Increasing temperature is likely to lead to increasing precipitation but the effects on storms are less clear.

Extreme weather

Storm strength leading to extreme weather is increasing, such as the power dissipation index of hurricane intensity. Precipitation hitting the US from hurricanes has increased by 7% over the twentieth century. Some studies have found that the increase in sea surface temperature may be offset by an increase in wind shear, leading to little or no change in hurricane activity.

Increases in catastrophes resulting from extreme weather are mainly caused by increasing population densities, and anticipated future increases are similarly dominated by societal change rather than climate change. Vecchi and Soden find that wind shear, the increase of which acts to inhibit tropical cyclones, also changes in model-projections of global warming. The study does not make claims about the net effect on Atlantic and East Pacific hurricanes of the warming and moistening atmospheres, and the model-projected increases in Atlantic wind shear. Water levels are decreasing every day. (See also “Global warming?” in tropical cyclone)

Increased evaporation

Increasing water vapor at Boulder, Colorado.

As the climate grows warmer and the causes of global dimming are reduced, evaporation will increase due to warmer oceans. Scientists have found evidence that increased evaporation could result in more extreme weather as global warming progresses. The IPCC Third Annual Report says: “…global average water vapor concentration and precipitation are projected to increase during the 21st century. Pielke et al. (2008) normalized mainland U.S. hurricane damage from 1900–2005 to 2005 values and found no remaining trend of increasing absolute damage. There is no agreement as to whether this hurricane is linked to climate change, but one climate model exhibits increased tropical cyclone genesis in the South Atlantic under global warming by the end of the 21st century.

Glacier retreat and disappearance

Lewis Glacier, North Cascades, WA USA is one of five glaciers in the area that melted away

In historic times, glaciers grew during a cool period from about 1550 to 1850 known as the Little Ice Age. Subsequently, until about 1940, glaciers around the world retreated as the climate warmed. Glacier retreat declined and reversed in many cases from 1950 to 1980 as a slight global cooling occurred. This process has increased markedly since 1995.

^[40] Currently glacier retreat rates and mass balance losses have been increasing in the Andes, Alps, Pyrenees, Himalayas, Rocky Mountains and North Cascades.

Glacier runoff declines in the summer as glaciers decrease in size, this decline is already observable in several regions. In warmer and drier years, glaciers offset the lower precipitation amounts with a higher meltwater input.

It has to be acknowledged, however, that increased seasonal runoff of Himalayan glaciers led to increased agricultural production in northern India throughout the 20th century.

The Lewis Glacier, North Cascades pictured at right after melting away in 1990 is one of the 47 North Cascade glaciers observed and all are retreating. Like rivers flowing from an enormous lake, numerous outlet glaciers transport ice from the margins of the ice sheet to the ocean.

Retreat of the Helheim Glacier, Greenland

Glacier retreat has been observed in these outlet glaciers, resulting in an increase of the ice flow rate. Three glaciers that have been researched, Helheim, Jakobshavns and Kangerdlugssuaq Glaciers, jointly drain more than 16% of the Greenland Ice Sheet. Glacier retreat and acceleration is also apparent on two important outlet glaciers of the West Antarctic Ice Sheet.

Oceans

The role of the oceans in global warming is a complex one. Furthermore, as the temperature of the oceans increases, they become less able to absorb excess CO₂. Global warming is projected to have a number of effects on the oceans. Ongoing effects include rising sea levels due to thermal expansion and melting of glaciers and ice sheets, and warming of the ocean surface, leading to increased temperature stratification. Other possible effects include large-scale changes in ocean circulation.

Sea level rise

Sea level rise during the Holocene.

Sea level has been rising 0.2 cm/year, based on measurements of sea level rise from 23 long tide gauge records in geologically stable environments.

With increasing average global temperature, the water in the oceans expands in volume, and additional water enters them which had previously been locked up on land in glaciers, for example, the Greenland and the Antarctic ice sheets. Meanwhile, the estimated total ice melting rate over Greenland is –239 ± 23 cubic kilometers per year, mostly from East Greenland.