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Earlier this week, I went to a seminar given by Charles Sheppard, on the impact of climate change on marine ecosystems. It was quite interesting, and thoroughly depressing. He opened with "It's very easy to get depressed looking at the evidence of the damage climate change is causing. Instead, as a scientist, I like to see it as exciting - we're taking part in the biggest experiment ever!", and it went from there...
One of the more obvious signs of climate change is the death of coral reefs. Here it's not the mean temperature rise that kills them, but the peak temperatures. Especially in shallower waters like the Persian Gulf, there have been several extreme temperature events, which have resulted in "bleaching" - the living parts of the corals die. It takes around 5 years for many corals to grow to maturity and be able to reproduce, so as these extremes of temperature become more frequent, they'll never be able to reproduce, and will go extinct at least locally. This is predicted to become common by about 2020. Furthermore, the marine parks where we try and keep pollution and over-fishing at bay were not rationally selected, so they often don't correspond to the more thermally resistant corals - i.e. they're essentially a waste of time.
Another problem for marine ecosystems is the acidification of the oceans. For reasons I don't quite recall (or failed to understand at the time!), this is a time-delayed process - if we never turned on another engine after today, the oceans would continue to acidify for another 40 years or so. Now, there's a lot of limestone at the bottom of the ocean which buffers the system, so it's not going to get especially acidic in chemical terms, but the biological impact will be significant. Already, little plankton are having their shells etched by the acidity of sea-water, and by 2050 it will be impossible to calcify things in the sea. That has significant impacts on all sorts of things, although whether we'll be stuck with "jelly-fish and chips" is anyone's guess. Particularly, it means that corals will be unable to grow at all, which means many people will starve. Already a few million extra deaths are year are due to malnutrition attributable to climate change (either directly, or due to increased susceptibility to disease).
Many of these changes are going to happen, unless we find a way to sequester vast amounts of Carbon out of the atmosphere, and fast.
As an aside, there is controversy regarding the role of air travel in climate change. After 11/09/2001, air travel was grounded in the USA for 3 days; this resulted in a raising of air temperatures across America, as reported in Nature (PDF). Charles' view was that this might well be significant - that the cooling effect of jet contrails (which are largely water vapour) might outweigh the CO2 produced by jets. He also claimed that CO2 output by air travel was tiny compared to other sources (especially shipping, and private car use), so we should stop worrying about flying places, and instead look at the bigger CO2 sources.
All a bit disheartening, really.
One of the more obvious signs of climate change is the death of coral reefs. Here it's not the mean temperature rise that kills them, but the peak temperatures. Especially in shallower waters like the Persian Gulf, there have been several extreme temperature events, which have resulted in "bleaching" - the living parts of the corals die. It takes around 5 years for many corals to grow to maturity and be able to reproduce, so as these extremes of temperature become more frequent, they'll never be able to reproduce, and will go extinct at least locally. This is predicted to become common by about 2020. Furthermore, the marine parks where we try and keep pollution and over-fishing at bay were not rationally selected, so they often don't correspond to the more thermally resistant corals - i.e. they're essentially a waste of time.
Another problem for marine ecosystems is the acidification of the oceans. For reasons I don't quite recall (or failed to understand at the time!), this is a time-delayed process - if we never turned on another engine after today, the oceans would continue to acidify for another 40 years or so. Now, there's a lot of limestone at the bottom of the ocean which buffers the system, so it's not going to get especially acidic in chemical terms, but the biological impact will be significant. Already, little plankton are having their shells etched by the acidity of sea-water, and by 2050 it will be impossible to calcify things in the sea. That has significant impacts on all sorts of things, although whether we'll be stuck with "jelly-fish and chips" is anyone's guess. Particularly, it means that corals will be unable to grow at all, which means many people will starve. Already a few million extra deaths are year are due to malnutrition attributable to climate change (either directly, or due to increased susceptibility to disease).
Many of these changes are going to happen, unless we find a way to sequester vast amounts of Carbon out of the atmosphere, and fast.
As an aside, there is controversy regarding the role of air travel in climate change. After 11/09/2001, air travel was grounded in the USA for 3 days; this resulted in a raising of air temperatures across America, as reported in Nature (PDF). Charles' view was that this might well be significant - that the cooling effect of jet contrails (which are largely water vapour) might outweigh the CO2 produced by jets. He also claimed that CO2 output by air travel was tiny compared to other sources (especially shipping, and private car use), so we should stop worrying about flying places, and instead look at the bigger CO2 sources.
All a bit disheartening, really.
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