The recent surge in global warming is driven by structural factors like the reduction of aerosols emitted by ships, argues Hansen, one of the world's leading climate scientists. We will exceed 2°C by 2045. Cutting emissions immediately is even more crucial to prevent the triggering of irreversible tipping points with devastating consequences for the planet’s climate system
It is now “impossible” to stay within the emissions pathway that limits global warming to under 2°C by 2100. The Paris Agreement’s minimum target is “dead” and could be surpassed as early as the first half of the century, around 2045.
This is the view of James Hansen, one of the most renowned climate scientists. He was among the first to warn policymakers about global warming trends, the consequences of the climate crisis, and the urgent need to implement emissions reduction measures. Hansen backs up his argument with extensive data in a paper published in Environment: Science and Policy for Sustainable Development.
Global warming crisis has burned the paris agreement
Hansen starts by analyzing the trend in global average temperature. It has risen by over 0.4°C in just two years, reaching a peak of +1.6°C in August 2024 compared to pre-industrial levels.
But what he urges us to focus on is not just the number itself, but the cause of this sharp increase. About half of this spike—unexpectedly high compared to climate model projections – is linked to the 2023-2024 El Niño event. The other half, however, is due to a structural factor.
What is it? The reduction of aerosols emitted by ships, a result of International Maritime Organization (IMO) regulations introduced in 2020. Aerosols reflect sunlight and help cool the planet, so their decline has intensified global warming. Paradoxically, our fight against pollution is now revealing a level of global warming that had, until now, remained somewhat hidden.
This has long-term effects, not just on current temperatures. Even with the shift to La Niña, Hansen predicts that global temperatures will not drop significantly below +1.5°C. In turn, this will lead to more frequent and severe climate events, including storms, floods, heatwaves, and sudden droughts.
“Further warming due to changes in ship aerosol emissions will be slower, but if greenhouse gas forcing continues to rise (and there is no evidence of a slowdown), the new rate of global warming will be higher than in 1970-2010,” Hansen warns. By 2025, the global temperature could momentarily dip just below +1.5°C before continuing its upward trajectory.
But these are not the worst consequences, the scientist cautions. The real concern is the increasing likelihood of triggering a “point of no return,” a tipping point—such as the collapse of the Atlantic Meridional Overturning Circulation (AMOC), the massive ocean current system that regulates the Atlantic. If it were to stop, the impacts would be felt worldwide. According to Hansen, without immediate efforts to curb global warming, AMOC could collapse within the next 20-30 years, leading to an irreversible sea level rise of several meters (though not in the short term).
And in the coming decades? Hansen predicts that global warming will continue at a rate of 0.2-0.3°C per decade, pushing temperatures past +2°C by 2045. Rising land and ocean temperatures will intensify storms, extreme rainfall, and other catastrophic climate events.
