Antarctic sea ice is “behaving strangely” and might have entered a “new regime”, the director of the US National Snow and Ice Data Centre (NSIDC) tells Carbon Brief.
Following an all-time low maximum in September 2023, Antarctic sea ice has been tracking at near-record-low extent for the past six months. Last month, it hit its 2024 minimum extent, tying with 2022 for the second-lowest Antarctic minimum in the 46-year satellite record.
Dr Mark Serreze, director of the NSIDC tells Carbon Brief that more warm ocean water is reaching the surface to melt ice and keep it from forming. He says that we “must wait and see” whether this is a “temporary effect” or whether the Antarctic has entered a “new regime”.
Meanwhile, Arctic sea ice has reached its maximum extent for the year, peaking at 15.01m square kilometres (km2) on 14 March. The provisional data from the NSIDC shows that this year’s Arctic winter peak, despite favourable winds that encouraged sea ice formation, was 640,000km2 smaller than the 1981-2010 average maximum.
This year’s maximum was the 14th lowest in the satellite record.
“Overall, the road remains downhill for Arctic sea ice, but it is quite bumpy along the way,” another scientist tells Carbon Brief. This relatively high winter peak is “notable and a good reminder that we have to communicate and account for this type of weather variability when we talk about Arctic climate change”, he says.
He adds that although the maximum is high compared to recent years, the ice is still “much thinner” than it was a few decades ago. The “wide coverage of this thinner ice” means total Arctic sea ice volume for the month of February was the third lowest on record.
Arctic winter peak
Arctic sea ice extent changes throughout the year. It grows each winter before reaching its peak for the year in February or March and then melts throughout the spring and summer towards its annual minimum, typically around September.
Using satellite data, scientists can track the growth and melt of sea ice, allowing them to determine the size of the ice sheet’s winter maximum and summer minimum extent. These are key metrics to monitor the “health” of the Arctic sea ice.
The NSIDC’s announcement says that this year’s Arctic winter peak of 15.01m is “below average”. Clocking in at 640,000km2 below the 1981-to-2010 average maximum extent, it ranks as the 14th lowest in the satellite record.
The NSIDC adds that the date of the maximum this year, 14 March, was two days later than the 1981-to-2010 average date of 12 March.
The plot below shows Arctic sea ice extent on 14 March, with the average sea ice extent for 1981-2010 shown by the orange line.
Arctic freeze
“The road remains downhill for Arctic sea ice, but it is quite bumpy along the way,” Dr Zack Labe – a postdoctoral researcher working at NOAA Geophysical Fluid Dynamics Laboratory and the atmospheric and oceanic sciences programme at Princeton University – tells Carbon Brief. He adds:
“While this winter was yet again consistent with the long-term trend toward a warmer Arctic with less ice, regional weather patterns can still contribute to ice expansion and slower net declines, especially if the winds align from a north-to-south direction.”
Arctic sea ice reached its minimum extent for 2023 on 19 September.
With an extent of 4.23m km2, this was the sixth-lowest minimum on record and 1.99m km2 below the average minimum recorded over 1981-2010.
Following its annual minimum, Arctic sea ice growth was “slower than average”, leading to the fifth-lowest September on record, according to the NSIDC.
Labe tells Carbon Brief that the freeze season started with “widespread open water across the Pacific side of the Arctic, with massive areas of ice missing north of Alaska”, which contributed to “well-above-average temperatures” in the region.
Throughout October, however, sea ice extent increased by 119,800km2 per day – faster than the 1981-2010 average of 89,200km2 per day, according to the NSIDC.
The Arctic freeze up was “particularly rapid” in the seas around Siberia. By the end of October, the ice cover had reached the Siberian coast, although open water remained in the Beaufort and Chukchi Seas.
Air temperatures over the Arctic Ocean, around 2,500 feet above surface level, were mostly above average during October – particularly in and around the Canadian Archipelago, which saw temperatures of 4-5C above average.
