While 2023 made headlines for smashing global temperature records, last year also saw some truly remarkable events in the Antarctic.
After crashing to a record-low summer extent in February, sea ice around the southern continent regrew extremely slowly.
By July, when sea ice should be approaching its maximum winter coverage, there was an area of ice “missing” that was bigger than Algeria – the world’s 10th largest country.
When the annual maximum extent arrived – early – it was the smallest on record by a “wide margin”.
This made 2023 the second record-breaking year in a row, continuing the recent erratic swings in sea ice cover that had otherwise been preceded by several decades of steady, gradual increase.
In our new paper, published in the Royal Meteorological Society’s journal Weather, my coauthor and I explore what happened to sea ice in 2023, what caused the dramatic events and what the implications are for the future.
The importance of Antarctic sea ice
Antarctic sea ice is a critical puzzle piece in the regional and global climate picture.
The frozen continent as a whole acts as the Earth’s principal refrigerator, reflecting the sun’s energy from its bright, white mirror-like surface, helping keep temperatures cool.
Sea ice formation around its coastline acts as an engine for ocean currents and influences weather patterns that can have far-reaching effects.
Floating ice also acts as a buffer that can protect the exposed edges of the ice sheet from the destructive action of waves, meaning that it can curb Antarctica’s contribution to sea level rise. By influencing the availability of water from the open ocean, it also affects how much snow can fall to replenish the ice sheet’s losses.
And sea ice is vitally important for marine life, as demonstrated by the “catastrophic breeding failure” of Emperor penguin chicks following the (then) record-low sea ice coverage in 2022.
Long-term trends
Thanks to satellite data, scientists have a detailed picture of how Arctic and Antarctic sea ice have behaved since the late 1970s. And for Antarctica, this picture has been something of a puzzle.
Between 1979 and 2015, average Antarctic sea ice extent – the area of ocean with at least 15% sea ice cover – increased slightly, but fairly steadily. This is in stark contrast to the Arctic, where sea ice at the minimum summer extent plummeted by nearly 12% per decade.
Then, after a record high year in 2014, Antarctic sea ice extent dropped to a record low in 2017. Several years of low sea ice came after that, with the summer minimum record smashed in 2022, when it fell below 2m square kilometres for the first time.
How extreme was 2023?
Antarctic sea ice waxes and wanes throughout the year, reaching a minimum in February at the end of the southern-hemisphere summer and a maximum in September after a long, cold winter.
This seasonal expansion causes the area covered by sea ice to grow six-fold within a single year – as the chart below shows. It depicts Antarctic sea ice extent for each day of 2023 (blue line), along with how it compares to the historical range (blue shading) and the record low for the time of year (dotted line).
Antarctic daily sea ice extent from the US National Snow and Ice Data Center. The bold lines show daily 2023 values, the shaded area indicates the two standard deviation range in historical values between 1979 and 2010. The dotted line shows the record low. Chart by Carbon Brief.
As the chart shows, 2023 was an exceptional year in the satellite record, remaining well below average for the entire year.
The year started with a record-breaking minimum extent of 1.79m km2 in February 2023, which was 10% lower than the already record-breaking 2022.
Although the autumn freeze-up started off as usual, from April the seasonal expansion of sea ice was very slow. By July, the total sea ice extent was 13.5m km2 – 15% lower than average for the month.
The area of “missing” sea ice for the month of July, relative to the 1981–2010 average, was nearly two-and-a-half million square kilometres – an area larger than Algeria.
The period of extreme departure from average persisted from mid-May until mid-November, with conditions recovering a little, meaning that by the end of the year, they were no longer record-breaking.
Overall, the largest deviations from average conditions in 2023 were recorded in winter (June to August). To see this in context, the chart below shows winter sea ice extent from 1979 to 2023 and highlights how dramatically low winter sea ice was last year.
