Retreating glaciers created 2,500km of “new” coastline and 35 “new” islands in the Arctic between 2000 and 2020, according to a new study.
The research uses satellite images of more than 1,700 glaciers in Greenland, Alaska, the Canadian Arctic, Russian Arctic, Iceland and Svalbard.
The findings show that 85% of these glaciers retreated over 2000-20, revealing 123km of new coastline per year on average.
The study, published in Nature Climate Change, links the acceleration in glacier melt to warmer ocean and air temperatures.
The authors find that just 101 glaciers – less than 6% of the total – were responsible for more than half of the total additional coastline length.
For example, the retreat of the Zachariae Isstrom glacier in north-east Greenland revealed 81km of new coastline alone.
The study warns that the freshly revealed coastlines are more prone to landslides, which may, in turn, create “dangerous tsunamis” that pose risks to human life and infrastructure.
A scientist not involved in the study tells Carbon Brief that it remains “unclear” what the implications of the new coastlines will be for the people and ecosystems of the Arctic.
He suggests that they “may become home to important ecosystems that play a hitherto unquantified role in the global carbon cycle”.
Glacier melt
Glaciers are slow-moving rivers of ice found on almost every continent in the world. They typically advance downhill by a few centimetres every day, driven by their own weight.
The head of a glacier is always found on land – typically at high altitude, where temperatures are low. Here, precipitation and avalanches cause snow to build up on the surface of the glacier. Over time, the snow compacts into ice, adding mass to the glacier.
Meanwhile, the tail end of the glacier is typically found at lower elevations where the air is warmer. Here, melting ice and evaporating water cause glaciers to lose mass.
As the planet warms, glaciers are melting more rapidly. This often causes the bottom of the glacier – known as the “terminus“, “snout” or “toe” – to recede, reducing the overall length of the glacier. This is known as terminus retreat.
Over 2000-19, glaciers collectively lost around 267bn tonnes (gigatonnes, or Gt) of ice every year. A recent report by the UN warned that many glaciers will “inevitably” disappear entirely over the coming decades.
A separate study estimated that even if the world successfully limits global warming to 1.5C, glaciers could lose a quarter of their total mass by 2100.
Glaciers can be broadly split into categories based on their location. For example, while “land-terminating” glaciers end on land, “marine-terminating” glaciers flow into the ocean, where they often end in a “floating glacier tongue” that sits on the surface of the water.
When marine-terminating glaciers melt and retreat, new areas of coastline are often revealed. Research shows that marine-terminating glaciers in the northern hemisphere have cumulatively lost 10Gt of mass every year over 2000-20 due to terminus retreat.
The northern hemisphere is home to around 1,500 of the world’s roughly 200,000 glaciers.
The new study assesses how much new coastline has been exposed due to terminus retreat in marine-terminating glaciers in the northern hemisphere over 2000-20.
Satellite monitoring
The authors used a pre-existing dataset to identify all the marine-terminating glaciers in the northern hemisphere. They then manually assessed satellite imagery – mainly from Sentinel-2 – to digitise the new coastline that was exposed as a result of glacier retreat around Greenland, Alaska, the Canadian Arctic, Russian Arctic, Iceland and Svalbard over 2000-20.
Dr Jan Kavan is the lead author of the study and a researcher at the University of South Bohemia’s Centre for Polar Ecology. He tells Carbon Brief that the researchers opted for a manual approach because algorithms trained to identify the position of glaciers “don’t work very well” on coastlines.
This is because Arctic coastlines tend to be highly variable, Kavan explains. For example, glaciers near the coastline may be covered in debris – making it hard for an algorithm to recognise them.
Dr Simon Cook is a senior lecturer in environmental sciences at the University of Dundee, who wrote a “news and views” piece about the study published in Nature climate change. He praises the study, telling Carbon Brief that manually identifying coastlines is “labour-intensive and slow work, but widely regarded to be robust”.
The authors inspected 1,704 marine-terminating glaciers in total. They find that 2,466km of new coastline formed between 2000 and 2020 – an average of 123km of new coastline every year.
The map below shows where the coastline was added (red) and lost (blue) due to changes in glacier terminus positions over 2000-20. The yellow circles the total length of new coastline added in different regions, where larger circles indicate greater additions.
The authors note that the rate of new coastline formation varies highly between regions. Just 101 glaciers were responsible for more than half of the total additional coastline length, they say.
Two-thirds of the new coastline identified in this study were in Greenland, the authors say. The melt of the Zachariae Isstrom glacier in north-east Greenland has resulted in the formation of 81km of new coastline – more than twice as much as any other glacier in the study – according to the paper.
Retreating glaciers also exposed 35 new islands with areas larger than 0.5 square kilometres (km2), according to the study.
Changing coastlines
Rising ocean and air temperatures are the main reason that marine-terminating glaciers are rapidly losing mass, the study says. However, many other factors may affect how quickly new coastline forms due to glacier melt.
According to the authors, 85% of the glaciers in the study retreated between 2000 and 2020.
