How Do We Know Global Warming Is Really Happening?

Over the last several decades, scientists have carefully studied patterns of climate change around the world. In its most recent assessment, the IPCC reviewed hundreds of these studies on such topics as past climate changes, observations of retreating ice, warming and rising seas, and other changes, as well as a wide array of supercomputer simulations to model how the planet has and will be affected by increasing amounts of greenhouse gases. Together these studies offer a stark portrait of a rapidly changing world:

 

* Temperatures have risen about 1.3 degrees F since the late 19th century. Greenhouse gas levels in the atmosphere have increased by 18% (nitrous oxide), 35% (carbon dioxide), and 148% (methane).

* Mountain glaciers and snow cover are declining in most parts of the world.

* The Greenland and Antarctic ice sheets are melting and breaking up.

* The area covered by Arctic sea ice in winter has shrunk about 2.7% each decade since 1978, with even greater summertime reductions.

* Global sea levels rose between 5 and 9 inches during the 20th century.

* The North Atlantic has shown increased hurricane intensity since 1970.

* Precipitation amounts have increased in northern Europe, the eastern Americas, and parts of Asia. Elsewhere, droughts have become longer and more severe.

 

Over the last several decades, scientists have carefully studied patterns of climate change around the world. In its most recent assessment, the IPCC reviewed hundreds of these studies on such topics as past climate changes, observations of retreating ice, warming and rising seas, and other changes, as well as a wide array of supercomputer simulations to model how the planet has and will be affected by increasing amounts of greenhouse gases. Together these studies offer a stark portrait of a rapidly changing world:
  • Temperatures have risen about 1.3 degrees F since the late 19th century. Greenhouse gas levels in the atmosphere have increased by 18% (nitrous oxide), 35% (carbon dioxide), and 148% (methane).
  • Mountain glaciers and snow cover are declining in most parts of the world.
  • The Greenland and Antarctic ice sheets are melting and breaking up.
  • The area covered by Arctic sea ice in winter has shrunk about 2.7% each decade since 1978, with even greater summertime reductions.
  • Global sea levels rose between 5 and 9 inches during the 20th century.
  • The North Atlantic has shown increased hurricane intensity since 1970.
  • Precipitation amounts have increased in northern Europe, the eastern Americas, and parts of Asia. Elsewhere, droughts have become longer and more severe.