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Blooms of pigmented microalgae accelerate glacier and ice sheet melting by reducing the surface albedo. Here, Halbach et al. use single-cell measurements of elemental composition and nutrient assimilation rates of glacier ice algae, showing that the algae are well adapted to the ice’s oligotrophic conditions and exhibit no significant changes in productivity in response to nutrient additions.

This study reveals dissociating methane hydrate mounds on the seafloor at more than 3600 m deep in the Greenland Sea. This gas hydrate cold seep supports chemosynthetic fauna similar to Arctic hydrothermal vents at similar depth, consistent with an overlap between vent and seep fauna in the region.

Rising atmospheric aridity may be an important driver of tree growth. Here the authors present analyse the global relationship between tree canopy height and vapour pressure deficit, and its potential shifts under future climate change.

Drainage of two surface lakes on Greenland’s fastest ice stream caused a pulse of faster flow to propagate downstream and triggered a long calving episode, suggesting the entire stream is strongly coupled, according to geophysical field observations.

Remotely sensed NDVI data and contemporary field data from 84 grasslands on 6 continents show increasing divergence in aboveground plant biomass between sites in different bioclimatic regions.

Despite their importance, the accuracy of the quantitative interpretation of Antarctic ice core stable water isotope records remains a matter of debate. Here, the authors use an isotope-enabled atmospheric general circulation model to test and validate the isotopic paleothermometer approach.

Anthropogenic climate change intensified an exceptional snowfall event termed Filomena in high-altitude northern Spain in January 2021 by up to 40%, whereas it reduced snowfall by up to 80% in lowland areas, according to analyses with a flow analogs technique and climate change attribution simulations.

The long-term effectiveness of assisted gene flow of trees could be jeopardised by rapid climate change. Here the authors analyse a large dataset of relocated black spruce populations in Canada, finding that local adaptation to climate of origin improved NPP responses, but only for up to ~15 years after planting.

Climate change is expected to intensify the global hydrological cycle and to alter evapotranspiration, but direct observational constraints are lacking at the global scale. Now a data-driven, machine-learning technique and a suite of process-based models have been used to show that from 1982 to 1997 global evapotranspiration increased by about 7.1 millimetres per year per decade. But since 1998 this increase has ceased, probably because of moisture limitation in the Southern Hemisphere.

An expert-elicitation process identifies current methodological barriers for monitoring terrestrial biodiversity, and how technological and procedural development of robotic and autonomous systems may contribute to overcoming these challenges.

Data from the Southern Ocean sea-ice extent, the biological productivity of the ocean, and atmospheric iron flux over the past eight glacial cycles indicate that during glacial terminations, changes in Patagonia apparently preceded Antarctic sea-ice reduction — showing that multiple mechanisms may be responsible for different phases of CO₂ increase during glacial terminations.

An enduring question in ecology is how new ecosystems form. Studying retreating glaciers, this study shows that life’s first foothold in these new environments is not established by photosynthetic organisms as long assumed, but rather by versatile microbes that harvest chemical energy from soil and thin air.

The Arctic is warming and undergoing rapid ice loss. This Perspective considers how changes in sea ice will impact the biogeochemistry and associated ecosystems of the region while calling for more observations to improve our understanding of this complex system.

Suture zones are abundant on Antarctic ice shelves and widely observed to impede fracture propagation. Here we show that fracture detainment is principally controlled by the zones’ enhanced seawater contents, reducing fracture-driving stresses by orders of magnitude and therefore greatly enhancing stability.

10,000 years of summer length changes are reconstructed. Longer summers occurred when the equator-to-pole temperature gradient weakened. A 1 °C drop added ~6 days; under high emissions, European summers could lengthen by up to 42 days by 2100.

Analysis of ground-sourced and satellite-derived models reveals a global forest carbon potential of 226 Gt outside agricultural and urban lands, with a difference of only 12% across these modelling approaches.

Channelized subsurface melting is an important process in the dynamics of ice shelves. Here the authors present observational data from Antarctic ice shelves and show that their basal melt is up to 50% higher than previously assumed.

The influence of the changing climate on individual snowstorms has been uncertain, in part due to the use of coarse model simulations. Now, research employing more detailed simulations finds fewer and smaller snowstorms as a result of warming, with a reduction in the amount and extent of extreme snowfall.

