Iceland sits just below the Arctic Circle yet stays far milder than its latitude would suggest, with average winter temperatures along the south coast hovering near freezing rather than plunging to the extremes found at comparable latitudes in Canada or Siberia. This relative warmth is the product of a tug-of-war between warm Atlantic ocean currents and cold Arctic air masses, punctuated by volcanic eruptions, fierce windstorms, and some of the most dramatic seasonal swings in daylight on Earth. The result is a climate that defies easy categorization and is now changing faster than most people realize.
Why Iceland Is Warmer Than It Should Be
If you drew a line around the globe at 64–66°N, the latitude band Iceland occupies, you would pass through interior Greenland, northern Canada, and central Siberia, places where winter temperatures regularly drop below minus thirty. Reykjavík’s January average is closer to zero Celsius. The reason is warm Atlantic water. A branch of the North Atlantic current system, sometimes loosely called the Gulf Stream extension, carries heat northward past Iceland’s western and northern coasts. One key component, the North Icelandic Irminger Current (NIIC), pushes warm water along the north shore. Modeling work has shown that the NIIC’s transport of Atlantic water roughly doubled between 1992 and 2006, driven by pressure differences across the submarine ridge that runs from Greenland to Scotland.1Copernicus Publications (Ocean Science). The circulation of Icelandic waters – a modelling study That pulse of warm water helps explain why northern Iceland saw particularly mild conditions during the same period.
The flip side is that any weakening of this Atlantic heat conveyor would hit Iceland hard. Climate simulations of a collapse of the broader Atlantic overturning circulation project winter cooling over Iceland on the order of 3 to 8°C relative to pre-industrial conditions, enough to push the country back toward Little Ice Age temperatures even as the rest of the planet warms.2EGUsphere. Climate and Carbon Cycle Responses to a 21st century AMOC Collapse under a 2 °C Stabilization Pathway Iceland’s comfortable-for-the-Arctic status, in other words, is contingent on ocean circulation that cannot be taken for granted.
The Icelandic Low and North Atlantic Weather
Most people who check an Icelandic weather forecast notice the wind before anything else. The island sits underneath one of the atmosphere’s most influential semi-permanent pressure features: the Icelandic Low, a broad area of low barometric pressure centered roughly between Iceland and southern Greenland. The Icelandic Low is one half of the seesaw known as the North Atlantic Oscillation (NAO). When the Low is deeper than usual relative to the Azores High to the south, westerly winds strengthen across the North Atlantic, channeling mild, wet air over northwestern Europe and stormy weather over Iceland. When the pressure difference weakens, the pattern shifts, and cold Arctic air can push farther south.
The Icelandic Low doesn’t just control weather over Iceland itself. Research has found that variations in the Icelandic Low are the dominant atmospheric influence on the position of the Gulf Stream’s northern boundary, with perturbations in the Low leading to shifts in the Gulf Stream wall one to three years later.3Geophysical Research Letters. The dominant influence of the Icelandic Low on the position of the Gulf Stream northwall In effect, the atmosphere over Iceland helps steer the ocean current that keeps Iceland warm, a feedback loop connecting the island’s weather to the broader Atlantic system.
On a more immediate and dangerous level, the NAO shapes Iceland’s avalanche risk. When the NAO index is persistently positive, meaning a strong Icelandic Low and vigorous westerly flow, snow accumulates rapidly on Iceland’s steep coastal mountains. Studies have linked the cumulative effect of this snow buildup to avalanche cycles, and tragic avalanche events in Iceland have coincided with prolonged rises in an NAO-derived snow accumulation index.4Geophysical Research Letters. The North Atlantic Oscillation and snow avalanching in Iceland
Volcanoes and Climate, in Both Directions
Iceland straddles the Mid-Atlantic Ridge and sits atop a mantle plume, making it one of the most volcanically active places on the planet. Eruptions shape Iceland’s climate in ways that are more complicated than the simple “volcanoes cool the planet” narrative.
