Polar Regions in the Earth System

There is growing scientific evidence showing the Polar climates are both influenced by, and exert influence on, the global climate system. The climate of the Polar Regions is changing faster than other parts of the world because of local feedbacks and their response to regional or hemispheric-wide changes. For example, the Arctic is warming more than twice as fast as the rest of the world, referred to as Arctic Amplification. This accelerated surface warming in the Arctic is expected to impact the world economy by almost €60 trillion by 2300, even if existing nationally determined contributions under the Paris Agreement (PA) are implemented. This can be reduced to €30 trillion under the PA target of 2ºC global warming. Changes in the Antarctic also have huge potential to impact humankind through rises in global sea level and via its role in the thermohaline and atmospheric circulations. The economic benefits alone make it imperative for European and global actors to enhance their efforts to reach the PA target. However, there is much that is still poorly understood about the interacting nature and feedback of polar processes and their consequences in both regional and global contexts. There is a critical knowledge gap on “teleconnections” between the Polar Regions and lower latitudes, the role that local-to-regional scale polar process play in them, and how they evolve in a changing climate system. Better understanding of these issues can have profound implications for people, policy, and businesses beyond the Polar Regions.
The overall objective of PolarRES is to improve understanding of local-regional scale processes that underlie ocean-atmosphere-ice (O-A-I) interactions in the Arctic and Antarctic, their response and influence on, a range of storylines of future changes in atmospheric and oceanic circulation and the implications for society and the environment in the Polar Regions and beyond.

Analysis has been performed on the latest global climate projections produced for the recent IPCC reports that identified influences from the global climate system on polar regions. Different global influences, called ‘Storylines’, have been developed for the Arctic and Antarctic that explain the range of projected changes in key climate variables for impact assessments. Additional analysis has identified global climate model projections for downscaling to higher resolutions by regional climate models (RCMs) that (1) represent these Storylines, (2) show a realistic representation of the present climate, and (3) have the necessary data available.
Three global models with novel grids have used these storylines and followed an experiment protocol that has been developed in PolarRES to simulate future climate of the Arctic and Antarctic. The purpose of these simulations is to investigate the influence exerted by the polar regions on the global climate system. These simulations have been completed recently and analysis is now underway.
An experiment protocol has been developed for the high-resolution polar climate projections which will be performed with regional climate models. In a community first, this was developed in partnership with impacts modellers to ensure that the high-resolution climate projections will be useful for impact assessments in the Arctic and Antarctic. Model developments necessary for the implementation of this protocol have been completed for all RCMs. Simulations of the present-day climate and future climate have been completed. Evaluation of these simulations is ongoing and analysis has begun of projected changes in the polar climates simulated by this multi-model ensemble. Since model evaluation requires both ground-based and satellite observations, and the expert knowledge of the communities that develop these products, PolarRES has built strong collaborations between climate modellers and remote sensing researchers who produce these satellite products for ESA and EUMETSAT. This has enabled the better use ESA and EUMETSAT datasets, not just in model evaluations but also in studies on the processes that underly the interactions between the atmosphere, ocean, and sea-ice (AOI).
Using high-resolution regional climate models and state-of-the-art observations PolarRES has advanced our understanding of processes that underly AOI interactions in both the Arctic and Antarctic. Specifically, PolarRES has improved our understanding of aerosol-cloud interaction, atmosphere and ocean boundary layer and its coupling, sea ice dynamics and thermodynamics, small-scale ocean mixing processes, and surface energy budget, and factors controlling snow/sea-ice albedo. This new knowledge has been widely disseminated through more than 20 international peer-reviewed journal publications and presented at key scientific conferences. Moreover, an online knowledge transfer tool and a visual online storytelling tool have been produced, which will be part of the project legacy to ensure the full dissemination and exploitation of the results.

PolarRES has developed projections of climate change in the Polar Regions in greater spatial detail and with more confidence than previous initiatives. This was achieved with state-of-the-art regional climate models and a novel methodology called the storylines approach. This work was realised under a novel framework that brings together scientists with different expertise to ensure that these novel climate projections of polar climate change will be useful for a variety of stakeholders.
Many of our state-of-the-art regional climate models have also performed simulations over the Arctic and Antarctic domains for limited periods of time selected from the Year Of Polar Predictions Special Observing Periods. These simulations have resolved atmospheric phenomena such as Atmospheric Rivers and polar cyclones in unprecedented detail, enabling researchers to further understand cloud formation and cloud-aerosol interactions in the polar regions.
PolarRES will continue to improve understanding of interactions between the atmosphere, ocean and sea-ice. PolarRES explores processes that are most relevant for both the Arctic and Antarctic: aerosol-cloud interaction, atmosphere and ocean boundary layer and its coupling, sea ice dynamics and thermodynamics, small-scale ocean mixing processes, and surface energy budget, and factors controlling snow/sea-ice albedo.
PolarRES is exploiting novel modelling tools that improve the representation of the polar climate processes in global climate models. PolarRES has used these tools to develop a first-of-its-kind ensemble of variable resolution global atmospheric models that enable researchers to improve our understanding of the underlying mechanisms of polar-lower latitude linkages.
The key exploitable results of PolarRES will be:
• better communication of uncertainty in future climate projections for the Arctic and Antarctic for assessments of climate change impacts. This will be done with the storylines of climate change that PolarRES has recently developed for the Arctic and Antarctic.
• a visual online storytelling tool that shares our new knowledge and scientific discoveries.
• policy-relevant and assessment reports describing our new knowledge on how climate change will impact permafrost, wildfires, marine ecosystems in the polar regions.
• high-resolution projections of climate change in the Polar Regions that will support future impact assessments in these regions.