Labe tells Carbon Brief that, overall, the Arctic winter can be characterised by “unusual warmth in the northern Arctic, but greater total ice extent”. This “counterintuitive” dynamic was caused by atmospheric circulation patterns, which led to “warmer, moist air blowing toward the north pole, while northerly winds contribute to expanding ice in the Greenland Sea and Sea of Okhotsk”, he says.
Throughout November, Arctic sea ice extent continued to increase faster than average. However, the NSIDC says the freeze up “temporarily stalled” for around five days from 22 November, as a series of three tropical cyclones brought warm, moist air into the north Atlantic.
The NSIDC says that a combination of low pressure to the north and west of Svalbard and a high-pressure centre to the south-east “created a strong, persistent flow from the south of relatively warm and moist air from the north Atlantic Ocean toward Svalbard”.
This flow of air can be seen as “an extension of an atmospheric river into the Arctic”, it says. It adds that the strong winds “helped to push the ice edge in the east Greenland and Barents seas northwards, limiting new ice formation”.
The NSIDC notes that pauses in Arctic sea ice freeze up have happened in November before, in 2013 and 2016, making such events “rare, but not unknown”.
Arctic sea ice extent continued to increase “markedly faster” than usual throughout December, the NSIDC says. It adds that “sea ice formation in Hudson Bay was unusually late, but the ice cover expanded quickly from west to east in mid-December”.
For December overall, 2023 saw the third-highest monthly gain on record, with 2.71m km2 of sea ice extent added throughout the month. Average Arctic sea ice extent over December 2023 was the ninth lowest in the satellite record, at 12m km2.
Arctic sea ice extent continued to move down the rankings as the new year rolled in, despite slower-than-average ice growth. In fact, the NSIDC says that Arctic sea ice extent actually declined for a few days at the end of the month, although it notes that this is “not unusual at this time of year” and says it is “caused by weather systems that temporarily halt ice growth or push the ice northwards”.
The average Arctic sea ice extent for January 2024 was 13.92m km2 – the 20th lowest on record.
This comparatively high sea ice extent is “notable and a good reminder that we have to communicate and account for this type of weather variability when we talk about Arctic climate change”, Labe tells Carbon Brief.
Arctic sea ice extent continued to grow throughout February, gaining 15.3m km2 of ice throughout the month. The February 2024 extent of 14.61m km2 was 690,000km2 below the 1981-2010 February average extent, and tied with 2022 as the 15th lowest on record, according to the NSIDC.
Temperatures are usually “well-below freezing” over the Arctic Ocean in February, but the NSIDC notes that in 2024, they were not as low as usual for the time of year. Over the central Arctic ocean, air temperatures at 2,500 feet above sea level were up to 10C warmer than average.
Labe notes that although sea ice extent was high compared to recent years, the ice is still “much thinner” than it was a few decades ago:
“Total Arctic sea-ice volume ended up as the third lowest on record for the month of February due to the wide coverage of this thinner ice.”
Variability and long-term decline of February #Arctic sea-ice thickness and sea-ice volume… (anomalously low for 2024)
+ Data information: https://t.co/PTJWaGkNua pic.twitter.com/a51VTWKFVA
— Zack Labe (@ZLabe) March 10, 2024
Antarctic ‘behaving strangely’
Meanwhile, at the Earth’s other pole, Antarctic sea ice hit its summer minimum sea ice extent on 20 February. With an extent of 1.99m km2, this year’s minimum ties with 2022 as the second-lowest on record, the NSIDC reports.
The plot below shows Antarctic sea ice extent on 20 February 2024, with the median sea ice extent for 1981-2010 shown by the orange line.
The Antarctic minimum was 850,000km2 smaller than the 1981-to-2010 average summer low of 2.84m km2, but 200,000km2 larger than the previous record low set on 21 February 2023.