Large explosive eruptions do, historically, cause cooling. The Laki eruption that began in June 1783 was followed by the textbook suite of volcanic climate effects: surface cooling, drought, and widespread crop failure across Iceland and parts of Europe.5Journal of Geophysical Research: Atmospheres. Modeling the 1783–1784 Laki Eruption in Iceland: 2. Climate Impacts But Laki was an exceptional event, one of the largest effusive eruptions of the last millennium. More typical Icelandic eruptions are smaller and tell a different story. Modeling of effusive eruptions at various scales shows that the climate response is strongly seasonal: mid-latitude cooling in summer, yes, but Arctic warming during autumn and winter. In other words, the blanket assumption that volcanic eruptions cause cooling is an oversimplification, particularly in the Arctic, where warming can be the dominant response during the colder months.6Atmospheric Chemistry and Physics. Modelled surface climate response to effusive Icelandic volcanic eruptions: sensitivity to season and size The same research found that as eruptions grow larger in terms of sulfur emissions, the climate response levels off, becoming increasingly insensitive to further increases in eruption size once emissions exceed roughly twenty to thirty times those of the 2014–2015 Holuhraun eruption.
Iceland’s volcanic plumbing also creates unusual interactions between fire and ice. Grímsvötn, one of the country’s most active volcanic systems, sits beneath the Vatnajökull ice cap. The volcano’s geothermal output of around two gigawatts melts ice from below, filling a subglacial lake covered by ice up to 300 meters thick.7Nature Communications. Subglacial water flow and ice dynamics during glacial lake outburst floods observed from space When the lake periodically bursts through the ice dam, it unleashes a glacial outburst flood, or jökulhlaup, sending enormous volumes of meltwater across the lowlands. These floods are among Iceland’s most destructive natural hazards, and as the ice cap thins from climate warming, the dynamics of the lake and the frequency of floods may shift in ways that are still being studied.
Shrinking Glaciers and Rising Land
Iceland’s glaciers covered roughly 11 percent of the country at their Little Ice Age maximum in the late 1800s and have been retreating since about 1890. The largest, Vatnajökull, has lost more than 400 cubic kilometers of ice since that retreat began.8Journal of Geophysical Research: Solid Earth. Glacio‐isostatic deformation around the Vatnajökull ice cap, Iceland, induced by recent climate warming: GPS observations and finite element modeling Modeling of Vatnajökull’s response to continued warming suggests that even a moderate warming rate of 2°C per century would shrink the ice cap’s area by 12 to 15 percent and its volume by 18 to 25 percent within the first hundred years, with individual outlet glaciers retreating three to six kilometers over that period and ten to thirty kilometers over two centuries.9Journal of Geophysical Research: Earth Surface. Sensitivity of Vatnajökull ice cap hydrology and dynamics to climate warming over the next 2 centuries
One striking consequence of glacier retreat is that Iceland is physically rising. As billions of tons of ice melt, the land beneath rebounds upward, a process called glacial isostatic adjustment. Satellite radar measurements between 1995 and 2009 recorded the ground near Vatnajökull’s edge rising at rates of roughly 24 to 31 millimeters per year, with the fastest uplift at low-elevation outlet glaciers where ice loss is greatest.10Journal of Geophysical Research: Solid Earth. Iceland rising: Solid Earth response to ice retreat inferred from satellite radar interferometry and visocelastic modeling GPS stations around the southern edge of the ice cap confirm vertical velocities of 9 to 25 millimeters per year.11Journal of Geophysical Research: Solid Earth. Glacio‐isostatic deformation around the Vatnajökull ice cap, Iceland, induced by recent climate warming: GPS observations and finite element modeling For context, that is fast enough to be relevant over a human lifetime: a centimeter of uplift per year adds up to nearly a meter in a century. The uplift has implications for coastal infrastructure, surveying, and even volcanic activity, since removing the weight of ice can reduce pressure on magma chambers and potentially increase eruption frequency, though quantifying that effect remains an active area of research.
