Humans are increasingly influencing the climate and the earth's temperature by burning fossil fuels, cutting down forests, and farming livestock.

   This adds enormous amounts of greenhouse gases to those naturally occurring in the atmosphere, increasing the greenhouse effect and global warming.

    Greenhouse gases
The main driver of climate change is the greenhouse effect. Some gases in the Earth's atmosphere act a bit like the glass in a greenhouse, trapping the sun's heat and stopping it from leaking back into space and causing global warming.

Many of these greenhouse gases occur naturally, but human activity is increasing the concentrations of some of them in the atmosphere, in particular:

     . carbon dioxide (CO2)
     . methane
     . nitrous oxide
     . fluorinated gases
    CO2 produced by human activities is the largest contributor to global warming. By 2020, its concentration in the atmosphere had risen to 48% above its pre-industrial level (before 1750).

    Other greenhouse gases are emitted by human activity in smaller quantities. Methane is a more powerful greenhouse gas than CO2, but has a shorter atmospheric lifetime. Nitrous oxide, like CO2, is a long-lived greenhouse gas that accumulates in the atmosphere over decades to centuries.

    Natural causes, such as changes in solar radiation or volcanic activity are estimated to have contributed less than plus or minus 0.1°C to total warming between 1890 and 2010.