There is ample evidence to show that human behaviors such as the burning of fossil fuels and industrial agriculture have led to climate change. Now researchers are trying to determine what the future might be like, and how warm it could get. Computer models are used to make these predictions.
Scientists have now created a rating system that evaluated these models. This work, which was reported in Nature Communications, has shown that about one-third of these models do not accurately reproduce real-world observations about data points such as sea surface temperatures. Another third of the models are valid but are not very sensitive to carbon emissions, while the final third are both valid and have a higher sensitivity to carbon emissions. This last third of models has also forecast a very hot future for Earth.
"We show that the carbon sensitive models, the ones that predict much stronger heating than the most probable IPCC estimate, are plausible and should be taken seriously," suggested corresponding study author Athanasios (Thanos) Nenes, a professor at Ecole Polytechnique Fédérale de Lausanne (EPFL).
"In other words, the current measures to reduce carbon emissions, which are based on lower carbon sensitivity estimates, may not be enough to curb a catastrophically hot future," noted first study author Lucile Ricard.
People have been recording climate data like temperature, wind, humidity, and precipitation since the mid-1800s. Those measurements have only gotten more precise, widespread, and sophisticated in recent decades, especially as satellites have also begun to collect this information. But crunching all of the numbers to make good predictions is challenging.
To address this, researchers have created a tool known as netCS, which uses machine learning to create clusters of climate model outputs, comparing them to existing data. NetCS enabled the researchers to examine which models performed the best when compared against actual observations.
"Our approach is an effective way to quickly evaluate a given climate model thanks to netCS's ability to sift through terabytes of data in one afternoon," explained Ricard. "Our model rating is a novel type of model evaluation, and highly complements those obtained from historical records, paleoclimate records, and process understanding outlined in the 2021 IPCC AR6 assessment report."
"The planet is literally burning. Temperatures worldwide are consecutively, year after year, breaking records with all of its consequences," said Nenes.
"Sometimes I feel that climate scientists are a bit like Cassandra of Greek mythology," Nenes added. "She was granted the power of prophecy, but was cursed so that no one would listen to her. But this inertia or lack of action should motivate not discourage us. We have to collectively wake up and really address climate change, because it may be accelerating much more than what we thought."
Sources: Ecole Polytechnique Federale de Lausanne (EPFL), Nature Communications