Fossil-fuel drilling in Alaska’s Arctic National Wildlife Refuge (ANWR) could put polar bears at risk of “lethal” oil spills, new research suggests.
Former president Donald Trump passed a law to enable drilling in the refuge in 2017.
This followed decades of fierce debate between Democrats and Republicans about whether to allow extractive activities in the 7.7m-hectare (19m-acre) expanse, a haven for wildlife sitting on top of an estimated 11bn barrels of oil.
On his first day in office, US president Joe Biden suspended drilling inside the ANWR pending a review. In 2023, his administration cancelled the seven oil and gas licences issued for the reserve under Trump.
However, by law, the Biden administration is still required to hold a second lease sale for the ANWR by December 2024, unless Congress is able to pass legislation undoing the provision set out in Trump’s tax bill.
And with Trump pledging to “drill, baby, drill” if reelected to power later this year, a Republican victory in the next US election would likely see the refuge opened up for oil and gas extraction once again.
The new study, published in Biological Conservation, uses modelling to examine how a series of “worst-case scenario” oil spills could impact polar bears that use the refuge to raise young and feast on bowhead whale carcasses.
The research finds that a serious oil spill inside ANWR could expose up to 38 bears to lethal levels of oil and dozens more to harmful levels.
The risk of exposure to oil spills could be worsened by climate change, which is forcing polar bears to spend greater amounts of time on land in summer as sea ice melts away, the study lead author tells Carbon Brief.
Wild north
Republicans and Democrats have been at loggerheads about whether to drill for oil in the ANWR since the 1970s.
It is located in Alaska’s north slope, directly adjacent to a vast expanse of land that is a hotbed for oil and gas activity (see chart below). This activity includes the highly controversial Willow oil project, which was given final approval by Biden in 2023.
At present, there are currently around 2,000 oil and hazardous substance spills each year in Alaska, in areas where extractive activities already take place.
In 1989, Alaska faced one of the worst environmental disasters in US history when the Exxon Valdez oil tanker ran aground, spilling 11m gallons of oil.
Conservationists have fought to protect the ANWR, a wilderness supporting migratory caribou, wolves, all three North American bear species and hundreds of bird species. The refuge is also the home of the Indigenous Gwich’in and Iñupiat people.
But Republicans have long called for the ANWR to be opened up for drilling. According to Outside Magazine, Republicans have attempted to pass laws to enable drilling inside the ANWR nearly 50 times.
They were finally successful in 2017, when Trump passed a tax bill requiring oil and gas licensing rounds to be held for an area inside the ANWR.
However, on his first day in office in 2021, Biden issued an executive order suspending drilling in the ANWR pending an environmental review.
In 2023, interior secretary Deb Haaland cancelled the seven oil and gas licences issued in the ANWR under Trump, arguing the lease sale was “seriously flawed” for a number of reasons, including failure to “properly quantify downstream greenhouse gas emissions” from the projects.
Despite these efforts, the Biden administration is still required by law to conduct a second lease sale for the ANWR by December 2024, unless Congress is able to pass legislation undoing the provision set out in Trump’s tax bill.
Biden’s presidential campaign promised “no new drilling, period” on federal land and waters, but since entering office he has several times been compelled to hold new licensing rounds in various locations by Congress or the courts.
Dr Ryan Wilson, a wildlife biologist at the US Fish and Wildlife Service in Alaska and lead author of the new study, says his research could help to inform decisions about issuing licences within the ANWR. He tells Carbon Brief:
“There is still an opportunity to inform where development and infrastructure would be allowed for the upcoming lease sale.”
Bear behaviour
For the study, the researchers used modelling to simulate how a series of “worst-case scenario” oil spills could affect polar bears resting in the ANWR.
Polar bears are known to be “especially susceptible to oiling” from spills, the researchers say. This is because oil can damage their fur, leaving them unable to thermoregulate in their harshly cold habitat.
According to the researchers, the ANWR provides an “important habitat” for polar bears from the Southern Beaufort Sea subpopulation, a group of around 900 bears that are currently in decline.
The ANWR hosts the highest density of polar bear dens in the US.
