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Antarctic sea ice in 2023

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Each year, from June-October, polar climate scientists from the Met Office produce a series of monthly sea ice briefings for the government and the general public. These briefings describe the state of Arctic and Antarctic sea ice, compare how these relate to historic patterns, and, where possible, assess causes of unusual behaviour.

Sea ice is frozen seawater that floats on the surface of the ocean and is found when temperatures are cold enough for sea water to freeze. The extent of sea ice is a key climate indicator, because sea ice cover insulates the ocean in winter and reflects sunlight in summer, as well as providing a habitat for a range of species. 

A view of Antarctica showing patches of sea ice, ice bergs and the Antarctic continent's mountains in the distance.

Here, Senior Scientist Alex West talks about the 2023 Antarctic sea ice minimum and its interaction with the ocean and atmosphere.

Lowest sea ice extent on record

Antarctic average sea ice extent for 2023 was the lowest on record. During the ice growth season from June-October, ice extent was exceptionally low for the time of year, reaching over 1 million square km below previous record lows and setting a new record low maximum extent by a very large margin. For much of the rest of the year, the ice was at record or near-record low levels, recording a second successive record low minimum in February (Figure 1).

The annual cycle of Antarctic sea ice build up and loss with individual years highlighted. 2023 was a record low year for Antarctic sea ice extent.

Figure 1. Antarctic sea ice extent in 2023 (bold black line) with other recent years indicated, as well as earlier years with notably low sea ice extent. The 1981-2010 average is also shown, with the shaded region indicating 2 standard deviation intervals.

The very low extent from June-October was partly caused by enhanced warm northerly winds, associated with persistent areas of high and low pressure (Ionita, 2024). Early in the ice growth season, from May-July, these were concentrated near the Antarctic Peninsula, in the Weddell and Bellingshausen Sea regions; later in the growth season, from August-October, the strongest winds were to be found further west, in the Ross Sea. The position of the lowest sea ice conditions changed similarly.

However, it is likely that the ocean also played a part. The low extent of 2023 continues a pattern of very high variability in Antarctic sea ice since 2007, with first high and then low sea ice conditions persisting for long periods of time, in a way unlikely to be caused by known atmospheric changes (Hobbs et al., 2024). A key moment in this period of high variability was a large reduction that occurred in 2016, and this is thought to be linked to changes in the upper ocean caused by stronger westerly winds mixing warmer waters below towards the surface (Earys et al., 2021; Zhang et al., 2022). Further mixing of warm waters cannot be ruled out as an additional cause of the very low extent of 2023.

The precise contribution of anthropogenic (human-caused) global warming to the record low sea ice of 2023 is not yet known. While climate models predict that Antarctic sea ice extent will decrease in response to anthropogenic warming, variability in the past 15 years has been considerable, with very high extent from 2012-2014 followed by the current period of very low extent (Figure 2). Further extreme variability in either direction remains possible in the years ahead.

The monthly extent of Antarctic sea ice from 1979 compared with the average from 1981-2010. This view makes it easier to see long-term changes in sea ice.

Figure 2. Antarctic sea ice monthly anomalies over the period of satellite observations. For each month, the 1981-2010 average ice extent for that month is subtracted. This largely removes the seasonal cycle so that subtler long-term changes can be viewed more easily.

During April we are exploring the topic of the ocean and climate. Follow the #GetClimateReady hashtag on X (formerly Twitter) to learn more throughout the month.

References

Eayrs, C., X. Li, M.N. Raphael and D.M. Holland (2021) Rapid decline in Antarctic sea ice in recent years hints at future change. Nat. Geosci., 14, 460–464. https://doi.org/10.1038/s41561-021-00768-3

Hobbs, W., and Coauthors (2024): Observational Evidence for a Regime Shift in Summer Antarctic Sea Ice. J. Climate, 37, 2263–2275, https://doi.org/10.1175/JCLI-D-23-0479.1

Ionita M (2024) Large-scale drivers of the exceptionally low winter Antarctic sea ice extent in 2023. Front. Earth Sci. 12:1333706, https://doi.org/10.3389/feart.2024.1333706

Zhang, L., T.L. Delworth, X. Yang, F. Zeng, F. Lu, Y. Morioka and M. Bushuk (2022) The relative role of the subsurface Southern Ocean in driving negative Antarctic Sea ice extent anomalies in 2016–2021. Commun. Earth Environ., 3, 302. https://doi.org/10.1038/s43247-022-00624-1

Antarctica map showing Antarctic Peninsula

A map of Antarctica showing the Antarctic Peninsula separated by the Bellingshausen and Weddell Seas. Map: Adobe Stock.



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Sea ice loss remains a serious issue

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The Met Office has just published its latest briefing on Arctic and Antarctic sea ice.

The update doesn’t reveal any record-breaking figures, but it does reveal that sea ice loss remains a serious issue.

A view of Antarctica showing patches of sea ice, ice bergs and the Antarctic continent's mountains in the distance.

Alex West who co-ordinates the sea ice briefings said: “After last year’s record-breaking minimum extent of sea ice in the Antarctic, the latest update shows greater sea ice extent than last year, but it is still the second lowest on record for the time of year.

