Mr. Pastirik's Daily Log 26 November 2005Take a breath. It is actually a wondrous thing that we take for granted. The blue sky with its readily available life-sustaining oxygen found in the air wasn’t always there.
Our planet formed, give or take, about five billion years ago from remnant dust of an exploded star. In effect, we are made up of recycled star waste. Our planet was molten for a while because of the heat generated by the impacts of falling comets, meteors and asteroids. One impact was so large that some of the planet was ejected and became our moon. At some point, the bombardment slowed down, and while it has not entirely stopped, occurs rarely in significant form, and an atmosphere formed. The atmosphere that surrounded early earth would have been deadly to us, but not to original life. Still, life developed, perhaps deep in primordial oceans, deep in rocks or some other place. Original life did not have the wonderful adaptations, interesting life-styles and exquisite beauty we associate with life now. Rather, it was very hardy, small, not very interesting to look at, and hungry. Hungry is important. Hungry things have to eat, and as their numbers increased the food supply dwindled. Starvation was a great possibility. Then, one cell made a mistake (called a mutation) when it was reproducing (making another one of its kind). It developed the ability to make its own food using sunlight. Other cells had made their own food before using energy found in chemicals (primarily sulfur), but this cell made its own food using sunlight. Sunlight, then, like now, is cheap and plentiful. This cell used the energy of the sun in a molecule called chlorophyll to combine the simple molecules of carbon dioxide and water to form a simple sugar called glucose. We all know of the energy found in sugars, just look at a group of kindergarteners after snack! This process, the formation of sugar from light and the building blocks of water and carbon dioxide, is called photosynthesis (light-building).
Interestingly enough, a product of photosynthesis is oxygen! For nearly all organisms found on the earth in the distant past, oxygen was a bad thing because it was a poisonous pollutant. Many died, and in effect a mass extinction occurred. Still, life survived, and since then, there has been a basic and everlasting struggle between organisms that make their own food (autotrophs; self-feeders; primarily plants) and those that can not make their own food (heterotrophs; other feeders; primarily animals, fungi, etc.).
Heterotrophs eat autotrophs to gain access to their stored energy sources and other nutrients, and in the process break down the sugars in a process called respiration releasing carbon dioxide and water. Thus, the carbon cycle is formed.
Carbon in the form of carbon dioxide is taken up by plants, and stored as sugar. Animals eat plants (thereby tapping the energy of the sun) and release carbon dioxide back into the atmosphere. As an aside, struggles occur between heterotrophs because food sources are often scarce, and autotrophs can compete against one another for exposure to sunlight, or access to water, etc. This struggle and the original struggle between autotrophs and heterotrophs is called evolution and is driven by natural selection. Evolution, by the process of natural selection driven by genetic change, is the cause for all the varied life forms found on our planet.
The oxygen released by these proto-plants began to change our planet. At first, the oxygen was taken up by the available iron and the planet, in effect, rusted. At some point, there was not enough iron and other metals to rust, and oxygen began to fill our atmosphere. Skies began to gain our familiar blue color, but life on earth’s surface was still, at best, difficult. Harmful radiation still pounded earth’s surface in the form of Ultra-violet (UV radiation). Early life, like life today, is very sensitive to UV radiation. However, oxygen would come to our rescue. Some oxygen, in what would become our stratosphere combined in threes instead of pairs. This three form part of oxygen is called ozone. Ozone blocks UV radiation from striking the surface of earth, and allowed life to rise to the surface of the oceans and spread to the land surface. The ozone found above the troposphere in the stratosphere has been dubbed the ozone layer, and has been much in the news due to its destruction by man-made chemicals named chlorinated fluoro- carbons (CFCs). Ozone is ozone, hazardous to us when we inhale it, but our protector high above us! The ozone hole (thinning or elimination of the protective ozone layer) above the poles (primarily the South Pole) is a cause for alarm. While initially a surprise, governments quickly recognized the need to preserve our ozone layer and damaging CFCs have been banned and replaced. Remember, UV doesn’t just cause sunburn, and contribute to cataracts, it kills life including plants. It is plants that form the basis of nearly all life on earth.
Over eons, life diversified and competed. Competition pit organisms against one another, and occurred against the background of a changing environment. Nearly 99 % of all the life forms that have existed on earth are now extinct. Some of these extinctions have been catastrophic and massive like the extinction of the dinosaurs that occurred about 65 million years ago, but most have been quiet deaths. The only evidence we have for most life forms are fossils, and even here the evidence is sketchy, because fossils best come from the hard parts such as bones, teeth, and shells. Animals with hard parts became widespread about 600 million years ago during the time period called the Cambrian. There is evidence of life before this time, but it is not quite so dramatic.
