The Antarctic Peninsula is warming rapidly, with more frequent extreme temperature and precipitation events, reduced sea ice, glacier retreat, ice shelf collapse, and ecological shifts. Here, we review its behaviour under present-day climate, and low (SSP 1–2.6), medium-high (SSP 3–7.0) and very high (SSP 5–8.5) future emissions scenarios, corresponding to global temperature increases of 1.8 °C, 3.6 °C and 4.4 °C by 2100. Higher emissions will bring more days above 0 °C, increased liquid precipitation, ocean warming, and more intense extreme weather events such as ocean heat waves and atmospheric rivers. Surface melt on ice shelves will increase, depleting firn air content and promoting meltwater ponding. Under the highest emission scenario, collapse of the Larsen C and Wilkins ice shelves is likely by 2100 CE, and loss of sea ice and ice shelves around the Peninsula will exacerbate the current trends of land-ice mass loss. Collapse of George VI Ice Shelf by 2300 under SSP 5–8.5 would substantially increase sea level contributions. Under this very high emissions scenario, sea level contributions from the Peninsula could reach 7.5 ± 14.1 mm by 2100 CE and 116.3 ± 66.9 mm by 2300 CE. Conversely, under the lower emissions scenarios, the Antarctic Peninsula’s sea ice remains similar to present, and land ice is predicted to undergo only minor grounding line recession and thinning. Changes in sea surface temperatures and the change from snow to rain will impact marine and terrestrial biota, altering species richness and enhancing colonisation by non-native species. Ranges of key species such as krill and salps are likely to contract to the south, impacting their marine vertebrate predators. These changing conditions will also influence Antarctic Peninsula research, fisheries, tourism, infrastructure and logistics. The future of the Peninsula depends on the choices made today. Limiting temperatures to below 2 °C, and as close as possible to 1.5 °C (by following the SSP 1–1.9 or 1–2.6 scenarios), combined with effective governance, will result in increased resilience and relatively modest changes. Any higher emissions scenarios will damage pristine systems, cause sustained, irreversible ice loss on human timescales, and spread to Antarctic regions beyond the Peninsula.

Antarctica's weather and climate have global impacts, influencing weather patterns, ocean currents and sea levels worldwide. However, Antarctica is vast and complex, and the atmospheric processes that govern its climate are strongly influenced by its steep terrain, particularly around the coastal periphery. Our scientific understanding of this complex environment is hampered by the lack of reliable observations and gridded datasets at sufficiently high spatial and temporal resolution. High-resolution regional climate models, RCMs, can provide a solution to the sparsity of observational data and low resolution of reanalyses, facilitating more in-depth assessments of crucial climate variables like precipitation, wind and temperature that are strongly influenced by topography. Here we present and evaluate a comprehensive, high-quality, similar to 11 km resolution RCM dataset, the PolarRES ensemble, for the period 2000-2019. We show that the ensemble largely out-performs ERA5, especially with regard to variables like coastal winds and precipitation. There are no consistent seasonal differences in biases, but there are persistent regional biases. Victoria Land and the Trans-Antarctic Mountains are the regions the RCMs and ERA5 struggle the most with, which suggests that further investigation and model development is needed in this area. Each RCM has strengths and limitations, but overall the ensemble captures the observed weather and climate of Antarctica well. The PolarRES ensemble offers a novel and exciting way of evaluating climate processes and features, and we encourage researchers to use the data, which are freely available, to explore pertinent climate questions of local, regional and global significance.

Abstract. The climate of Antarctica is showing increasing signs of being impacted by the warming trend in global temperatures, which has potential to result in accelerated break up of key ice shelves, which would contribute to global sea level rise. Here, we present a novel database of Antarctic extreme weather events over a selection of key ice shelves (Larsen, George VI, Wilkins, Abbot, Thwaites, Totten, Amery, Lazarev), using simulations from four regional climate models (RCMs: RACMO2, HCLIM, MetUM and MAR), driven by the ERA5 reanalysis, examining surface air temperature, precipitation, wind and surface pressure. In addition, we examine trends in the frequency of extreme events above or below specified thresholds (5th, 10th, 50th, 90th and 95th percentiles) and spatial atmospheric circulation and temperature anomaly patterns over Antarctica that are commonly associated with extreme events over key ice shelves. The RCM simulations have been compared with station observations close to the ice shelves, and we developed regressions to estimate simulated values during periods when only one or two of the RCMs were available.

