Li Wenhong author Li Laifang author Ting Mingfang author Columbia University. Lamont-Doherty Earth Observatory Columbia University. Earth and Environmental Sciences Liu Yimin author Columbia University. Lamont-Doherty Earth Observatory originator text Articles 2012 English Semi-permanent high-pressure systems over the subtropical oceans, known as subtropical highs, influence atmospheric circulation, as well as global climate. For instance, subtropical highs largely determine the location of the world’s subtropical deserts, the zones of Mediterranean climate and the tracks of tropical cyclones. The intensity of two such high-pressure systems, present over the Northern Hemisphere oceans during the summer, has changed in recent years. However, whether such changes are related to climate warming remains unclear. Here, we use climate model simulations from the Intergovernmental Panel on Climate Change Fourth Assessment Report, reanalysis data from the 40-year European Centre for Medium-Range Weather Forecasts, and an idealized general circulation model, to assess future changes in the intensity of summertime subtropical highs over the Northern Hemisphere oceans. The simulations suggest that these summertime highs will intensify in the twenty-first century as a result of an increase in atmospheric greenhouse-gas concentrations. We further show that the intensification of subtropical highs is predominantly caused by an increase in thermal contrast between the land and ocean. We suggest that summertime near-surface subtropical highs could play an increasingly important role in regional climate and hydrological extremes in the future. Meterology Climate change http://dx.doi.org/10.1038/NGEO1590 http://hdl.handle.net/10022/AC:P:14956 NNC NNC 2012-10-16 10:27:58 -0400 2012-10-16 10:36:01 -0400 8960 eng