In a recent BBC article, Matt McGrath talks about the Arctic "time bomb": the frozen methane stored in the Arctic tundra and under the Arctic Sea which is start to thaw and escape into the atmosphere.
Methane is an extremely powerful greenhouse gas, 22 times more effective at holding heat in the atmosphere than carbon dioxide. It can also directly cause ocean acidification (see previous post) if it bubbles through sea water as it is released from the sea bed. The good news is, however, that methane spends a relatively short amount of time in the atmosphere before it breaks down...into carbon dioxide.
The Arctic is starting to thaw. Each year the amount of sea ice is gradually decreasing, and the length of time the tundra is frozen for is less. Based upon the geological record, there is a very high chance that eventually the Arctic will be ice-free all year round. However, as with every change, there are winners as well as losers.
As Matt McGrath's article outlines, one major problem with the Arctic thawing is it's potential to increase the rate of climate change, both by adding methane to the atmosphere, and the decrease in albedo - the amount that a surface reflects the sun's rays. A white, ice-covered surface will reflect much more of the sun's heat back into space than a dark, thawed surface of either tundra or sea which will absorb the heat. The increase in heat-retention is likely to make the sea expand (water expands as it heats and shrinks as it cools - put warm water in a plastic bottle and let in cool - the sides of the bottle will gradually suck in as the water shrinks) which will lead to sea level rise and flooding. The change in temperature will also affect the poles more than the equator, reducing the temperature difference between the two. This will have a knock-on effect on the ocean currents which control weather on land. Thus we may see more extremes of weather such as more rain where we already get rain, such as in Britain, less rain where we already get less, such as the Sahara, and an increase in wind strength and intensity in hurricanes and monsoons.
As well as affecting the global climate, the reduction in ice at the Arctic is affecting the local environment with less habitat for animals such as polar bears and arctic foxes, both of which are starting to move south. This displacement is causing conflict as the more northerly animals fight for territory with animals which live further south, and this is also leading to increased contact with humans. Native American tribes are also starting to be displaced as the frozen ground where they normally live thaws, turning into unstable mud, and the rivers rise due to the increase in thawed water.
The escape of methane from it's frozen holding place at the bottom of the Arctic Sea is also causing ocean acidification in large parts of the Arctic Sea, affecting the entire marine ecosystem, which in turn feeds into the fish stocks of the northern hemisphere.
On the plus side, however, with a decrease in sea-ice the economic opportunities open up. The decrease in Arctic sea-ice has opened up new shipping routes, significantly decreasing transport time between East Asia and Europe, and will also allow more fishing within the sea. Large amounts of oil and gas are also thought to be held below the Arctic Sea and with the decrease in ice these are now becoming viable sources.
With the Arctic changing so rapidly, many are worried that the area may become exploited where the changes not effectively managed. The Arctic Resilience Report was set up in 2011 to assess the changes and their impacts on the Arctic, with an interim report published in May this year; the full report is due in 2015. Whatever their conclusions, it will always be a compromise between environment and economic concerns, and the Arctic will change regardless. The question is, what is the best way to manage it?
No comments:
Post a Comment