For scientists, fossils have given evidence about the climate of the earth. Even tree rings, both fossilized and recently cut trees, give evidence about climate. For example, trees with thick growth rings indicate a benevolent climate; warm, sunny, readily available sunlight, etc. This indicates a warm planet, or at the minimum a location on earth that is warm such as a tropical setting (sounds real good writing from Antarctica). Other clues about earth’s climate come from a variety of sources including glaciers and their effects on the land’s surface. Evidence about the distant past is found in rock, while more recent evidence is found locked away in the frozen ice of Greenland and Antarctica. The gases found trapped in the earth’s Polar Regions have been used to show the relationship between greenhouse gases (again, our familiar carbon dioxide) and the earth’s average temperature. The ice found overlaying Antarctica averages more than two miles in thickness, and at a rate of 4-5 inches of snowfall a year. The gases found trapped in the ice give evidence about earth’s atmosphere for quite an extended period of time.
Climatologists, glaciologists, paleontologists, and other scientists have clear evidence relating the amount of atmospheric certain gases and earth’s climate. For example, increased carbon dioxide levels are associated with warmer climates. When I queried a climatologist about our recent warm summers, he said it wasn’t warm summers that concerned him, but warm winters. It is during winter that ice freezes, glaciers grow, etc. If winters aren’t cold, then these things don’t happen, glaciers melt and polar ice sheets shrink. Evidence for glacial melting is plentiful, and study is ongoing as with regards to the polar ice. Melting glaciers mean an increase in sea level with its devastating effects on coastal cities, etc. and increased atmospheric water results in the probability of an increased number and ferocity of storms. If the climate shifts, so will agricultural belts, and in some climate models the American West becomes even drier and primary food producing regions will move northward into Canada. The U.S. would then be a net importer of food. This would dramatically alter our economic position in the world. Other scenarios indicate that warmer climates will open up vast areas for the movement of tropical diseases into regions that do not have them yet. An atmospheric scientist said to me that humans are in the process of running an experiment with the earth’s atmosphere by the unrelenting and ever-growing burning of “fossil fuels” (coal, oil and natural gas) and its subsequent release of carbon dioxide.
In addition to the burning of fossil fuels, climate change is affected by deforestation and agricultural practices that promote the production of other atmospheric gases such as methane (”natural gas”). Natural gas is a byproduct of cow digestion caused by the digestion of the plants it eats. Bluntly, cows poot natural gas. Natural gas has even a greater effect than carbon dioxide on climate. Interestingly enough, water is a green house gas too. If you doubt water’s heat trapping ability, think about how easy it is to cool oneself on a dry day as opposed to a humid day. It was summed up to me in a recent trip to Las Vegas that it is so much more comfortable here because it is dry heat (at literally, 120 degrees Fahrenheit).
This rambling brings me to the focus of the reason scientists are studying atmospheric gases here as opposed to Tahiti. Antarctica is incredibly cold because most of the continent experiences a prolonged period of darkness during winter. For example, at McMurdo, where I am, we are in summer and the sun is up twenty-four hours of the day. The days are relatively warm (20 degrees F), and will get a bit warmer as the summer season progresses. The sun will set here on February 20, 2006, and the long, cold, dark polar winter (with the opportunity for one to see the auroras, and do lots of great astronomy) will begin. Months later, the sun will rise and summer will return.
During daylight, sunlight strikes the earth and is absorbed. Then, energy of the sun is released back into the atmosphere (and ultimately outer space) in the form of infra-red (IR) radiation (heat). Some of this heat is trapped in our atmosphere by greenhouse gases (which are great and necessary up to a point, otherwise we would freeze!) Scientists studying earth’s climate have made assumptions and created models that help them understand atmospheric chemistry and its relationship to climate. Recent work by ANTCI scientists has brought into question aspects (not the major ideas given above) about some assumptions made as to the interpretation of climate models that depend on ice cores. It turns out that in the ice surface, is not a static place chemically. The energy of the sun is promoting reactions (primarily of those compounds containing nitrogen; but all chemical reactions are linked together in cycles forming something not unlike a giant web of chemical interaction) that were not anticipated, and the “ice” appears to be surprisingly active chemically. This activity could modify beliefs concerning the reactivity of certain chemicals found in and above the ice’s surface need. If this is so, then ice core samples will need reexamining, and climate models could be modified. I don’t know if major media outlets will report on the workings of ANTCI scientists, but their work is necessary to our total understanding of earth’s atmosphere. They are working in the realm of pure science.
You can exhale now, but appreciate it!
McMurdo’s Turkey Trot was canceled today because of snow. Don’t ask me, but I thought if any place on earth would be relatively unaffected by winter conditions, this would be it. So, instead of the race/walk I am going to take a walk before Thanksgiving dinner.
The feast follows, and then I am off to wash pots and pans for my holiday volunteer effort. I am done writing for the day. Be well, and take care of one another. mp