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Because the oceans are highly effective sites of heat storage, they will continue to warm if the atmosphere warms. Computer models give scenarios over the next 100 years of a global mean warming of 1 to 4°C. The greatest warming (>5°C) is projected at higher latitudes. Models indicate that the bulk of this recent warming is due to increased concentrations of anthropogenic greenhouse gases - CO2 and air pollutants. The uncertainty in model output is due to differences in various models, a lack of spatial resolution of physical features, and a less than complete inclusion of physics, as well as our own uncertainty of the real world's complex interactions. However all of the major climate change models project a scenario of warming given the current rate that atmospheric CO2 is increasing. Moreover similar rates of warming are projected, even if anthropogenic greenhouse gases are stabilized to present levels. As our understanding of the character and mechanisms of natural climate change improves, scientists will be able to better determine the recent and future contribution of anthropogenically-forced climate change.
Another likely response to global warming would be a rise in sea level. Predicting just how much the sea level will rise is more difficult. Water expands as it warms, requiring more space, and the melting of glaciers and ice caps adds water to the oceans. Glaciers and ice caps have been receding for the last 100 years and that is expected to continue. The current estimate is that global mean sea level may rise by 50-65 cm (about 1.5-2 ft.) in the next 100 years.
Ecosystems are tuned to the patterns of local climate parameters, for example temperature and ocean currents. If these environmental patterns shift as a result of climate change, plants and animals may no longer be able to thrive or survive in that region. Ocean warming is likely to lead to more evaporation, producing more clouds over the oceans, enhanced winds, and an increased source of energy for storm development - including hurricanes and typhoons. But the oceans’ feedback to the atmosphere may also mitigate global warming effects. For example, increased cloud cover due to greater evaporation from the oceans may reflect more incoming solar radiation back into space.
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