Has the Rate of Global Warming More Than Doubled?
Hansen: If the current La Niña minimum temperature is high, we'll know that global warming has sped up even more.
Last December we featured a piece, “Near-Term Climate News and Other Tall Tales,” which included the following chart. The source is James Hansen’s December 2025 climate letter, available here. I’ve highlighted in red two areas of special interest.
First, note the meaning of the lime-green and lavender lines. The lime-green line projects future global warming using the best linear fit of climate data from the years 1970-2010. That rate is +0.18°C per decade.
Yet, as the data above shows, the real rate of global warming is not constant at all; there’s a clear rise in measured temperature starting in 2015. Climate change has accelerated.
With that in mind, consider the lavender line. It projects future warming using the best linear fit of data from 2010 to 2024. That rate is +0.31°C per decade, almost double the earlier rate.
Now look to the extreme right of the graph, where the lavender line crosses the vertical for the year 2040 (the X-axis is time). Based on this projection, global warming will cross above +1.8°C in 2040 and cross above two-degrees warming in the mid-2050s.
A disaster to be sure, but 25 years away, so it’s easy for the comfortable to think there’s still time to act, still time to enjoy March Madness for a few more years untroubled by troubling thoughts.
Not So Fast, My Friend
It’s now February, just two short months since then, and new data has come in regarding the next El Niño. Hansen on that:
Another El Nino Already? What Can We Learn from It?
Abstract. The world seems headed into another El Nino, just 3 years after the last one. Such quick return normally would imply, at most, an El Nino of moderate strength, but we suggest that even a moderately strong El Nino may yield record global temperature already in 2026 and still greater temperature in 2027. The extreme warming will be a result mainly of high climate sensitivity and a recent increase of the net global climate forcing, not the result of an exceptional El Nino, per se. We find that the principal drive for global warming acceleration began in about 2015, which implies that 2°C global warming is likely to be reached in the 2030s, not at midcentury.
His accompanying chart shows this updated data (again, highlights are mine):
Three things to note:
First, on the left there’s a third line (in purple) showing the climate change rate from 2015 in addition to the earlier lines. The new rate is 0.41°C per decade, more than double the rate from 1970-2010.
Second, note on the line showing the 12-month running mean of global temperature (in blue), the most recent La Niña minimum. That’s a projection, since 12 months have not passed. But if the La Niña minimum is the number above, it — the minimum of the El Niño-La Niña cycle — will be higher than any previous El Niño maximum.
If this turns out to be true — that the next minimum is higher than any previous maximum — it will confirm the accuracy of the higher projected acceleration.
Hansen again:
Two years ago, when many doubted the reality of global warming acceleration, we noted that the peak of the ongoing El Nino and the following La Nina valley could help confirm the reality of acceleration and assess whether average global temperature has already reached 1.5°C. The La Nina valley is yet to be determined, as the 12-month mean is still declining. We projected a minimum of 1.4°C to be achieved by the second quarter of 2026. A minimum about 1.4°C will be strong support of global temperature acceleration, as such La Nina minimum is higher than any El Nino maximum in the prior decade, which included a “Super El Nino.” In turn, it supports the mechanisms that we suggest are behind acceleration: high climate sensitivity (at least 4°C for doubled CO2) and reduction of aerosol cooling due to declining aerosol emissions from East Asia and ships at sea (Global warming in the pipeline, and Global warming has accelerated).
I am confident he’s right about the next La Niña minimum. To my knowledge, no scientist has predicted too much warming; for decades, every projection has been for too little. Those conservative estimates are what keep us watching the game instead of pummeling politicians.
Finally, look what happens to the warming projection as it reaches the top. It crosses +2.0°C in the 2030s, not in the 2050s. That’s clearly not later. That’s very close to now.
A Short Note on What to Do
The real bottom line of this piece is immediately above — two-degrees warming is likely just ahead. And now that ideologues have replaced the corporatists, we’re about to race to the end at break-neck speed.
So what should we do? Regular readers know I’m no doom-and-gloomer. The world needn’t control how you feel. We all try to live well, even in the face of our death. That doesn’t make life mean nothing — if anything, it makes life matter more. What we do until then can still bring pleasure and joy. As with that, so here.
In addition, each day we plan for bad things to come. So what should you do with this news? Have trust in yourself. Plan. Prepare to adapt. And live your life well regardless of circumstance. That task hasn’t changed.
Thanks for the clear-headed analysis and update, Thomas. I've only recently realized myself how most of the worst and likely projections have been downplayed. +2 by ~2030 already seems baked in.
Thomas, I think that it’s important to define what it means to “live your life well regardless of circumstance.” Until July of 2019 Jeffrey Epstein would have vigorously argued that he was able to “live his life well” even though that involved transactionally exploiting every single person with whom he came into contact for his personal pleasure and enrichment. Yes, “living well” includes material comforts, but the explosion in American billionaires from 66 in 1990 to over 900 in 2025 allows a few oligarchs to live in obscene sumptuousness.
We must begin with the assumption that the climate crisis is a direct result of a planetary carrying capacity crisis caused by the explosion of human lives in simultaneous being from 2.5 billion when I was born in the mid-1950’s to 8.25 billion today and 9 billion by 2035. This is not simply down to the “wrong” people having “too many children” — more children are surviving infancy and more of us are living much longer than the life expectancy 70 years ago. Is the “solution” euthanizing old people and more Gazas? I find both options morally repugnant (and a threat to my personal safety).
I propose the revival of an old definition of “living well” — Don’t do to others that which would be repugnant if done to you. The climate crisis is real and no person, rich or poor, will ultimately evade the consequences. Let’s all try to make the end as painless as it can be, for as many of our fellow human beings as possible.