Third hottest September ever

From Berkeley Earth.

This chart shows the temperature anomaly relative to the 1850 -1900 September average temperature, for each September since 1850.  You can see how temperatures spiked during El Niño, and have since been falling as El Niño was replaced by La Niña.  The red line shows the trend, which you can see is accelerating.  This is the third-warmest September on record.

September 2025 was the third warmest September on record behind 2023 and 2024, with a global average of 1.48 ± 0.15 °C (2.67 ± 0.26 °F) above the 1850-1900 average.

This chart shows the 12-month moving average of the temperature anomalies up to September 2025.  The 12-month moving average has rolled over after the end of El Niño, but don't mistake this for a change in the longer-term trend, shown by the red LOESS smoothed line.

With the Paris Climate Agreement (COP21), 10 years ago, the world agreed to aim for a maximum increase in temperatures over the 1850-1900 average of 1.5 degrees C.  We're there already, and even though temperatures have fallen marginally from the El Niño high 3 years ago, the trend is inexorably upwards.  We have failed.  COP conferences have turned into pointless gabfests, where lobbyists from fossil fuel industries outnumber government delegates.

Only the continued decline in solar panel, battery and EV costs gives me any hope that mankind will act quickly enough to cut emissions and prevent a climate catastrophe.

Berkeley Earth June temperature updates

 From Berkeley Earth

June 2024 Temperature Update

Posted on July 17, 2024 by Robert Rohde

The following is a summary of global temperature conditions in Berkeley Earth’s analysis of June 2024.

• Globally, June 2024 was the warmest June since records began in 1850.
• The previous record for warmest June, set in 2023, was broken by a relatively large margin (0.14 °C / 0.25 °F).
• The ocean-average and land-average each also set new records for the warmest June.
• Particularly warm conditions occurred in South America, parts of Asia, Africa, and large areas of the Atlantic Ocean.
• Parts of Antarctica exhibited unusually cold monthly averages in June.
• We estimate that 63 countries set new national monthly-average records for June.
• The El Niño that began last year has now ended. La Niña is expected later this year.
• The 12-month moving-average sets a new record at 1.68 ± 0.07 °C (3.02 ± 0.13 °F) above the 1850-1900 average.
• 2024 is likely to be the warmest year on record.

Gobsmackingly bananas

 In September, global temperatures charts went off the scale

ClimateCrocks:

The BBC:

From Denis Gilbert

Berkeley Earth report:

The following is a summary of global temperature conditions in Berkeley Earth’s analysis of September 2023.

• Globally, September 2023 was the warmest September — and the largest monthly anomaly of any month — since records began in 1850.
• The previous record for warmest September was broken by 0.5 °C (0.9 °F), a staggeringly large margin.
• Both land and ocean individually also set new records for the warmest September.
• The extra warmth added since August occurred primarily in polar regions, especially Antarctica.
• Antarctic sea ice set a new record for lowest seasonal maximum extent.
• Record warmth in 2023 is primarily a combined effect of global warming and a strengthening El Niño, but natural variability and other factors have also contributed.
• Particularly warm conditions occurred in the North Atlantic, Eastern Equatorial Pacific, South America, Central America, Europe, parts of Africa and the Middle East, Japan, and Antarctica.
• 77 countries, mostly in Europe and the tropics, set new monthly average records for September.
• El Niño continues to strengthen and is expected to continue into next year.
• 2023 is now virtually certain to become a new record warm year (>99% chance).
• 2023 is very likely (90% chance) to average more than 1.5 °C above our 1850-1900 baseline.

Yet still we dither and phaff, instead of moving aggressively to slash emissions.  Our politicians continue to accept bribes from fossil fuel companies.  Voters continues to let them do so.

2023 likely to exceed 1.5 degrees

 From a toot by Robert Rohde (of Berkeley Earth) 

The recent extreme conditions have led to another upward revision to our forecast for 2023.

In addition to 2023 almost certainly becoming the warmest directly measured year, we now estimate roughly even odds that 2023 will be at least 1.5 °C (2.7 °F) above the 1850-1900 baseline.

Potentially exceeding – at least temporarily – the Paris Agreement target of limiting long-term global warming to no more than 1.5 °C.

#GlobalWarming #ClimateChange #ParisAgreement #Temperature

 

This current period of record warmth is driven by a combination of man-made & natural factors.

The long-term trend is driven primarily by man-made global warming due to the accumulation of greenhouse gases in the atmosphere.

On top of this we also see short-term swings due to natural variability, including that associated with the recent transition from La Niña to El Niño.

#GlobalWarming #ClimateChange #Temperature #Climate #ElNino

2022 warmest year in UK

From The BBC

The Met Office has said 2022 will be the warmest year on record for the UK.

