clouds, and surface reflection – to identify the Earth’s energy imbalance, the “unique fingerprints of anthropogenic activity in the Earth’s variable energy budget. ”
The study concluded that human activity increased this imbalance, also known as “radiation emission,” by about 0.5 watts per square meter between 2003 and 2018, largely as a result of increasing greenhouse gas density. rise. For context, that equates to keeping nearly 5 trillion 60-watt light bulbs lit all over the Earth’s surface at all times.
Zeke Hausfather, a climate scientist at the environmental research group Breakthrough Institute, said the study “largely confirms what we already know but in a simpler way based on observation,” noting a 2015 study in Nature that measured CO2 radiation emission on Earth. surface as another example.
That data goes well with scientists ’climate models, but it also offers a faster way to track how mitigation efforts are working and to validate computer-intensive models. It could also affect those who remain skeptical of the climate consensus among 97% of published climate scientists. “In my experience,” Hausfather said, “skeptics tend to be more concerned with the ideas of the models, so it’s definitely helpful. It creates a very high bar for interpretation. ”