The climate has undergone major changes throughout the history of the Earth, due to natural causes. For example, in the last glacier period, which ended about 10,000 years ago, the earth's climate was colder than the current one and the glaciers occupied wide areas of the earth's surface.

However, the current climate change is very different from previous ones, essentially for two reasons:

Its causes: the scientists agree that the cause of the current climate change is the emission, as a result of human activity, of the so-called “greenhouse gases”. These gases increase the ability of the Earth's atmosphere to retain heat, leading to the phenomenon of global warming.

Its speed: the current climate change is happening very quickly, which makes it very difficult, both for nature and for human societies, to adapt to the new conditions.

Climate change is already a reality that is expressed throughout the planet through the rise in average temperatures, the rise in sea level, the thaw in the Arctic or the increase in extreme events.

Climate change causes diverse changes in natural systems: if they have a chance, wild species move around looking for the climatic conditions to which they are adapted; They can also change their vital rhythms to try to adjust to changes in the seasons. As a result, ecological imbalances and imbalances can occur.

But climate change also affects human societies because it changes the scenarios of economic activities such as agriculture, forestry or tourism; and to human health itself, threatened by heat waves and new diseases.