This year marks the third consecutive minimum Antarctic sea ice extent below 2m km2. The table below shows the five years with the lowest minimum Antarctic sea ice extent on record, which includes 2022, 2023 and 2024 towards the top.
| Rank | Year | Minimum ice extent (m km2) | Date |
|---|---|---|---|
| 1 | 2023 | 1.79 | 21 Feb |
| 2 | 2022 | 1.98 | 25 Feb |
| 2= | 2024 | 1.99 | 20 Feb |
| 4 | 2017 | 2.11 | 3 March |
| 5 | 2018 | 2.22 | 21 Feb |
“The Antarctic has been behaving strangely,” Dr Mark Serreze, director of the NSIDC, tells Carbon Brief. He continues:
“In the past few years, [southern hemisphere] summer extent has dropped to record lows. Before that, we saw record highs! What has changed?
“The answer seems to lie in the ocean – more warm water getting up the the surface to melt ice or keep it from forming. Is this a temporary effect, or, as many have argued, have we entered a ‘new regime’ in which the ocean will continue to strongly affect the sea ice? Again, we must wait and see.”
Record-breaking Antarctic extent
Antarctic sea ice has been tracking at or near record-low levels for months.
The Antarctic set a record-low maximum on 10 September 2023, with an extent of 16.96m km2. This was “the lowest sea ice maximum in the 1979 to 2023 sea ice record by a wide margin”, and one of the earliest, the NSIDC says.
Antarctic conditions over 2023 were “truly exceptional” and “completely outside the bounds of normality”, one expert told Carbon Brief.
As 2023 progressed, Antarctic sea ice melt was “slower than average”, the NSIDC says. The total decline in Antarctic sea ice extent through October was 903,000km2, while the October average was 985,000km2.
Nevertheless, Antarctic sea ice extent continued to track at a record low. On 31 October 2023, Antarctic sea ice extent was still tracking at a record-low of 15.79m km2. This is 750,000km2 below the previous 31 October record low.
The decline in Antarctic sea ice paused for a few days from 9 November, allowing sea ice extent to creep above the November 2016 value, the NSIDC says. This marked the first time that the daily 2023 Antarctic sea ice extent was not the lowest in the record since early May 2023. By the start of December, Antarctic sea ice extent was again at a record low, it notes.
The Antarctic saw in the new year with a sea ice extent of 6.37m km2, marking the sixth-lowest New Year’s Day Antarctic sea ice extent on record, the NSIDC says. Ice melted rapidly throughout the month, and by the end of January, daily Antarctic sea ice extent reached 2.58m km2 – tying with 2017 for second lowest on record.
The post Antarctic sea ice ‘behaving strangely’ as Arctic reaches ‘below-average’ winter peak appeared first on Carbon Brief.
Antarctic sea ice ‘behaving strangely’ as Arctic reaches ‘below-average’ winter peak
Drought and heatwaves occurring together – known as “compound” events – have “surged” across the world since the early 2000s, a new study shows.
Compound drought and heat events (CDHEs) can have devastating effects, creating the ideal conditions for intense wildfires, such as Australia’s “Black Summer” of 2019-20 where bushfires burned 24m hectares and killed 33 people.
The research, published in Science Advances, finds that the increase in CDHEs is predominantly being driven by events that start with a heatwave.
The global area affected by such “heatwave-led” compound events has more than doubled between 1980-2001 and 2002-23, the study says.
The rapid increase in these events over the last 23 years cannot be explained solely by global warming, the authors note.
Since the late 1990s, feedbacks between the land and the atmosphere have become stronger, making heatwaves more likely to trigger drought conditions, they explain.
One of the study authors tells Carbon Brief that societies must pay greater attention to compound events, which can “cause severe impacts on ecosystems, agriculture and society”.
Compound events
CDHEs are extreme weather events where drought and heatwave conditions occur simultaneously – or shortly after each other – in the same region.
These events are often triggered by large-scale weather patterns, such as “blocking” highs, which can produce “prolonged” hot and dry conditions, according to the study.
