Arctic open-water periods are projected to lengthen dramatically by 2100

Abstract

The shrinking of Arctic-wide September sea ice extent is often cited as an indicator of modern climate change; however, the timing of seasonal sea ice retreat/advance and the length of the open-water period are often more relevant to stakeholders working at regional and local scales. Here we highlight changes in regional open-water periods at multiple warming thresholds. We show that, in the latest generation of models from the Coupled Model Intercomparison Project (CMIP6), the open-water period lengthens by 63 days on average with 2 °C of global warming above the 1850-1900 average, and by over 90 days in several Arctic seas. Nearly the entire Arctic, including the Transpolar Sea Route, has at least 3 months of open water per year with 3.5 °C warming, and at least 6 months with 5 °C warming. Model bias compared to satellite data suggests that even such dramatic projections may be conservative.

Constraining Arctic Climate Projections of Wintertime Warming With Surface Turbulent Flux Observations and Representation of Surface-Atmosphere Coupling

“…Thus, how climate models represent the sea ice is very important, not just for the surface-based inversions, but also T S and q S and the boundary layer structure. However, climate models continue to struggle to represent sea ice cover extent and recent decline compared to observations (Schweiger et al, 2011;Stroeve J. et al, 2014;Holland et al, 2010;Jahn et al, 2012;SIMIP Community, 2020, Smith et al, 2020Crawford et al, 2021;Watts et al, 2021; Figure 1), let alone the snow and ice thickness and surface characteristics. These sea ice and snow properties (e.g.…”

“…Climate models often represent Arctic sea ice simplistically and cannot reproduce the sea ice extent, thickness and loss from observations and lack arepresentation of surface topography (Schweiger et al, 2011;Stroeve J. et al, 2014;Holland et al, 2010;Jahn et al, 2012). While there have been improvements in representing sea ice properties and seasonality in recent climate models, there are still significant biases compared to observations and a range in future predictions ( SIMIP Community, 2020;Smith et al, 2020;Crawford et al, 2021;Watts et al, 2021). These errors in the sea ice can feedback on the near surface atmospheric variables, for example, in a largeeddy simulation model, a 1% variation in sea ice concentration was found to change the surface air temperature by 3.5 K in winter (Lüpkes et al, 2008a).…”

Variability in terrestrial characteristics and erosion rates on the Alaskan Beaufort Sea coast

“…Comparing long-term to short-term rates of shoreline change also indicates that exposed coasts have experienced an acceleration in erosion rates while sheltered coasts have had roughly constant rates of change. As the Arctic continues to warm, we expect that rising permafrost temperatures (Biskaborn et (Crawford et al 2021) will contribute to even faster erosion rates along exposed permafrost coasts. Coastlines protected by barrier islands may remain protected from the increased wave activity, but will still be subject to increased temperatures and thermodenudation.…”

Clouds Increasingly Influence Arctic Sea Surface Temperatures as CO2 Rises

“…In observations, the dates of when sea ice begins and then completely melts are occurring earlier, on the order of 5–10 days earlier per decade (Bliss et al., 2019; Peng et al., 2018), and Arctic oceans are already absorbing more solar radiation now than in previous decades (Sledd & L’Ecuyer, 2021). These trends are predicted to continue in coming years (Crawford et al., 2021; Lebrun et al., 2019), which will further alter the surface energy balance as the ocean continues warming (Carton et al., 2015).…”