Following a warm June, Arctic sea ice extent is below average for the time of year but some way above record low levels, with conditions fairly typical of recent years.

“Extent is particularly low in the Laptev Sea and in the Atlantic sector, but nearer average in other parts of the Arctic.

“This year’s September Arctic sea ice extent is likely to be well below average, but there are not yet heightened indications of a new record low.”

See here for the full briefing.

Arctic insights

The Advancing Arctic Capabilities programme – a new project led by the Met Office -brings international partners to develop an improved understanding of what is happening to the region’s ice, ocean and atmosphere to support global climate resilience.

The project will deliver cutting-edge insights into Arctic weather patterns and ocean currents.



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What has been driving Hurricane Beryl?

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Hurricane Beryl, which has been tearing through the Caribbean, has been hitting the headlines for several reasons.

Firstly, there is the undeniable fact that during her existence as a Category 4 and 5 hurricane Beryl caused much damage and loss of life across several nations and territories, including Grenada, St Vincent and the Grenadines, Jamaica and the British Overseas Territory of the Cayman Islands.

Hurricane Beryl crossing Jamaica in early July 2024 as visualised by the Met Office computer model.

Satellite image of Hurricane Beryl crossing Jamaica in early July 2024

Secondly, Beryl has become infamous for being the earliest Category 5 hurricane in the historical record in the Atlantic Basin. Category 5 is the highest ranking for hurricanes requiring sustained wind speeds of at least 157 mph. Hurricane Beryl’s wind actually peaked at 165 mph on 2 July. The earliest date in the year any previous Atlantic hurricane had achieved winds of this strength was a full month later on 5 August.

Active hurricane season

Julian Heming is a Met Office tropical cyclone expert who has been studying these systems for many years. He said: “In the second half of May several prediction centres, including the Met Office, forecast an active Atlantic hurricane season with between 150% and 200% of usual activity.

“These Atlantic seasonal forecasts have been influenced by the development of cooler waters in the equatorial eastern Pacific in recent months – in line with the anticipated La Niña or cooler phase of the naturally-variable El Niño Southern Oscillation (ENSO) cycle.

“Developing La Niña conditions have a known association with a more active Atlantic hurricane season. So, we know that natural variation in the climate system has a huge observable effect on hurricane activity.

“But this trend towards La Niña favouring hurricane development would not solely explain Hurricane Beryl and the prediction of an active hurricane season.

“Sea temperatures across the tropical Atlantic and Caribbean Sea have been well above average since the Spring of 2023 which provides fuel for intense hurricanes like Beryl. There is much meteorologists do not yet understand about how these high sea-surface temperatures have developed and why they have persisted for so long. This is an active area of research.”

“Furthermore, higher sea-surface temperatures in line with a warming climate are expected to favour the development of a greater proportion of intense tropical cyclones in the long term.”

International effort

Will Lang is the Met Office’s head of Situational Awareness. He said: “Met Office forecasts are a crucial part of the international effort to predict Atlantic hurricanes, and our experts work at the heart of UK Government’s international response to damaging hurricanes such as Beryl.”

You can watch an interview about Hurricane Beryl here.



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Green light for space weather forecasting satellite

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The European Space Agency (ESA) today confirmed the contractors for the long-awaited Vigil mission which will transform global space weather forecasting.

The confirmation of the building of the satellite is the next step in the process positioning a satellite with a side-on view of the Sun to provide enhanced space weather forecasting.

The Met Office Space Weather Operations Centre, now celebrating its tenth year in operation, is one of a number of centres that will benefit from the new satellite.

The Vigil mission, as it’s known among space weather scientists, will enhance space weather forecasting capabilities and help provide more notice for potentially impactful space weather events such as coronal mass ejections.

Mark Gibbs, who leads the Met Office Space Weather Operations Centre (MOSWOC), said: “The Vigil mission represents a step-change in space weather forecasting capability. As well as replacing aging satellites, this mission will help to improve our forecasting capability and deepen our scientific understanding of coronal mass ejections (CMEs) that generate geomagnetic storms.”

Confirmation of the contract for the mission, which is being managed by the European Space Agency, represents the next milestone in the process of launching the new satellite by the end of this decade and will revolutionise imagery and data available to space weather forecasts.

Mark continued: “A side-on view of the Sun-Earth line is critical to provide accurate predictions of CME arrival at Earth. We’ll get access to more reliable, more advanced data to initialise models to predict CME arrival and also to monitor their progress as they head towards the Earth. We’ll be continuing to work with ESA to help ensure there’s as much benefit as possible to not just us at MOSWOC, but also to forecasting centres around the world. The Vigil mission will work in tandem with the current and future US missions stationed at L1.”

The news comes after geomagnetic storms two weeks ago brought aurora visibility to much of the UK in what was the strongest event since 2003 to impact Earth. While auroras provide immaculate photos, impactful space weather has the potential to affect everyone and is recognised on the UK’s National Risk Register. The ability to forecast these events can help to mitigate the worst impacts.

Find out more about the contract announcement.

Find out more about the Met Office Space Weather Operations Centre.




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