Temperature, CO2 and Sea Levels move together

Sea levels, Carbon dioxide concentrations, and Global temperatures have moved together over the last 450,000 years.


The graphs show the movement over the last 420,000 years of:

  • Carbon dioxide concentrations in the air (the green line),
  • Global temperatures (the red line), and
  • Sea levels (the blue line).

The carbon dioxide concentrations have fluctuated between about 180 and 280 parts per million (ppm) over this period of 420,000 years, but in the last 50 years, it has rocketed to above 410 ppm. (See the red circle on the green carbon dioxide graph.)  

The sea levels and temperatures have moved with carbon dioxide levels in the past.  This suggests that the recent increase in carbon dioxide will lead to large rises in sea level and temperature.

The graph shows five periods of high temperatures. We are living in one of those warm periods. During the previous warm period, about 120,000 years ago, the temperature was a few degrees warmer than at present, and the sea level rose about 8 meters higher than the present – and carbon dioxide levels were a lot lower than they are now.

The work of Hansen and Sato provided the basis of this graph

(John Englander: Oceanographer)

Glaciers in retreat:

Glaciers around the world are in retreat. Out of 250 alpine glaciers studied, the Taku Glacier in Alaska was the only glacier not retreating until, in 2019, it too began retreating. At 1,500 metres thick, it’s one of the world’s thickest mountain glaciers, now retreating by up to 390 billion tons of snow and ice a year.

(This is a big deal. Mighty glacier finally succumbs to climate change: The Age: 8 Nov 2019)

The glacier altitude feedback cycle

This feedback occurs because the average temperature at the top of a mountain is lower than at sea level – and this is relevant because we have some thick ice sheets, for example:

  • up to 4,900 meters deep in Antarctica,
  • up to 3,000 metres in Greenland, &
  • up to 1,500 meters for mountain glaciers.
More glacial surface meltingA drop in the altitude of the glacier surface
*A rise in average temperature at the glacier surface

When the “glacier altitude feedback” is dominant:

  • more glacial surface melting causes
  • the altitude of the glacial surface to drop, causing
  • higher temperatures at the glacial surface, which closes the cycle by causing
  • more glacial surface melting.

This feedback cycle indirectly increases global temperatures. As the “glacier altitude feedback cycle” decreases the area of reflective glacial ice, the area will absorb more heat from the sun. So, another feedback, the “ice reflection feedback cycle“, will increase global temperatures.

The Extreme Ice Survey

The Extreme Ice Survey collects visual evidence of the impact of global warming on our planet, like time-lapse photos of the contraction of the glaciers.  Outside of the Antarctic, 95% of the world’s glaciers are retreating. See:

  • the film “Chasing Ice”, produced in cooperation with National Geographic. It won an Emmy award as an outstanding nature program, or
  • the TED talk by James Balog in July 2009.

Related pages

Updated 28 March 2022