Warm air intrusions (WAIs) along the North Atlantic pathway are key drivers of warm extremes in the central Arctic. The Svalbard archipelago acts as a major topographic barrier in the middle of this gateway, but its role in modulating WAIs and their impacts has not been studied in detail. We combine (i) high-resolution regional ICON simulations with and without Svalbard's topography, (ii) Lagrangian back-trajectories, and (iii) observations from the MOSAiC expedition to analyze a strong WAI event in mid-April 2020, and extend the analysis with (iv) climatological composites from an ICON simulation for 2000-2022. Based on the April 2020 case study, we show that Svalbard's influence can extend similar to 500 km downstream over sea ice and was observed near 84 degrees N during MOSAiC. The response depends on the static stability of the impinging flow: stable conditions favor flow-around response, characterized by accelerated barrier winds along the eastern and western flanks of Svalbard and gap winds through the Hinlopen Strait, together with a broad lee wake north of the archipelago. In this wake, wind speed, near-surface temperature, and column-integrated water vapor are reduced by > 5 m s(-1), > 3 K, and > 1 kg m(-2), respectively. Under less stable flow-over conditions, f & ouml;hn signatures yield lower-tropospheric warming (> 1 K) and drying, reduced low-level cloud cover (> 20 %), and decreased (increased) downwelling longwave (shortwave) radiation (> 20 W m(-2)). Springtime composites reveal that these signals recur during southerly advection events, can extend several hundred kilometers into the central Arctic, and vary in character with poleward wind speed, moisture transport, and static stability linked to the synoptic situation. Together, the results demonstrate that Svalbard's topography systematically modulates the dynamical and thermodynamic imprint of WAIs, with effects detectable far downstream in both model experiments and MOSAiC observations.

From a combination of the operational system of reindeer herding and meteorological seasonality, we developed a range of climate indices reflecting critical events in the reindeer herding year that influence the success of this livelihood. These critical events can be described as combinations of specific meteorological conditions, and therefor rendered as equations we can compute from climate model output, creating a capability for analysing different projections of the future and delivering relevant information on climate change to reindeer herding communities. For this purpose, we can use a wealth of different global and regional climate projections, with distinct advantages and disadvantages (e.g. model resolution, different greenhouse gas futures, high number of models in the ensemble for uncertainty estimates, process representation, availability of variables). For example, the CMIP6 ensemble enables the analysis of a broad range of greenhouse gas futures from a wide variety of models, allowing us to assess scenario uncertainty, but it is limited by its coarse spatial resolution. On the other hand, the PolarRES ensemble has a higher spatial resolution but is only available for one RCP/greenhouse gas future. The PolarRES ensemble consists of regional climate simulations generated by multiple regional climate models that dynamically downscale CMIP6 global climate simulations selected using a novel storyline approach. Both ensembles provide hindcast simulations that allow us to evaluate the ensemble performance with regard to the climate indices we defined. This study uses these simulations to evaluate and compare model performance to understand the potential and limitations of future projections of specific climate indices relevant for reindeer herding. We use in-situ based observations from the data set Global Summary of the Day to evaluate onset and end of the continuous freezing period, hot summer days, thawing days in autumn and freeze-thaw cycles in both spring and autumn.

Surface meltwater is predicted to become increasingly important for Antarctic mass loss as atmospheric temperatures rise, due to its potential to influence ice dynamic, hydrofracture and radiative processes. However, our understanding of Antarctic surface meltwater is limited, with previous studies restricted in spatial or temporal scope. Here, using cloud computing, we produce an Antarctic-wide, monthly dataset of surface meltwater for 2006 to 2021. Surface meltwater covered 3,732 km2 across Antarctica on average during each melt season, with 30% on grounded ice. High interannual variability in meltwater area across the Antarctic Peninsula and in East Antarctica correlates with large-scale modes of climate variability. In west Antarctica, meltwater area is comparatively low and this correlation is absent. An increase in the magnitude and variability of surface meltwater area without a coincident increase in modelled snowmelt in East Antarctica indicates that the ice-sheet surface might be becoming more favourable to meltwater ponding.

