The Race Against Time: Why the Climate Crisis is Worse Than We Thought
A Warning We Can’t Afford to Ignore
In 1988, James Hansen, a NASA climate scientist, made history by warning the world that human activities were causing the planet to warm. His testimony brought climate change into the public consciousness, setting the stage for decades of research and international negotiations. Now, nearly four decades later, Hansen is sounding the alarm again. But this time, his message is even more urgent.
The pace of global heating has been significantly underestimated, and the international goal of keeping warming below 2°C is now impossible. The climate crisis is unfolding faster than scientists predicted, and if we don’t act urgently, we may soon cross a threshold from which there is no return.
Why Global Warming is Accelerating
For decades, climate scientists have relied on models to predict how quickly the planet will warm. But Hansen and his colleagues argue that these models have overlooked two critical factors:
The loss of sun-blocking pollution
For decades, the cooling effect of aerosols, particularly those from industrial and shipping emissions, has masked the full impact of greenhouse gas emissions by blocking sunlight. However, in 2020, the International Maritime Organization (IMO) introduced new regulations to lower sulphur emissions from ships, significantly reducing pollution. While beneficial for air quality, this also unexpectedly eliminated a substantial cooling effect, resulting in an acceleration of warming.
Hansen’s team estimates that this change alone added 0.5 watts per square meter (W/m²) of extra heat to the planet’s energy balance, a number significantly higher than other studies, which put the figure between 0.07 and 0.15 W/m². If true, this explains why global temperatures have spiked in the last two years, even beyond what scientists expected from El Niño and rising CO₂ levels.
2. Climate Sensitivity Higher Than We Thought
Another factor driving faster warming is climate sensitivity—a measure of how much the Earth warms in response to rising carbon dioxide levels. The study challenges the Intergovernmental Panel on Climate Change (IPCC) estimates that a doubling of CO₂ will raise global temperatures by around 3 °C, arguing that it is closer to 4.5°C or even 6°C when incorporating revised aerosol forcing estimates. That means that the world will warm more than previously anticipated.
A Future Arriving Faster Than Predicted
If Hansen and his team are correct and independent scientists say their conclusions cannot be ruled out, the implications are dire:
The world will hit 2°C of warming by 2045, not by the late 21st century as previously thought.
Extreme weather—heatwaves, floods, wildfires—will become more intense and more frequent, earlier than expected. The continued warming of the oceans will lead to stronger and wetter storms.
The risk of catastrophic tipping points—like the collapse of the Atlantic Ocean current system (AMOC)—is significantly higher.
The last two years have already shown disturbing trends. In 2024, global temperatures shattered records, even as El Niño subsided. In January 2025, temperatures remained at unprecedented highs despite the cooling influence of La Niña. This suggests that the extra heat is not just a temporary anomaly but a sign that climate change is accelerating dangerously.
The Point of No Return
The authors stress that Earth is at risk of crossing the "Point of No Return", beyond which human intervention will be unable to prevent severe, long-term climate consequences.
The greatest climate threat is probably the danger of the West Antarctic ice sheet collapsing catastrophically, raising sea level by several meters and leaving the global coastline in continual retreat for centuries. It rests in a deep, broad bowl that dips thousands of feet below sea level - making it vulnerable to warm ocean waters.
The problem of West Antarctic ice sheet collapse is complicated because it may be linked to the shutdown of the North Atlantic overturning circulation (AMOC), which is part of a global ocean conveyor that normally transports heat from the Southern Ocean into the Northern Hemisphere. If AMOC collapses it would disrupt global climate patterns and accelerate regional climate extremes. Hansen warns that it could happen within the next 20-30 years if the world continues on its current path.
The 2°C Target is Dead. What Now?
In 2015, nearly every country in the world signed the Paris Agreement, pledging to keep global warming “well below 2°C” and strive for 1.5°C. But with current global trends, those targets are no longer realistic. So, what can we do? Hansen and his team propose urgent measures:
Put a Price on Carbon: Number-one policy priority is a carbon fee and dividend system, where fossil fuel companies are charged for carbon emissions and the money is redistributed directly to the public in the form of dividends. This market-driven approach would incentivise businesses and individuals to cut emissions while ensuring fairness for lower-income households.
Scale Up Nuclear Power: The world is finally beginning to realise that nuclear power is needed to address climate change. The study calls for rapid investment in next-generation nuclear reactors that can provide stable, carbon-free power, particularly for industrial sectors that cannot rely on intermittent energy sources like solar and wind.
Researching Geoengineering as a Last Resort: One of the most controversial topics in climate science is solar geoengineering. Hansen does not advocate immediate deployment but he insists that research should continue—because if global warming accelerates beyond control, we may have no choice but to intervene.
Reform Political Systems to Break the Grip of Corporate Influence: Hansen argues that special interests, like fossil fuel industries, have too much power in global politics, preventing the urgent climate action needed. He calls for political reforms that reduce corporate influence and ensure governments prioritise long-term environmental stability over short-term profits.
“Special financial interests, with their influence on Congress, provide the fuel not only for the military-industrial complex and endless wars, but for many other problems.” __Hansen et al
Time is running out, and the trajectory we’re on is unsustainable. If we don’t act now, the climate crisis will spiral into an era of permanent disruption, displacing millions, reshaping coastlines, and threatening global stability.
We should be eager for the opportunity to save not only our democratic system but our climate and all that entails for humanity and nature. __Hansen et al
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Notes:
Hansen, J. E., Kharecha, P., Sato, M., Tselioudis, G., Kelly, J., Bauer, S. E., … Pokela, A. (2025). Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed? Environment: Science and Policy for Sustainable Development, 67(1), 6–44. https://doi.org/10.1080/00139157.2025.2434494
Climate change target of 2C is ‘dead’, says renowned climate scientist https://www.theguardian.com/environment/2025/feb/04/climate-change-target-of-2c-is-dead-says-renowned-climate-scientist