Yes, history has shown that there has been global climate changes that were not brought about by human activities; but—and this is a big but—human activity is accelerating global change and not for the better.
Len Calderone for | AltEnergyMag
Climate change is a reality, presenting great dangers, but it is also an opportunity for us to make a difference. Most of us are in support of a switch to clean or alternative energy. We just need to accelerate the transition.
With today's knowledge, we all can take action to reduce the effects of climate change from changing to new efficient light bulbs to sharing information with friends and family. What will a clean energy future look like? What’s at stake if we ignore the facts and proceed as we have in the past?
The Earth's climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era and of human civilization. Most of these climate changes can be attributed to very small variations in the Earth’s orbit that change the amount of solar energy our planet receives.
Today's climate is actually a warm interval between these many periods of glaciations. The most recent period of glaciation is what many people think of as the "Ice Age."
Between 52 and 57 million years ago, the Earth was relatively warm. Tropical conditions actually extended all the way to northern Spain or the central United States with the Polar Regions experiencing temperate climates. This warm period was followed by a long cooling trend from 36 to 20 million years ago. At this time a continental-scale temperate ice sheet emerged in East Antarctica, while in North America, the mean annual air temperature dropped by approximately 54 degrees.
If we go back even further, between 600 and 800 million years ago, evidence suggests that the Earth underwent an ice age so cold that ice sheets not only covered the polar latitudes, but may have extended all the way to sea level near the equator. Reflecting ever more sunlight back into space, the ice sheets cooled the climate and reinforced their own growth. Obviously, the Earth didn’t remain stuck in the freezer, so how did the planet thaw?
While ice sheets covered much of the Earth’s surface, tectonic plates continued to drift and collide, so volcanoes were active, emitting the greenhouse gas, carbon dioxide. In our world today, the natural weathering of silicate rock by rainfall consumes carbon dioxide over geologic time scales, but during the frigid conditions of the ice age, rainfall was rare. With volcanoes pumping out carbon dioxide and little or no rainfall to weather rocks and consume the greenhouse gas, temperatures climbed.
Stretching from about 66-34 million years ago, the Paleocene and Eocene were the first geologic eras following the end of the age of the dinosaurs that was punctuated by "hothouse" conditions. During this period, Geologists and paleontologists think that the poles were free of ice caps, and palm trees and crocodiles lived above the Arctic Circle. The transition between the two epochs around 56 million years ago was marked by a rapid spike in global temperature with the average temperature as high as 73°F. Today's average is 60°F. Climate is always changing. Ice ages have occurred in a hundred thousand year cycle for the last 700 thousand years, and warm periods that have appeared to have been warmer than today despite carbon dioxide levels being lower than they are today.
The current warming trend is of particular significance because most of it is very likely human-induced and proceeding at a rate that is unprecedented in the past 1,300 years.
The heat-trapping ability of carbon dioxide and other gases to affect the transfer of infrared energy through the atmosphere is the scientific basis of many instruments flown by NASA. There is no question that increased levels of greenhouse gases cause the Earth to warm in response.
Ice cores drawn from Greenland, Antarctica, and mountain glaciers show that the Earth’s climate changes as greenhouse gas levels change. They also explain that in the recent past, considerable changes in climate have happened very quickly, geologically speaking in tens of years, not in millions or even thousands as has happened in the past.
So, what effect does climate change have on the world? The global sea level rose about 7" in the last century doubling in the last decade compared to the last century. Most of the earth's warming has occurred since the 1970s, with the twenty warmest years having occurred since 1981 and with all ten of the warmest years occurring in the past twelve years. The oceans have absorbed much of this increased heat, showing a warming of 0.3 degrees Fahrenheit since 1969.
The mass of the Greenland and Antarctic ice sheets have decreased with Greenland losing 36 to 60 cubic miles of ice a year between 2002 and 2006, while Antarctica lost about 36 cubic miles of ice between 2002 and 2005. Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades.
Glaciers are retreating almost everywhere around the world from the Alps, Himalayas, Andes, Rockies, Alaska to Africa Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and that the snow is melting earlier.
We are paying the price for accelerated climate change with extreme droughts as experienced by California; flooding in the mid-west; wildfires destroying hundreds of acres in the West; and super-storms everywhere.
We can expect a certain amount of inevitable warming of about 2.3 degrees Fahrenheit compared to pre-industrial levels because of emissions already placed into the atmosphere. De-forestation is also contributing to the warming. We must limit warming to under 3.6 degrees Fahrenheit to prevent the worst effects of climate change. If our greenhouse gas emissions are not controlled, the speed of climate change over the next hundred years will be faster than anything known since before the dawn of civilization. We could see a sudden and irreversible climate shift, as scientists do not know how much global warming it would take to trigger such a doomsday scenario.
We need to move more quickly to alternative energy, such as wind, solar, biomass, geothermal, and hydroelectric power, along with the use of wood in new construction rather than concrete and steel. Wood buildings absorb CO2
Yes, history has shown that there has been global climate changes that were not brought about by human activities; but—and this is a big but—human activity is accelerating global change and not for the better. With a shift to alternative clean energy, we can still create a sustainable future for our children; but we have to act now.
For more information:
Len Calderone - Contributing Editor
He also writes short stores that always have a surprise ending. These can be found at http://www.smashwords.com/profile/view/Megalen.
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