Ice

I am not quite sure what to call this post as it is likely to end up jumping all over the place but seeing as ice should feature in all of the things I am going to try to explain I thought that it would do.

Firstly I am going to discuss albedo. Albedo is a measure of the reflectivity of different objects and surfaces on the earth and the lower the number the more energy that is absorbed, which is believed to contribute to global environmental climate change (or what ever the new term for global warming is). The most reflective surfaces are snow and ice, which have the ability to reflect as much as 90% of the sun's energy back to space. Black carbon (I think it is practically that same as soot) is considered to be one of the largest contributors to climate change, even though unlike all of the other polluntants it is not a gas and it is the shortest lived as once we stop emitting it, it would stop trapping heat in the atmosphere within a couple of weeks. If this is true, then why is black carbon emissions so potentially problematic and what is its link to albedo? Well, black carbon has been closely linked with the acceleration of the melting of ice and snow around the world and thereby a reduction in albedo. The largest source of black carbon is from the burning of biomass which occurs a lot in Brazil, Indonesia, Central Africa and this accompanied with the black carbon produced in Siberia and Eastern Europe by forest fires and the seasonal burning of ground cover has contributed greatly to the progressive disappearance of the Arctic's sea ice cover, as the prevailing winds have carried this polluntant to the Arctic. This is also effecting the Himalayan glaciers. It is believed that 20% of the black carbon in the atmosphere is the result of burning wood, dung and crop residues for household cooking and heating in India. The increasing use of coal-fired power stations in China has added to the black carbon that it produced in this region and, due to the seasonal weather patterns experienced, black carbon poses a particular threat to both India and China. The Indian subcontinent normally experiences 6 months lacking in rain surrounded either side by monsoon seasons and this temperature inversion (a situation where the temperature of the air in the lower troposphere (the lowest layer of the earth's atmosphere) increases with height), which forms over much of South Asia during that period, traps the black carbon above the glaciers and snow of the Himalayas and the Tibetan Plateau. When the black carbon falls on the glaciers, it darkens their surface which causes the snow and ice to absorb the sunlight instead of reflecting it (basically it reduces its albedo) which accelerates the rate of melting. Not only is this likely to present huge issues surrounding water supplies for countries like India, Bangladesh and China who rely on the seasonal melting of the glaciers, for example 70% of the water flowing in the Ganges comes from the melting of ice and snow in the Himalayas, but also that it is reducing the earths natural ability to reflect the sun's energy. The results of a 30 year study of the Northern Hemisphere's albedo was recently published and it suggests that the reduction is albedo due to snow and ice loss is more than double than previously thought. The study involved comparing the model estimates of changes in the Northern Hemisphere's cryosphere (portions of the earth where water is in its solid form e.g sea ice, glaciers, permafrost etc.) with the changes in actual snow, ice and albedo measurements over the same period. The study concluded that, during the 30 year period, cryosphere cooling in the Northern Hemisphere declined by 0.45 watts per square metre and that, on average, for every degree of warming 0.6 fewer watts of solar radiation, per square metre, are reflected to space due to reduced snow and sea ice coverage. The reduction in albedo across the global is increasingly worrying scientists who have seriously considered proposing that all building roofs should be painted white to try and imitate the role that ice and snow play in reflecting solar energy to accompany plans to reduce black carbon emissions. However, as densely populated countries such as India and China continue to develop reductions in the global emissions of black carbon are going to be increasingly hard to meet because the burning of coal and biomass are the largest contributors to the production of black carbon.

I am going to go back to the Himalayan glaciers again but this time in reference to the recent publication of research that suggests that debris on the Himalayan glaciers may be helping to keep them intact. The new research suggests that debris such as rocks and pebbles may help to shield glaciers in the Himalayas from the solar energy and therefore slow the rate at which they are melting. The research that was carried out between 2000 and 2008 on 286 glaciers between the Hindu Kush on the Afghanistan-Pakistan border and Bhutan, disovered that half of the studied glaciers in the northwestern regions of the Himalayas were stable whereas two thirds, elsewhere in the region where in retreat. Retreat rates were also found to be high on the Tibetan Plateau, an area that lacks in debris. The scientists have attributed this difference to the amount of debris present on glaciers and they concluded that debris, in the form of rocks and pebbles, has the opposite effect on glaciers to black carbon and dust. It is hoped that this research could help to explain why glaciers in the Himalaya's haven't all responded in the same way to rising atmospheric temperatures and therefore possibly make it easier for us to predict how glaciers are going to respond to changes in atmospheric temperatures in the future which may enable us to predict the impact that the melting of the Himalayan glaciers will have on the people of China and India.

It is a well known fact that the melting of earth's ice sheets could play havoc with sea levels but to what extent has often be debated. The most recent report (sorry - I realise that this post has involved lots of 'recent reports') by the Intergovernmental Panel on Climate Change suggested that sea levels, before taking into account the Greenland and Antarctic ice sheets, could rise by between 18 and 59 centimetres by 2100. Another report, that did include the ice sheets of Greenland and the Antarctic claim that sea levels woudl rise globally by 56 centimetres by 2100. This prediction was calculated by using NASA satellites to estimate the changes in the ice mass by measuring earth's gravity field over Greenland and Antarctica (the gravity field is apparently affected by changes in ice mass - don't ask me how) and by using monthly measurements of glacier movement and ice thickness. Both reports seemed to produce similar predictions and they also noth agreed that the rate of loss of ice is increasing by 36 gigatonnes a year which is roughly three times as fast as the rate of loss from mountain glaciers and ice caps. However the melting of glaciers and ice caps should not be overlooked as it is estimated that melt from mountain glaciers and ice caps will contribute around 12 centimetres to global sea levels by 2100.

From all of the above I think that it is clear to see that the melting of ice has the potential to have catastrophic human consequences from displacing millions due to rising sea levels and hugely influencing th ewater supply of the most densely populated countries in the world and that little is still known about patterns to glacier melts and why some respond differently to changes in atmospheric temperatures.

Sorry it is all over the place and a bit brief but I hope some of you might have found it vaguely interesting. I am ensure as to whether or not it links to any of the Geography ones or not - perhaps one to do with climate change - but even if it doesn't I think it is quite interesting to see what research is being conducted in terms if ice sheets and glaciers and the effects that human activities have on them.