In addition, the table below shows the average winter sea ice extent and the anomaly – that is, the departure from the 1981-2010 average. It is clear that at 2.34m km2, the anomaly in the winter of 2023 was larger than in any other year. The next largest was 0.93m km2 in 2022.
| Year | JJA mean extent (million km2) | JJA anomaly (million km2) |
|---|---|---|
| 2023 | 13.34 | -2.34 |
| 2022 | 14.75 | -0.93 |
| 2002 | 14.95 | -0.73 |
| 2017 | 14.97 | -0.71 |
| 1986 | 15.00 | -0.69 |
Table showing the top five years with largest negative winter sea ice extent anomalies with respect to 1981–2010, ranked from lowest sea ice extent to highest. All extents and anomalies are shown in millions of square kilometres. Source: Gilbert & Homes (2024)
Drivers of low sea ice conditions
There is no single cause of record-low sea ice conditions, but it is likely that a combination of oceanic and atmospheric factors conspired to produce 2023’s record sea ice conditions.
Recent studies have pointed to the important role of ocean processes and heat stored below the surface, which have kept sea ice extent low since 2016. Warm sea surface temperatures in the Southern Ocean during the first half of 2023 probably also partly explain both the record minimum extent in February and the slow freeze-up afterwards.
But Antarctic sea ice is also closely controlled by atmospheric circulation. One such circulation pattern is the Amundsen Sea Low, which is a low-pressure weather system that consistently forms off the coast of West Antarctica. Exactly where it is and how low the atmospheric pressure gets can control winds and temperature in the region, impacting the movement, breakup, formation and destruction of sea ice.
The pattern in sea ice in 2023 was closely tied to the behaviour of the Amundsen Sea Low, which was unusually deep and far to the east in winter when the sea ice anomalies were at their peak.
This situation tends to blow warm air towards the coast and push sea ice back, limiting sea ice growth during the freeze-up season.
Other large-scale weather patterns – such as the Southern Annular Mode and El Niño-Southern Oscillation have historically contributed to the ups-and-downs observed in Antarctic sea ice, but they do not seem to have had a major influence in 2023.
These weather patterns can interact to either amplify or suppress sea ice changes by affecting the ways that sea ice moves, melts and freezes.
Links with climate change
Deciphering the role of climate change in Antarctic sea ice trends is much more complicated than in the Arctic because conditions are impacted by so many competing factors.
However, the sheer magnitude of 2023’s sea ice lows suggests that something unusual is happening.
Sea ice conditions during 2023 were far outside the bounds of normality, but it is difficult to say exactly how far. That is because the satellite record is relatively short (45 years) and the system is highly variable. In addition, climate change is already impacting the Southern Ocean in complex ways, making an estimation of what is “normal” impossible.
Climate models project a decline in Antarctic sea ice in response to greenhouse gas emissions and rising temperatures. However, until 2015 this prediction was largely at odds with what scientists were seeing – in part due to the complexity and uncertainty of the processes involved, and the impractically high detail required to accurately represent sea ice in models.
However, despite their limitations, it seems inescapable that models will ultimately be correct about Antarctic sea ice decline. Human emissions are raising temperatures in the Southern Ocean, and studies show a link between ocean warming and low Antarctic sea-ice extents.
Several papers – including one discussed in a previous Carbon Brief guest post – have argued that recent record-low sea ice years may be a taste of what is to come.
With 2024 likely to be another year of high global average temperatures and weather extremes, it may emerge as another year of low Antarctic sea ice. Although current sea ice extent is no longer the lowest on record, conditions are still well below the 1981-2010 average, and this situation may well persist into the 2024 melt season.
So, while it is too early to say conclusively that the recent sea-ice lows are the beginning of a regime shift in Antarctic sea ice, it seems inevitable that it will eventually decline in response to human-caused climate change.
For now, all scientists can say for certain is that the events of 2023 were entirely remarkable and unlike anything seen in the satellite record.
The post Guest post: Why 2023 was an exceptional year for Antarctic sea ice appeared first on Carbon Brief.
Guest post: Why 2023 was an exceptional year for Antarctic sea ice
FOR IMMEDIATE RELEASE
CCL applauds 21 Republicans for supporting clean energy tax credit support
March 12, 2025 – Citizens’ Climate Lobby is very encouraged to see 21 House Republicans sign onto a letter in support of America’s clean energy tax credits.
Jennifer Tyler, CCL’s Vice President of Government Affairs, said, “More and more Republican House members are recognizing that clean energy tax credits are benefiting their districts — and that constituents and businesses don’t want to lose them. It’s clear that these policies are delivering real economic value in communities nationwide.”
