Why is this happening?
Greenhouse gases, mainly carbon dioxide
Scientists believe that gases released from industry and agriculture (known as emissions) are adding to the natural greenhouse effect, the way the Earth's atmosphere traps some of the energy from the Sun.
Human activities such as burning fossil fuels like coal, oil and natural gas are increasing the amount of carbon dioxide (CO2), the main greenhouse gas responsible for global warming. Carbon-absorbing forests are also being cut down.
The concentration of CO2 in the atmosphere is now higher than at any time in the last 800,000 years and reached a record high in May this year.
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