An important scientific article was published a few weeks ago by a group of leading climate scientists. The title already tells its significance and shows that quite possibly we are at a turning point in climate change. Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed?
“Global temperature leaped more than 0.4°C (0.7°F) during the past two years, the 12-month average peaking in August 2024 at +1.6°C relative to the temperature at the beginning of last century (the 1880-1920 average). This temperature jump was spurred by one of the periodic tropical El Niño warming events, but many Earth scientists were baffled by the magnitude of the global warming, which was twice as large as expected for the weak 2023-2024 El Niño.”
The Paris Climate Agreement targeted a 1.5°C degree warming by the end of this century – a goal that now seems gone. The authors explain that a surge in average temperatures was somewhat expected as we were in a so-called El Niño period which is normally warmer than average. But this is not the whole picture.
Why did scientists detect such a jump in temperature? A restriction on sulfur content in ship fuels implemented in 2020 by the International Maritime Organization had a larger impact on global warming than previously estimated. Interestingly a pollutant that was eliminated had an artificial cooling effect on the climate system as the emitted particles reflected some sunlight to space, preventing part of the warming.
This new finding shows that scientific models underestimated “climate sensitivity” or in other words, the “speed of climate change”. This metric shows how much greenhouse gases are necessary to get a certain amount of warming in the atmosphere.
This is not a change in how the planet works, this is a change in our understanding. There was an artificial cooling effect from a pollutant that we have removed – this has masked the real sensitivity of our planet.
Now we have to face the fact that we are likely on track to reach the worst climate scenario presented by the IPCC. Even if we implemented every single policy recommended by the IPCC, it would be impossible to remain below 2°C warming, additional and significantly faster measures would be necessary.
Having this new forecast, we should expect more severe impacts:
“As a result, shutdown of the Atlantic Meridional Overturning Circulation (AMOC) is likely within the next 20-30 years, unless actions are taken to reduce global warming – in contradiction to conclusions of IPCC. If AMOC is allowed to shut down, it will lock in major problems including sea level rise of several meters – thus, we describe AMOC shutdown as the “point of no return.”
What is the AMOC shutdown? AMOC is a current in the Atlantic Ocean (Atlantic Meridional Overturning Circulation) that may stop operating due to the melting Northern ice cap. This is the phenomenon that is often referred to in popular culture as “the Gulf Stream stops”. AMOC is not the Gulf Stream, but if this happens, Northern Europe will likely face a sudden drop in temperature, basically similar to an ice age. This would be a major catastrophe, an irreversible change that would bring massive economic losses due to weather extremes and more specifically losses in agricultural productivity (thus in food security) never seen in our lifetimes.
In short, if this article is correct, we missed our opportunity to stop climate change at an acceptable level, and the Paris Climate Agreement failed. What remains is adaptation and damage control. To be clear, fast and complete decarbonization is still necessary, otherwise things will get even worse.
Is it correct? Scientific tradition is extremely cautious with such claims, you would read elsewhere that more research is needed to confirm these results. But I have to admit that while this overly cautious approach seems wise, waiting for more evidence is the worst possible reaction for such a warning. James Hansen, the lead author of the paper is an eminent climate scientist and in this paper, he explains an observation (faster than expected warming observed) that puzzled many researchers in the last years. Unfortunately, most likely the claims in this paper are correct.
Unavoidably the article brings up the question of intentionally modifying the climate by some form of geo-engineering. The basic observation behind the results, the sulphur pollution of ships already did something like this, which raises the question of doing so intentionally to stop the warming. This idea was considered a moral taboo for many decades, because of the likely side effects and potential additional risks, that could prove catastrophic.
Geo-engineering brings up a dark moral dilemma: should we risk many unknown and potentially catastrophic side-effects for potential temporal support in the fight against climate change, or should we start respecting the planet, but endure catastrophic climate change? Can we build institutions, accountability and coherence in global politics to navigate such a risky scenario, after failing to do so to solve climate change?
Béla Kuslits
JESC Senior Ecology Officer