When female polar bears are pregnant, they dig dens in the snow, where they give birth and care for their cubs for the first few months of their life. It is the “most vulnerable period in the polar bear’s life cycle”, according to Polar Bears International. Wilson tells Carbon Brief:
“We’re not sure why maternal polar bears are drawn to the ANWR coastal plain for denning, but records of denning events indicate that over the last 30-40 years there is a higher density of dens there than elsewhere on the northern coast of Alaska.”
The ANWR coastal plain also provides “important resting areas” and a “movement corridor” for bears during autumn, when sea ice is near its lowest levels, the researchers say.
At this time, polar bears feast on the remains of bowhead whale carcasses left behind by hunters from Indigenous communities.
To understand how oil spills might affect polar bears, the researchers simulated spills from three locations along the north-western coast of the ANWR coastal plain: Brownlow Point, Anderson Point and Camden Bay. (These sites are represented with hazard symbols on the map below.)
These regions have the highest oil potential – and are also areas where polar bears come ashore to feed on whale carcasses, according to the researchers.
For each spill site, the researchers simulated an underwater pipeline release of 4,800 barrels of oil every day for six days, totalling 28,000 barrels. They then tracked the path of the oil spill for 50 days.
They simulated the oil spills in autumn, when the maximum number of bears would be using the ANWR.
To estimate how many bears would be exposed, they overlaid trajectories of simulated polar bear movements with the oil spills.
They found that a spill at Brownlow Point would be the most deadly, exposing up to 38 bears to lethal levels of oil. Meanwhile, a spill at Anderson Point would expose up to 28 bears, while a spill at Camden Bay would expose up to 19 bears.
All three of the spills would also expose up to 50-60 bears to sub-lethal levels of oil each week, the researchers find.
Mounting risks
While the simulations track the movements of oil and polar bears over 50 days, they do not consider any efforts that might be made to clean up the oil and take bears to safety, the authors say.
Because of this, they describe their results as a “worst-case scenario that could help managers and oil producers prepare for the most impactful scenario they might encounter with an active oil spill”.
Wilson adds to Carbon Brief that the risk to bears from oil spills has increased because of climate change, which is causing sea ice cover in the Arctic Ocean to rapidly shrink, forcing bears to spend more time on the land surrounding the ocean, including the ANWR:
“The primary risk to polar bears in the Southern Beaufort Sea subpopulation is the loss of sea ice habitat due to climate change. The loss of sea ice is causing more polar bears to come on shore in summer and autumn for longer periods of time, which can lead to more human-polar bear conflicts, putting both bears and people at risk. This increased time on land also leads to greater risk to polar bears from an oil spill in the region.”
The study is “well-conceived and significant” says Prof Andrew Derocher, a polar bear researcher at the University of Alberta in Canada, who was not involved. He tells Carbon Brief:
“The risk to polar bears from an oil spill remains an ongoing concern and for a population like the one in the Southern Beaufort Sea subpopulation, which has already declined in abundance due to climate change, the risk of additional mortality from an oil spill is a serious concern. An oil spill in Alaska as modelled would clearly have significant negative impacts on polar bears there.”
One aspect not covered in the study is how an oil spill would likely affect polar bear prey, including ringed and bearded seals, he says:
“If there were population-level impacts on the seals, this could be an additive impact that would further slow polar bear population recovery. In addition, there is a very high likelihood that polar bears would feed on dead and dying wildlife that were oiled in a spill – specifically, seals, walrus, possibly belugas and birds. Polar bears are consummate scavengers and this secondary form of impact isn’t addressed by this paper.”
He adds the study raises the important issue of being prepared for the environmental impacts of an oil spill in the Arctic:
“I believe that no jurisdiction is prepared for a significant oil spill in the Arctic. Our ability to respond is limited by preparedness, infrastructure and staff.”
The post Alaska refuge drilling could threaten polar bears with ‘lethal’ oil spills appeared first on Carbon Brief.
Alaska refuge drilling could threaten polar bears with ‘lethal’ oil spills
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.
Latest climate research
- Sea levels are already “much higher than assumed” in most assessments of the threat posed by sea-level rise, due to “inadequate” modelling assumptions | Nature
- Accelerating human-caused global warming could see the Paris Agreement’s 1.5C limit crossed before 2030 | Geophysical Research Letters covered by Carbon Brief
- Future “super El Niño events” could “significantly lower” solar power generation due to a reduction in solar irradiance in key regions, such as California and east China | Communications Earth &