Project Report
No matter where on Earth we live, we are connected to the polar regions. This connection is forged by the fundamental role the polar regions play in the global food web, economy, and physical climate system. Thus, climate variability and change in the polar regions are important not only for the local inhabitants and ecosystems but for society globally. Changes in polar ice conditions and the polar energy budget have ripple effects with a global reach influencing global sea level (via melting glaciers and ice sheets), the global energy budget (via surface albedo change from melting snow and ice, as well as other radiative feedbacks), the carbon cycle (via permafrost thaw and methane release), and atmospheric and oceanic circulations.
Observations show the recent, rapid, and in many cases, unprecedented changes that are occurring in the Arctic are outpacing the rest of the globe. On the other hand, the Antarctic has been changing more slowly than anywhere else. This polar warming asymmetry has perplexed the science community and models do not generally simulate this feature of the polar climate well. In addition, observations indicate a faster rate of Arctic warming than most models predict but a slower rate of Antarctic warming and sea ice loss than models predict. In addition to this hemispheric asymmetry, analysis of seasonal asymmetry (e.g., lengthening period of ice-free conditions) in polar warming offers opportunities to understand the underlying mechanisms of polar climate change, the factors that contribute to the warming asymmetry, and the evolution with increased forcing. Understanding the polar climate system and narrowing the range in predictions of the future polar climate state is an urgent scientific and societal matter.
Building upon previous polar amplification workshops, the objectives of the workshop are to 1) identify knowledge gaps and deficiencies in model diagnostics that limit our understanding and simulation of the hemispheric and seasonal asymmetries of polar amplification and; 2) prioritize these knowledge gaps as areas for future research; 3) identify strategies, approaches, and data needs (e.g., process studies, collaborative modeling activities, satellite missions) to address the identified knowledge gaps; 4) identify candidate observational emergent constraints on the key processes driving polar amplification; and 5) identify steps for enhancing community collaboration.
A unique aspect of this workshop was the focus on the seasonally resolved processes that also relate to the asymmetries between Arctic and Antarctic amplification. As indicated by the results of previous Arctic and polar amplification workshops, expanding our focus beyond the atmospheric response to the oceanic response and sea ice loss is required to understand polar amplification more fully and reduce the inter-model spread in projections. The workshop brought together researchers studying Arctic and Antarctic climate change from observational and modeling perspectives (ranging from paleoclimate to future projections) to cross-pollinate ideas, forge new collaborations, and generate recommendations to accelerate our understanding of polar amplification.
The 2.5-day hybrid workshop, held in person in Boulder, CO, USA, facilitated discussions between Arctic and Antarctic scientists with expertise in ocean, sea ice, atmosphere, and ice sheet science from both modeling and observational perspectives. The discussions were organized around the goal of identifying priorities and develop strategies for better understanding and predicting polar climate change. The workshop was organized around five sessions (see below). Each sessions included an invited overview talk, two oral presentations selected from the abstracts, and poster presentations. Each day concluded with a 2.5 hours of breakout discussions and report-outs where participants identify key knowledge gaps and action items to address the knowledge gaps.
The session topics included:
Observed and Projected Polar Amplification: This session explored the observed changes in the polar climate systems and the fidelity with which contemporary climate models represent these changes and welcomed submissions that address observed polar climate trends, model projections and biases, sources of model uncertainty, model diagnostic approaches (shortcomings and opportunities), and emergent constraints using present-day observations and/or paleoclimatic proxies.
Causes of Polar Amplification: This session explored the causes of polar amplification, its seasonal expression, and hemispheric differences. We welcome submissions that elucidate the processes that contribute to these features of polar amplification, including discussions on the relative roles of different climate forcings and feedback processes.
Role of Atmospheric and Oceanic Transport in Polar Amplification: This session explored the dynamics and impacts of energy transports into the polar regions, as well as their interactions with local feedback processes. We welcome submissions on the influence of dry and moist atmospheric energy transport, ocean heat transport, and episodic/synoptic phenomena (e.g., moisture intrusions, atmospheric rivers, and polar cyclones) on polar amplification.
Drivers of Observed Sea Ice Trends and Variability: This session explored the causes of the sea ice variability and trends in the Arctic and Antarctic regions, with an emphasis on recent extremes such as the rapid decline in Antarctic sea ice observed in 2023.
Non-Local Effects of Polar Amplification: This session explored the non-local effects of polar amplification and sea ice changes, including their influence on mid-latitude or tropical atmospheric dynamics, ocean circulation, global sea-surface temperature patterns, global energy flows, and global warming from the observational, modeling, and theoretical perspectives.
Key Knowledge gaps identified:
- Role of Ocean heat transports and vertical mixing in polar amplification and sea ice variability
- The effects of the ocean mesoscale and sub-mesoscale processes on polar amplification and the representation of the mean state ocean circulation and sea ice properties
- Improved understanding of the sensitivity of ocean-atmosphere exchanges on sea ice properties
- Quantification of the efficacy of ocean and atmosphere heat transports to sea ice melt and warming
- Understanding in the mechanisms of remote impacts on and of polar change
- Ice cloud processes in mixed phase clouds (nucleation, secondary ice production, aerosol cloud interactions)
- Influence of freshwater forcing the Southern Ocean circulation and SSTs
- Precipitation and the role of snow in the polar systems
- Role of the land surface on polar amplification
- Metrics and diagnostics for quantifying PA and the process contributions
- Contributions of internal variability vs. forced trends to Antarctic sea ice
Through the presentations and break out discussions several key takeaways were identified that point to future actions.
Key Science takeaways and actions:
- A complete and statistically representative set of observations is required across the full suite of polar conditions.
- Meeting this need requires the greater use and development of autonomous systems to collect data in the polar regions and additional investments in the development of new, enabling autonomous technologies (especially the enhanced collection of under sea ice measurements).
- Improve the utility of existing expeditions/cruises/campaigns to polar amplification science by establishing “essential variables” (including sea ice, atmosphere, and ocean) that any polar field campaign should include.
- We must move beyond diagnostic approaches and get at causality; making high frequency model output (atmosphere, ocean, and sea ice) from CMIP simulations and utilizing these outputs are key.
- We must accelerate the incorporation of interactive ice sheet components within climate models.
- Additional efforts are needed to advance atmosphere-ocean-sea ice reanalysis capabilities in polar regions
Date and Location
Boulder, CO I January 17-19, 2024.
IASC Working Groups funding the project
- Atmosphere WG
- Cryosphere WG
Project Lead
Patrick Taylor (NASA Langley Research Center, USA)
Year funded by IASC
2023