Contributing factors are thermal expansion of the oceans, and melting of glaciers and ice caps. This estimate reflects improvements in model estimation procedures. Anthropogenic climate change will persist for many centuries. Several centuries after CO2 emissions occur, about a quarter of the increased concentration is projected to be still present in the atmosphere. Global mean surface temperature increases and rising sea level are projected to continue for hundreds of years after stabilization of greenhouse gas concentrations owing to the long time scales on which the deep ocean adjusts to climate change.
Further action is required to address remaining gaps in information and understanding.
Systematic observations and data reconstructions Modelling and process studies. Recent regional climate changes, particularly temperature increases, have already affected many physical and biological systems. There are preliminary indications that some human systems have been affected by recent increases in floods and droughts. Natural systems are vulnerable to climate change, and some will be irreversibly damaged. Many human systems are sensitive to climate change, and some are vulnerable.