The letter, led by House Climate Solutions Caucus co-chair Rep. Andrew Garbarino (R-NY-02), was signed by 20 of his fellow House Republicans: Reps. Amodei, Bacon, Bresnahan, Carter, Ciscomani, Evans, Fong, Houchin, Hurd, James, Joyce, Kean, Kiggans, Kim, LaLota, Lawler, Mackenzie, Miller-Meeks, Newhouse and Valadao.
“We have 20-plus members saying, ‘Don’t just think you can repeal these things and have our support’” for the larger budget reconciliation package, Rep. Garbarino told Politico.
That’s a bigger group than the 18 Republicans who sent a similar letter last fall.
In last week’s Conservative Climate Leadership Conference and Lobby Day, 50 right-of-center climate advocates from CCL visited 47 Republican offices on Capitol Hill to reinforce that message.
These grassroots volunteers “found that Republican offices are receptive to the case that these tax credits have spurred unprecedented private investment, driven innovation, and created well-paying jobs across the country,” Tyler added.
CONTACT: Flannery Winchester, CCL Vice President of Communications, 615-337-3642, flannery@citizensclimate.org
###
Citizens’ Climate Lobby is a nonprofit, nonpartisan, grassroots advocacy organization focused on national policies to address climate change. Learn more at citizensclimatelobby.org.
The post CCL applauds 21 Republicans for supporting clean energy tax credit support appeared first on Citizens' Climate Lobby.
CCL applauds 21 Republicans for supporting clean energy tax credit support
FOR IMMEDIATE RELEASE
50 grassroots conservatives visit Capitol Hill to support clean energy tax credits
March 10, 2025 – Last week, conservatives from across America gathered in Washington D.C. for Citizens’ Climate Lobby’s fifth annual Conservative Climate Leadership Conference and Lobby Day.
After receiving communications training from CCL staff, 50 right-of-center volunteers visited 47 Republican offices on March 5.
“I think this is one of the most impactful things that we do,” said Drew Eyerly, CCL’s Action Team Director, in CCL’s national volunteer call sharing highlights and reflections from the event.
Eyerly remarked on Republican offices’ enthusiasm for speaking with CCL volunteers, often giving them more time than originally planned. “They’ll say 10 minutes, and those meetings will turn into 20 to 30 minutes,” he reflected. “Just really, really great conversations.”
Those conversations centered on one main ask: For Republican lawmakers to protect America’s clean energy tax credits.
“As we talk about how competitive American businesses can be in clean energy and how many jobs it can bring to their district, the members are much more open to that discussion,” said Jennifer Tyler, CCL’s Vice President of Government Affairs.
This week, Citizens’ Climate Lobby launched a new action for volunteers around the country to call Republican members of Congress about the clean energy tax credits, reinforcing our recent lobby day message.
Volunteers will be back on Capitol Hill this summer for CCL’s annual Summer Conference and Lobby Day in late July.
CONTACT: Flannery Winchester, CCL Vice President of Communications, 615-337-3642, flannery@citizensclimate.org
###
Citizens’ Climate Lobby is a nonprofit, nonpartisan, grassroots advocacy organization focused on national policies to address climate change. Learn more at citizensclimatelobby.org.
The post 50 grassroots conservatives visit Capitol Hill to support clean energy tax credits appeared first on Citizens' Climate Lobby.
50 grassroots conservatives visit Capitol Hill to support clean energy tax credits
Greenhouse Gases
DeBriefed 21 March 2025: Germany’s climate win; Conservatives’ net-zero row-back; Key messages from major UK climate conference
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Germany’s €100bn climate funding
BILLIONS IN FUNDING: Germany’s parliament on Tuesday voted to create a €500bn defence and infrastructure fund and relax “constitutionally-protected debt rules”, the Guardian reported, with “the last-minute backing of the Greens” in return for “guarantees that €100bn of the funds destined for infrastructure would be allocated for climate and economic transformation investments”. The deal came following “clumsy” initial negotiations from Germany’s chancellor-in-waiting, Friedrich Merz, Bloomberg said. It reported that the Greens “finally came around” after Merz’s negotiators “conceded to their key demands”, which also included adding Germany’s 2045 climate-neutrality target into the constitution.