Prof Sang-Wook Yeh is one of the study authors and a professor at the Ewha Womans University in South Korea. He tells Carbon Brief:
“When heatwaves and droughts occur together, the two hazards reinforce each other through land-atmosphere interactions. This amplifies surface heating and soil moisture deficits, making compound events more intense and damaging than single hazards.”
CDHEs can begin with either a heatwave or a drought.
The sequence of these extremes is important, the study says, as they have different drivers and impacts.
For example, in a CDHE where the heatwave was the precursor, increased direct sunshine causes more moisture loss from soils and plants, leading to a drought.
Conversely, in an event where the drought was the precursor, the lack of soil moisture means that less of the sun’s energy goes into evaporation and more goes into warming the Earth’s surface. This produces favourable conditions for heatwaves.
The study shows that the majority of CDHEs globally start out as a drought.
In recent years, there has been increasing focus on these events due to the devastating impact they have on agriculture, ecosystems and public health.
In Russia in the summer of 2010, a compound drought-heatwave event – and the associated wildfires – caused the death of nearly 55,000 people, the study notes.
The record-breaking Pacific north-west “heat dome” in 2021 triggered extreme drought conditions that caused “significant declines” in wheat yields, as well as in barley, canola and fruit production in British Columbia and Alberta, Canada, says the study.
Increasing events
To assess how CDHEs are changing, the researchers use daily reanalysis data to identify droughts and heatwaves events. (Reanalysis data combines past observations with climate models to create a historical climate record.) Then, using an algorithm, they analyse how these events overlap in both time and space.
The study covers the period from 1980 to 2023 and the world’s land surface, excluding polar regions where CDHEs are rare.
The research finds that the area of land affected by CDHEs has “increased substantially” since the early 2000s.
Heatwave-led events have been the main contributor to this increase, the study says, with their spatial extent rising 110% between 1980-2001 and 2002-23, compared to a 59% increase for drought-led events.
The map below shows the global distribution of CDHEs over 1980-2023. The charts show the percentage of the land surface affected by a heatwave-led CDHE (red) or a drought-led CDHE (yellow) in a given year (left) and relative increase in each CDHE type (right).
The study finds that CDHEs have occurred most frequently in northern South America, the southern US, eastern Europe, central Africa and south Asia.
Threshold passed
The authors explain that the increase in heatwave-led CDHEs is related to rising global temperatures, but that this does not tell the whole story.
In the earlier 22-year period of 1980-2001, the study finds that the spatial extent of heatwave-led CDHEs rises by 1.6% per 1C of global temperature rise. For the more-recent period of 2022-23, this increases “nearly eightfold” to 13.1%.
The change suggests that the rapid increase in the heatwave-led CDHEs occurred after the global average temperature “surpasse[d] a certain temperature threshold”, the paper says.
This threshold is an absolute global average temperature of 14.3C, the authors estimate (based on an 11-year average), which the world passed around the year 2000.
Investigating the recent surge in heatwave-leading CDHEs further, the researchers find a “regime shift” in land-atmosphere dynamics “toward a persistently intensified state after the late 1990s”.
In other words, the way that drier soils drive higher surface temperatures, and vice versa, is becoming stronger, resulting in more heatwave-led compound events.
Daily data
The research has some advantages over other previous studies, Yeh says. For instance, the new work uses daily estimations of CDHEs, compared to monthly data used in past research. This is “important for capturing the detailed occurrence” of these events, says Yeh.
He adds that another advantage of their study is that it distinguishes the sequence of droughts and heatwaves, which allows them to “better understand the differences” in the characteristics of CDHEs.
Dr Meryem Tanarhte is a climate scientist at the University Hassan II in Morocco, and Dr Ruth Cerezo Mota is a climatologist and a researcher at the National Autonomous University of Mexico. Both scientists, who were not involved in the study, agree that the daily estimations give a clearer picture of how CDHEs are changing.