Sea Ice and Iceland’s Long Climate Memory
For most of recorded Icelandic history, sea ice was a regular visitor. Drift ice carried south from the Arctic by the East Greenland Current would sometimes pack against Iceland’s northern and eastern coasts, extending the winter, killing livestock, and shutting down fishing. Chronicles from the settlement era onward are filled with references to ice years. The Little Ice Age, roughly the fourteenth through nineteenth centuries, brought some of the worst conditions, with bottom water temperatures off northwestern Iceland fluctuating dramatically and overall conditions marked by instability and cold pulses.12Jökull. Marine climate variability from Arnarfjörður, NW Iceland, during the Medieval Warm period and early/middle Little Ice Age
Looking further back, sediment records from the seabed around Iceland reveal a long-term increase in drift ice delivery to the North Atlantic over the past five to six thousand years, a trend linked to the gradual cooling of the late Holocene. Periods of increased drift ice correspond to cold intervals in the wider North Atlantic, including the Little Ice Age itself.13Paleoceanography. Holocene history of drift ice in the northern North Atlantic: Evidence for different spatial and temporal modes Quartz grains found in marine sediments off northern Iceland serve as a reliable marker of this drift ice, since the quartz originates from continents far to the north and west and arrives embedded in icebergs and sea ice.14The Holocene. A robust, multisite Holocene history of drift ice off northern Iceland: implications for North Atlantic climate Today, sea ice rarely reaches Icelandic shores. Whether that absence is permanent or simply a warm-phase reprieve depends on what happens to the Atlantic overturning circulation in the coming decades.
Shifting Ecosystems on Land and at Sea
Warming is reshaping what lives in Iceland, both in the ocean and on land. In Icelandic waters, a large study tracking 82 fish species found that about 70 percent shifted northward as sea temperatures rose, moving roughly a quarter of a degree of latitude for every 1°C of warming. Most also shifted westward.15Scientific Reports. Shifting fish distributions in warming sub-Arctic oceans For a country whose economy has long depended on fishing, the redistribution of commercially important species like cod, haddock, and capelin has real consequences for fleet logistics, quota negotiations, and international fishing disputes. Some species previously rare in Icelandic waters, like mackerel, have become abundant, while cold-water species risk being pushed off the shelf.
On land, subarctic grasslands are responding to warming by growing for longer each year. Experimental warming of Icelandic grassland soils shows the growing season extends by about two days for every degree Celsius of warming, with no sign of saturation even at warming levels of 10°C above ambient. Researchers found the response held consistently whether the warming was short-term or sustained over decades, suggesting it is driven more by physiology than by genetic adaptation or shifts in plant community composition.16PubMed. Phenological responses of Icelandic subarctic grasslands to short-term and long-term natural soil warming A longer growing season sounds benign, but it interacts with other changes. Soil erosion is already a severe problem across the Icelandic highlands, where centuries of overgrazing stripped vegetation and exposed fragile soils. Research at eroded sites shows that soil moisture drops sharply near the edges of erosion patches, vegetation there grows less vigorously, and the drier, weaker margins become more vulnerable to further erosion, creating a self-reinforcing feedback loop.17European Journal of Soil Science. Soil moisture, stressed vegetation and the spatial structure of soil erosion in a high latitude rangeland If future warming brings drier summers or altered precipitation patterns, this erosion feedback could accelerate even as growing seasons lengthen elsewhere.
Downslope Windstorms and Extreme Weather
Iceland’s position beneath the Icelandic Low guarantees frequent storms, but the island’s geography creates its own extreme wind events. When strong airflow crosses Iceland’s mountains and ice caps, gravity waves can amplify on the lee side, producing downslope windstorms of startling intensity. One well-studied case involved winds cascading off Öræfajökull, Iceland’s highest peak, in the southeast. High-resolution modeling captured the gravity-wave breaking that triggers these events, with simulated wind speeds closely matching the observed storm.18Atmospheric Chemistry and Physics. Downslope windstorm in Iceland – WRF/MM5 model comparison These localized storms can generate gusts far exceeding anything forecast for surrounding areas, making them dangerous for drivers, hikers, and structures near mountain passes.
Moisture plays a surprisingly important role. The same modeling work showed that how well the atmosphere’s moisture distribution is captured strongly affects the accuracy of windstorm predictions, because condensation and evaporation processes alter the stability of the air layers that determine whether a gravity wave breaks or simply passes overhead. For forecasters, this means that getting precipitation right and getting wind right are linked problems in Iceland’s rugged terrain.
