A Climate change is a lasting change (of the decade million years) statistical parameters (mean parameters, variability) the Earth's global climate or its various regional climates. These changes may be due to processes intrinsic to the Earth, external influences or, more recently, human activities.
Anthropogenic climate change is caused by emissions of greenhouse gases caused by human activities, modifying the composition of the atmosphere of the planet. In addition this development the natural variations in climate.
In the work of the IPCC, the term "climate change" refers to any change in time, whether due to natural variability or human activity.
Instead, the United Nations Framework Convention on Climate Change, the term refers only changes due to human activities. The Framework Convention uses the term "climate variability" to refer to climatic changes of natural origin.
The ancient climate changes
1 The previous phases in human history are the paleoclimatology. They can track, over the continental drift and successive periods of glaciation, variations related to climate change affecting soils and species, by their nature. The carbon cycle is now involved;
2 Glaciations: the cycle of climate change can now detail the seven previous glaciations:
2. until 450,000 years ago: de Waal Interglacial
3. until 400,000 years ago: Beestonian stage or Nebraskan
4. until 350,000 years ago: Cromer interglacial or Aftonien
5. until 320,000 years ago: Mindel Glaciation, Elster or Kansien or
6. until 270,000 years ago: Holstein Interglacial or Yamouthien
7. until 200,000 years ago: Wolstonian, or Saal, or Illinoian
8. until 125,000 years ago: Eem Interglacial of Sangamonian or Eemian
9. until 70,000 years ago: Würm glaciation, the Weichselian or Wisconsin or
10. until 11,625 years ago: the Holocene Interglacial (Holocene Climatic Optimum), sometimes referred to as "the new warming" of the Holocene
3 Beginning of written human history and recognition of changes in climate by the chroniclers.
1. 535-536: 535-536 of Climate Change (Climate Exchange of 535-536), found by the Byzantine Procopius
2. Tenth century - the fourteenth century: Climate Optimum of the Middle Ages, a localized heating in Europe and even North America
3. 1550s - 1850s: Little Ice Age
4 The last phase is contemporary attempts to describe the multiple effects of global warming, it is separated from the rest given the constant interference of anthropogenic climatic balances since the advent of the industrial revolution and control of polluting energy by mankind.
1. Retreat of glaciers since 1850
The recent global warming
It was first mentioned by several authors, then modeled by Svante Arrhenius in 1896. The term (global warming in English) was invented by climatologist Wallace Broecker (in) in the journal Science August 8, 1975. Since then, the IPCC says that global warming tends to get carried away and the process cycles and climate control are standard and exceeded by 1950, including:
1. The thawing of permafrost containing methane (CH4), whose action on the greenhouse effect is 23 times the carbon dioxide (CO2).
2. The melting of polar ice and glaciers increases absorption by soils and oceans of solar radiation.
3. During heat waves more frequent, the vegetation slows its growth and thus its ability to extract carbon from the atmosphere.
It would be a shift to a climate of high magnitude imbalance, without that we can usually know if a point of no return is reached.
The IPCC does not conduct research in its own name but has the task of evaluating scientific information, technical and socio-economic surveys are needed to better understand the science behind climate change risks to human, identify possible consequences of this change and consider possible strategies for adaptation and mitigation. At least eight of the ten warmest years since 1850 are after 1997.
The exhaust emissions from volcanoes have two opposite effects:
1. aerosols (SO2 and dust) darken the atmosphere, increasing rainfall and cool climate;
2. in a second time, large quantities of greenhouse gases emitted causing a greenhouse effect. The greenhouse effect has resulted, like the climate in a greenhouse, to amplify the temperature difference: where the sun's heat is reflected and preserved if there is no Sun, heat comes more difficult and therefore it is colder.
The majority of species extinctions in the past seems due to a sudden climate change.
The fall of the Chicxulub meteor is often cited as a cause of the collapse of biodiversity in the late Jurassic, but it seems (Courtillot, 2004) that volcanic eruptions (or self-induced shock meteor) that have left traps (in the Deccan, India) have the most gigantic drastically disrupted the climate for hundreds of years at a rate exceeding the pace of evolutionary adaptations of species possible. In particular, the crisis of the Siberian Traps is associated with the disaster of the Permian.
Significant and measurable disturbances following the eruption of Pinatubo (1991) and in 1783-1784, that of Laki (Iceland eruption cloud which has left a trace in the records of mortality in Europe (Courtillot, 2005)). In 1815, the Tambora eruption has also affected global climate, with strong disturbances in 1816.
See also Environmental health