Knowing the Earth’s energy imbalance is critical to avoiding global warming, research shows

The Earth’s energy imbalance is the single most important metric for measuring the magnitude and effects of climate change, according to a new study published today in the first issue of Environmental research: climate†

Leading scientist at the National Center of Atmospheric Research (NCAR) and highly cited lead author Kevin Trenberth along with climate scientist and co-author Lijing Cheng have made a new complete inventory of all the different sources of excess heat on Earth. He studied energy changes of the atmosphere, ocean, land and ice as climate system components from 2000 to 2019 and compared this to the radiation at the top of the Earth’s atmosphere to find the imbalance.

“The net energy imbalance is calculated by looking at how much heat is absorbed by the sun and how much heat can radiate back into space,” explains Trenberth, whose paper was published today. “It is not yet possible to directly measure the imbalance, the only practical way to estimate it is through an inventory of the changes in energy.”

Understanding the net energy gains of the climate system from all origins, how much extra energy there is and where it is being redistributed in the Earth system, is vital to informing and addressing the climate crisis. Previously, the focus of climate research was on the increase in the global average surface temperature on Earth. However, this is just one result of the total energy imbalance we face on Earth.

Excess energy affects weather systems, directly increasing the number or intensity of extreme weather events, such as: heavy rain and floods, hurricanes, droughts, heat waves, and forest fires. Weather conditions move energy and help the climate system get rid of energy by beaming it into space, which also influences global temperature rise. The study further revealed that 93% of the extra heat from the imbalance ends up in Earth’s oceans, raising their overall temperature and sea level, leading to 2021 being the hottest global ocean year to date.

“Modelling the Earth’s energy imbalance is challenging, and the relevant observations and their synthesis need to be improved. Understand how all forms of energy are scattered around the world and are sequestered or beamed back to room will give us a better understanding of our future,” added Lijing Cheng, co-author of the study.