Friday, March 13, 2015

Era of human dominance over Earth began in 1610, say scientists

[MNN]  The Anthropocene Era refers to the period of time humans have had a measurable global impact on Earth's ecosystems. Though it's clear we're currently living in it, scientists have long debated when exactly this epoch of human dominance over the planet first began.
 
Did it start with the advent of agriculture around 10,000 years ago? With the Industrial Revolution? With the first explosions of nuclear weapons in the 1940s? As it turns out, new data suggests it may have actually started in the year 1610. 
 
What happened in 1610 that made it such a tipping point for humanity's impact on Earth? According to Simon Lewis, an ecologist at University College London, and geologist Mark Maslin of Leeds University, a "golden spike" can be seen in the global geological record in this year — a threshold, if you will — which can be directly attributed to humans, reports the Independent.
 
Two global signatures appear in 1610: Pollen from imported New World crops begins to appear in Europe, and a massive dip in carbon dioxide levels can be seen in Antarctic ice cores dating to that time. Both of these events are a direct result of increased trade and transport of animals and plants across the Atlantic Ocean — a barrier which had previously kept the New and Old Worlds separated for millions of years.
 
In the case of the global dip in carbon dioxide, Lewis and Maslin believe this to be the result of the deaths of millions of indigenous people in the aftermath of European colonization. As many as 50 million Native Americans died in the aftermath of European expansion into the New World, mostly as a result of infectious diseases such as smallpox. As their numbers dwindled, the resultant loss in agriculture allowed for forests to re-grow throughout the Americas. These expanded forests scrubbed the atmosphere of carbon dioxide. Read More