We explore how atmospheric rivers (ARs) in a summer and winter case interact with the topography of the Amundsen Sea Embayment, West Antarctica, and deposit significant precipitation amounts. To do this we use results from three regional climate models (RCMs: MetUM, Polar-WRF, HCLIM) at a spatial resolution of 1 km. Estimates of snowfall associated with both events from all three RCM simulations compare well against observed snow height measurements over the Thwaites and Pine Island ice shelves. By contrast, snowfall estimates from ERA5 reanalysis for both events are severely underestimated (by 3–4 times) compared to the measurements. Outputs from the RCMs also show that the ARs may be associated with several millimetres of rain in both the summer and winter cases, although in the absence of in situ measurements of rainfall, this result cannot be directly verified. The RCM simulations suggest that rainfall during these events can fall directly as supercooled drizzle but also that rainfall is concentrated around steep terrain due to the interaction of ARs with complex orography. We also show that while the amount of MetUM-simulated snowfall was comparatively resolution-insensitive, the amount of rainfall simulated was not, with rainfall amounts over Thwaites Ice Shelf 4–16 times higher in 1 km simulations compared to 12 km simulations. Our work highlights that kilometre-scale models are useful tools to investigate the total precipitation amount and its partitioning into rain and snow over this globally important and climatically sensitive region, and it highlights the critical need for in situ observations of rainfall.

Extreme precipitation events in the Amundsen Sea Embayment, West Antarctica deposit significant precipitation amounts, often during atmospheric river (AR) events. In this work, we use observations, reanalysis, and three regional climate models (RCMs: MetUM, Polar-WRF, HCLIM) at a spatial resolution of 1 km to evaluate the characteristics of two AR cases: one in winter, and another in summer. We quantify the magnitude of snow and rain falling over the Thwaites and Pine Island ice shelves and explore the drivers and mechanisms of this extreme precipitation. The model results indicate that supercooled liquid precipitation fell during these cases, generated in particular by the interaction of the AR with steep topography. Model estimated snowfall compares well against observed snow height measurements, but ERA5 estimates for both events are severely underestimated (by 3-4 times) compared to the measurements. Our work highlights that kilometer-scale models are useful tools to investigate the total precipitation amount and its partitioning into rain and snow over this globally important and climatically sensitive region, and the critical need for in situ observations of rainfall.

The Ross Ice Shelf, West Antarctica, experienced an extensive melt event in January 2016. We examine the representation of this event by the HIRHAM5 and MetUM high-resolution regional atmospheric models, as well as a sophisticated offline-coupled firn model forced with their outputs. The model results are compared with satellite-based estimates of melt days. The firn model estimates of the number of melt days are in good agreement with the observations over the eastern and central sectors of the ice shelf, while the HIRHAM5 and MetUM estimates based on their own surface schemes are considerably underestimated, possibly due to deficiencies in these schemes and an absence of spin-up. However, the firn model simulates sustained melting over the western sector of the ice shelf, in disagreement with the observations that show this region as being a melt-free area. This is attributed to deficiencies in the HIRHAM5 and MetUM output and particularly a likely overestimation of night-time net surface radiative flux. This occurs in response to an increase in night-time downwelling longwave flux from around 180–200 to 280 W m−2 over the course of a few days, leading to an excessive amount of energy at the surface available for melt. Satellite-based observations show that this change coincides with a transition from clear-sky to cloudy conditions, with clouds containing both liquid water and ice water. The models capture the initial clear-sky conditions but seemingly struggle to correctly represent cloud properties associated with the cloudy conditions, which we suggest is responsible for the radiative flux errors.