A global assessment of the status of tropical cloud forests shows that they have declined overall by ~2.4% since 2001, with much of this occurring despite formal protection and with up to 8% loss in some regions.

Atmospheric rivers associated with blocking events are related to a large fraction of the surface ice melt events in West Antarctica, suggest observation-based analyses of atmospheric dynamics and West Antarctic surface melt.

Data from the oil- and gas-producing basin of northeastern Utah and a box model are used to assess the photochemical reactions of nitrogen oxides and volatile organic compounds that lead to excessive atmospheric ozone pollution in winter.

Analyses of the relationships between temperature, moisture and seven key plant functional traits across the tundra and over time show that community height increased with warming across all sites, whereas other traits lagged behind predicted rates of change.

According to the Milankovitch theory, glacial to interglacial climate variability — as recorded in Antarctica ice cores — is governed by summer insolation at high northern latitudes. It is now shown that accumulation of Antarctic snow is biased towards austral winter and may be explained simply by variations in local insolation, with no recourse to northern influences. Although not constituting a complete negative proof, the results show that the Antarctic ice core records do not, in themselves, provide sufficient support for the Milankovitch theory.

The mass balance of Hindu-Kush–Karakoram–Himalaya glaciers has been debated, partly because of a severe lack of observations from the region. An analysis of the regional mass balance of Karakoram glaciers by comparison of digital elevation models from 1999 to 2008 reveals a small glacier mass gain in the area.

This study investigates the effects of forestation on temperature in Europe using climate model experiments. The findings indicate that conversion from coniferous to broadleaved trees in currently forested areas can provide cooling for summer hot extremes.

Detailed mapping of the distribution of water and semiheavy water in the coma of Halley-type comet 12P implies a D/H ratio that is consistent with that of Earth’s water, indicating a common heritage.

Extreme ice sheet melt events in northeast Greenland occur after intense water vapor transport into northwest Greenland by atmospheric rivers. Through the foehn effect, the air becomes warmer and drier as it descends the ice sheet slope.

As tundra ecosystems respond to rapid Arctic warming, satellite records suggest a widespread greening. This Perspective highlights the challenges of interpreting complex Arctic greening trends and provides direction for future research by combining ecological and remote sensing approaches.

Atmospheric rivers provide the majority of water vapour transport to the high latitudes. This Review summarizes Antarctic atmospheric river dynamics and climatology and discusses their impacts on the mass balance of the Antarctic ice sheet.

Projections of Arctic sea-ice loss vary significantly between global circulation models. Analysis of the CMIP5 ensemble reveals that these differences can be related to background ice thickness and corresponding growth/melt processes, and not variations in the sea-ice model used.

Mercury is emitted by anthropogenic activities and accumulates in the Arctic. This Review presents a mercury budget for the Arctic, describing fluxes and cycling.

A sixteenth-century Dutch master's carefully orchestrated winter landscape may have benefited from his knowledge of geographers' techniques of the time, explains Martin Kemp.

Mercury isotope signatures in groundwater, soil gas, solid peat, and atmosphere suggest that dark abiotic reduction of peat soil Hg^II to volatile Hg⁰ does not play a significant role in mobilizing Hg during peat mass loss

Three techniques for estimating mass losses from the Greenland Ice Sheet produce comparable results for the period 1992–2018 that approach the trajectory of the highest rates of sea-level rise projected by the IPCC.

The authors use experimental and modelling approaches to understand the response of microbial photosynthesis to peatland warming. They show that warming amplifies microbial photosynthesis, which could offset rising CO₂ emissions from northern peatlands by 6.0–13.7% in 2100 (SSP 2-4.5–SSP 5-8.5).

Glacial mass is dependent on the balance between melt and snow accumulation, which is impacted by rising Arctic temperatures. Glacier mass balances in Svalbard and northern Canada were asynchronous since the 1990s, related to changes in patterns of atmospheric heat advection.

Climate models predict that precipitation will increase in Antarctica, leading to potential ice mass gain and an offset to sea level rise, but here it is shown that enhanced snowfall on Antarctica is likely to increase ice discharge and thereby negate 30% to 65% of the snowfall-induced ice gain.