Hansen’s report on climate change has been getting a lot of publicity so I thought a ‘Bob Bingham’ summary might help explain the overall picture.
Hansen comments that we have been burning fossil fuels and producing CO2 without any idea of the consequences to our planet. The report compares the Eemian period, which was the previous warm period, 125,000 years ago, when the temperature was only 0.5 C warmer than today, and sea levels were 2m to 7m higher.
The level of CO2 at that time was 300 ppm compared with 400 ppm today but the temperatures were similar.
Hansen comments that we have been burning fossil fuels and producing CO2 without any idea of the consequences to our planet. The report compares the Eemian period, which was the previous warm period, 125,000 years ago, when the temperature was only 0.5 C warmer than today, and sea levels were 2m to 7m higher.
The level of CO2 at that time was 300 ppm compared with 400 ppm today but the temperatures were similar.
His report centres on the ‘Great ocean conveyor, or thermohayline circulation which flows round the world and distributes heat around the planet.
With CO2 in the atmosphere at 400 ppm, heat from the sun is warming the planet and most heat goes into the oceans. This heat in the oceans melts the grounded ice shelves from below and increases the release of fresh water.
This fresh water interferes with the sinking of the salt laden sea water at the poles and slows the thermohayline circulation and consequently slows the distribution of heat around the planet.
As the ice shelves break up there is an increase in the speed at which the big ice sheets move towards the sea and consequently they are melted by the warmer ocean water.
With CO2 in the atmosphere at 400 ppm, heat from the sun is warming the planet and most heat goes into the oceans. This heat in the oceans melts the grounded ice shelves from below and increases the release of fresh water.
This fresh water interferes with the sinking of the salt laden sea water at the poles and slows the thermohayline circulation and consequently slows the distribution of heat around the planet.
As the ice shelves break up there is an increase in the speed at which the big ice sheets move towards the sea and consequently they are melted by the warmer ocean water.
The physical action of ice melting uses heat and keeps the poles cooler.
The result is that the Poles remaining cold and the tropics becoming warmer makes an energy imbalance in the planet which can drive much more powerful storms. Typical instances would be along the course of the Gulf stream, across the Pacific Ocean and round the Southern Ocean. Read the report
The result is that the Poles remaining cold and the tropics becoming warmer makes an energy imbalance in the planet which can drive much more powerful storms. Typical instances would be along the course of the Gulf stream, across the Pacific Ocean and round the Southern Ocean. Read the report
Hansen is warning about sudden pulses of sea level rise of several metres, which has happened before, but for the people here today a sudden increase of one metre would be catastrophic to the economies of the rich nations. London for instance is currently protected to one metre and could withstand two metres given enough time but after that it is flooded and this would be true for the USA East coast, South West coast and California, China and Holland.
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