2°C Climate Warming Target Is ‘Dead,’ Pioneering Climate Scientist Says

The port of Rotterdam, the Netherlands with a shipping container terminal and power plant. Sjo / E+ / Getty Images

In a new analysis, acclaimed climate scientist Professor James Hansen and colleagues said that scientists had greatly underestimated the rate of global heating, and that the international target of two degrees Celsius is “dead.”

The analysis concluded that the combination of recent reductions in shipping pollution — which have the effect of blocking the sun — and increasing emissions from fossil fuels have been greater than previously thought, reported The Guardian.

“A shocking rise of warming has been exposed by, ironically, a reduction of pollutants, but we now have a new baseline and trajectory for where we are,” said Professor Jeffrey Sachs, director of the Center for Sustainable Development at Columbia University, as The Guardian reported.

Climate change target of 2C is ‘dead’, says renowned climate scientist – Prof James Hansen says pace of global heating has been significantly underestimated, though other scientists disagree #climatecrisis Story by me www.theguardian.com/environment/…

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— Damian Carrington (@dpcarrington.bsky.social) February 4, 2025 at 12:51 PM

The study, “Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed?” was published in the journal Environment: Science and Policy for Sustainable Development.

“Global warming caused by reduced ship aerosols will not go away as tropical climate moves into its cool La Niña phase. Therefore, we expect that global temperature will not fall much below +1.5°C level, instead oscillating near or above that level for the next few years,” Hansen and colleagues wrote in the study. “The largest practical effect on humans today is increase of the frequency and severity of climate extremes. More powerful tropical storms, tornadoes, and thunderstorms, and thus more extreme floods, are driven by high sea surface temperature and a warmer atmosphere that holds more water vapor. Higher global temperature also increases the intensity of heat waves and – at the times and places of dry weather – high temperature increases drought intensity.”

Independent experts said that, though the results of the study are on the high end of the range of mainstream climate science, they cannot be ruled out, reported The Guardian.

“It’s important to emphasise that both of these issues – [pollution cuts] and climate sensitivity – are areas of deep scientific uncertainty,” said Dr. Zeke Hausfather, a climate scientist who did not participate in the study. “While Hansen et al are on the high end of available estimates, we cannot say with any confidence that they are wrong, rather that they just represent something closer to a worst-case outcome.”

If the estimates are correct, more extreme weather will happen sooner, with a bigger risk that the planet will surpass tipping points like the collapse of crucial Atlantic ocean currents.

“The Intergovernmental Panel on Climate Change (IPPC) defined a scenario which gives a 50% chance to keep warming under 2C – that scenario is now impossible,” Hansen said, as The Guardian reported. “The 2C target is dead, because the global energy use is rising, and it will continue to rise.”

Hansen formerly worked as a climate scientist for NASA. His testimony to a United States Senate Committee on Energy and Natural Resources in 1988 was an early warning to the public of the greenhouse gas effect causing climate change.

According to the new analysis, without changes the planet will likely warm by about two degrees Celsius by 2045.

“The basic problem is that the waste products of fossil fuels are still dumped in the air free of charge,” Hansen said, as reported by The Guardian.

Hansen and the research team estimated that freshwater flowing into the North Atlantic from polar ice melt would cause the Atlantic Meridional Overturning Circulation (AMOC) to shut down within the next two to three decades, AFP reported.

The important ocean current brings warmth to parts of the planet while carrying nutrients needed to sustain marine life.

The authors of the study said the ceasing of AMOC would “lock in major problems including sea level rise of several meters — thus, we describe AMOC shutdown as the ‘point of no return.’”

The 2015 Paris Agreement established a target of keeping global heating from surpassing 1.5 degrees Celsius above pre-industrial levels over a period of decades. The threshold is critical, scientists say, to preventing AMOC and other major ocean circulation systems from breaking down, as well as stopping the thawing of boreal permafrost and the collapse of warm-water coral reefs.

The past two years have brought global heating above the 1.5 degree Celsius threshold, according to the European Union’s Copernicus Climate Change Service.

Warming of two degrees Celsius would bring even greater climate impacts, including irreversible loss to the planet’s ice sheets, sea ice, mountain glaciers and permafrost.

“Failure to be realistic in climate assessment and failure to call out the fecklessness of current policies to stem global warming is not helpful to young people,” the authors of the study wrote, as reported by AFP.

“Special interests have assumed far too much power in our political systems. In democratic countries the power should be with the voter, not with the people who have the money. That requires fixing some of our democracies, including the U.S.,” Hansen said, as The Guardian reported.

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