The Laden Bough, 35th Day of Childwinter, 525 M.E. (Electra): As temperatures at the North Pole soared to more than 20° C (68° F) above average on Sunday, rising above the temperature for ice to melt, a recent study headed by climate scientist James Hansen of Columbia University, warned that the pace of global warming has been significantly underestimated. 

Temperatures north of Svalbard in Norway had already risen to 18° C warmer than the 1991–2020 average on Saturday, with actual temperatures close to ice’s melting point of 0° C (32° F). By Sunday, the temperature anomaly had risen to more than 20° C.

The burning of fossil fuels has warmed the planet by about 1.3° C since preindustrial times, but the poles are warming much faster as reflective sea ice melts. Since 1979, the Arctic has warmed nearly four times faster than the global average, and extreme heat has become hotter and more common. 

The Intergovernmental Panel on Climate Change (IPPC) defined a scenario which gave a 50% chance to keep warming under 2° C. "That scenario is now impossible,” according to Hansen. “The 2° C target is dead, because the global energy use is rising, and it will continue to rise.”  Hansen first sounded the alarm about climate change in testimony he gave to the UN in 1988.

The world’s nations pledged in Paris in 2015 to keep global temperature rise below 2° C above preindustrial levels and to pursue efforts to limit it to 1.5° C. However, the climate crisis has already supercharged extreme weather across the world with just 1.3° C of heating on average. While 2° C would be far worse, on his first day in office, Trump announced that the US would withdraw from the Paris agreements.

The unusually mild polar temperatures seen in the middle of the winter were linked to a deep low-pressure system over Iceland, which was directing a strong flow of warm air towards the north pole. Abnormally warm seas in the north-east Atlantic further strengthened the wind-driven warming. Temperatures rising above freezing in the Arctic are of particular concern because polar ice, which reflects away warming solar radiation, gets melted.

Hansen's recent study, published in the journal Environment: Science and Policy for Sustainable Development, stated, “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 primary cause of the increase in temperatures over the last two years is deforestation and the relentless rise in CO₂ emissions from the burning of fossil fuels. The peak of the El Niño climate cycle in 2024 added an extra temperature boost. However, these two factors do not fully explain the extreme temperatures, or their persistence after the El Niño ended in mid-2024. This left climate scientists wondering if there was another factor not previously accounted for, or if the extra heat was an unusual but temporary natural variation.

A key focus has been on emissions from shipping. For decades, the sulphate particles produced by ships burning fuel have blocked some sunlight from reaching the Earth’s surface, suppressing temperatures. But in 2020, new anti-pollution regulations came into force, sharply cutting the level of the aerosol particles. This led to more heat from the sun reaching the surface

Hansen is concerned that the accelerated global heating will increase ice melting in the Arctic and as a result, shutdown of the Atlantic Meridional Overturning Circulation (AMOC), the primary system of ocean currents that moves water within the Atlantic Ocean. “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’.” The estimate on the timing of an AMOC collapse is 2050.

However, Hansen said the point of no return could be avoided, based on the growing conviction of young people that they should follow the science. He called for a carbon fee and dividend policy, where all fossil fuels are taxed and the revenue returned to the public. "The basic problem," he noted, "is that the waste products of fossil fuels are still dumped in the air free of charge.”