PreambleGlobal warming is the phenomenon of increasing average ocean and atmospheric temperatures due to excessive greenhouse gas emissions.These emissions exceed the absorption capacity of the oceans and the biosphere and increase the greenhouse effect, which traps heat at the earth's surface. The term "global warming" more commonly refers to the global warming observed since the beginning of the 20th century, while the term "climate change" refers more to the naturally occurring warming or cooling episodes that occurred before the industrial era. In 1988, the UNO (organization of the united nations) created the Intergovernmental Panel on Climate Change (IPCC) to synthesize scientific studies on the climate. In its fourth report from 2007, in which more than 2,500 scientists from 130 countries participated, the IPCC asserts that global warming since 1950 is "very likely" due to the increase in anthropogenic greenhouse gases ( related to human activities). The conclusions of the IPCC have been endorsed by more than forty scientific societies and academies of sciences, including all the national academies of sciences of the major industrialized countries. The degree of certainty was changed to "extremely likely" in the 2014 Fifth Report.The latest IPCC projections are that the earth's surface temperature could rise an additional 1.1 to 6.4 ° C over the course of the 21st century.The differences between these projections come from the different sensitivities of the models for greenhouse gas concentrations and the different scenarios of future emissions. Most studies have chosen 2100 as the horizon, but warming is expected to continue beyond that because, even if all emissions suddenly stopped, the oceans having already stored a lot of heat, carbon sinks need to be restored, and the the lifespan of carbon dioxide and other greenhouse gases in the atmosphere is long.Uncertainties remain about the extent and geography of future warming, due to the precision of the models, the unpredictability of volcanism, but also variable state and individual behavior (present and future). The socioeconomic, political, health, environmental, even geopolitical or moral issues being major, they give rise to numerous debates, at the international level, as well as controversies. Nevertheless, since 2000, a consensus has emerged that the effects of global warming are already being felt significantly, that they should increase in the medium and long term and that they would be irreversible except for concerted actions, local as well as planetary.Amor Abbassi