Antarctic sea ice is a vitally important part of the regional and global climate. In 2023, sea ice extent fell to record lows, reaching unprecedented values for both the summer minimum, winter maximum and intervening freeze-up period. Here, we show that the extreme values observed were truly remarkable within the context of the satellite record, despite the challenge of quantifying how rare such an event might be, and discuss some contributing factors. While this could be part of a decline in sea ice associated with human-caused climate change, it is too early to say conclusively if this is the case. Antarctic sea ice extent in 2023 was astoundingly low throughout the year: from the record low summer minimum to the slow freeze-up and most recently to the record low winter maximum. Here we show that these events are truly exceptional within the context of the longer-term satellite record. It is too early to say conclusively whether these events are tied to human activity, but it appears increasingly likely that human-caused climate change is playing a role in Antarctica's sea ice lows.image

I have always loved nature – you would have struggled to get me down from a tree or out of the water as a kid. I also loved geography – there's something about understanding the hows and whys of the environment that got me hooked from day one. So, when I learned about climate change in a geography class aged about 13 or 14, I was totally enraged and convinced that if I shouted loudly enough about it, people would wake up and take action to stop it (ah, the assuredness of youth!). That was the beginning of a lifelong passion and commitment to tackling climate change that has morphed a lot in the intervening years. I went to university initially to study environmental geography, but became more interested in the physical processes of weather and climate. I discovered meteorology, and ended up going down a polar rabbit-hole, chasing knowledge about our fascinating frozen regions. And that's how I wound up as a polar climate scientist! That's a tough question! I haven't necessarily enjoyed it all, because if I've learned one thing, it's that science is hard, but I love learning about how our beautiful planet works and knowing that I'm contributing in some small way to tackling the climate crisis. I suppose it started in Norwich at the University of East Anglia (UEA). I loved the freedom to learn about such a wide range of topics at university, and the cutting-edge climate research at UEA was particularly inspiring. I discovered meteorology during my undergrad and clearly couldn't get enough of it, so I did an MSc in climate change immediately afterwards. It was then that I developed a taste for Antarctic weather and climate. After taking some time off from academia to run a music venue (naturally), I jumped at the opportunity to do a PhD at the British Antarctic Survey (BAS). I spent about 3.5 years there modelling the atmospheric causes of Antarctic ice-shelf melt, including a life-changing trip to Antarctica in 2017. I handed in my PhD thesis in the same week as the first national lockdown – not the best timing! I then held an assortment of research-adjacent jobs during the pandemic, before I landed at the University of Reading working on the climate impacts of aviation. However, I missed polar science, so in my spare time I co-authored a short course for the Open University about polar climate change. I really loved being on the other side of learning, helping to create top-quality teaching materials about the polar regions and sharing my passion for the poles with others. I'm now back at BAS modelling how the polar regions might change into the future, and trying to build a name for myself in mainstream media so I can enthuse more people about polar climate. The things that really got me going as a young teenager were stories about how climate change was affecting real people across the world, and how climate impacts compounded existing inequalities to hurt those who were least responsible the most. That felt deeply unfair. Of course, impacts then were less visible than they are today. Now, almost 20 years later, we are all affected by extreme weather events or climate impacts – although it's still the people with least responsibility for the climate crisis who are bearing the brunt of its effects. Later, visiting Antarctica solidified my passion and desire to work on polar climate change. I got into research and climate science because I saw it as a way to use my strengths to contribute to solving the problem. But until I went and got my boots on the ice, the polar regions had been a pretty abstract concept. It might sound strange, but everything sort of ‘fell into place’ in my mind once I had seen Antarctica with my own eyes, especially the Larsen C ice shelf which I spent my PhD thinking about. Climate change impacts us all, so I feel very strongly that everyone should be able to understand how and why it is changing our planet. Climate science can sometimes appear to be pretty dense and complex when it need not be. I see myself as a translator between scientists and, well … everybody else. TV is a direct connection to peoples' living rooms, barber shops and waiting rooms, which makes it a powerful tool to relate to people who might not often think about science or climate. It's a leveller and cuts across divides of class, race, ability, age, and gender. Creating online content means I can speak to, and learn from, people across the world. I've learned so much from other YouTube creators; you can build an amazing community there (although there's plenty of less-than-pleasant comments too). In fact, my audience is mostly outside the UK – people I could never reach via domestic media. I love making long-format content – even more so in the era of 90-s vertical videos that dominate TikTok and Instagram. I'm told that my videos are being used in teaching all over the world, which makes it all worth it! I got involved with RMetS during my PhD – I think the 2017 Student Conference was the first academic event I ever presented at (a terribly designed poster, since you're asking). Since then, my involvement has slowly increased: first as a member, then attending a few meetings, and then giving talks at events like the polar meteorology meeting in 2021, and more recently helping with the Society's online training course for weather presenters and giving a keynote at the 2022 Atmospheric Science Conference. I joined the Editorial Board of Weather in early 2022, and I now also sit on the society's Youth and Early Career Special Interest Group. I was also recently involved in a fun project developing and delivering a series of climate change training sessions for community leaders. Play to your strengths! There are so many ways to contribute to climate science. In some ways, I've followed a pretty traditional academic route so far, but there are many different versions of working in climate science beyond the academy. If you love climate research and want to work in an academic setting, great – but if that's not you, that's fine too. That's easy: Altocumulus lenticularis. I was lucky enough to see some great ones in Antarctica perched over the mountains just over the bay from Rothera research station (Figure 1). There's something about them that's just so otherworldly – maybe it's their resemblance to UFOs.

