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Natural Perspectives: The big bad wolf is back in Yellowstone

October 09, 2012|By Vic Leipzig and Lou Murray
(LOU MURRAY )

The world around us is constantly changing, more so now than ever before in recorded history. Humans are dramatically affecting the natural world.

Between global warming and the exploding growth of the human population, which results in the need to convert more and more wild land to agriculture and housing, it is becoming increasingly difficult for species in the wild world to survive and thrive. Species have always gone extinct, and new ones are slowly evolving by genetic changes too subtle for humans to witness in their lifetimes. But now extinction is happening at a rate that is 1,000 times the normal background rate.

In fact, scientists say that we are now in the sixth great extinction. There have been five great extinctions of species in the past, the fifth one being when a comet crashed into earth 65 million years ago, resulting in the demise of dinosaurs.

The current great extinction began about 12,000 years ago, when the climate warmed abruptly in the Northern hemisphere and ended the last ice age. Yes, climate changes have happened in the past, and no, humans weren't responsible for them. But we are responsible for this one.

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Over a period of 150 years, we have burned up a huge amount of the carbon that was sequestered in the form of petroleum, natural gas and coal. This carbon went into the atmosphere in the form of carbon dioxide. The physical chemistry of this gas is known to produce a greenhouse effect. Present-day earth warming was predicted in the late 1800s based on the knowledge of how carbon dioxide absorbs heat energy.

Population growth and the entry of large numbers of people into previously scarcely populated areas has also had an effect. Early settlers to this country wiped out the passenger pigeon, which had numbered in the billions. The Carolina parakeet in the Eastern and Midwestern U.S. was also hunted to extinction.

But amid this doom and gloom, there are bright spots of hope. While some people are oblivious to the destruction of the wild world, others are aware and care. Several species that were hunted to near extinction have been brought back from the brink. Bison and wolves in the lower 48 states are two notable examples.

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