Our Planet is Heating Up Twice as Fast as in 2005

A comparison of overlapping one-year estimates at 6-month intervals of net top-of-the-atmosphere annual energy flux from CERES satellite data (solid orange line) and in situ observational estimates of energy by the Earth's climate systems (solid turquoise line). Graphic Credit: NASA/Tim Marvel

To reach this new and disturbing conclusion, investigators for the new research made use of two sensor systems to gather global heating data.

One is NASA’s Clouds and the Earth’s Radiant Energy System (CERES) array of satellite sensors. The space agency uses CERES to determine how much solar energy penetrates the Earth’s atmosphere, as well as how much energy leaves the planet, after sum either being absorbed in lands, oceans, or other waterways, with the rest either trapped in the atmosphere or reflected out into space.

The second is the Argo program’s group of over 3000 floats always at sea in every ocean, which measure water temperatures, salinity, bio-optical properties, and current information. With backing from over 30 nations, it has been online since the early 2000s, and reached its goal of having 3000 total floats in the system in 2007. As part of the Global Ocean Observing System (GOOS), Argo provides import correlation information as to precisely how much of the solar energy coming onto the planet ends up being stored in the ocean.

With around 90 percent of the energy which is trapped on and close to the planet historically being absorbed by the oceans, Argo is a critical means of understanding in real time what is happening in the world’s waters.

With data both from CERES and Argo recorded accurately going back almost two decades, scientists at NASA and the National Oceanic and Atmospheric Administration used this data to calculate the varying imbalance between the amount of energy absorbed or trapped by the Earth and the amount of energy re-radiated into space by the planet. Since the way the two systems carry out their observations are very different, having both sets of independent data provides a means of validating the final measurements.

"The two very independent ways of looking at changes in Earth's energy imbalance are in really, really good agreement,” said Norman Loeb, lead author for the study that published the analysis of these measurements. Loeb is also principal investigator for CERES at NASA’s Langley Research Center in Hampton, Virginia.

What his team discovered was that, after seasonal fluctuations were factored out, the energy imbalance on the planet has roughly doubled over the years 2005 to 2019.

According to Loeb, the data gathered from CERES and the Argo program correlate well. This “gives us a lot of confidence that what we’re seeing is a real phenomenon and not just an instrumental artifact,” he said in comments released at the same time as his group’s study results were published.

By tracking other data as well, the study’s author found there were multiple reasons for the energy imbalance increasing so fast. One is the increased pumping of greenhouse gases such as methane and carbon dioxide into the atmosphere. A second was the significant increase in water vapor in the atmosphere, a secondary climate change effect which is tied to higher rates of evaporation of ocean, lake, river, and streams. The water vapor presence amplifies the global heating effect of the atmosphere, trapping even more heat close to the Earth’s surface regardless of whether more greenhouse gases were even released into the air.

A third issue involved a long-term shift in temperatures within what NOAA refers to as the Pacific Decadal Oscillation (PDO), from cold to “intensively warm,” as the scientists refer to what happened. The PDO is a way of referring to climate variability in a fairly large water pattern in the eastern Pacific. Like the El Niño ocean current changes which can have significant impacts on global rainfall patterns, the change in PDO temperatures has in recent times been cause major changes in cloud formation in the atmosphere.

In this study, the researchers found the PDO had “flipped” from its normal pattern of shifting back and forth between cold and warm periods, starting in 2014. What happened instead was that the PDO shifted to what the scientists called an “intensely warm” mass of ocean water, which lasted from 2014 to 2020. With that pattern itself likely caused by continued global heating generally, when the PDO’s temperature characteristics altered so much it caused what the researchers described as “a widespread reduction in cloud coverage over the ocean and a corresponding increase in the absorption of solar radiation.”

The combination of the effects produced a net 2X increase in the global energy imbalance over a period of 15 years.

While it is true this was calculated for the unique time frame from 2005-2019 and therefore cannot predict what may happen in the future, the trends here are clear. The world is heating up faster now. It is also doing that not just because of direct anthropogenic (human-caused) means such as the continuing burning of fossil fuels, but also because of secondary effects such as increased water evaporation and the PDO “flip” referred to here, both of which will continue to be an issue over decades to come.

It also means we can count on impacts such as increased sea level rise, ocean storm intensification, more widespread patterns of drought, and continuing hotter temperatures, all happening faster as well.

The paper describing the results of this study, “Scientific and Ocean Data Reveal Marked Increase in Earth’s Heating Rate,” by Norman G. Loeb, et. al., was published in the journal Geophysical Research Letters on June 15, 2021.