According to provisional figures, every month was hotter than average, with the exception of December when the UK experienced a notable cold snap.

The year's average temperature will likely beat the previous all-time high of 9.88C, set in 2014.

The exact mean temperature is set to be confirmed in the new year but the Met office said the consistent heat this year had been noteworthy.

Dr Mark McCarthy, a senior climate scientist at the Met Office, said the provisional figures are in line with the "genuine impacts we expect as a result of human-induced climate change".

"Although it doesn't mean every year will be the warmest on record, climate change continues to increase the chances of increasingly warm years over the coming decades," Dr McCarthy added.

A spell of heatwaves in June led to the UK experiencing its fourth warmest summer on record, as temperatures broke the 40C mark for the first time.

During the intense heat in July, the Met Office issued its first ever red warning for extreme heat. The temperatures seen in mid-July would have been "extremely unlikely in the pre-industrial period - the era before humanity started emitting lots of greenhouse gases," Dr McCarthy explained.

"As we have seen in the first two weeks of December, our climate is still subject to notable cold spells during the winter season, but our observational data show these have generally become less frequent and less severe as our climate warms," he said.

Last week, the Met Office said it was expecting 2023 to be warmer than this year, and one of the hottest on record.

Predictions suggest it will be the 10th year in a row where the global temperature is at least 1C above average.

Scientific evidence shows that climate change is driving up the global temperature, and governments around the world have promised to cut emissions to keep temperature rises below 1.5C.

In a separate report, the National Trust warned that extreme weather seen throughout the year has set a benchmark for what a typical year could be like.

The charity said high temperatures, drought and back-to-back storms have created major challenges for nature in years to come.

In its annual review, it said this year was a "stark illustration" of the difficulties many UK species could face without more action to tackle climate change.

The hot summer and months of low rainfall dried up rivers, fragile chalk streams and ponds, damaged crops and natural habitats, and fuelled wildfires that destroyed landscapes, the charity said.

The National Trust's climate change adviser, Keith Jones, said there was "no escaping" how challenging this year's weather had been for nature.

"Drought, high temperatures, back-to-back storms, unseasonal heat, the recent cold snap and floods means nature, like us, is having to cope with a new litany of weather extremes," he said.

He added weather experts were predicting the future would see more torrential downpours, along with very dry and hot summers.

Record heat in October

 From Berkeley Earth

Year-to-date, 7.8% of the Earth’s surface has experienced record warmth. No part of the Earth’s surface has been record cold in its year-to-date average.

2020 temperature tied record

 From ClimateCrocks

Temperatures last year tied the modern record, climate scientists reported today. Overall, the planet was about 1.25°C warmer than in preindustrial times, according to jointly reported assessments from NASA, the U.K. Met Office, and other institutions.

The annual update of global surface temperatures—an average of readings from thousands of weather stations and ocean probes—shows 2020 essentially tied records set in 2016. But the years were nothing alike. Temperatures in 2016 were boosted by a strong El Niño, a weather pattern that warms the globe by blocking the rise of cold deep waters in the eastern Pacific Ocean. Last year, however, the Pacific entered La Niña, which has a cooling effect. That La Niña didn’t provide more relief is an unwelcome surprise, says Nerilie Abram, a climate scientist at Australian National University. “It makes me worried about how quickly the global warming trend is growing.”

The past 6 years are the six warmest on record, but the warming of the atmosphere is unsteady because of its chaotic nature. The ocean, which absorbs more than 90% of the heat from global warming, displays a steadier trend, and here, too, 2020 was a record year. The upper levels of the ocean contained 20 zettajoules (1021joules) more heat than in 2019, and the rise was double the typical annual increase, scientists reported yesterday in Advances in Atmospheric Sciences. The subtropical Atlantic Ocean was particularly hot, fueling a record outbreak of hurricanes, says Lijing Cheng, a climate scientist at the Chinese Academy of Sciences’s Institute of Atmospheric Physics who led the work.

This heat, monitored down to 2000 meters by a fleet of 4000 robotic probes, is spreading deeper into the ocean while also migrating toward the poles. An extreme heat wave struck the northern Pacific, killing marine life. For the first time, warm Atlantic waters were seen penetrating into the Arctic Ocean, melting sea ice from below and driving its extent nearly to a record low. The warming ocean and melting ice sheets are raising sea levels by 4.8 millimeters per year, and the rate is accelerating.

[Read more here]

US winter one month shorter

Straws Lane, Macedon Ranges (Victoria) this July

You can clearly see how the world is warming using average temperatures or the temperature anomaly, as calculated by NASA, NOAA, Berkeley Earth, of the 3 or 4 other organisations which make the effort.  But you can also see global warming in how much later the winter begins and how much earlier summer starts. 