This is the data used in the paper "The importance of cloud phase when assessing surface melting in an offline coupled firn model over Ross Ice shelf, West Antarctica"

Extreme warm events in the South Orkney Islands (SOIs) are investigated using synoptic observations from Signy and Orcadas stations for 1947–1994 and 1956–2019 respectively. Defining the extremes as temperatures exceeding the 95th percentile of the temperature distribution, we reveal the characteristics and associated drivers of the warm events, especially the top 10 events in both summer and winter. At both stations, extreme warm events often involve a combined effect of atmospheric rivers (ARs) and localised föhn warming, with distinct characteristics due to the station locations relative to Coronation Island, the largest and highest island of the SOIs. For example, warm events at Signy are warmer (by an average of around 3°C) than the corresponding concurrent temperatures at Orcadas. The number of warm events per year has significantly increased over the record periods at both stations, which could potentially impact ecosystems by increasing melting of snow and ice. Extreme warm events at Signy are dominated by föhn warming in combination with ARs originating from the Southern Atlantic Ocean, where warm, moisture‐rich air is rapidly advected towards the islands by enhanced northerly winds. By contrast, the Orcadas warm extremes involve both warm‐air advection and föhn warming associated with enhanced northwesterlies/westerlies with ARs originating in the Pacific Ocean that travel across the Drake Passage. Simulation of one of the top 10 warm events for Signy station using a 1‐km grid spacing configuration of the atmosphere‐only UK Met Office Unified Model is used to disentangle the role of local versus large‐scale forcing. We find that the majority of the warming can be attributed to föhn effects for the case study. These results demonstrate the complexity of Antarctic temperature extremes.

We calculate a regional surface “melt potential” index (MPI) over Antarctic ice shelves that describes the frequency (MPI-freq, %) and intensity (MPI-int, K) of daily maximum summer temperatures exceeding a melt threshold of 273.15 K. This is used to determine which ice shelves are vulnerable to melt-induced hydrofracture and is calculated using near-surface temperature output for each summer from 1979/80 to 2018/19 from two high-resolution regional atmospheric model hindcasts (using the MetUM and HIRHAM5). MPI is highest for Antarctic Peninsula ice shelves (MPI-freq 23-35%, MPI-int 1.2-2.1 K), lowest (2-3%, < 0 K) for Ronne-Filchner and Ross ice shelves, and around 10-24% and 0.6-1.7 K for the other West and East Antarctic ice shelves. Hotspots of MPI are apparent over many ice shelves, and they also show a decreasing trend in MPI-freq. The regional circulation patterns associated with high MPI values over West and East Antarctic ice shelves are remarkably consistent for their respective region but tied to different large-scale climate forcings. The West Antarctic circulation resembles the central Pacific El Niño pattern with a stationary Rossby wave and a strong anticyclone over the high-latitude South Pacific. By contrast, the East Antarctic circulation comprises a zonally symmetric negative Southern Annular Mode pattern with a strong regional anticyclone on the plateau and enhanced coastal easterlies/weakened Southern Ocean westerlies. Values of MPI are 3-4 times larger for a lower temperature/melt threshold of 271.15 K used in a sensitivity test, as melting can occur at temperatures lower than 273.15 K depending on snowpack properties.