TAKING CLIMATE ‘SERIOUSLY’: The Greens said in a statement on social media that the agreement “finally takes the challenges of the future seriously”, according to the New York Times. Paula Piechotta, a member of the Greens in the German Bundestag, told the German newspaper Tagesspiegel that the deal was a “great success for democracy in our country, for sustainability and intergenerational justice”. The newspaper added that the far-right Alternative for Germany (AfD) and the Left party, “unsurprisingly”, criticised the agreement.
UK opposition breaks cross-party climate consensus
BREAKING AWAY: In a speech, Kemi Badenoch, leader of the UK opposition Conservative party, said it was “impossible” for the UK to meet its net-zero target by 2050, marking a “sharp break from years of political consensus”, BBC News reported. She did not offer an alternative target for the goal, the broadcaster said, quoting her telling reporters that if the Conservatives “do find a target is necessary, then yes we will have one”. Badenoch “failed to cite any evidence in support” of her arguments, according to a factcheck published by Carbon Brief, which concluded that much of the existing evidence “contradicts” her claims.
TORY BACKLASH: In response, Conservative former prime minister Theresa May, who was responsible for passing the 2050 target into law, warned the move “will hurt future generations and cost Britons”, the Times reported. The Confederation of British Industry (CBI) also criticised the speech, warning that “now is not the time to step back from the opportunities of the green economy”, according to the i newspaper. In the Daily Telegraph, Ambrose Evans-Pritchard said Badenoch’s “rant comes close to political tragedy”.
Around the world
- CARNEY CUTS: New Canadian prime minister Mark Carney removed the country’s “consumer carbon tax”, CBC News reported, adding that the policy had been a “potent point of attack” for his political opponents.
- GREENPEACE BILL: Greenpeace has been ordered to pay $660m in damages over its protests against the Dakota Access pipeline in 2016, which could “bankrupt its US operations” if upheld, the Financial Times said.
- UK-CHINA FORUM: The UK and China agreed to establish an “annual climate dialogue”, with the first meeting to be held in London later this year, the Times reported.
- CHEQUES AND BALANCES: A US judge has “temporarily barred” attempts by the Trump administration to recoup at least $14bn in “grants issued by the Biden administration for climate and clean-energy projects”, the Washington Post said.
- EXTREME HEAT: “Severe heatwave conditions” have begun affecting several areas across India “unusually early in the season”, the Hindustan Times reported.
- SOUTH AFRICAN SUPPORT: The EU will fill a “$1bn hole” in South African’s “just energy transition partnership” left by the US, the Financial Times reported. The US is also “stalling” $2.6bn of climate finance for South Africa, Bloomberg said.
152
The number of “unprecedented” extreme weather events that occurred in 2024, according to the World Meteorological Organization’s State of the Climate 2024 report. Heatwaves were the most common type of unprecedented events – defined as events “worse than any ever recorded in the region” – followed by “rain or wet spells” and floods.
Latest climate research
- New research in Climate and Development explored how environmental justice featured in the climate action plans of rust-belt cities in the US, finding that few “provided enough details” to determine if it was a priority.
- A new Science Advances study identified “increasing storminess” in the south-western Caribbean, which was attributed to “industrial-age warming”.
- Marine heatwaves are now 5.1 times more frequent and 4.7 times more intense since records began, new research in Communications Earth & Environment found.
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured
The UK’s high electricity prices are primarily driven by gas prices, according to an analysis published by Carbon Brief, with the UK typically seeing gas set electricity prices 98% of the time – compared to an average in the EU of 40%.
Spotlight
Chatham House talks climate and resilience
Carbon Brief outlines key takeaways from Chatham House’s climate and energy summit.
Chatham House, the UK’s leading international affairs thinktank, held its annual summit on climate and energy on 18-19 March. This year’s theme was: “Securing a resilient future.”
Carbon Brief attended the conference, where speakers including COP30 CEO Ana Toni, UK climate envoy Rachel Kyte and Moroccan minister for energy transition and sustainable development Leila Benali shared their thoughts on encouraging and enacting climate action.
