Fram Strait: Possible key to saving Arctic ice

Detelina Ivanova^1*Subarna Bhattacharyyaa¹Velimir Mlaker¹Anthony Strawa²Leslie Field³Tim Player²Alexander Sholtz²

• ¹Climformatics Inc, Fremont, United States
• ²Arctic Ice Project, Redwood City, California, United States
• ³Bright Ice Initiative, Portola Valley, California, United States

Arctic amplification caused by global warming is accelerating an unprecedented loss of Arctic sea ice due to thinning of multi-year sea ice and increased export through Fram Strait, which is the largest Arctic gateway for ice export. The latter is controlled by the second mode of Arctic variability featuring an east-west dipole with low pressure anomaly center in the Barents/Kara Sea and high in Canadian Archipelago. This pressure system forces northerly winds which drive the Transpolar Drift and Fram Strait ice export (FSIE). The annual and summer FSIE has increased respectively by 6% and 11% per decade which further accelerates the Arctic ice loss. Surface Albedo Modification (SAM) has been considered among variety of climate intervention solutions to slow down the transition of the Arctic into a seasonally ice-free ocean by mid-century, in concert with the greenhouse emissions mitigation efforts. Using climate model simulations, we evaluate the impacts of SAM application on the Arctic radiation budget and ice cover in two deployment scenarios: Arctic-wide and regional in Fram Strait. We model such an increase in sea ice albedo as a perturbation to the present-day climate state. We found that the Fram Strait perturbation enhances the albedo over Barents and Kara Seas (areas most sensitive to ice-albedo feedback) and changes the radiation balance there resulting in cooling which creates a high-pressure anomaly. This triggers the negative phase of the Arctic Dipole anomaly, and consequently weakens the Transpolar Drift, thus reducing the FSIE. Regionally, this reduces the energy absorbed by the surface, increases the outgoing radiation at the top-of-the atmosphere, thickens the sea ice pack, and slows down sea ice export. In contrast the atmospheric dynamics for the Arctic-wide case drives strong Transpolar Drift and increased Fram Strait ice export. This creates a risk of excessive ice melt in the Nordic Seas, freshening the ocean stratification with implications for the Atlantic meridional overturning circulation. Our findings highlight an important role that Fram Strait plays in restoring Arctic sea ice, with far-reaching implications to mitigate climate change impacts elsewhere.