Recent warm atmospheric conditions have damaged the ice shelves of the Antarctic Peninsula through surface melt and hydrofracturing, and could potentially initiate future collapse of other Antarctic ice shelves. However, model projections with similar greenhouse gas scenarios suggest large differences in cumulative 21st century surface melting. So far it remains unclear whether these differences are due to variations in warming rates in individual models, or whether local surface energy budget feedbacks could also play a notable role. Here we use the polar-oriented regional climate model MAR to study the physical mechanisms that will control future surface melt over the Antarctic ice shelves in high-emission scenarios RCP8.5 and SSP585. We show that clouds enhance future surface melt by increasing the atmospheric emissivity and longwave radiation towards the surface. Furthermore, we highlight that differences in meltwater production for the same climate warming rate depend on cloud properties and particularly cloud phase. Clouds containing a larger amount of liquid water lead to stronger melt, subsequently favouring the absorption of solar radiation due to the snow-melt-albedo feedback. Since liquid-containing clouds are projected to increase the melt spread associated with a given warming rate, they could be a major source of uncertainties related to the future Antarctic contribution to sea level rise.

Abstract The future sea-level contribution from the Antarctic ice sheets is highly uncertain. Ice dynamic, hydrofracture, and radiative processes related to surface meltwater are predicted to become increasingly important for Antarctic mass-loss as atmospheric temperatures rise. Our understanding of Antarctic surface meltwater, however, remains limited, with previous studies restricted in spatial or temporal scope. Here, we leverage cloud computing to overcome these limitations and produce the first Antarctic-wide, monthly dataset of surface meltwater spanning 2006 to 2021. Surface meltwater covered 3732 km2 across Antarctica on average during each melt season, with 30% on grounded ice. High interannual variability in meltwater coverage across the Antarctic Peninsula and in East Antarctica correlates with large-scale modes of climate variability, but this control is absent where meltwater coverage is comparatively low in West Antarctica. In East Antarctica, we find a significant increasing trend in meltwater area of 66 km2 per year (197% total change) which, in the absence of a clear climatic trend, we attribute to ice sheet surfaces becoming more favourable to ponding. Future increases in melt rate could therefore cause proportionally larger increases in meltwater coverage with implications for the resilience of ice shelves, and increased surface-to-bed hydraulic connections on grounded ice.

Following collapses of the neighboring Larsen A and B ice shelves, Larsen C has become a focus of increased attention. Determining how the prevailing meteorological conditions influence its surface melt regime is of paramount importance for understanding the dominant processes causing melt and ultimately for predicting its future. To this end, a new, high‐resolution (4 km grid spacing) Met Office Unified Model (MetUM) hindcast of atmospheric conditions and surface melt processes over the central Antarctic Peninsula is introduced. The hindcast is capable of simulating observed near‐surface meteorology and surface melt conditions over Larsen C. In contrast with previous model simulations, the MetUM captures the observed east‐west gradient in surface melting associated with foehn winds, as well as the interannual variability in melt shown in previous observational studies. As exemplars, we focus on two case studies—the months preceding the collapse of the Larsen B ice shelf in March 2002 and the high foehn, high melt period of March‐May 2016—to test the hindcast's ability to reproduce the atmospheric effects that contributed to considerable melting during those periods. The results suggest that the MetUM hindcast is a useful tool with which to explore the dominant causes of surface melting on Larsen C.