Warm climates in the Arctic: Lessons from the past and long-term future

The Arctic is changing: sea ice is retreating and the Greenland Ice Sheet is melting. The impact of a different Arctic realm has yet to fully unfold, and extensive impacts are expected on ocean currents, stratification, marine heat waves and ecosystems. I will study past warm periods during the Quaternary, Pliocene and Miocene with focus on the Arctic. Marine heatwaves (MHWs), defined as extreme ocean warming episodes, have strengthened over the past decades. High-resolution climate models improve understanding of MHWs under global warming, but such events in the future Arctic are currently overlooked. In a high-resolution climate model, we find Arctic MHWs intensify on orders of magnitude during the warming twenty-first century, following sea ice retreat. However, with little sea ice coverage, strong interannual variability emerges, which could surpass the amplitude of former intensification. Additionally, the intensification of MHWs is linked to a substantial increase in the rate of temperature anomaly change. Cenozoic climate changes have been associated with tectonic activity and fluctuations in atmospheric CO2 levels. To explore these dynamics, we present the Holocene, Last Interglacial, Miocene and Pliocene sensitivity experiments. These experiments incorporate variations in paleogeography, ocean gateway configurations, atmospheric CO2 concentrations, and a range of ocean vertical mixing. 

 

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