Climate change may boost ocean levels by about 3.5 feet by 2550, according to Jerry Mahlman of the National Oceanic and Atmospheric Administration. Mahlman’s computer model assumes that by 2050, carbon dioxide concentrations will be double what they were in the 1700s and then stabilize at that level because of conservation measures. Mahlman stresses that the effects of climate change will be seen for hundreds of years.