As the sun's rays reach 
the Earth's surface

some are absorbed and re-emitted as heat

greenhouse gases such as water 
vapor and carbon dioxide

absorb and re-radiate some of this heat

increased amounts of greenhouse gases 
in the atmosphere mean more

heat is trapped

warming the Earth

human activities

especially the burning of fossil 
fuels have increased

concentrations of atmospheric 
carbon dioxide by 40%

mainly since 1900

global average surface temperature 
has increased by 0.8 degrees

Celsius over that time.

Other changes to the climate 
in recent decades,

can be seen in the warming of the oceans.

A rise in sea level

decreasing snow and ice cover 
in the northern hemisphere

and a decline in sea ice in the Arctic.

If emissions continue unchecked 
then further warming of 2.6 to

4.8°

Celsius would be expected by 
the end of the century.

Even at the low end.

This would have serious implications 
for human societies

and the natural world.

For more information about climate 
change from leading science academies,

please visit

royalsociety.org/climatechange

or nas-sites.org/americasclimatechoices