The next el Niño---James Hansen

 From James Hansen's Climate Uncensored Substack

You can read the full article yourself, and I'll just post the main chart and the conclusion here.

Fig. 1. Global surface temperature (relative to 1880-1920 base period).[1]
click on chart to enlarge

 Abstract: 

The world seems headed into another El Niño, just 3 years after the last one. Such quick return normally would imply, at most, an El Niño of moderate strength, but we suggest that even a moderately strong El Niño 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 Niño, per se. We find that the principal drive[r] 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.

The key lines on the chart are the 1970-2010 linear trend, of an increase of 0.18 C per decade, the linear trend from 2010 to the present of 0.3 C per decade (last 15 years) and the linear trend from 2015 to date of 0.41 C per decade.

It's really a clear-cut proposition:  either we slash emissions very fast, or there will be climate catastrophe.  Yes, emissions have probably peaked, but they're only likely to fall slowly at first, and for the rate of increase in temperatures to slow to, say, 0.1 C per decade, we will need to cut emissions by 2/3rds or 3/4qtrs.

Can we do that?  

The chart below, from Our World in Data, shows emissions by sector, which includes direct emissions, as well as indirect emissions.  For example, you could be burning oil directly to heat your house, or using fossil fuels indirectly, via electricity.  Electricity generation produces roughly 30% of global emissions.  Apart from aviation and shipping, almost all of the sectors in the red quadrant can be electrified.  Converting the grid to green tech will be a huge step towards eliminating all emissions from these sectors.

So it is possible.  But that means green electricity, and the electrification of everything.  Wind and solar and batteries instead of coal and gas power stations, plus EVs and heat pumps.  Electric trains, electric planes, electric ships.  Chemicals and cement.  Landfill.

And we need to deal with emissions in agriculture.  That will be complicated and will vary by source, so the sooner we start, the better.

It's doable.  But will we do it?  It's up to us.

Source: Our World in Data

 

Global heating is accelerating

The research suggests that a ‘dangerous’ burst of heating will be unleashed, pushing temperatures 2C hotter by 2050. Photograph: Dmitry Rukhlenko/Travel Photos/Alamy

From The Guardian

Global heating is accelerating faster than is currently understood and will result in a key temperature threshold being breached as soon as this decade, according to research led by James Hansen, the US scientist who first alerted the world to the greenhouse effect.

The Earth’s climate is more sensitive to human-caused changes than scientists have realized until now, meaning that a “dangerous” burst of heating will be unleashed that will push the world to be 1.5C hotter than it was, on average, in pre-industrial times within the 2020s and 2C hotter by 2050, the paper published on Thursday predicts.

This alarming speed-up of global heating, which would mean the world breaches the internationally agreed 1.5C threshold set out in the Paris climate agreement far sooner than expected, risks a world “less tolerable to humanity, with greater climate extremes”, according to the study led by Hansen, the former Nasa scientist who issued a foundational warning about climate change to the US Congress back in the 1980s.

Hansen said there was a huge amount of global heating “in the pipeline” because of the continued burning of fossil fuels and Earth being “very sensitive” to the impacts of this – far more sensitive than the best estimates laid out by the UN’s Intergovernmental Panel on Climate Change (IPCC).

“We would be damned fools and bad scientists if we didn’t expect an acceleration of global warming,” Hansen said. “We are beginning to suffer the effect of our Faustian bargain. That is why the rate of global warming is accelerating.”

The question of whether the rate of global heating is accelerating has been keenly debated among scientists this year amid months of record-breaking temperatures.

Hansen points to an imbalance between the energy coming in from the sun versus outgoing energy from the Earth that has “notably increased”, almost doubling over the past decade. This ramp-up, he cautioned, could result in disastrous sea level rise for the world’s coastal cities.

The new research, comprising peer-reviewed work of Hansen and more than a dozen other scientists, argues that this imbalance, the Earth’s greater climate sensitivity and a reduction in pollution from shipping, which has cut the amount of airborne sulphur particles that reflect incoming sunlight, are causing an escalation in global heating.

“We are in the early phase of a climate emergency,” the paper warns. “Such acceleration is dangerous in a climate system that is already far out of equilibrium. Reversing the trend is essential – we must cool the planet – for the sake of preserving shorelines and saving the world’s coastal cities.”

To deal with this crisis, Hansen and his colleagues advocate for a global carbon tax as well as, more controversially, efforts to intentionally spray sulphur into the atmosphere in order to deflect heat away from the planet and artificially lower the world’s temperature.

So-called “solar geoengineering” has been widely criticized for threatening potential knock-on harm to the environment, as well as over the risks of a whiplash heating effect should the injections of sulphur cease, but is backed by a minority of scientists who warn that the world is running out of time and options to avoid catastrophic temperature growth.

