Cfe Higher Geography - climate change Watch
Hi, I am currently studying climate change and I am not sure about the physical causes? if anyone could help this would be great thanks
Physical causes for short term climate change:
Major volcanic eruptions are able to influence the climate. Volcanic eruptions that produce a lot of ash reflect solar radiation, making the climate colder in the short term by lowering average global temperatures before falling back to Earth.
Fluctuations in solar radiation
The solar constant (total amount of energy received by earth from the sun) is not actually constant, and has varied by about 0.1% over the last 400 years or so. Sunspots are dark areas on the surface of the sun. An increase in sunspot activity seems to produce a slight increase in the solar constant and therefore warmer temperatures.
Physical causes for long term climate change:
Eccentricity cycle - the shape of the Earth's orbit varies from a circular orbit to an elliptical orbit, over a 100,000 year cycle.
- A circular orbit causes a decrease in seasonality – mild winters and cool summers. Not all of the snow melts in the summer, so this orbit produces glacial conditions.
- An elliptical orbit causes an increase in seasonality – cold winters and hot summers. Snow melts in the warm summer, so this orbit produces interglacial conditions.
- At maximum tilt (24.5°), polar areas receive more sunlight during the summer. This causes melting of ice and produces interglacial conditions.
- A minimum tilt (22.1°),polar areas receive less sunlight during the summer. This causes an expansion of ice and produces glacial conditions.
Methane ice is a solid form of methane, which remains stable and solid up to approximately 18°C. As global temperatures rise due to other factors, both physical and human, the methane ice becomes unstable and is able to move, rising up through the ocean and entering the atmosphere. Because methane is more potent than carbon dioxide as a greenhouse gas, it accelerates global warming further.
I hope that helps