The smooth meshing of the carbon cycle's many parts depends on large quantities of carbon being withdrawn from the atmosphere and stored in forests, oceans, underground deposits of coal, natural gas and petroleum.

Sadly, the human animal has disrupted this fine balance by releasing carbon prematurely from these reservoirs, beginning with the burning of forests. This trend has been accelerated by the burning of fossil fuels which has flooded the atmosphere with enough carbon dioxide to affect global climate.

Present estimates are that humanity dumps roughly 8.5 billion metric tons of carbon into the atmosphere each year. This comprises 6.5 billion tons from fossil fuels and 1.5 billion tons from deforestation. However, only 3.2 billion tons remains in the atmosphere to warm the planet. Research continues to suggest that forests, grasslands, and the waters of the ocean are acting as carbon sinks, taking back roughly half the carbon dioxide that we emit. In doing this, they slow the build-up of  carbon dioxide in the air and delaying the effects on climate. In this context the term "sink" is taken to be a reservoir that uptakes a chemical element or compound from another part of its cycle - for example, the absorption of billions of tons of carbon in the form of CO2 by oceans, soils, and trees.

The problem is, however, that scientists cannot be sure how long this situation will last. The capacity of the oceans, soils, and trees to continually absorb carbon is obviously limited and the concern is that the forests and other ecosystems may change from carbon sinks to carbon sources and, in doing so, release more carbon into the atmosphere than they absorb. The ramifications of this happening are quite frightening, as even mild changes in the pattern of global warming will produce scorching hot summers, fiercer storms and altered rainfall patterns.

Clearly the fundamental concern is the ability of the forests and other ecosystems remain as carbon sinks rather than to become carbon sources and, in doing so, release more carbon into the atmosphere than they absorb. Once this happens we are in very serious trouble.

Certainly one would hope for a solution in terms of a lowering of greenhouse gas emission, although in this respect, the non ratification of the Kyoto Protocol by several major industrialized nations, is a major disappointment. On the other hand, an extensive program of forestation would provide excellent carbon sinks, as growing forests have the capacity to absorb large quantities of carbon. In any event, one should hope that we can soon be on the road to solving this very significant problem.

The Taylor Glacier in Antarctica

Photo: British Antarctic Survey/Professor Robert Carter

In order to gain a greater understanding of the impact of global warming on the ice regions of the North and South Poles, scientists have concentrated much of their research in this area. European scientists recently revealed that they had obtained an ice core from Antarctica that extends back 740,000 years. This core spans eight previous ice ages and eight warmer interglacial periods. A subsequent report from Australian researchers indicated that they had now drilled deep into marine sediments off the coast near Christchurch, New Zealand, that were deposited by glaciers in the New Zealand alps. This record of climate change goes back much further than the ice core, almost 4 million years. Many researchers are firmly of the view that understanding what has happened in the past to the climate is the only way to predict its future accurately.

More than a million years ago, ice ages waxed and waned on a 40,000 year cycle. In the past half a million years, these cycles have become about a 100,000 years long, with colder glacials and much warm inter-glacials lasting only about 10,000 years. The complicating factor, however, is human intervention and the increasing level of greenhouse gases.

Australian researchers have also been studying the Antarctic ecosystem gathering information on how its ecosystem functions as a baseline indicator for detecting and predicting possible impacts on global change. This involves measuring the feeding rates of animals found under ice such as sponges and comparing areas that were exposed to light after the summer ice breakout with those where there was still ice cover even at the height of summer.

Primarily findings were that if global warming resulted in loss of ice cover, there would be significant changes to the underwater ecosystem in that algae will out compete other organism if given enough light. Some theories suggest that if the oceans' temperature increases, all the plankton, which is anything floating in the water at the whim of the currents, is going to downsize and the smaller organisms that exist now will do better. This would certainly benefit some animals such as sponges, because they really only feed on ultra plankton in other words the very tiny stuff. Other animals and plants, however, such as scallops and oysters, feed on much bigger particles, and thus will be disadvantaged. This will obviously impact on others further along the food chain and may have significant implications in a broader sense. 

In the Arctic region, the vaulting heap of ice that is the Greenland icecap and the swirling seas nearby have emerged as vital pieces of a puzzle posed by global warming. Each piece of this puzzle is a dynamic and complicated body of water. In this region, the North Atlantic is about three kilometers deep and liquid and the icecap is three kilometers high and solid. Experts say that the ice and waters here are in a state of profound flux and if the trend continues, they could result in higher sea levels and widespread coastal flooding.

In the past few years, Greenland's melting zone has extended to elevations of almost two kilometers high in some places. Recent measurements by NASA scientists show that such melting can have dramatic effects on the ice sheet, with melted water percolating thousands of meters down through fissures and allowing the ice to slide more easily over the bedrock below, accelerating its march to the sea. Indeed, many oceanographers say that global warming may already be pushing the North Atlantic toward instability with waters deep in the north Atlantic and Arctic become significantly fresher, matched by growing saltiness in the tropical Atlantic.

In past millenniums when such oceanic breakdown occurred, the climate across much of the Northern Hemisphere changed dramatically with deep chilled and abrupt shift in patterns of precipitation and drought from Europe to Venezuela. It is unclear whether the new melting will result in something similar. Certainly, the gaps in understanding are enormous, but Greenland is being monitored and measured as never before by satellite, aircraft and scientists braving the 30-below-zero temperatures.

Scientists and researchers do agree that, if Greenland melts, it would raise sea levels by six meters. This would mean the end of so many of our Pacific Islands, along with Florida, the Mississippi embayment, Manhattan and Bangladesh.