In the southern hemisphere, mid-winter is in the middle of the year.  Autumn is in March and spring in September.  When we first moved here 25 years, the first frosts came in the last week of April, the first warm day in mid-October.  Now the first frosts don't come till early June and the first warm day comes in early September.  But that isn't very scientific: we need to know the average and we need to properly measure the data.  This winter for example was a lot like it was 25 years ago: we got snow down to 600 metres.  We haven't had that for a long time.  Does it mean global warming is over? Prolly not.

Somewhat more scientific than my impressions:  using records from 700 weather stations, NOAA has calculated that winter in the USA is on average 1 month shorter than it was 100 years ago.

The trend of ever later first freezes appears to have started around 1980, according to data from 700 weather stations across the US going back to 1895 and compiled by Ken Kunkel, a meteorologist at the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information.

Kunkel compared the first freeze from each of the 700 stations to the station’s average for the 20th Century. Some parts of the country experience earlier or later freezes every year, but on average freezes are coming later.

The average first freeze over the last 10 years, from 2007 to 2016, is a week later than the average from 1971 to 1980.

This year, about 40% of the Lower 48 states have had a freeze as of 23 October, compared to 65% in a normal year, according to Jeff Masters, meteorology director of the private service Weather Underground.

In Ottawa, Illinois, the average first freeze for the 20th century was 15 October. The normal from 1981 to 2010 based on NOAA computer simulations was 19 October. Since 2010, the average first freeze is on 26 October. Last year, the first freeze in Ottawa came on 12 November.

Last year was “way off the charts” nationwide, Kunkel said. The average first freeze was two weeks later than the 20th century average, and the last frost of spring was nine days earlier than normal.

Overall the United States freeze season of 2016 was more than a month shorter than the freeze season of 1916. It was most extreme in the Pacific Northwest. Oregon’s freeze season was 61 days – two months – shorter than normal.

[Read more here]

If Mt Agung erupts

Big volcanic eruptions temporarily reduce global temperatures because they release sulphur high into the atmosphere, which combines with water to produce sulphuric acid aerosols which reflect incoming sunlight, thus cooling the earth.  If the eruption is large enough, the cooling effect can last a couple of years. There's an excellent article about it on Carbon Brief.

The last time Mt Agung erupted, in 1963, it reduced global temperatures by 0.2 C, as you can see in the chart below.   The blue line in the chart suggests the possible impact on the underlying upward trend if (when) Mt Agung erupts.  No doubt when this happens, denialists will argue that global temperatures will have stopped rising and we can stop worrying about carbon emissions.  Which will be nonsense.

Source: Zeke Hausfather at Carbon Brief

But it does raise the question:  could we simulate volcanic eruptions by artificially releasing sulphur dioxide at very high altitudes (18 kms plus) which will help offset the impact of global warming? This is called geo-engineering. 

There are questions about geo-engineering: cost (who will pay? will it be cheaper than just switching to a green economy? At what scale would we need to do it? ); environmental impact (remember acid rain? is it safe to have a continuous layer of sulphuric acid in the atmosphere?); and politics (would it stop attempts to reduce carbon emissions?)

The Economist has done a short video on it, which you might find interesting.

I was wrong

The difference between a skeptic and a denialist is that a skeptic will change his/her mind if he/she finds new evidence that shows he/she was mistaken.  This is what happened to Dr Richard Muller. (I mentioned him before in this post.)

Dr Richard Muller doubted the reality of climate change.  So he started a new research  body to go back to the basic data and recalculate global temperatures from scratch.  Here's an interview with him where he discusses his findings.




And here's the chart showing the 10 year average of average land global temperatures compared with a simple regression fit based on CO2 levels and volcanic activity.  Note: this is not the temperature anomaly relative to some average base period--it's actual temperatures.

Source

Muller's model has carbon dioxide driving a strong upward trend and sulphate emissions from vulcanism causing short-lived downward spikes.  Sulphate emissions from volcanic eruptions temporarily cool the atmosphere. As Dr Muller says, it's a very good fit.

 Dr Muller was the darling of the Right until he said that global warming was real and caused by man, and even received funding from the Koch brothers.  In the end, his analysis produced a similar pattern to what other groups had calculated, while calculating a longer record allowed his group to show more precisely the negative effect of sulphate emissions.

I suppose we could simulate volcanic eruptions by pumping sulphur dioxide into the stratosphere if temperatures keep on rising.  But I have no idea how much that would cost, or whether the cure would be worse than the disease.  We stopped emitting sulphates from our industrial chimney stacks because of acid rain.  Matters would have to be dire indeed to go back to that.

