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Climatic Change Causes

CLIMATE AND WEATHER

Arctic Tundra

The arctic tundra, in the far northern reaches of the Earth, around the North Pole, is characterized by low temperatures and short growing seasons. The angle of the sun's rays is always low in the tundra. Therefore, it never receivesmuch energy from the sun at any time.

Summer

In the tundra, summer lastssix to eight weeks. Summer days are very long. The long days allows enough heat from the sun to build up so that the upper layer of soilcan thaw. The lower layer of soil, known as the permafrost, is always frozen. Because melting snow cannot drain into the permafrost, water collects on the surface. Thus, in the summer, the tundra becomes covered in marshes and ponds. During this short growing season, grasses and sedges become abundant. Low mats of lichens and mosses cover large areas. Some trees, such as birches and willowsgrow close to the ground. They rarely grow more than a few centimeters tall. The leaves of most plants are small. Flowers bloom and quickly develop seeds. Arctic hares and arctic foxes can be seen in brown coats. (Their coats turn white in winter.) Reindeer, also known as caribou, are plentiful. Lemmings are also active. Snowy owls and weasels, which prey on lemmings, can be seen when the lemming population is high.

Winter

When winter arrives, ponds and lakes freeze. With short days and low temperatures, there is little energy available. Food is scarce. Living things become dependent on stored energy for survival. Almost all tundra plants are dormant in winter. Many insects remain in the egg or larval stage. Reindeer migrate southward. Many birds also travel south. Lemmings and other small animals burrow under sheltered spots in the snow, where they consume seeds and parts of plants that they stored during the summer.

Climatic Change Causes

The causes of climatic fluctuations have not yet been fully elucidated, although many different theories have been proposed. Some scientists believe that small variations in the Earth's orbit around the Sun (which would affect the intensity of solar radiation reaching the Earth) are the principal cause. But others have hypothesized that minute alterations in the Earth's tilt on its axis may cause the climatic belts to shift, thus changing the climate as a whole. It has also been suggested that long- and short-term fluctuations in the Sun's activity - those caused by the 11-year sunspot cycles, for example - may affect the climate. Changes may also occur following prolonged volcanic activity. Volcanic dust can reduce the amount of solar radiation reaching the surface, causing changes in the weather. After the eruption of Krakatoa in 1883, for example, dust stayed in the atmosphere for three years; during this period a 10 per cent fall in solar radiation was recorded in southern France. There is also some concern that major climatic changes may result from Man's activities, such as deforestation and pollution of the atmosphere.



Heating Up: Facts about Global Warming

Although often debated, most scientists will assure you that global warming is occurring on our planet earth. Global warming is a change in climate which has been resulting in higher temperatures. According to NASA, the global overall temperature has increased 1.4 degrees Fahrenheit since 1880. Human activities have increased the number of greenhouse gases, mainly carbon dioxide, in our atmosphere. Global Warming is a result of the burning of fossil fuels (emittingCO2) around the world. Fossil fuels are the main energy source for transportation worldwide. Global warming has caused a decrease in the number of glaciers and snow covered areas which has caused the world’s sea level to rise. Extreme weather patterns will become noticeable, certain species will become extinct and agriculture around the world will be affected if global warming continues at its current rate. To decrease the rate of global warming, the population of the world as whole needs to begin using less fossil fuels and more alternative fuels such as solar, wind, and hydrogen energy.


Date: 2015-12-24; view: 1151


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