Highlights – InteRFACE

January 28, 2022March 17, 2022 T Miller Highlights

Climate signatures on lake and wetland size distributions in arctic deltas

Abstract

Understanding how thermokarst lakes on arctic river deltas will respond to rapid warming is critical for projecting how carbon storage and fluxes will change in those vulnerable environments.

Yet, this understanding is currently limited partly due to the complexity of disentangling significant interannual variability from the longer-term surface water signatures on the landscape, using the short summertime window of optical spaceborne observations. Here, we rigorously separate perennial lakes from ephemeral wetlands on 12 arctic deltas and report distinct size distributions and climate trends for the two waterbodies. Namely, we find a lognormal distribution for lakes and a power-law distribution for wetlands, consistent with a simple proportionate growth model and inundated topography, respectively. Furthermore, while no trend with temperature is found for wetlands, a statistically significant decreasing trend of mean lake size with warmer temperatures is found, attributed to colder deltas having deeper and thicker permafrost preserving larger lakes.

Plain Language Summary

Arctic river deltas are landscapes facing significant risk from climate change, in part due to their unique permafrost features. In particular, thermokarst lakes in ice-rich permafrost are expected to both expand and drain under warming-induced permafrost thaw, reconfiguring deltaic hydrology and impacting the arctic carbon cycle. A limitation in understanding how thermokarst lake cover might be changing is the significant interannual variability in water cover in flat regions such as deltas, which makes it difficult to distinguish between perennially inundated, thermally relevant waterbodies, and ephemerally inundated waterbodies. Here, we present a pan-Arctic study of 12 arctic deltas wherein we classify observed waterbodies into perennial lakes and ephemeral wetlands capitalizing on the historical record of remote sensing data. We provide evidence that thermokarst lake sizes are universally lognormally distributed and that historical temperature trends are encoded in lake sizes, while wetland sizes are power law distributed and have no temperature trend. These findings pave the way for quantitative insight into lake cover changes on arctic deltas and associated carbon and hydrologic cycle impacts under future climate change.

Vulis, L., Tejedor, A., Zaliapin, I., Rowland, J. C., & Foufoula-Georgiou, E. (2021). Climate signatures on lake and wetland size distributions in arctic deltas. Geophysical Research Letters, 48, e2021GL094437. https://doi.org/10.1029/2021GL094437

January 28, 2022January 28, 2022 T Miller Highlights

Arctic Sea Ice Growth in Response to Synoptic- and Large-Scale Atmospheric Forcing from CMIP5 Models

Abstract. We explore the response of wintertime Arctic sea ice growth to strong cyclones and to large-scale circulation patterns on the daily scale using Earth system model output in phase 5 of the Coupled Model Intercomparison Project (CMIP5). A combined metrics ranking method selects three CMIP5 models that are successful in reproducing the wintertime Arctic dipole (AD) pattern.

A cyclone identification method is applied to select strong cyclones in two subregions in the North Atlantic to examine their different impacts on sea ice growth. The total change of sea ice growth rate (SGR) is split into those respectively driven by the dynamic and thermodynamic atmospheric forcing. Three models reproduce the downward longwave radiation anomalies that generally match thermodynamic SGR anomalies in response to both strong cyclones and large-scale circulation patterns. For large-scale circulation patterns, the negative AD outweighs the positive Arctic Oscillation in thermodynamically inhibiting SGR in both impact area and magnitude. Despite the disagreement on the spatial distribution, the three CMIP5 models agree on the weaker response of dynamic SGR than thermodynamic SGR. As the Arctic warms, the thinner sea ice results in more ice production and smaller spatial heterogeneity of thickness, dampening the SGR response to the dynamic forcing. The higher temperature increases the specific heat of sea ice, thus dampening the SGR response to the thermodynamic forcing. In this way, the atmospheric forcing is projected to contribute less to change daily SGR in the future climate.

Cai, L., Alexeev, V.A., and Walsh, J.E., 2020. “Arctic Sea Ice Growth in Response to Synoptic- and Large-Scale Atmospheric Forcing from CMIP5 Models” Journal of Climate 33 (14), DOI: https://doi.org/10.1175/JCLI-D-19-0326.1. (RMGA)

January 28, 2022January 28, 2022 T Miller Highlights

Effect of corporate sustainability policies and investment risks for future Arctic oil and gas development in Alaska

The feasibility of new Arctic oil and gas development activity is strongly tied to global supply and demand. The evolution of oil development in Alaska represents responses to external pressures such as economic viability, and changes in domestic and foreign oil production. Climate change is another external pressure that affects the cost of developing Arctic oil and gas.

Direct impacts can occur from improved access routes for ships in ice-free waters, or increased costs from infrastructure damage due to permafrost thaw or coastal inundation. An emerging globally-driven factor that may limit future oil and gas activity in the Arctic is the recent trend in corporate sustainability goals driven by social responsibility to mitigate climate change. In 2020 several major US banks expressed policies that would prohibit financing of Arctic oil and gas exploration or development. The extent that such corporate policies could impact future oil development in Alaska is explored in the context of changing regulatory environments, and the diversity of oil companies invested in Alaska. Indicators on company interests are used to assess threats for future Alaska oil and gas development. The results emphasize that financing challenges would make it difficult for smaller companies to share the investment risk in Arctic oil exploration and development. Comparisons of oil and gas investments in other Arctic states show that the strength of state-backed oil and gas companies, investments from Asia, and access to technology innovations are important factors that may offset the effects of more limited Arctic oil and gas financing by major US and European banks.

Lee O. “Effect of corporate sustainability policies and investment risks for future Arctic oil and gas development in Alaska.” Arctic Yearbook, 2020. (MSD)

January 27, 2022January 28, 2022 T Miller Highlights

Sea ice loss amplifies summer-time decadal CO2 increase in the western Arctic Ocean

Ouyang Z., Qi, D., Chen, L., Takahashi, T., Zhong, W., DeGrandpre, M.D., Chen, B., Gao, Z., Nishino, S., Murata, A., Sun,H.,. Robbins, L.L, **Jin**, M., Cai, W. (2020), Sea ice loss amplifies summer-time decadal CO2 increase in the western Arctic Ocean. *Nature Climate Change*, 10, 678-684. (RGMA)

Abstract. Rapid climate warming and sea-ice loss have induced major changes in the sea surface partial pressure of CO₂ (𝑝CO2). However, the long-term trends in the western Arctic Ocean are unknown. Here we show that in 1994–2017, summer 𝑝CO2 in the Canada Basin increased at twice the rate of atmospheric increase.

Continue reading →