Introduction
One of the challenges faced by scientists is predicting the future climatic conditions. The change of climate can have a varying effect on people depending on their specific location on the surface of the earth. Some people can end up benefiting greatly because the region that they occupy could previously have been a desert only to change to a place that receives rainfall. Places (like in Africa) that have always been prone to highly infectious diseases may become better with climate change. The recent concern about global warming which is brought about by man-made greenhouses has increased the need of understanding the processes that bring about climate change. This paper looks at the process of finding out the past climate patterns by digging deep into the ice that has accumulated for hundreds of years. From these past patterns, the future climate can be predicted. There are a lot of secrets about the past climate that is hidden in the many layers of ice.
Information in ice cores
The determination of the age of the specimen (accurately) is very important when studying ice cores. The age of the ice is determined by counting the layers, which differ from summer to winter in places like Greenland. The layers are easily seen with even naked eyes. A lot of information is gotten from the layers like the climate at the time of the layer formation. The annual layering can also be found by measuring the acidity of the ice which is normally high during the summer. Layers can also be used in the determination of the dust concentration in the ice specimen. The number of dust particles tends to increase in spring due to the increased wind strength. By use of such information scientist have been able to obtain chronology that has matched with independent methods. A good example is the analysis of the ash that was found in certain layers of the ice that enabled a team of scientist to identify the type of volcanoes that were involved. Through such corroborative testing it has been proved that the counting of the yearly strata does not introduce errors of any form for the land ice which could be centuries old. The Holocene warm period has been found to be within an accuracy of 1%. This method starts becoming unreliable for very old ice but its reliability can still be counted upon up to measurement of 50 000 years old ice. The annual layers can still appear for ice which is 100,000 years but there are a lot of distortions in the layers.
The question that triggers in ones mind is what causes the distortion in the ice in the deeper layers? As much as the ice is solid with extreme pressure from the upper layers ice starts yielding and spreading out. With the continuation of the movement the ice is drawn extremely (sometimes disappearing completely) and the ice consequently crumbles when the glacier ooze on the ground below. As a result of the deformation it becomes very difficult if not impossible to count the annual layers continuously beyond a certain depth. A clear example could be the core that was obtained by a US team in Greenland. The layers changed from being horizontal to having small wiggle shapes, then showing the Z-shaped folds to being slanted.
The difference in the characteristics has shown the variation of the climate over the years. Temperature variation for example can be derived from the fact that the elements from which water is made have different isotopes which make the water either heavy or light. Light isotopes consist of ordinary hydrogen and oxygen. On the other hand, the heavy isotopes are made up of either hydrogen with an extra neutron or the oxygen will have one or two added neutrons that are denoted as oxygen 17 and oxygen 18 respectively. When the air mass is cooled with the occurrence of precipitation it results in the removal of the heavy water (due to its lower vapor pressure) from the atmosphere that has a lot of moisture. Due to the early removal of the heavy water, the snowfall in the inland areas will be made of the lighter water as the heavy water would have been squeezed out as the wind traveled overseas. The concentration of the different isotopes in ice can be to predict the temperature at which the ice piling occurred. The other method considers the current temperature of the ice at the time of drilling. This temperature is the same as the temperature of the ice at the time of deposition.
The wind-blown materials that are trapped in the ice can also give important clues about the past climate. Courser materials will indicate strong winds at the time of deposition while fine particles will suggest weak wind. The dust particles can also be used in determining the pattern of the wind that blew on the earth’s surface. The layers also could have radioactive isotopes produced in the air by cosmic rays and chemicals from the sea algae. A decrease in the concentration of the material can either be interpreted as a decrease in the supply or it could be the rate of snowfall has increased. Because in the green land the rate of the icefall can be determined scientists have been able to separate the two effects. There is also air which is normally trapped in the massive ice layers that provide vital information to the scientist. A close analysis of the air will reveal the composition of the atmosphere at the time of the ice deposition. It has been found that the occurrence of greenhouse gases has varied naturally.
Celestial effect and ice cores
The celestial effect was put forward by Milankovitch who was a Serbian astronomer who studied how gravitational pull from other planets causes changes in the orbit of the earth. The changes in the orbit cause the change in the distribution of the intensity of sunshine on the earth’s surface which in turn brings about climate changes that take tens of hundreds to thousands of years. The three orbital variables investigated were the tilt of spin, the precession of the tilt, and the eccentricity around the sun. The changes in the three parameters were cited to cause distinct oscillations whose period is about 40,000 years for the tilt, 20,000 years caused by precession, and 100,000years for the eccentricity. The studies of Milankovitch were never accepted by many scientists until when other studies of the sea bed showed that the past climatic conditions had a repetitive pattern similar to what the scientist had proposed. The studies revealed that the past few million years were characterized by a repetitive temperature variation that was accompanied by the advancement and retreating of glaciers on vast areas of land. The analysis of the Greenland ice cores, the Antarctic cores, and deep seas have agreed with Milankovitch’s astronomical theory. This agreement makes the ice core studies to be authentic.
Ice core (Green ice-core) results have also revealed the interstadial events that last from a few hundred to few thousands of years. The ice core shows that the Green land has experienced a dozen of interstadial events which were never predicted by Milankovitch theory. The Greenland ice core demonstrated an increase in methane concentration in the atmosphere during each of the interstadial events. The abruptness of the events is very intriguing as a change in temperature of up to 8 degrees Celsius, the doubling of the ice accumulation, with up to ten times increase in dust concentration. Methane production is associated with bacteria being in environments that do not have enough oxygen like the tropical swamps. The increase in methane is believed to have been caused by the expansion of the tropical wetlands. The expansion of the wetlands could have been caused by an increase in rainfall. Because the abrupt changes are caused by changes in the concentration of methane, this has sounded an alarm on the release of methane in the air. There is fear that if the activity of man continues releasing methane, carbon dioxide, and other greenhouse gases in the air there could, be drastic climate change that could be disastrous.
There are many fears that scientists have suggested things that could befall the planet if the greenhouse emission into the atmosphere is not reduced to a safe level. It is believed that it could make some of the areas which are being occupied by a man and other living things inhabitable i.e. could become too hot. The other fear is that of the Polar Regions being warmed up resulting in the melting of the snow masses. This will cause water volumes in the oceans to increase with the chances of losing the entire infrastructure at the affected coasts. This will result in loss of residence of the coast dwellers. The economies of many countries will also be affected because of losing tourist revenue. This will be caused by the fact that most tourist destinations are at the coasts and when the infrastructure is lost the industry will go with it.
References
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