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Glaciers & Global Warming |
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Snow falling on more snow. For thousands of years. This is how a glacier is formed... A glacier advances Glaciers are open systems that take moisture, store it as ice and send it back to the atmosphere.
Input:
Output: Through evaporation or ‘ablation’ of ice,
Under the pressure of its weight and gravity, the glacier moves or flows. It begins to slide at its base, that has a thin layer of water. Sometimes, it cracks up on the slope due to rapid melting. As it advances, it erodes rocks and deposits ice. At one point, the glacier stops growing and begins to move, in retreat... Glacier landforms Through advance and retreat, glaciers jostle debris and sculpt glacier landscapes. Cirques form when glaciers erode backwards, creating rounded hollows on the mountainside. Those that carve valleys along coasts are fjords. Glaciers originate on a mountain and flow down valleys. When they extend to the plains, they are piedmont glaciers. When they meet between two valleys, they form valley glaciers. If the valley glacier reaches the sea and forms small icebergs, it erodes. A wave action follows and forms a tide glacier. Sometimes, glaciers leave rocky material like till as they retreat. The debris are used to study ancient climates...
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Glaciers can be found anywhere, in every continent. Even in Africa. But like you have seen in the previous page, they need some specific climatic conditions to exist—high rainfall in winter and cool temperatures in summer. So they are mainly concentrated in regions above the snow line. In mountainous areas or the polar regions. However, snow line occurs at different altitudes: in Washington State the snow line is around 1600 metres, while in Africa it is over 5100 metres, and in Antarctica it is at sea level. Glaciers, say scientists, are remnants from the last Ice Age, when ice covered nearly 32 percent of the land, and 30 percent of the oceans. What is an Ice Age? It occurs when the planet experiences ‘ice-cool’ temperature for long stretches of time. These periods last long enough to make polar ice reach down to lower latitudes. For example, during the last Ice Age, giant glacial ice sheets extended from the poles to cover most of Canada, all of New England, much of the upper Midwest, large areas of Alaska, most of Greenland, Iceland, Svalbard and other Arctic islands, Scandinavia, much of Great Britain and Ireland, and the northwestern part of the former Soviet Union. Within the past 750,000 years, scientists know that there have been eight Ice Age cycles. They are punctuated by warmer bouts—called interglacial periods. Currently, the Earth is nearing the end of an interglacial, meaning that another Ice Age is due in a few thousand years. This is part of the normal climate variation cycle. Frozen links…to past and future
In this way, past eras can be reconstructed, showing how and why climate changed, and how it might change in the future. Ice cores have been taken from around the world, including Peru, Canada, Greenland, Antarctica, Europe, and Asia. Scientists have analysed various components of cores, particularly the trapped air bubbles. Just think about it. Glaciers actually preserve bits of atmosphere from thousands of years ago in these tiny air bubbles! Reaching the melting point Absolutely fascinating, right? The bad news is, if glaciers are the ‘crystal balls’ to read the future of global climate, they paint a horribly alarming picture for Planet Earth. Since the early 20th century, with few exceptions, glaciers around the world have been shrinking at unprecedented rates. In fact, some ice caps, glaciers and even an ice shelf have disappeared altogether in this century. Many more are retreating so rapidly that they may vanish within a matter of decades.
What triggers this ‘Melt’? Build up of greenhouse gases (GHGs)—the major ones being carbon dioxide, methane and water vapour in atmosphere, say scientists. They heat up the Earth like a garden greenhouse. The Earth’s surface temperature increases, glaciers melt as a result of the rising heat, and cause oceans to slowly creep up and swallow low-lying islands. Nature had, of course, provided an in-built solution to this problem. The Earth’s ecological sinks — its oceans and vegetation— have the capacity to absorb the harmful gases. When GHG emissions exceed the cleansing capacity of these ‘carbon sinks’, global warming crosses its limit. And we have crossed this limit. Many times over. Cores drilled through a glacier in the high Tibetan Plateau reveal that the last 50 years were the warmest in 1,000 years.
