This week at the Exeter MOOC that looks at ‘Climate Change’ and its complexity we first looked at the impact of global warming on ice sheets, glaciers and sea ice. Understanding how the warming earth disturbs, amplifies or changes the natural processes of glacier calving and ice sheet melting is really critical. We are depending on this when we estimate how fast and how high sea levels will rise in the coming years. If all the ice sheets melt the sea rise would be 65m but of course that will take quite a long time. Even so with many people living at elevations little more the a meter or two above sea level things will get a bit uncomfortable. Understanding how the glaciers behave will also be critical for understanding the fresh water cycles I think, countries in Asia with high populations and huge rivers may well be put under threat because many of the Asian rivers are fed by Himalayan glacial meltwater. We were given web addresses that showed photographic evidence of a massive decrease in the size of the Himalayan glaciers. There were panoramic photographs taken by the British in the 1920s and again in recent years the glaciers have been photographed from the same positions. Side by side (or actually one above the other) they make a sobering comment on the future.
Glacierworks:Everest is definitely worth exploring.
Well that was the first half of the week and the second half was just as challenging because we now started to look at the effects of CO2 being absorbed into the ocean. This is quite a complex thing to get your head around as well.
It involves a bit of chemistry but not too much because I could follow most of it (I think) and chemistry was never my strong point. It works like this … the CO2 dissolves in the sea water and forms a weak acid which then dissociates into free H (hydrogen) ions and carbonates. The carbonates would normally be available to be combined with calcium and used to form the shells of the tiny sea creatures at the bottom of the food chain, but if the environment is made more acidic by an excessive amount of free hydrogen ions the process starts to fail. The acidity in the ocean starts to damage the shells of the tiny phytoplankton and pteropods that form the basis of the ocean food chain and it also makes it much harder for their shells to form. I think of this as being similar to plant sensitivity to soil ph, for example many vegetables can only access nutrients within a certain ph range and we can test our soils and adjust them if necessary. Pity we can’t do that with the ocean.
This ocean acidification is one big long term threat to the ocean food chain and all the people that depend on reefs, estuaries, lakes and inlets, fishing and aquaculture for much of their protein, sport and relaxation. We all need to worry.
Andrew Glikson mentions something called “serpentine sequestration” but all I could find on that was a rather heavy paper from Bath Uni which talks of capturing CO2 and reusing some of it in high tech manufacturing of polymers etc. but the paper recognises that the big problems are cost and finding enough space to sequester the CO2 once it has been captured. It seems to be another attempt at using the mind set that created the problem to attempt to solve it.
On the other hand he also speaks of using soil carbon and a world wide effort to sequester carbon in forests and agricultural projects. And of course we must cut our emissions to Zero ASAP.