Ocean Circulations, Heat Budgets, and Future Commitment to Climate Change

Earth's surface will continue to warm for decades, and the sea level to rise for centuries, even if the atmospheric concentration of greenhouse gases (GHGs) is held fixed at current levels. This is referred to as “committed” climate change because it is essentially unavoidable. Committed climate change arises due to the large thermal inertia of the oceans and their consequent time lag in adjusting to altered GHG concentrations. This work describes the basic heat balance of the oceans, the physical reasons for the long time lag in ocean temperature and sea-level rise, and the observational evidence for human-induced ocean warming over the past 50 years.