“In the last 100 years alone, the global mean temperature has increased by about 0.5 to 1° C ... and the rapid receding of glaciers, to a major extent, is a consequence of global warming,” says Jagdish Bahadur, a leading glaciologist and former joint advisor at the Department of Science and Technology, New Delhi. |
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The cores say more. In the late 18th Century, there were at least eight major droughts caused by a failure of the South Asian monsoon in this region (now a part of India). Then the dry spell lasted for seven years, and more than six hundred thousand people died here. In a similar situation, now, with a population of over six billion people, the scale of disaster would be far far higher. Scientists predict worse if concentrations of GHGs continue to build up in Earth’s atmosphere. In fact, the damages are evident already. “Glaciers in the Himalaya are receding faster than anywhere else, and if the present rate continues, the likelihood of them disappearing by the year 2035 is very high,” says the International Commission for Snow and Ice ( ICSI ) in its recent study on Asian glaciers. “But if the Earth keeps getting warmer at the current rate, it might happen much sooner,” says Syed Iqbal Hasnain of the School of Environmental Sciences, Jawaharlal Nehru University, New Delhi. And the doomsday prophecies are coming true. Over the last 25 years, the Gangotri glacier has shrunk more than 850 metres, with a recession of 76 metres from 1996 to 1999 alone! Now let us consider how this melt down is going to affect the global climate: The most critical link between glaciers and climate is maintaining the earth’s water balance. In fact, glacier melt has contributed as much as 30 per cent of sea level change in the 20th century. Alaska’s melting glaciers, sea ice, and a type of frozen soil called permafrost are adding an extra 0.3 millimetre an year to the depth of oceans. Between the 1950s and 1990s, Alaskan glaciers contributed only half that much water. If drastic steps are not taken, the world can expect sea levels to rise by 19-86 cm by 2100. This will spell doom for small island states and low-lying deltas like Bangladesh and Egypt. There will be dramatic changes in weather patterns. Storms and hurricanes will become more frequent. Threats of natural hazards, ranging from cloudbursts, avalanches, landslides, to glacial lake outburst floods (GLOFs), mudflows and earthquakes will intensify. GHGs…what’s the source? All this sounds pretty familiar, right? Even though we have been talking in the future tense, the world already seems to be in the throes of this catastrophe! Are we prepared to deal with this crisis? Have we, the global community, taken some steps already? But before we take stock of that, lets find out a little more about the main culprits—the greenhouse gases.
Before the industrial era (1750-1800) the CO2 concentration in the Earth’s atmosphere was 280 ppm (parts per million) and today it is around 375 ppm. Add to this the presence of the other GHGs and you can begin to gauge how explosive the situation really is.
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Also, the richer a country, the more it emits. Because, the use of fossil fuels is, unfortunately, closely linked with economic growth and lifestyle. As a nation grows more prosperous, its consumption of fuel — for transport, power generation and various other so-called ‘necessities’ of life — zooms up, too. So, in today’s world, any limit on carbon emissions amounts to a limit on economic growth. No wonder the ongoing international negotiations under the UN Framework Convention on Climate Change ( UNFCCC)see box on Warm Terms) — aimed at cutting down GHG emissions — have turned into a tug of war between the developed (read rich) and the developing nations (ranging from middle-class to poor). While the rich are unwilling to tone down their lifestyle, countries in the opposite camp refuse to take on emission cut at their current stage of development. Developing countries like India, are demanding their space to ‘grow’. Asking them to reduce carbon emissions now, amounts to asking them to freeze their standards of living as they stand today. This, in fact, amounts to freezing global inequality. Because, in that case, some countries will always be more developed than the rest.
Why should they accept that?, Especially since the Unites States — the largest emitter of them all — still refuses to make a firm commitment to cut its use of carbon-based fuels. So the stalemate continues. But the heat is on. Not only on the glaciers, but on every living organism in this planet. What can be the way out of this carbon-mess? The richer nations must take more responsibility, and cut down carbon use drastically. Because in a way, global warming is their creation. Every human being in this planet has an equal right to atmosphere, and the people in these countries have used more than their share of absorptive capacity. Just sample this. In early 1990s (when the world community first began to pay heed to the alarm signals) the GHG emission of one US citizen was equal to 19 Indians, 30 Pakistanis, 17 Maldivians and 107 Bangladeshis!
Since the Earth’s cleansing capacity belongs to every human being on Earth, the carbon sinks must be divided among them equally. So the ‘sinks’, specially the oceans, which do not belong to any particular country, but are ‘common property of mankind’ should be apportioned on the basis of the country’s share of population. This would encourage the developing
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Because glaciers are so sensitive to changes in temperature, they are used as barometers by scientists. To study ‘paleoclimatic data’, that is, climatic conditions of the past ages. And to find vital clues to what may happen in the future. To see a long-term climate record an ice core is drilled and extracted from the glacier. Ice cores are long cylinders that are carved out of ice sheets. Since each layer (consisting of dust, air, sediment particles) in the ice core corresponds to one year, the frozen archives tell us that there have been several Ice Ages.
GHGs are produced by carbon-based ‘fossil’ fuels like coal, gas and oil. And as we all know, these are the fuels which run factories, cars and power stations around the world. In other words, they drive the economy of every country in this planet! Scientists trace the phenomenon of glacial retreat to the Industrial Revolution, which began around 1760.
The belching rich 