Climate backlash
A sense of urgency permeated discussions at the summit, underpinned by concerns over growing anti-climate narratives.
Toni argued climate scepticism proves climate action is on the right track.
She said: “First people ignore you, then they laugh at you, then they fight you – and this is where we are – then we win.”
Other speakers said that increasing support for climate action by building new norms and creating overlapping interests could also be effective strategies.
Former US climate envoy Todd Stern pointed to increasing adoption of electric vehicles, while ClientEarth CEO Laura Clarke raised the example of community-owned renewable power.
Fretting over finance
Clean Earth Gambia founder Fatou Jeng warned that climate finance, as ever likely to be an important issue at COP30, has “not progressed much”.
“Blended finance” – using public money to leverage private funds – was heavily criticised in several panels. Ben Parsons, a partner at consultancy firm Oaklin, noted that only 72 such deals were agreed in 2024.
Speakers agreed that innovative mechanisms to derisk climate finance were needed, with Morocco’s Benali critiquing “exclusive” and inflexible private financing options.
Ndongo Samba Sylla, head of research and policy at International Development Economics Associates, argued that using local currencies would significantly boost climate finance.
Resilience through renewables
A key benefit of the UK’s “climate leadership”, Kyte argued, is that the energy transition will “make British people more secure”.
Parsons said the argument – recently deployed by Conservative leader Badenoch – that the energy transition replaced reliance on Russian fossil fuels with reliance on Chinese technology was incorrect.
“Fossil fuels are fuel – they require constant replenishment. Renewables are infrastructure,” he said, adding that arguably the UK should be accelerating its deployment of clean-energy technology.
On cybersecurity challenges in renewable power systems, Alex Schoch, vice president and group director of flexibility and electrification at Octopus Energy, argued that the key issue is how renewable energy “hardware” is managed, rather than where it is sourced from.
Parsons agreed, noting that the UK’s current power system has “plenty of cybersecurity vulnerabilities in it today”.
He said: “We have to make sure we’re putting [cybersecurity strategies] in place…But I don’t think that goes hand in hand with thinking we should avoid buying renewables from certain parts of the world.”
In a session on energy security in war-time Ukraine, held under the Chatham House rule, participants noted that the country was a case study for the importance of energy security.
Speakers said that since Russia’s invasion of Ukraine, attacks on thermal power plants have seen growing use of low-carbon energy – particularly distributed solar.
Watch, read, listen
ELEPHANT IN THE ROOM: The Columbia Energy Exchange podcast explored how the new Trump government underpinned discussions at the energy industry event CERAWeek.
‘CONFLICT BLINDSPOT’: A new report by ODI found that “less than 10% of international climate finance” in 2022 went to fragile and conflict-affected countries.
METHANE INACTION: Leading supermarkets in the global north are “failing to address the methane pollution in their supply chains”, according to a study covered by Desmog.
Coming up
- 24-26 March: 16th Petersberg Climate Dialogue, Berlin, Germany
- 24-26 March: IPCC lead author meeting for methodology report on inventories for short-lived climate forcers, Bilbao, Spain
- 24-28 March: 20th session of the UN FAO commission on genetic resources for food and agriculture, Rome, Italy
- 25 – 28 March:First G20 climate and environment sustainability working group meeting, online
Pick of the jobs
- ClientEarth, lawyer or legal consultant, energy systems, Asia | Salary: 455m-585m Indonesian rupiah. Location: Jakarta
- European External Action Service, policy officer for green diplomacy | Salary: Unknown. Location: Brussels
- Bloomberg, climate reporter | Salary: Unknown. Location: Hong Kong
- The Grantham Research Institute on Climate Change and the Environment, project manager | Salary: £42,679-£51,000. Location: London
DeBriefed is edited by Daisy Dunne. Please send any tips or feedback to debriefed@carbonbrief.org.
This is an online version of Carbon Brief’s weekly DeBriefed email newsletter. Subscribe for free here.
The post DeBriefed 21 March 2025: Germany’s climate win; Conservatives’ net-zero row-back; Key messages from major UK climate conference appeared first on Carbon Brief.
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