Policy vs statistics

My last post was about how 2017 might actually be hotter than 2016.  So let’s look at the chart again, only, this time with two trend lines drawn in.  I haven’t used statistical methods to fit the trend lines, I’ve just drawn them in by eye, doing what I would for share prices or stock market indices.  And we don’t really have enough data yet to draw a new trend for the last 4 or 5 years.  But some points are instructive.  First, this is the biggest breakout above the 50-year trend in 50 years. Second, after the last big El Nino in 1998, temperatures in the subsequent year fell sharply.  This time, they might not.  A statistician or climate scientist would be cautious about forecasting a change in trend based on 5 years of data.  They’d point out that we need 25 or 30 years to be sure of the trend.  And they’d be right.

But what happens if you are a politician, entrusted with the welfare of your fellow citizens and of your country?  Indeed, what if you are a citizen, with just your vote, and you're concerned about the welfare of your children and grandchildren?  Do you wait for certainty?  Temperatures have on average risen a bit less than 0.2 degrees C per decade since the 1970s.  So that is very likely to be the minimum trend increase over the next 20 years, unless we stop pumping CO2 into the atmosphere.  But what if in fact the trend has possibly doubled, to 0.4 degrees per decade?  This makes action far more urgent than was agreed at the Paris conference.

The scientists would, rightly, say we don’t have enough data to forecast with any certainty that the trend increase in global temperatures has risen.  But policymakers have to face a different calculus.  They have to assess risk and the probability of worse-case scenarios.

Back in the 80s and 90s, global temps hadn’t risen a lot, and the costs of renewables were far greater than the costs of business as usual (BAU).  Taking action against relatively uncertain risks was expensive, especially for poor countries.  Only the countries most concerned about environmental risks, like Denmark and Germany, actually made any serious moves to green their electricity system.  And we thank them for it, because they pushed us down the renewables learning curve, making renewables cheaper for the rest of us.

But what is the position now?  Well, the evidence of the last 50 years is unambiguous. Remember, the chart isn’t from those “leftists” and “greenies” at NASA, NOAA etc.  It’s from Berkeley Earth, a totally reconstructed series going back 200 years.  And then there’s some credible risk that the trend has accelerated, based on the data, probably driven by malign doom-loop feedbacks from the rapid disappearance of Arctic sea ice to the melting of methane clathrates in the Arctic.  Meanwhile instead of being much higher, the costs of renewables are now lower than the costs of fossil fuels.  Batteries are plunging in cost too, and there are a whole plethora of new storage technologies popping up everywhere.

Whereas the costs of acting in the 80s and 90s relative to the certainty of rising temps was high, now it is extremely low.  The risk/cost equation has blown out dramatically.  Scientists might urge caution, but policy makers have to act now.

We can’t wait til 2050 to reach zero emissions.  We now need to try and get there in 15 or 20 years,  not in 35 years.  How?

• Aim to increase the renewables percentage in generation by 5% a year
• A carbon tax, starting low but increasing inexorably year by year, or a cap-and-trade program with the cap declining by 5% a year
• Taxes on imports from countries which do not have similar initiatives
• Subsidies for EVs funded by raising taxes on petrol and diesel
• Encouraging behind-the-meter batteries for homes and businesses
• An end to forest clearing and burning in the Amazon, Indonesia, etc.

Cost declines are already moving us towards a 100% green energy system.  My fear is that we'll be too slow; that vested interests will try to stop or slow that move.  We put a man on the moon in just 10 years -- an extraordinary technical and technological achievement.  We can de-carbonise our economies rapidly too, if we wanted to.  Do we want to?  Will the recent rises prompt a rethink?   What do you think, readers?

2017 hotter than 2016?

We've had two (or three, depending on who calculates it)  successive years of record global temperatures, and expectations were that 2017 would show a retreat from the 2016 highs.  But so far -- and yes, we've only had two months of data -- it looks as if 2017 could be another record.  Normally, after an El Niño ends, global temperatures fall back to or below the longer-term underlying uptrend.  This hasn't happened this time.  El Niño has ended but the temperature anomaly has actually risen.

Just a reminder: Berkeley Earth was set up by Richard Muller who doubted that global warming was happening.  He was even funded by the Koch brothers.  The denialists promised faithfully that they would accept whatever he found, convinced that the evidence of rising temperatures from everyone else was because they were biased and were cooking the books.  So Muller went away and totally reconstructed the temperature record down to the level of individual weather stations.  And came up with pretty much the same picture.  The denialists, needless to say, did not accept these results.  Muller also looked at correlations, and the only data which fitted the rising chart was the level of atmospheric CO2 (with positive sign) and volcanic eruptions (with a negative sign).

It's not statistical evidence (we'd need several more years of data to be sure) but it looks to me as if the rate of increase in global temps may be accelerating.  And that is very bad news indeed.

Source: Zeke Hausfather, Berkeley Earth

2016 will be a scorcher

Based on the first 3 months of this year, 2016 is likely to be the hottest year on record.

Hat tip