Climate change observations

Global annual mean temperature change from 1850 to 2020

Source: IPCC, 1st Working Group, 2021

The increase in the global mean temperature of land surface air and sea surface water is very clear. The deviation from the average of the pre-industrial reference period 1850-1900 is small until the mid-1930s, and then becomes mostly slightly positive until about 1980. Since the beginning of the 1980s, the warming has increased markedly, and each of the last four decades has successively been the warmest since 1850. The warming of the last decade (2011-2020) is 1.1°C compared to the pre-industrial era.

Although slightly cooler than 2020, 2021 was one of the seven warmest years on record.

Glacier melt from 2000 to 2020

Note: the blue sector of the disk indicates the share of ice melt that comes from pack ice 27%) ; the blue arc indicates the share of the pack ice surface in the total global ice surface 40%) . The histogram describes the annual loss of ice thickness (0.56 min 2020).
Source: Hugonnet R., McNabb R., Berthier E.et al, Accelerated global glacier mass loss in the early twenty-first century. Nature 592, 726-731 (2021)

From the Himalayas to the Arctic, the melting of the world's glaciers, caused by global warming, has accelerated in the last 20 years. The melting of these glaciers has contributed to the rise in sea level by 21%, at a rate of 0.74 mm per year. Since 2000, they have lost an average of 267 billion tons of ice each year. The complete melting of the glaciers would raise the sea level by 40 cm.

Evolution of the global average sea level since 1993

Source: E.U. Copernicus Marine Service Information

Mean sea level rose by 1.7 ± 0.3 mm/year over the period 1901-2010. The rate of sea level rise has accelerated in recent decades, reaching 3.5 ± 0.4 mm/yr over the period 1993-2020 (satellite measurements). About 30% of the sea level rise is due to expansion caused by increased water temperature.

Evolution of the average annual temperature in Metropolitan France since 1900

Note: the change in mean annual temperature is shown as the deviation from the average observed over the period 1961-1990 (11.8°C).
Field: Metropolitan France.
Source: Météo-France

As on a global scale, the evolution of average annual temperatures in mainland France shows a clear warming since 1900. The rate of warming has varied, with a particularly marked increase since the 1980s. The average annual temperature over the country reached 14.1°C in 2020, exceeding by 2.3°C the average temperature observed over the period 1961-1990. The year 2020 thus ranked as the warmest year over the period 1900-2020, ahead of 2018 (13.9°C) and 2014 (13.8°C). With an average annual temperature of 12.9°C, the year 2021 remains 1.1°C warmer than the 1961-1990 average but is in line with the 1991-2020 average (12.9°C).

Summer drying of rivers
Percentage of measuring stations having experienced at least one summer drying of rivers or ponds (assec) in 2020 by department

Source : Eaufrance

Over the 2012-2021 period, nearly half of the monitored stations in mainland France were affected by at least one summer river or pond drying (assec). For more than a third of them 34%), this situation was repeated at least two years over the period, while one station out of five was dry at least five years out of ten. Finally, 110 stations, or 3% of them, were dry every year, mainly in the Rhone-Mediterranean-Corsica river basin.

Colonization of departments in metropolitan France by the tiger mosquito
Percentage of communes colonized by Aedes albopictus in metropolitan France on January 1, 2022

Source: Ministry of Solidarity and Health

The Aedes albopictus mosquito (commonly known as the"tiger mosquito") is a mosquito native to Asia. It is the vector of diseases such as dengue, chikungunya and zika. In metropolitan France, the rise in temperature has been accompanied by a gradual extension of the establishment of this mosquito since 2004; it is now established in 67 departments (out of 96 metropolitan departments). The tiger mosquito is essentially urban. Its anthropophilic nature (it likes places inhabited by humans) explains why once it has settled in a town or department it is practically impossible to get rid of it.

Departments in which the tiger mosquito is established and active are more or less colonized. 53 departments are considered weakly colonized, in the sense that less than 40% of the communes are colonized. Conversely, 14 departments are highly colonized.