Intensification and spatial homogenization of coastal upwelling under climate change

• Published in: Nature (London) 2015-02, Vol.518 (7539), p.390-394
• Main Authors: Wang, Daiwei, Gouhier, Tarik C., Menge, Bruce A., Ganguly, Auroop R.
• Format: Article
• Language: English
• Subjects: 704/106/694/2739; 704/106/829/2737; Animals; Aquatic Organisms - physiology; Atlantic Ocean; Biodiversity; Chlorophyll; Climate Change; Climate models; Climatic changes; Ecosystem; Ecosystems; Environmental aspects; Forecasts and trends; Geographical distribution; Global warming; Greenhouse effect; Heterogeneity; Humanities and Social Sciences; Latitude; letter; Marine ecosystems; Marine fish; Models, Theoretical; multidisciplinary; Ocean basins; Oceans; Offshore; Pacific Ocean; Photosynthesis; Science; Seasons; Seawater - analysis; Temperature; Trends; Upwelling; Upwelling (Oceanography); Water Movements; Wind
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature14235

An ensemble of climate models shows that by the end of the twenty-first century the coastal upwelling season near the eastern boundaries of the Atlantic and Pacific oceans will start earlier, end later and become more intense at high latitudes, thus becoming more homogeneous; these changes may affect the geographical distribution of marine biodiversity. Influence of climate change on coastal upwelling Coastal upwelling provides nutrients that sustain healthy marine ecosystems along the eastern margins of the world's oceans. Analysis of historical records has suggested an intensification of upwelling in some coastal currents, but to date no consensus has been reached in predictions of future changes in upwelling in a warming climate. Daiwei Wang and colleagues have analysed twenty-two simulations from the CMIP5 model archive — an extensive series of coordinated climate model experiments — which suggest that by the end of the twenty-first century, the coastal upwelling season near the eastern boundaries of the Atlantic and Pacific oceans will start earlier, end later and become more intense at high latitudes, thus becoming more homogeneous. These changes may affect the geographical distribution of marine biodiversity. The timing and strength of wind-driven coastal upwelling along the eastern margins of major ocean basins regulate the productivity of critical fisheries and marine ecosystems by bringing deep and nutrient-rich waters to the sunlit surface, where photosynthesis can occur 1 , 2 , 3 . How coastal upwelling regimes might change in a warming climate is therefore a question of vital importance 4 , 5 . Although enhanced land–ocean differential heating due to greenhouse warming has been proposed to intensify coastal upwelling by strengthening alongshore winds 6 , analyses of observations and previous climate models have provided little consensus on historical and projected trends in coastal upwelling 7 , 8 , 9 , 10 , 11 , 12 , 13 . Here we show that there are strong and consistent changes in the timing, intensity and spatial heterogeneity of coastal upwelling in response to future warming in most Eastern Boundary Upwelling Systems (EBUSs). An ensemble of climate models shows that by the end of the twenty-first century the upwelling season will start earlier, end later and become more intense at high but not low latitudes. This projected increase in upwelling intensity and duration at high latitudes will result in a substantial reduction of the existing