The scientist who sounded the climate alarm in the 1980s says the planet is warming faster than expected

CNN
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The planet is warming at a much faster rate than scientists previously expected, that is Key greenhouse threshold They could be breached this decade, according to a new study co-authored by James Hansen – the American scientist widely credited with being the first to publicly sound the alarm on the climate crisis in the 1980s.

In the paper, published Thursday in the Oxford Open Journal of Climate Change, Hansen and more than a dozen other scientists used a range of paleoclimate data, including data from polar ice cores and tree rings, climate models and observational data, to conclude that Earth is much, much more than that. more sensitive to climate change than previously understood.

“We are in the early stage of the climate emergency,” according to the report, which warns that rising temperatures are “already in the making” and will quickly push global temperatures even further. It was predictedThis will lead to temperatures rising more than 1.5 degrees Celsius above pre-industrial levels in the 2020s, and more than 2 degrees Celsius before 2050.

These results are added to a large number of recent research that have concluded that the world is like this It rushes about 1.5 degreesThis is the threshold beyond which the effects of climate change – including extreme heat, drought and floods – become difficult for humans to adapt to.

“The 1.5-degree limit is more lethal than a doornail,” Hansen said in a call with reporters. “The two-degree limit can only be saved with the help of targeted measures.”

However, some other scientists have questioned the paper’s conclusions that climate change is accelerating faster than models predict.

Hansen, director of the Earth Institute at Columbia University, is a renowned climate scientist whose 1988 testimony before the US Senate was the first to bring global attention to climate change.

He has previously warned that Earth suffers from an energy imbalance, with more energy coming in through sunlight than out through heat radiating into space.

The resulting excess heat is equivalent to 400,000 Hiroshima atomic bombs per day, with the ocean absorbing most of this energy, Hansen’s research found a decade ago.

In this latest paper, Hansen and colleagues say that energy imbalance has now increased, partly due to successful efforts to address the problem. Particulate matter air pollution, especially in China and through global restrictions on shipping pollution. While this type of pollution poses a serious health risk, it also has a cooling effect, as particles reflect sunlight away from the Earth.

The imbalance is expected to accelerate global warming, leading to catastrophic consequences, according to the paper, including rapid sea level rise and climate change. Possible closure of vital ocean currents During this century.

Hansen said he was particularly concerned Melting of the Antarctic ice sheet Especially Thwaites Glacierwhich acts as a cork, holding back ice on land and providing an important defense against catastrophic sea level rise.

But the rise in temperatures is not necessarily stopping, according to the research paper, which calls for “extraordinary measures.”

The measures it recommends include taxing carbon pollution, increasing nuclear power to “complement renewable energies” and strong action by developed countries to help developing countries transition to low-carbon energy. The report found that while the top priority is to significantly reduce pollution from heating the planet, this alone will not be enough.

“If we want to keep sea level close to where it is now, we have to cool the planet,” Hansen said.

The report suggests that one way to do this is Solar geoengineering. This controversial technology aims to cool temperatures by reflecting sunlight away from Earth, or allowing more heat to escape into space. This could be done by injecting aerosols into the atmosphere or sprinkling clouds with salt particles to make them more reflective, for example.

Critics warn of unforeseen consequences, including impacts on rainfall and monsoons, as well as a “termination shock” if geoengineering is suddenly stopped and pent-up global warming is released.

But Hansen said that should be considered. “Instead of describing these efforts as ‘threatening geoengineering,’ we should realize that we are geoengineering the planet right now,” he said, by burning large amounts of fossil fuels that heat the planet.

The study’s findings are alarming and come at a time when the world is experiencing unprecedented heat. This year is on track to be the hottest on record, with every month from June onwards Breaking records for the warmest such month.

But while the science is clear that the rate of global warming is increasing, the idea that it is accelerating beyond what models predict is controversial.

Michael Mann, a leading climate scientist at the University of Pennsylvania, said the results are “largely outside the trend.”

While the Earth’s surface and oceans are warming, the data does not support claims that the rate is accelerating, he told CNN in an email. “As I like to say, the truth is bad enough!” Mann said. “There is no evidence that models do not predict human-caused warming.”

He also questioned the role of pollution reduction in global warming trends, saying the overall impact was very small, and warned that solar geoengineering was “unprecedented” and “potentially very dangerous.”

“Whether or not the 1.5°C target can be reached is a matter of politics, not climate physics, at this point,” Mann said.

But Hansen rejected criticism of the research, saying it was based on hard numbers and clear physics.

“This is not fringe, this is correct physics, this is the real world, and sometimes it takes society a while to understand it,” he said.