Arctic Report Card 2024: Tundra Turns Carbon Source, Caribou Decline, Record Rain

An ice seal in the Arctic Ocean. NOAA / Josh M. London, NMFS Research Permit #23858.

The Arctic keeps warming faster than the rest of the planet. NOAA's 2024 Arctic Report Card records record and near-record observations: Arctic tundra shifting from carbon sink to carbon source, declines in once-large inland caribou herds, and increasing winter precipitation. Changes also vary sharply by region, so people, plants and animals experience them differently. The report's message: rapid change demands stronger adaptation and global cuts in fossil fuel pollution, and Indigenous Knowledge and community-led research are essential to understanding and responding.

Air temperature

The Arctic (60–90° N) is warming faster than the globe — Arctic amplification. After accounting for natural variability, it has warmed about three times faster than the global mean since 1980. Signs include shrinking spring snow cover, summer sea ice loss and Greenland Ice Sheet melt; cold extremes have warmed twice as fast as annual temperatures since 1979; and western Alaska salmon and western Arctic caribou have shown sensitivity to warming.

• October 2023–September 2024 was the 2nd warmest Arctic year since 1900.
• The last nine years are the nine warmest on record.
• Autumn 2023 ranked 2nd and summer 2024 3rd warmest.
• An early August 2024 heat wave set all-time daily records in several northern Alaska and Canada communities.

Arctic air temperatures, October 2023–September 2024, compared with 1991–2020 (warmer in orange and red, colder in blue), and yearly Arctic (red) and global (gray) temperatures since 1900. NOAA Climate.gov.

Precipitation

Arctic precipitation varies enormously — polar-desert dryness over the Canadian Arctic Archipelago and central Arctic Ocean, much wetter conditions on the Atlantic side, and boosts where mountains force air upward.

• Summer 2024 (July–September) was the wettest on record across the pan-Arctic.
• Since 1950, annual Arctic precipitation has increased, especially in winter.
• Autumn 2023 was dry over the East Greenland and Barents seas and wet from the U.K. east into Eurasia.

Where the heaviest 5-day winter precipitation events of 2024 ranked among the ten wettest on record (blues and greens), and winter precipitation since 1950 from two data sources, both rising. NOAA Climate.gov.

Snow

Snow shapes Arctic land from autumn to spring — energy balance, ground temperature, permafrost, ecosystems — and the timing of spring melt affects rivers, soil moisture, plant growth and fire risk long after.

• Winter 2023/24 snow accumulation was above average in both Eurasia and North America.
• Much of the Eurasian Arctic had a longer snow season; parts of central and eastern Arctic Canada had their shortest in 26 years.
• Over the past 15 years, snowmelt has often come 1–2 weeks earlier in May and June on both continents.

Length of the 2023–24 snow season ranked against 1998–2024, and five-year average June snow cover since 1967 compared with 1991–2020. Late-spring snow cover has declined across the North American Arctic. NOAA Climate.gov.

Ocean temperatures and productivity

Summer sea-surface temperatures (SSTs) depend on sunlight absorbed — more where ice is gone — and warm inflows from the Atlantic, Pacific and rivers. They drive the ice-albedo feedback: less bright ice, more dark ocean absorbing heat, more melting.

• August 2024 SSTs were about 2–4 °C warmer than the 1991–2020 average in most marginal seas, though the Chukchi Sea was about 1–4 °C cooler.
• North of 65° N, August SSTs have risen about 0.3 °C per decade since 1982.

August sea-surface temperature trends, 1982–2024, where statistically significant; white shows August 2024 sea ice, the black line the 1991–2020 median ice edge. Image from the National Park Service's page.

Marine algae — the base of the food web — respond in complicated ways: thinner ice, more open water and upwelling have boosted productivity in many areas, but the retreating ice edge remains the most productive zone, and ice-derived material is still vital year-round.

