BBC Science — The average temperature of the Earth’s surface has increased by about 0.85°C (1.4F) in the last 100 years. Thirteen of the 14 warmest years were recorded in the 21st Century, with 2015 on course to set another record.
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.
Higher temperatures, extreme weather events and higher sea levels are all linked to a warming climate and could have a drastic effect on the world’s regions.
Since 1900, sea levels have risen by on average about 19cm globally. The rate of sea-level rise has accelerated in recent decades, placing a number of islands and low-lying countries at risk.
The retreat of polar ice sheets is an important contributor to this rise.
Arctic sea ice is also shrinking because of higher temperatures, though it makes little contribution to raised sea levels.
An area of sea ice roughly 10 times the size of the UK has been lost when the current day is compared with average levels from the early 1980s. (12/09/2015)