Global warming: Human activity is causing significant changes in the climate

The increase in the concentration of greenhouse gases emitted by human activities causes global warming. Rising temperatures on the surface of the Earth, the seas and the oceans, on a planetary scale over a continuous period are unanimously observed by the climatologists.

The assessment of all climate change data is done by the Intergovernmental Panel on Climate Change (IPCC). According to their latest report of 2013, global warming is "unequivocal" because it is evident in the observation of the increase of global average temperatures on land, seas and oceans, the general melting of snow, glaciers, of the pack ice and the rise of the average sea level in particular. The 21st century is one of the 14 warmest years ever since the first meteorological surveys in 1850.

Temperature increases are not uniform across the globe: at the North Pole average temperatures over the past decade have increased 2 times faster than globally. Temperatures on the surface of permafrost (permanently frozen surface) have risen by 3 ° C over the past 20 years.

According to the IPCC, surface temperatures (land and sea) increased by 0.85 ° C (range: 0.65-1.06 ° C) during the period 1880-2012; 2100 temperature increase forecasts range from 0.3 ° C to 4.8 ° C.

The average temperature of the oceans has increased to a depth of 3000 meters, with the oceans absorbing more than 80% of the heat added to the climate system. Between 1901 and 2010, the average global sea level rose by 0.19 m on average (from 0.17 to 0.21 m).

The melting of glaciers and the expansion of the water under the effect of heat cause sea level rise: estimates of the increase by 2100 range from 26 cm to 82 cm from the end of the year. last century. The consequences of global warming on man and the environment are very wide and worrying.