Global Warming?

Indeed, he is not at all convinced that global warming is even a real phenomenon (please refer to this BBC article). He acknowledges that the average global temperature has risen by three tenths of a degree Fahrenheit in the past thirty years. However, he points out that during the previous thirty years, average global temperatures actually declined (the article doesn't say by how much, I presume by some fraction of a degree). He sums up his position doubting the existence of the phenomenon of global warming thusly: "I think there's only one position, and that is the position that the data leads you to". He has looked at the temperature data and he has made his determination. However, I must ask, is this the only parameter that should be considered in evaluating the presence or absence of global warming? In my opinion, the answer to this question is no.

It is a fact that glaciers all over the world have been in retreat for approximately the past 100 years. I have seen numerous examples providing photographic evidence that glaciers have retreated up mountain slopes, in some cases by miles, in the past 100 years. High altitude glaciers that occur on mountain tops in tropical regions, such as Mt. Kilimanjaro in Kenya, are expected to completely disappear within the next several decades. Glaciers in Europe that have been relatively stable in size and thickness for thousands of years have experienced dramatic reductions in size in the past 100 years. You may recall the discovery of the now famous Iceman, a stone age hunter who died high in the Italian Alps about 5000 years ago and was entombed and preserved in ice all those long years, only to be exposed by the recent rapid melting of his frozen grave.

It is not only mountain glaciers that are rapidly diminishing. The ice sheets of Greenland and Antarctica, which hold enough frozen fresh water to dramatically raise global sea levels if it were all to melt (not to the point of the somewhat ridiculous movie Waterworld, but you get the idea), have been showing some definite signs of melting much faster than falling snow can rebuild them. These gigantic ice sheets, some as much as three miles thick, are in constant slow motion. New snow falls in the interior of these huge islands. The weight if this new snow slowly compacts previous layers into ice. As more weight is added, the ice flows slowly outward toward the ocean. In the case of Greenland, the ice near the ocean is simply receding inland, exposing long ago covered rocks and soil. In the case of Antarctica, the glaciers actually extend far out to sea, in some cases, by hundreds of miles. In the past few decades, these floating glaciers have been getting thinner and the outward extent of the sea ice, which varies from winter to summer, as the ocean water freezes and thaws, has been rapidly diminishing. A few years ago, a gigantic ice berg over 100 miles long and 20 miles wide broke off of one of these huge Antarctic ice sheets and is currently drifting near Antarctica, as it slowly melts. Some scientists are very concerned that in the next 50 years or so, all of the floating glaciers surrounding Antarctica will thin to the point of breaking away and melting. The consequences of this potential rise in global sea levels, will be dire to low lying islands and countries like Bangladesh, much of whose land area is near to the current sea level.

There is one other area of great concern. It is the sea ice that covers much of the Arctic Ocean. Satellites have been monitoring the thickness and area of the Arctic sea ice for more that ten years. In that time, the ice has lost a significant percentage (about 20 percent, if I remember correctly) of its thickness. Also, the greatest annual winter extent of the sea ice has been getting smaller every year. Some wildlife biologists who study polar bears are very worried that large numbers of polar bears may eventually die of starvation because their habit of hunting on the pack ice during the winter is becoming increasingly difficult as the area of ice coverage continues to diminish.

Ok, the facts so far are that the global average temperature has increased slightly and the Earth's volume of frozen water has been measurably reduced. Any first year chemistry student should be able to deduce a possible correlation between these two sets of data. It takes heat to melt ice. It is quite possible that the phenomenon of global warming has been masked because the increase in atmospheric heating, caused by the greenhouse effect of carbon dioxide trapping infrared radiation from the sun, is being counterbalanced by the melting of ice.

Now lets consider one additional set of data. Michael Crichton apparently only considers atmospheric temperature data. I think that oceanic temperature data is also very important. The oceans role in regulating the Earth's climate is not entirely understood, however, the existence of vast oceanic currents has been known for at least 200 years. It was Ben Franklin, the noted scientist and American revolutionary thinker, who discovered the Gulf Stream, the giant river of warm water which flows from the tropics up the eastern seaboard of the U.S. and Canada and then across the Atlantic past Iceland and on to England. It is this gigantic conveyor belt of heat that makes life so much more pleasant and tolerable in northwestern Europe. During the 20th century, oceanic scientists discovered that the Pacific Ocean experiences a periodic oscillation of warm water from one side of the ocean to the other, from east to west and then back again. When this large area of warm water returns to the eastern side of the Pacific Ocean, off the coast of Baja California, a phenomenon called El Nino occurs. The presence or absence of El Nino can have dramatic effects on the weather of the entire United States, Mexico, and Central America. In the past twenty years, the period of years between the recurrence of El Nino events has been growing smaller. This strongly suggests that the oscillation of the warm water from one side of the ocean to the other and back again is gaining speed. This would indicate, to a student of physics, that the system is gaining energy. Assuming that the oceans are absorbing heat energy from the atmosphere, it is possible that the oceans, like the ice, could be playing a role in masking the existence of global warming.

There are two potentially disastrous problems associated with the melting of ice, and the increase of oceanic water temperatures, respectively. Lets consider the effect of the melting of fresh water ice from Greenland and the Arctic Ocean first. Scientists who have studied the mechanism that drives the Gulf Stream, have discovered that there are huge columns of water in the North Atlantic in which the salinity (salt content) is much higher than the average oceanic salinity. Water with higher salinity is heavier than water with lower salinity, and thus it sinks. These columns of saline enriched water are continuously regenerated by evaporation from the ocean's surface. The sinking of these columns of "heavier" water is the engine that drives the circular flow of the Gulf Stream around the Northern Hemispheric Atlantic Ocean. The problem with adding large quantities of fresh water from the melting of Greenland's ice sheet and the melting of Arctic ice, is that the North Atlantic will become gradually less saline. There may be a point at which the water will simply stop sinking and the Gulf Stream will stop flowing. Ironically, this could actually be the same mechanism which in the past has been the triggering cause of new ice ages.

The second potential disaster involves a substance called methane hydrate. This is a frozen combination of methane and water that occurs in huge deposits on sea floors all over the world. If a chunk of methane hydrate is brought to the surface and allowed to warm up to air temperature, it will simply melt and evaporate. Or, it can actually be set on fire, burning slowly until all the methane has been consumed. What is important about methane is that it is a very potent greenhouse gas. If huge amounts of methane were suddenly released into the atmosphere, it could cause a very dramatic increase in global atmospheric temperatures. Some oceanic scientists are concerned that if the water temperature of the oceans rise enough, huge amounts of methane hydrate may melt and separate into water and methane. The resultant release of this methane would cause a significant increase in the Earth's average atmospheric temperature.

So, we may be faced with the potential of a new ice age, or perhaps a very uncomfortable increase in temperature, or maybe some bizarre combination of both. Certainly, not all the facts are in and more data needs to be collected before we can make accurate predictions about what will actually occur as a result of the continued increases in atmospheric greenhouse gasses that human beings are producing. However, wouldn't it be far more wise to err on the side of caution and take strong steps to reduce the emission of gases like CO2 into the world's atmosphere, rather than wait and do nothing, as Michael Crichton suggests? I think that we should be proactive and do everything we can as soon as possible. If we do nothing, our descendants may be very very angry with us. What do you think?