A Relationship between Changes of Surface Air and Sea Floor Temperatures at the Arctic Shelf from the Coupled Models Intercomparison Project, Phase 6 Data

The sensitivity of seafloor temperature $T_{\mathrm{B}}$ to the warming of surface air temperature $T_{\mathrm{a}}$ is examined for 1850–2300, based on simulations with five models from the Coupled Models Intercomparison Project phase 6 ensemble and driven by a scenario with high anthropogenic emissions of greenhouse gases. In this historical period (until 2015), sensitivity coefficients $\alpha =\Delta T_{\mathrm{B}}/\Delta T_{\mathrm{a}}$ ($\Delta$ indicates changes relative to the pre-industrial period) were typically ≤0.12 for annual means and up to 0.43 in summer. However, during the same period in the Barents Sea sector, the sensitivity coefficients were as large as 0.6 in summer. For summer, the obtained results are consistent with the limited measurements available for the Siberian shelf. In future, sensitivity coefficients will increase markedly, and $\alpha \ge 0.7$ will become common for the part of the Arctic shelf that becomes ice-free in summer. Our results have implications for estimating the future thermal state of subsea sediments, as well as for oceanic biota.