Hansen said that while cutting emissions should be the highest priority, “thanks to the slowness in developing adequate carbon-free energies and failure to put a price on carbon emissions, it is now unlikely that we can get there – a bright future for young people – from here without temporary help from solar radiation management”.

This year is almost certain to be the hottest ever reliably recorded, with temperatures in September described as “gobsmackingly bananas” by one climate researcher. A report this week found that the carbon budget to limit the world to 1.5C of heating is now nearly exhausted due to the continued burning of fossil fuels and deforestation.

But while scientists are clear about this being part of an upward trend of global heating, there is as yet no agreement that this trend is accelerating.

Michael Mann, a climate scientist at the University of Pennsylvania, said that Hansen and his co-authors are “very much out of the mainstream” in identifying an acceleration in surface heating that has “continued at a remarkably constant rate for the past few decades”. Mann said that cuts to shipping emissions have only a tiny effect on the climate system and that calls for solar geoengineering are misguided and a “very slippery slope”.

Bärbel Hönisch, a paleoclimatologist at Columbia University, said she had “some reservations” about the certainties expressed in Hansen’s research about the state of the Earth’s climate millions of years ago, which helps predict the consequences of warming today. “I’d be a little more reserved, but they may well be correct – it’s a nicely written paper,” she said. “It raises a lot of questions that will trigger a lot of research that will bring our understanding forward.”

Some other researchers are less skeptical of Hansen’s dire warning of supercharged global heating, highlighting his previous prescient warnings about the climate crisis that have largely played out due to decades of inaction to stem the use of fossil fuels.

“I think [Hansen’s] contention that the IPCC has underestimated climate sensitivity somewhat will prove to be correct,” said Rob Jackson, a Stanford University scientist and chair of the Global Carbon Project. “It’s hard to know what’s unlikely any more in terms of warming. No fossil fuel has declined in use yet globally, not even coal.

“I think Hansen’s pessimism is warranted. He stood up 35 years ago and sounded the alarm – and the world mostly ignored him, and all of us.”

Will Earth breach 1.5 degrees soon?

‘James Hansen and co have joined other scientists in noting events in Antarctica this year, particularly a sharp fall in the amount of sea ice surrounding the continent, may indicate it is joining the Arctic in becoming an important contributor to global heating.’ Photograph: Anadolu Agency/Getty Images

From The Guardian

People tend to notice when James Hansen speaks, and with good reason. Sometimes described as the godfather of climate science, Hansen came to global attention in June 1988 when he was director of the Nasa Goddard Institute for Space Studies.

Invited to speak before a US Senate committee, he warned Nasa was 99% confident that human-made greenhouse gas emissions were already causing global warming, and the likelihood of extreme weather was increasing. Scientists and historians generally agree this forceful testimony 35 years ago was a turning point in mass awareness of a looming climate problem.


Hansen worked at Nasa for more than 40 years and moved towards advocacy and activism as his repeated warnings about the need to act were not properly heeded. Now, at 82, he is an adjunct professor at Columbia University, where he publishes regular analyses of the latest climate evidence.

His most recent commentary, written with three colleagues under the heading “El Niño fizzles. Planet Earth Sizzles. Why?”, looks at why this year is almost certainly going to be the hottest on record. Their most eye-catching conclusion, at least in terms of the global political response to the climate crisis, is that by early next year the world may have reached 1.5C warming above the long-term temperature average.

Trying to limit heating to 1.5C is a key global aspiration inscribed in the landmark Paris climate agreement, and has been widely adopted as a guardrail for avoiding worsening devastation that affects lives, livelihoods and nature.

As the Guardian has reported, the average global temperature last month was what scientists described as a gobsmacking 1.7C or 1.8C above historic levels, and more than 0.5C above the previous hottest September on record.

This doesn’t mean the 1.5C guardrail is gone – that will only happen if temperatures stay that high for an extended period. That has generally been considered to be years away. The Intergovernmental Panel on Climate Change said only that it was likely within the next two decades. Hansen argues recent temperatures challenge that.

For the past four months, the globe has been 0.44C hotter than in 2015, a year chosen because it was the last time we were heading into an El Niño, which tends to warm the planet. The scientists argue if this keeps up until the northern spring (the southern autumn) the 12-month average will be at least 1.6C above temperatures more than a century ago.

They say that would mean 1.5C had been reached “for all practical purposes” and “there will be no need to ruminate for 20 years, as the IPCC proposes” about whether we have actually got there. “On the contrary, Earth’s enormous energy imbalance assures that global temperature will be rising still higher for the foreseeable future,” they say.

