Global Climate Change KEY INDICATORS

Sea Level


The chart on the left shows historical sea level data derived from coastal tide gauge records. The chart on the right shows the average sea level since 1993 derived from global satellite measurements, updated here monthly. Sea level rise is associated with the thermal expansion of sea water due to climate warming and widespread melting of land ice.

Arctic Sea Ice

The graph on the left charts the annual Arctic sea ice minimum extent from 1979 to 2008, derived from satellite observations. The illustration on the right shows the Arctic sea ice extent for September 2008, which was the second-lowest in the satellite record.

Carbon Dioxide Concentration

Carbon dioxide (CO₂) is an important greenhouse gas released through natural processes such as respiration and volcano eruptions and through human activities such as deforestation and burning fossil fuels. The chart on the left shows the historical levels of CO₂ in the Earth's atmosphere. The chart on the right shows CO₂ levels in recent years, corrected for average seasonal cycles.

Global Average Temperature

The time series shows the combined global land and marine surface temperature record from 1850 to 2008. The year 2008 was 10th warmest on record, exceeded by 1998, 2005, 2003, 2002, 2004, 2006, 2001, 2007 and 1997.

Ozone Hole


Latest single-day maximum - Sept. 12, 2008:
27 million square km (10.5 million square miles)
Fifth largest on record

The "ozone hole" is a severe depletion of the ozone layer high above Antarctica. It is primarily caused by human-produced compounds that release chlorine and bromine gases in the stratosphere. The ozone layer acts to protect life on Earth by blocking harmful ultraviolet rays from the sun.

The image at left is a view of the most recent Antarctic ozone hole, derived from satellite measurements that monitor the ozone layer. The blue and purple colors are where there is the least ozone, and the greens, yellows, and reds are where more ozone is present.

There are signs that ozone depletion is slowing in response to the 1987 Montreal Protocol, which resulted in a significant reduction in global emissions of ozone-depleting chemicals. However, climate change may cause the ozone hole to expand further.

More Info : http://climate.nasa.gov