Natural Climate Changes

Climate scientists have known since the eighteenth century that Earth's climate can change dramatically due to natural causes. In fact, evidence from ice cores extracted from the Arctic and Antarctic regions show that planetary temperatures have varied by more than 20 degrees Fahrenheit (11.2 degrees Celsius) during the last 350,000 years. Long periods of lower temperatures have resulted in prolonged ice ages that lasted tens of thousands of years. Approximately every 100,000 years, these cold phases have been interspersed with warmer but shorter interglacial periods. More than 18,000 years ago during the last ice age, called the Pleistocene Ice Age, massive glaciers up to eight thousand feet thick covered almost a third of the Earth's land surface, including much of North America, Europe, and Asia. Areas not covered by glaciers were largely cold and desolate deserts that supported only very hardy plant and animal life.

Within these larger climate fluctuations, smaller-scale warming and cooling cycles have historically occurred. Many of these climate changes have been abrupt, and they appear to have caused mass extinctions of large numbers of the planet's animal and plant species. The end of the dinosaur era, for example, coincided with a sudden global cooling that may have been caused by a large asteroid colliding with the Earth. Since before the dawn of human

These Pleistocene-era human footprints may have been preserved for more than 18,000 years at the height of the last ice age. During this time period, massive glaciers covered almost a third of the Earth's land surface.

These Pleistocene-era human footprints may have been preserved for more than 18,000 years at the height of the last ice age. During this time period, massive glaciers covered almost a third of the Earth's land surface.

civilization, however, the Earth has been experiencing an interglacial period of unprecedented stability, with no major climate fluctuations. Cold deserts and glaciers have given way to lush forests, grasslands, and an abundance of plant and animal species, and the human population has soared under these conditions.

Yet today's relatively stable global climate is fueled by a number of climate forces—such as volcano activity, cloud cover, the changing intensity of the sun's radiation, and varying ocean currents and temperatures—that have caused fluctuations in temperatures during the last thousand years. During the Medieval Warm Period, for example, which lasted from approximately a.d. 1000 to 1350, temperatures were warm and comfortable for humans. From around 1400 to about 1860, however, the Earth experienced what has been called the Little Ice Age—a small drop of about 0.9 degree Fahrenheit (0.5 degree Celsius) that produced harsh winters, shorter growing seasons, and a drier climate. Yet even this slightly colder period caused crop failures and other problems, including a potato famine in Ireland that reduced the Irish population by about 25 percent in just six years between 1845 and 1851.

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Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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