However, not all of these led to the development of new stretches of coastline.
For example, glaciers that stretch out far into the sea could experience “extensive retreat” without any new coastline forming, according to the paper.
Conversely, glaciers in “deep and narrow fjords” can expose long new areas of coast by losing only a small volume of ice.
The authors note that the most “dramatic” glacier retreats are due to ice shelves or floating tongues breaking off the main glacier and collapsing into the water.
Meanwhile, glacier advances – when glaciers gain mass more quickly then they lose it, or temporarily “surge” forwards – can cause a loss of coastline. (Surges are short-lived periods when the glacier moves faster than its normal rate, often due to meltwater which builds at the base of the glacier and acts as a lubricant.)
The paper finds that more than 50 metres of coastline was lost due to glacier advances. Two-thirds of this gain was in Svalbard due to a “surge” of the Nathorstbreen glacier system, according to the paper.
Lead author Kavan tells Carbon Brief that other studies have assessed coastline gain from “individual glaciers” or “small regions”, but says this is the first paper to quantify coastline gain across the entire northern hemisphere for a uniform time period.
Dr Robert McNabb, a lecturer at Ulster University who was not involved in the study, tells Carbon Brief the study “highlights the importance and immense value of having long-term, freely available satellite archives for research”.
Tsunami risk
Glacier melt is often discussed in the context of water security, as the world’s 200,000 glaciers store around 70% of the Earth’s fresh water. However, Kavan tells Carbon Brief that the impact of retreating glaciers on the bedrock is often “neglected”.
Using a map of rock types across the Arctic, the authors analyse the changing conditions of the new coastlines. They find that most of the new coastline is formed of metamorphic bedrock – a type of rock formed from intense heat and pressure. Meanwhile, softer sedimentary rocks, which are more susceptible to erosion, dominate the newly formed coastlines in eastern Svalbard.
In his news and views piece, Cook – the University of Dundee environmental sciences lecturer – explains that the newly revealed coastlines are known as “paraglacial”. He writes:
“Paraglacial coasts differ from other established areas of Arctic coastline because permafrost will not yet have had time to develop in these freshly revealed areas, meaning that they are more easily eroded by wave action, mass wasting and other processes because of a lack of icy cement. They are, therefore, expected to be highly dynamic.”
Cook says it is “currently unclear” what the implications of the new paraglacial coastlines will be for the people and ecosystems of the Arctic. He suggests that the new coastlines “may become home to important ecosystems that play a hitherto unquantified role in the global carbon cycle”.
Freshly revealed paraglacial coastlines can be more prone to landslides, which may, in turn, cause “dangerous tsunamis”, the paper notes. As an example, it points to a tsunami on 17 June 2017 in Greenland, which caused “substantial infrastructure damage and loss of life”.
Dr Anna Irrgang is a coastal geomorphologist at the Alfred Wegner Institute and was not involved in the study. She tells Carbon Brief that the study “may help in detecting potential risk-zones” for such tsunamis.
She adds that the dataset provided in this study can be used as a “first estimation of the hazard potential”, but adds that “a more in-depth risk analysis needs to be undertaken at the local scale, where communities might be exposed to these arising dangers”.
Meanwhile, Kavan tells Carbon Brief that marine-terminating glaciers are considered “biodiversity hotspots”. Meltwater from the glacier causes upwellings at the terminus of the glacier, creating “nutrient-rich water” that is vital for many polar species, he says.
As a result, ongoing glacier retreat may result in many of these habitats being lost, putting species like bearded seals and Arctic-dwelling birds at risk, he adds.
The post Global warming is ‘exposing’ new coastlines and islands as Arctic glaciers shrink appeared first on Carbon Brief.
Global warming is ‘exposing’ new coastlines and islands as Arctic glaciers shrink
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 analysis of the plan. China Daily reported that the strategy “highlights measures to promote the climate targets of peaking carbon dioxide emissions before 2030”, which China said it would work towards “actively yet prudently”.
Around the world
- EU RULES: The European Commission has proposed new “made in Europe” rules to support domestic low-carbon industries, “against fierce competition from China”, reported Agence France-Presse. Carbon Brief examined what it means for climate efforts.
- RECORD HEAT: The US National Oceanic and Atmospheric Administration has said there is a 50-60% chance that the El Niño weather pattern could return this year, amplifying the effect of global warming and potentially driving temperatures to “record highs”, according to Euronews.
- FLAGSHIP FUND: The African Development Bank’s “flagship clean energy fund” plans to more than double its financing to $2.5bn for African renewables over the next two years, reported the Associated Press.
- NO WITHDRAWAL: Vanuatu has defied US efforts to force the Pacific-island nation to drop a UN draft resolution calling on the world to implement a landmark International Court of Justice (ICJ) ruling on climate, according to the Guardian.
98
The number of nations that submitted their national reports on tackling nature loss to the UN on time – just half of the 196 countries that are part of the UN biodiversity treaty – according to analysis by Carbon Brief.