Given the consistent emphasis on the 1.5C goal, it is likely some people may interpret this, if it were to happen, as the battle to limit the climate crisis having been lost. Some might be tempted to give up. But this is not the message from the scientific community, and not all climate scientists agree there is enough data to say the pace of warming is accelerating.

Hansen and co dedicate most of their paper to what is causing the recent heat surge. They suggest the current El Niño is a relatively minor player compared to previous similar events, and may ultimately be smaller than the “super” El Niños in the hot years of 1997-98 and 2015-16.

They argue a more likely explanation for a warming spike could be a reduction in human-made aerosols, particularly from power plants and factories in China and the global shipping fleet. Aerosols interact with sunlight and clouds to produce a cooling effect that until recently has offset some of the underlying heat caused by greenhouse gases in the atmosphere. A decline in aerosols pollution, motivated by a desire to improve air quality, could unmask human-induced heating already in the global system.

Hansen has long described this as the Faustian climate bargain. Using fossil fuels releases both aerosols and greenhouse gases, but the cooling effect of the former lasts only days, while the warming of the latter lasts centuries. He says eventually the payment – a rapid increase in warming – was going to come due.

The other area of significant change this year is Antarctica, where warming this year has been off-the-charts. Until recently, there has not been a global heating signal over much of Antarctica despite scientists having long expected that polar regions would warm faster than the rest of the planet. Hansen and co join other scientists who have noted that events this year, particularly a sharp fall in sea ice cover, may indicate this has changed and the continent is becoming an important contributor to global heating.

It is important to stress that not all climate scientists are as pessimistic as Hansen and his colleagues that 1.5C is about to be breached. Debate over whether the guardrail is already lost is not new. The Australian Academy of Science created a wave of controversy in 2021 when it argued that it was “virtually impossible” to stay within that mark.

Michael Mann, a professor at the University of Pennsylvania and celebrated author, is among those who cautions against over interpreting a relatively short period this year that could be explained by an El Niño and natural variability on top of “steady, long-term human-caused warming”.

Mark Howden, a professor at the Australian National University and an Intergovernmental Panel on Climate Change vice-chair, says the most worrying thing about the current heat is that it’s broadly consistent with what scientists have long forecast would happen.

He says the degree to which aerosols are driving record temperatures remains open to debate, noting there was not an equivalent leap when Covid-19 shutdowns caused a significant drop in aerosol use in 2020, and suggests it will be a while before we know if heating has reached 1.5C, given that assessment needs to be based on long-term averages.

But Howden agrees that we are rapidly headed in that direction, and governments are not doing anything like what’s required in response to clear evidence that human and environmental security are at risk.

What does it mean if 1.5C is soon passed? A lot to millions of people and countless species. But it’s worth remembering this threshold was to some extent an arbitrary choice, driven by politics. It could have been 1.2C, 1.4C or 1.6C.

The fundamental message from many scientists is simpler than a guardrail. It’s the same one Howden posted on social media five years ago: every fraction of a degree matters, every year matters, every choice matters.

The question, as always, is: who’s listening?

50 years on, climate models surprisingly accurate

From ScienceAlert:

It's a common refrain from those who question mainstream climate science findings: The computer models scientists use to project future global warming are inaccurate and shouldn't be trusted to help policymakers decide whether to take potentially expensive steps to rein in greenhouse gas emissions.

A new study effectively snuffs out that argument by looking at how climate models published between 1970 - before such models were the supercomputer-dependent behemoths of physical equations covering glaciers, ocean pH and vegetation, as they are today - and 2007.

The study, published Wednesday in Geophysical Research Letters, finds that most of the models examined were uncannily accurate in projecting how much the world would warm in response to increasing amounts of planet-warming greenhouse gases. Such gases, chiefly the main long-lived greenhouse gas pollutant, carbon dioxide, hit record highs this year, according to a new UN report out Tuesday.

They are now higher than at any other time in human history.

The study does fault some of the models, including one of the most famous calculations by former NASA researcher James Hansen, for overestimating warming because they assumed there would be even greater amounts of greenhouse gases in the atmosphere than what actually occurred. These assumptions mostly involved non-CO2 greenhouse gases, such as methane.

Hansen's projection, says study lead author Zeke Hausfather, a researcher at the University of California at Berkeley, erred by about 50 percent because it did not foresee a significant drop in emissions of substances that deplete the stratospheric ozone layer.

Many of those gases are also powerful global warming agents. Hansen also didn't foresee a temporary stabilization in methane emissions during the 2000s, Hausfather says.

