Global warming, the phenomenon of increasing average air temperatures near the surface of
Earth over the past one to two centuries. Climate scientists have since the mid-20th century
gathered detailed observations of various weather phenomena (such as temperatures, precipitation,
and storms) and of related influences on climate (such as ocean currents and the atmosphere’s
These data indicate that Earth’s climate has changed over almost every conceivable timescale
since the beginning of geologic time and that the influence of human activities since at least the
beginning of the Industrial Revolution has been deeply woven into the very fabric of climate change.