Geothermal Greenhouses and Food Security
Iceland’s volcanic geology shapes more than its hazards; it also makes possible an unusual form of agriculture. Geothermally heated greenhouses have been a feature of Icelandic farming since at least the 1920s, using hot water piped from the ground to grow produce in a climate that would otherwise make year-round cultivation impossible. As of a 2012 survey, total greenhouse area in Iceland was about 194,000 square meters, roughly half dedicated to edible plants and the rest to ornamental flowers and tree seedlings. The results are striking: Icelandic tomatoes supply about two-thirds of the domestic market, and Icelandic cucumbers claim nearly 99 percent of it.19ResearchGate / European Countryside. Greenhouse Agriculture in the Icelandic Food System
Outdoor crops remain vulnerable to Iceland’s unpredictable weather. A late July frost in 2009 destroyed around 35 percent of the potato crop, and a cold summer in 2013 slashed the harvest by 40 percent compared to the previous year.20ResearchGate / European Countryside. Greenhouse Agriculture in the Icelandic Food System These episodes illustrate a persistent tension in Icelandic food security: the average climate is warming and growing seasons are lengthening, but year-to-year variability remains high enough that a single cold snap or late frost can still devastate outdoor production. The greenhouse system, insulated by geothermal energy, offers a buffer against that volatility.
Hydropower and the Peak Water Problem
Iceland generates nearly all its electricity from renewable sources, with hydropower and geothermal splitting the load. Many of the country’s hydropower stations depend on glacial meltwater, which creates a peculiar long-term problem. As glaciers thin, meltwater runoff initially increases, boosting the water supply to reservoirs and rivers. But once the glaciers shrink past a tipping point, runoff begins to decline. This trajectory is called “peak water,” and modeling of Icelandic glaciers under future warming scenarios suggests that most glacial catchments feeding operational hydropower areas will reach peak water between roughly 2040 and 2050, with power production potential peaking around the same time.21SIT Digital Collections. Estimating “Peak Water” Runoff and Power Production for Hydropower-relevant Icelandic Glaciers Under Future Climate Scenarios After that, the glaciers still produce meltwater, but in diminishing volumes. By 2100, the net change in production capacity becomes much more variable and uncertain.
The same modeling of Vatnajökull projects a maximum increase in glacier-derived runoff of about 25 percent, peaking roughly 130 years into a sustained warming scenario, before declining.22Journal of Geophysical Research: Earth Surface. Sensitivity of Vatnajökull ice cap hydrology and dynamics to climate warming over the next 2 centuries Energy planners in Iceland are therefore looking at a few decades of abundance followed by a gradual squeeze, making decisions about new dam construction and reservoir capacity more complicated than they might first appear.
Turning Basalt into a Carbon Sink
Iceland’s geology has also made it a testing ground for one of the more promising approaches to carbon capture. The CarbFix project, based in southwest Iceland, injects carbon dioxide dissolved in water into basalt rock formations underground. Basalt is rich in the right minerals for reacting with dissolved CO₂ and locking it away as solid carbonate minerals, a process called mineral carbonation. Iceland’s young volcanic bedrock, composed almost entirely of basalt, offers vast quantities of reactive rock at relatively shallow depths.23International Journal of Greenhouse Gas Control. Mineral sequestration of carbon dioxide in basalt: A pre-injection overview of the CarbFix project Early results showed that injected CO₂ mineralized far faster than expected, turning to stone within a couple of years rather than the centuries originally anticipated. The project has since expanded and attracted international attention as a model for geological carbon storage in volcanic regions worldwide.
Seasonal Darkness, Mood, and Well-Being
No discussion of Iceland’s climate is complete without addressing the dramatic swings in daylight. Reykjavík gets roughly 21 hours of daylight around the summer solstice and fewer than four hours around the winter solstice. Research on healthy Icelandic women found that mood, cognitive sharpness, perceived social support, and self-rated physical health were all significantly higher in summer than in winter, though interestingly, self-reported tiredness did not differ between seasons.24PubMed. Well-being in healthy Icelandic women varies with extreme seasonality in ambient light The implication is that the darkness itself, or perhaps the cascade of changes it triggers in routines and social activity, affects well-being in ways that go beyond simply feeling sleepy.
Broader research on environmental mood responses has found that people who report strong adverse reactions to cold weather and reduced daylight tend to have higher depressive symptom severity. But the relationship is not one-directional. As temperatures rise, those same cold-sensitive individuals see their depressive symptoms improve, while people who actually prefer cold weather experience worse symptoms as things warm up.25Journal of Environmental Psychology. When the weather gets colder and days get shorter: Environmental mood responses and their link to depressive symptom severity In a warming Iceland, then, the psychological effects of climate change will not be uniform. For some residents, milder winters and slightly more daylight at the margins of the season may bring genuine relief. For others, the change may erode something they valued about the climate as it was.