In Alaska and Western Canada, winter temperatures have already increased by 3-4° centigrade in the last 50 years.
Climate systems
The Polar Regions provide important cooling processes for the world climate system. Global atmospheric and ocean circulations transfer energy from the equator towards the poles and bring cooler air and water down to the equator.
Climate change is caused by warming or cooling of the earth’s atmosphere over a prolonged period. Recently it has been because an increase in ‘greenhouse’ gasses such as carbon dioxide and carbon monoxide has built up in the atmosphere which means the lowers layers retain heat.
The Intergovernmental Panel on Climate Change (IPCC) states that warming will occur most rapidly in the Arctic. For example, in Alaska and Western Canada, winter temperatures have already increased by 3-4°C in the last 50 years. The largest temperature increases will be in the winter and autumn.
Changes to the Arctic coastline and mountains
Aaju talks about how the Arctic coast line and mountains have changed appearance dramatically over the space of just ten or twenty years.
Why is the Arctic so sensitive?
Feedback mechanisms respond to changes in atmospheric, ocean and surface conditions all over the world. Sometimes the feedback can increase the effects of the process (positive +), sometimes it can restore conditions to their original state (negative -).
Here is an example of a positive feedback loop:
Feedback mechanisms interactive
Because the global atmospheric and oceanic systems are linked throughout the world any small changes in one place could have large effects in other places. The atmosphere responds quickly to changes in the heating and cooling rates at the poles and equator with changing storm tracks and intensity. Oceanic changes of circulation have a longer timescale.
Thermohaline circulation
The importance of ocean current has been shown in the interactive above. This circulation links the major oceans and it plays an important role in the transference of heat from the equator to the poles. It is caused by the different density of sea water caused by temperature and salinity
Surface wind driven warm currents flow towards the Arctic in the northern hemisphere, cooling as they travel northwards. Eventually, they sink in the high latitudes and the dense cold water flows into the ocean basins. Some of this water can take over 1500 years to complete its journey!
If the water doesn’t cool enough it won’t sink and then the circulation will break down with possibly catastrophic effects. This would be further enhanced if the melting sea ice and ice sheets of the Arctic add freshwater to the sea and decrease its salinity.
Consequences
What do you think might be the consequences if the thermohaline circulation breaks down? Use the links below to help you.
- Climactic Research Unit – The thermohaline circulation
- Cape Farewell – Ocean circulation
- Carbon Dioxide Information Analysis Center – Ocean circulation (pdf)