Cerezo-Mota adds that another major contribution of the study is its global focus. She tells Carbon Brief that in some regions, such as Mexico and Africa, there is a lack of studies on CDHEs:
“Not because the events do not occur, but perhaps because [these regions] do not have all the data or the expertise to do so.”
However, she notes that the reanalysis data used by the study does have limitations with how it represents rainfall in some parts of the world.
Compound impacts
The study notes that if CDHEs continue to intensify – particularly events where heatwaves are the precursors – they could drive declining crop productivity, increased wildfire frequency and severe public health crises.
These impacts could be “much more rapid and severe as global warming continues”, Yeh tells Carbon Brief.
Tanarhte notes that these events can be forecasted up to 10 days ahead in many regions. Furthermore, she says, the strongest impacts can be prevented “through preparedness and adaptation”, including through “water management for agriculture, heatwave mitigation measures and wildfire mitigation”.
The study recommends reassessing current risk management strategies for these compound events. It also suggests incorporating the sequences of drought and heatwaves into compound event analysis frameworks “to enhance climate risk management”.
Cerezo-Mota says that it is clear that the world needs to be prepared for the increased occurrence of these events. She tells Carbon Brief:
“These [risk assessments and strategies] need to be carried out at the local level to understand the complexities of each region.”
The post Heatwaves driving recent ‘surge’ in compound drought and heat extremes appeared first on Carbon Brief.
Heatwaves driving recent ‘surge’ in compound drought and heat extremes
Greenhouse Gases
DeBriefed 6 March 2026: Iran energy crisis | China climate plan | Bristol’s ‘pioneering’ wind turbine
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Energy crisis
ENERGY SPIKE: US-Israeli attacks on Iran and subsequent counterattacks across the Middle East have sent energy prices “soaring”, according to Reuters. The newswire reported that the region “accounts for just under a third of global oil production and almost a fifth of gas”. The Guardian noted that shipping traffic through the strait of Hormuz, which normally ferries 20% of the world’s oil, “all but ground to a halt”. The Financial Times reported that attacks by Iran on Middle East energy facilities – notably in Qatar – triggered the “biggest rise in gas prices since Russia’s full-scale invasion of Ukraine”.
‘RISK’ AND ‘BENEFITS’: Bloomberg reported on increases in diesel prices in Europe and the US, speculating that rising fuel costs could be “a risk for president Donald Trump”. US gas producers are “poised to benefit from the big disruption in global supply”, according to CNBC. Indian government sources told the Economic Times that Russia is prepared to “fulfil India’s energy demands”. China Daily quoted experts who said “China’s energy security remains fundamentally unshaken”, thanks to “emergency stockpiles and a wide array of import channels”.
‘ESSENTIAL’ RENEWABLES: Energy analysts said governments should cut their fossil-fuel reliance by investing in renewables, “rather than just seeking non-Gulf oil and gas suppliers”, reported Climate Home News. This message was echoed by UK business secretary Peter Kyle, who said “doubling down on renewables” was “essential” amid “regional instability”, according to the Daily Telegraph.
China’s climate plan
PEAK COAL?: China has set out its next “five-year plan” at the annual “two sessions” meeting of the National People’s Congress, including its climate strategy out to 2030, according to the Hong Kong-based South China Morning Post. The plan called for China to cut its carbon emissions per unit of gross domestic product (GDP) by 17% from 2026 to 2030, which “may allow for continued increase in emissions given the rate of GDP growth”, reported Reuters. The newswire added that the plan also had targets to reach peak coal in the next five years and replace 30m tonnes per year of coal with renewables.
ACTIVE YET PRUDENT: Bloomberg described the new plan as “cautious”, stating that it “frustrat[es] hopes for tighter policy that would drive the nation to peak carbon emissions well before president Xi Jinping’s 2030 deadline”. Carbon Brief has just published an in-depth