Less than 1% chance that Earth's energy imbalance has occurred naturally

Politics has for years obfuscated the debate over climate change, with deniers claiming time and time again that any increase in carbon dioxide content or temperature is due simple natural changes and variations. A new study from scientists at Princeton University can put that claim to rest. The experts report that there is a less than a one percent probability that Earth’s energy imbalance has occurred naturally. 

Satellite data has consistently shown that the Earth is undergoing a warming trend. The authors state in the new paper that the satellite record provides clear evidence of a human-influenced climate system. 

“Knowing that human activity is responsible for the acceleration of planetary heat uptake implies the need for significant policy and societal action to reduce anthropogenic greenhouse gas emissions to curb further increases in Earth’s energy imbalance.”

The energy imbalance the authors are referring to essentially means we are retaining more of the sun’s radiation then we are putting out. While the normal greenhouse effect plays a significant role, the retention of more infrared heat from the sun is also influenced by other factors. 

“We always think, ‘Increasing greenhouse gases means trapping more infrared heat’ – the classic greenhouse effect becomes larger. This is correct, but the flip side is that the resulting warmer planet now also radiates more infrared heat away to space, so the greenhouse gas heating impact is canceled,” explained study lead author Shiv Priyam Raghuraman.

“Instead, much of the imbalance increase comes from the fact that we are receiving the same amount of sunlight but reflecting back less, because increased greenhouse gases cause cloud cover changes, less aerosols in the air to reflect sunlight – that is, cleaner air over the U.S. and Europe – and sea-ice decreases.”

The only explanation is “anthropogenic forcing” – humans adding more energy into the Earth’s natural systems. “Our study shows that even with the given observational record, it is almost impossible to have such a large increase in the imbalance just by Earth doing its own oscillations and variations.” 

While science is an ever-ongoing process that operates on falsification, this is yet another nail in the denialists coffin. 

“It is exceptionally unlikely – less than 1% probability – that this trend can be explained by natural variations in the climate system,” said Raghuraman.

The study is published in the journal Nature Communications.

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By Alex Ruger, Earth.com Staff Writer