However, his model, like many of the others examined in the new study, got it right on the basic relationship between greenhouse gas emissions and the amount of warming they would cause. The errors came from poorly predicting bigger wild cards: How societal factors would govern future emissions through economic growth, emissions reduction agreements, and other factors.

"The big takeaway is that climate models have been around a long time, and in terms of getting the basic temperature of the Earth right, they've been doing that for a long time," Hausfather said in an interview.

Image: Comparison of trends in temperature vs. time (top) and implied transient climate response (TCR), or the amount of temperature increase that might take place when carbon dioxide doubles (bottom) between observations and models over the periods displayed.

For the uninitiated, a brief explanation of computer models.  All computer models involve two main arms.  The first is the structure of the model itself--what it depends on and what the internal and external relationships are.  The second is the inputs.  For example, let's suppose that the world had listened when Hansen issued his global warming warnings, and had moved to cut CO2 and methane emissions.  Then global temperatures wouldn't have risen.  But that doesn't make the models wrong.  Equally, if emissions had risen as fast as Hansen assumed, then actual temperatures would have matched what the model predicted.  The model was fine; the forecast inputs turned out to be wrong.  GIGO, or "garbage in garbage out" as they say in the computer industry.  That in turn means that forecasts of a 3 degree plus rise by 2100 depend on whether we slash emissions or not.  If we do, we will avoid that terrible situation.  If we do not, we won't. 

What the models got right on average, was the decadal rise in temperatures, which they forecast would be about 0.2 degrees and which in fact turned out to be very close to that.

Hansen: projections and reality

It's been 30 years since Jim Hansen warned us about global warming.  "The greenhouse effect is here", he said on 23rd June 1988 to the US Senate.  What have we done since then?

The first chart below shows the three scenarios projected by Hansen back in 1988.  Scenario A has the highest growth in CO2, NO2, methane and CFCs, scenario B lower rates and scenario C projected stability, i.e., no increase in greenhouse gases. 

And at first you'll say, but hang on, his projected temperature is much higher than what actually happened.  The model was wrong!  Um, no.  Remember that to get these results his team had to project what would happen to the inputs to the model, i.e., the emissions/levels of the greenhouse gases I mentioned above.  Actual CO2 turned out to be pretty much what Hansen and co projected they would be.  But Hansen projected ongoing rises in CFCs , which are very powerful greenhouse gases.  In a rare win for co-operation and good sense, CFCs were phased out of production after the Montreal Protocol came into force in 1988.  If Hansen had factored in the levelling off in CFCs  in the atmosphere, he would have got a result quite close to what actually happened (see the second chart below).

(Source for both charts: RealClimate)

There's good and bad news from all this. 

The good news is that the world actually agreed to phasing out CFCs back in 1988, and that saved us 0.5 degrees C of global warming.   If we could agree then, we might yet be able to agree with CO2 and NO2.  Yes, fossil fuel industries now are bigger and more powerful than CFC industries were then, and yes, that well hadn't been poisoned by the Right's demented passion for coal.  But the power of coal and oil industries is dwindling.  The evidence of global warming gets every day more scary.  Most ordinary people, as opposed to politicians, are convinced that global warming is real and that we need to do something about it.  And the costs of renewables have fallen and keep on falling so precipitously that the switch to renewables is happening anyway, despite the rantings of the Right.  The opposition to a genuine climate agreement with teeth is diminishing, while the necessity for it grows every day more pressing.

The bad news is that Hansen's scenario C, which assumed that production of all greenhouse gases would stop immediately, still had temperatures rise by 0.5 degrees over the next 20 years, before slowly starting to decline.  This is because there are lags in the system.  For example, daily temperatures don't peak at midday when insolation is at its peak but a few hours later, when the sun's power is already waning.  These lags mean that even if we cut output of greenhouse gases to zero by 2050, temperatures will likely go on rising by another 0.5 degrees C up to 2070 before starting to gradually decline.  And by 2050, temperatures will already have risen another 0.6 degrees from the greenhouse gases which we will continue to emit into the atmosphere up till then.  So that means another 1.1 degree C rise in global temperatures.  The 1 degree we have had so far is bad enough.  What will another 1 degree do?

[Read more here]

Why I must speak out on climate change

A compelling video from James Hansen.  It's longish, but worth every minute.

A presentation by James Hansen

James Hansen was one of the first people to point out the probability of global warming.  He's the author of Storms of my Grandchildren, a compelling analysis of global warming and carbon pollution.

This a presentation he made recently.  It's long, but worth every minute.  Though Hansen seems to favour it, I doubt that nuclear is the answer but on the other hand it is undoubtedly better than the "business as usual" approach.  Hansen's comments on the likely rise in the sea level are truly scary.