WHAT ARE THE KEY POLAR ECOSYSTEM PROCESSES THAT WILL BE THE “FIRST RESPONDERS” TO CLIMATE FORCING?

Workshop participants discussed the role of Arctic and Antarctic polar regions in highly coupled systems, with strong links between land, ocean, ice, atmosphere, and humans. These individual components cannot be fully understood independently of one another, as a perturbation to one system component will likely cause cascading effects throughout the entire polar system. For example, current regional and global models have not been able to accurately capture patterns of recent Arctic change (e.g., sea ice decline) and pathways for model improvements are currently sought. Some of the workshop participants emphasized the importance of understanding and quantifying the system interactions (rather than simply the isolated components) to accurately predict polar ecosystem response to climate forcing. Models that address the complex interactions between living organisms and their environment (i.e., a focus on “biocomplexity”) are critical to understanding how climate change influences ecosystem processes. Developing these models in concert with observational studies is essential to developing predictive tools that are useful to policymakers and have benefits for society. As such, these models can be used to support judgments to create adaptive systems of decision making.

Terrestrial

In the terrestrial realm, major uncertainties in current modeling capabilities include the ability to quantify shifts and feedbacks associated with ecosystem disturbances (e.g., fires, logging, insect infestation), migrations of flora and fauna, coastal erosion, and hydrological and carbon-related impacts of warming and permafrost degradation. Major ice-albedo and greenhouse gas feedbacks may be associated with these changes as well. These feedbacks have the potential to drastically alter predicted outcomes if they are not modeled properly. For example, it is estimated that ~1024 Pg C is currently locked away in the top 0–3 meters of permafrost soils (which amounts to twice the current atmospheric carbon pool) (Schuur et al., 2008). However, with warming and permafrost thaw, this pool of carbon may be reintroduced to the contemporary carbon cycle through release of significant CO2 and CH4 to the atmosphere through decomposition and methanogenesis of organic carbon. Major uncertainties surrounding the rates of change in these scenarios of permafrost thaw, the magnitude of released CO2 and CH4 to the atmosphere, as well as whether climate forcing will result in wetter or drier landscapes, need to be resolved if the overall impact and the direction of feedbacks to the polar and global climate system is to be assessed critically. Improved modeling capabilities and understanding of system interactions are not only essential to improve



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement