Scientific evidence in 2025 showed global warming accelerating faster than expected, while emissions continued to rise and climate policy lagged dangerously behind physical reality.

Climate warming is a field of fast-changing physical realities – in many cases beyond scientific expectations – and gob-smacking new flood and heatwave and fire extremes, month after month, enhanced by a heating climate. And we are now ending a year when climate denial reached new peaks in the American Presidency and within our home-grown Liberal-National-Party coalition.

Fossil-fuel carbon dioxide (CO2) emissions are expected to increase by 1.1 per cent in 2025 to reach a record high; the global average concentration of CO2 rose by 3.5 parts per million which was the largest increase since modern measurements started in 1957; and it is projected that fossil fuel emissions by 2050 will be barely lower than today, according to the 2025 Production Gap report (see diagram).  In fact, both oil and gas supply are projected to continue rising till 2050.

This year, it was confirmed by scientists that the extraordinary jump in global average temperature in 2023 to 1.5°C was not a one-off, but indicative of a pattern of accelerated global warming. The 2024 year was 1.6°C; the first eleven months of 2025 was 1.48°C; and the three-year average will exceed 1.5°C.

It is unlikely that any future three-year average will drop below that figure. James Hansen, perhaps the world’s greatest living climate scientist, says that “averaged over the El Nino/La Nina cycle, the 1.5°C limit has been reached”.

The projections of continuing high emissions and the weakening of the carbon sinks in forests and in soils and permafrost means we are likely to exceed 3°C of warming. “We are potentially headed towards 3°C of warming by 2100 if we carry on with the policies we have at the moment,” says IPCC Chair Professor Jim Skea. And it may be a good deal higher than that.

Five years ago the late Professor Will Steffen argued that:

“Given the momentum in both the Earth and human systems, and the growing difference between the ‘reaction time’ needed to steer humanity towards a more sustainable future, and the ‘intervention time’ left to avert a range of catastrophes in both the physical climate system (e.g., melting of Arctic sea ice) and the biosphere (e.g. loss of the Great Barrier Reef), we are already deep into the trajectory towards collapse.”

The evidence over the last year only reinforces that conclusion. So how, in all of this, and thousands of new scientific papers, is it possible to select the “big” stories of 2025?

Running AMOC 

Sometimes there are events in climate research and observation which are truly shocking – even to scientists. One was the extraordinary “big melt” of Arctic sea-ice in 2007 which led one leading glaciologist to exclaim that it was happening “100 years ahead of schedule.” And then there was the 2014 research which concluded that “a rapidly melting section of the West Antarctic Ice Sheet appears to be in an irreversible state of decline” and had passed a tipping point. Previously the IPCC had reported that Antarctica would likely be stable for a 1000 years, so it was a real eye-opener.

This year, it was research about the AMOC, the Atlantic Meridional Overturning Circulation. New modelling showed it was at a point of collapse that would mean agriculture – and perhaps living – would become non-viable in north-western Europe. AMOC is the vast ocean circulation system across the breadth and depth of the........

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