‘It’s much worse’: climate scientist Hansen warns of unexpected rate of global warming

Our planet is on track to warm at a much faster rate than scientists previously predicted, meaning a key global warming threshold could be passed this decade, says a new study co-authored by James Hansen, an American scientist widely known as first to publicly sound the alarm about the climate crisis in the 1980s.

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

“We are in the early stages of a climate emergency,” says the report, which warns that the heat surge “already expected” will quickly raise global temperatures above forecasts, leading to warming that will exceed pre-industrial levels by 1.5 degrees Celsius levels in the 2020s and above 2 degrees Celsius until 2050.

As CNN notes, the findings add to a slew of recent studies that conclude the world is rapidly approaching the 1.5-degree mark, a threshold beyond which it will become much more difficult for people to adapt to the impacts of climate change, including extreme heat, drought and floods.

“The 1.5 degree limit is more dangerous than a door nail,” Hansen told reporters. “And the 2-degree limit can only be saved through targeted action.”

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

James Hansen, director of Columbia University’s Earth Institute, is a renowned climate scientist whose testimony in the U.S. Senate in 1988 first brought climate change to global attention.

He has previously warned that there is an energy imbalance on Earth because more energy comes in through sunlight than goes out through heat radiated into space.

The resulting excess heat is equivalent to 400,000 atomic bombs dropped on Hiroshima per day, with most of the energy absorbed by the ocean, Hansen’s research showed a decade ago.

In this recent paper, Hansen and his co-authors say that the energy imbalance has now widened, in part due to successful efforts to combat particle pollution, especially in China, and due to global restrictions on shipping pollution. While this kind of pollution poses a serious health hazard, it also has a cooling effect as the particles reflect sunlight away from the Earth.

According to the document, the imbalance will cause global warming to accelerate, with catastrophic consequences including rapid sea level rise and a potential shutdown of vital ocean currents within this century.

Hansen is particularly concerned about the melting of the Antarctic ice sheet and especially the Thwaites Glacier, which acts as a plug, keeping ice on land and providing important protection against catastrophic sea level rise.

But warming is not necessarily locked in, says the document, which calls for “extraordinary action.”

The study’s recommended policies include taxing carbon emissions, increasing nuclear power to “complement renewable energy sources,” and strong action by developed countries to help developing countries transition to low-carbon energy. While the highest priority is to sharply reduce warming pollution on the planet, this alone will not be enough, the report says.

“If we’re going to keep sea levels the same, we really need to cool the planet,” Hansen warned.

One way to do this, as the report suggests, is solar geoengineering. This controversial technology aims to lower temperatures by reflecting sunlight away from Earth or releasing more heat into space. This can be done, for example, by injecting aerosols into the atmosphere or spraying clouds with salt particles to make them more reflective.

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

But Hansen said it’s something to consider. “Instead of describing these efforts as ‘threatening geoengineering,’ we should recognize that we are geoengineering the planet right now,” he said, burning large amounts of planet-warming fossil fuels.

The report’s findings are alarming and come as the world experiences unprecedented heat. This year is shaping up to be the hottest on record, with every month since June breaking records for the number of hot months.

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

The findings are “very much outside the box,” said Michael Mann, a leading climate scientist at the University of Pennsylvania.

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

He also questioned the role of pollution cuts in warming trends, saying the overall impact is very small and warning that solar geoengineering is “unprecedented” and “potentially very dangerous.”

“Whether the 1.5 degrees Celsius target is achievable or not is at this point a matter of politics, not climate physics,” Mann said.

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

“It’s not a fringe thing, it’s proper physics and it’s the real world,” he said, “and sometimes it takes a while for the community to catch on.”