In which way climate is changing in our world?

Global perspective

Over the past 157 years our world- both lands and oceans- has been warming up.

• In the last century this warming has been occurred in two phases, from the 1910s to the 1940s (0.35°C), and more strongly from the 1970s to the present (0.55°C).
• The rate of warming has increased over the past 25 years, and 11 of the 12 warmest years on record have occurred in the past 12 years.
• The temperature increase is widespread over the globe and is greater at higher northern latitudes.
• Land regions have warmed faster than the oceans.

Following the global temperature increase, global sea level has been rising consistently.

• Global sea level rose by about 120 m during the several millennia that followed the end of the last ice age (approximately 21,000 years ago), and stabilized between 3,000 and 2,000 years ago, and did not change significantly from then until the late 19th century.
• Global average sea level has risen since 1961 at an average rate of 1.8 [1.3 to 2.3] mm/yr and since 1993 at 3.1 [2.4 to 3.8] mm/yr.
• The two major causes of global sea level rise are thermal expansion of the oceans and the loss of land-based ice due to increased melting.
• Sea level is not rising uniformly around the world. In some regions, rates are up to several times the global mean rise, while in other regions sea level is falling. It is mostly due to non-uniform changes in temperature and salinity and related to changes in the ocean circulation.

Global-scale decline of snow and ice has been observed since 1980 with an increase during the past decade.

• Mountain glaciers and snow cover on average have declined in both hemispheres.
• Sea ice in the Arctic is shrinking in all seasons(2.7 [2.1 to 3.3]% per decade), most dramatically in summer (7.4 [5.0 to 9.8]% per decade)
• Reductions are reported in permafrost, seasonally frozen ground and river and lake ice
• Coastal regions of the ice sheets on Greenland and West Antarctica, and the glaciers of the Antarctic Peninsula, are thinning and contributing to sea level rise

Changes have been occurred in the amount, intensity, frequency and type of precipitation during past 100 years.

• Precipitation increased significantly in eastern parts of North and South America, northern Europe and northern and central Asia but declined in the Sahel, the Mediterranean, southern Africa and parts of southern Asia.
• There are also increases in some regions in the occurrences of both droughts and floods.
• More precipitation now falls as rain rather than snow in northern regions.
• Widespread increases in heavy precipitation events have been observed, even in places where total amounts have decreased.

There has been a change in extreme weather events like Heat Waves, Droughts, Floods and Hurricanes since 1950

• The number of heat waves has increased and widespread increases have occurred in the numbers of warm nights
• The extent of regions affected by droughts has increased
• In some areas numbers of heavy daily precipitation events that lead to flooding have increased
• Tropical storm and hurricane frequencies vary considerably from year to year, but evidence suggests substantial increases in intensity and duration since the 1970s
• Variations in tracks and intensity of storms reflect variations in major features of the atmospheric circulation, such as the North Atlantic Oscillation.

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Source:
IPCC Fourth Assessment Report: Climate Change 2007, Working Group I Report "The Physical Science Basis"

IPCC Fourth Assessment Report: Climate Change 2007, Working Group II Report "Impacts, Adaptation and Vulnerability"