Emerging risks from marine heat waves

Abstract

Recent marine heat waves have caused devastating impacts on marine ecosystems. Substantial progress in understanding past and future changes in marine heat waves and their risks for marine ecosystems is needed to predict how marine systems, and the goods and services they provide, will evolve in the future.

Fig. 1

Summary of prominent recent marine heat waves that are documented and analyzed in the literature. The figure shows the maximum sea surface temperature anomaly in regions where temperature exceeds the 99th percentile using NOAA’s daily Optimum Interpolation sea surface temperature dataset. The numbers indicate the year of the MHW occurrence. The 99th percentile is calculated over the 1982–2016 reference period. The map was created using the NCAR Command Language (https://www.ncl.ucar.edu)

Fig. 2

The effect of a simple shift towards a warmer climate on the probability of land-based and marine heat waves. a shows the observed distribution of the linearly detrended and deseasonalized local daily surface air temperature anomalies over land using the CRU-NCEP-v8 data set^,; b as for a but for local daily sea surface temperature anomalies using NOAA’s daily Optimum Interpolation sea surface temperature data set. Solid black lines show the distributions over the 1982–2016 period and solid gray lines indicate the same shape of the distributions, but the land is shifted by ΔT_land =2°C and the ocean by ΔT_ocn = 1.33 °C. Here we assume ΔT_land/ΔT_ocn =1.5²⁰. A heat wave is defined as temperature exceeds the 95th percentile (red and blue shaded areas). The inset highlights the changes in land-based heat waves