This week, the Intergovernmental Panel on Climate Change (IPCC) released a new report assessing the state of the oceans and cryosphere (the frozen part of the planet) and how they are being affected by climate change. It concludes that a significant part of the additional heat resulting from the human emission of the greenhouse gas CO2, has been absorbed by the cryosphere. This has resulted in the thinning and decreased extent of Arctic sea ice, the worldwide retreat of glaciers and ice sheets and the warming of permanently frozen soils (called permafrost). However, over 90% of the human induced heat as well as part of the artificially introduced CO2 has been absorbed in the oceans resulting in a warmer and more acidic surface ocean on a global scale. The latter, in combination with accelerating sea level rise from the melting ice sheets and thermal expansion of the ocean is causing problems for the marine ecosystems by shifting the geographical range of many species. Furthermore, people are increasingly being affected by the changes in sea level (e.g. flooding and storms), cryosphere (e.g. water resources) and the resulting changes in ecosystem services (e.g. food provided by fisheries).
The map of the week shows the change in sea surface temperature in degrees Celsius over a 10 year period (from 2005 to 2015) as recorded by the MODIS temperature satellite sensor. Calibration of this sensor was performed using in situ sea surface temperature measurements by buoys1 like the ones supplying data to EMODnet Physics. It allows you to see how different parts of the ocean are being affected by climate change. Note the large temperature increase in the Arctic Ocean, which results from the ever decreasing extent of the sea ice. As less of the Arctic region is covered by ice, which is very reflective to incoming sunlight (in scientific terms this is called high albedo), more of the sunlight gets absorbed, warming the region. This in turn causes more of the ice to melt in a self-enhancing cycle called the ice albedo feedback2.
If we do not start to cut our CO2 emissions on a global scale, the report predicts the future will look even more grim with sea ice and glacial melting as well as sea level rise accelerating to unprecedented rates.
The data in this map were provided by the Joint Research Centre (JRC).
1 K.A. Kilpatrick, G. Podestá, S. Walsh, E. Williams, V. Halliwell, M. Szczodrak, O.B. Brown, P.J. Minnett, R. Evans, A decade of sea surface temperature from MODIS, Remote Sens. Environ., 165 (2015), pp. 27-41, 10.1016/j.rse.2015.04.023