• Six of nine regions had lower productivity in 2024 than their 2003–22 average.
• All regions except the Amerasian Arctic still show rising trends over 2003–24 — most in the Eurasian Arctic (+57.3%), Barents Sea (+20.5%) and Sea of Okhotsk (+13.5%).

Sea ice

Sea ice reflects sunlight, separates ocean from air, provides habitat, and has long been part of Indigenous life; its decline is opening the Arctic to more shipping and resource and security activity.

• September 2024 extent was the 6th lowest since 1979; the last 18 Septembers are the 18 lowest.
• Long-term declines in extent and in older, thicker ice continue, though extent since 2007 has stayed low without a significant trend.

March (red) and September (blue) sea ice extent, 1979–2024, and multiyear ice in September (green), 1984–2024, with trend lines. Image from the National Park Service's page.

Tundra: greener, and now a carbon source

The Arctic tundra covers 5.1 million km². The "greening of the Arctic" — more productive tundra vegetation — became evident by the late 1990s and continues.

• In 2024, circumpolar peak tundra greenness was the 2nd highest in the 25-year MODIS record, with a record in North America.

For thousands of years, Arctic land has been a carbon sink, storing at least 1.4–1.6 trillion tonnes of carbon in soils and permafrost. But warming thaws permafrost, letting microbes release CO₂ and methane, and wildfires release pulses of both.

• Including wildfire emissions, the tundra has shifted to a CO₂ source and is a consistent methane source.
• In 2024, permafrost temperatures were the highest on record at nearly half of Alaska's long-term stations — the 2nd warmest year on average.
• Wildfires in North American permafrost regions have increased since the mid-20th century; circumpolar fire emissions have averaged 207 teragrams of carbon a year since 2003, and 2024 was the 2nd highest year north of the Arctic Circle.

Caribou

Caribou on the fall range of Alaska's Western Arctic Herd. NPS / Kyle Joly.

Climate touches nearly every part of caribou life, and caribou spend about three-quarters of their day eating and digesting, so how warming changes their forage is key.

• Migratory tundra caribou have declined by 65% overall over the last 2–3 decades. Smaller coastal herds in the western Arctic show signs of recovery, while larger inland herds are stable or still declining.
• Warmer summers and falls, changing winter snow and a growing human footprint together stress the herds.
• Regions with the most projected summer warming are expected to see the largest continued declines.
• Sharing knowledge is essential to managing caribou while respecting northern peoples' cultural, nutritional and spiritual ties to them.

Trends and herd status among migratory tundra caribou since peak numbers in the 1990s and early 2000s. Image from the National Park Service's page.

Ice seals of Alaska

Four ice seals — ringed, bearded, spotted and ribbon — live in the Bering, Chukchi and Beaufort seas and are hunted by Alaska Natives for subsistence. Ringed and bearded seals were listed as threatened in 2012 because of expected sea ice loss.

• All four populations are large (hundreds of thousands) and the subsistence harvest is sustainable.
• Harvest monitoring since the 1960s shows no sustained change in body condition, stable or younger maturity, high pregnancy rates and pup survival past weaning.
• As expected with warmer water, fewer ringed seals eat Arctic cod and more eat saffron cod — with no change in health.

Blubber thickness in four ice seal species harvested by Alaska Natives since the 1960s: after declines in the 2010s, body condition recovered. Red squares mark harvest locations. NOAA Climate.gov.

About the report

Issued every year since 2006, the Arctic Report Card is a peer-reviewed NOAA Technical Report for scientists, teachers, students, decision-makers and the public. The 2024 edition has 12 essays by 97 scientists from 11 countries, peer-reviewed through the Arctic Monitoring and Assessment Programme.

Sources

Based on "Arctic Report Card 2024," National Park Service, summarizing Moon TA, Druckenmiller ML, Thoman RL, eds., Arctic Report Card 2024, NOAA; the report's essays, written by an international team, are rewritten in hubnx's own words.