A study co-authored by University environmental sciences professor emeritus William Ruddiman concluded that the agricultural methods of ancient human populations may have had an effect on global climate change.\nRuddiman built his conclusion off of a hypothesis made more than five years ago, which stated that humans started having a measurable effect on carbon dioxide values as populations started practicing agriculture about 7,000 years ago. According to the hypothesis, this increase in carbon dioxide values resulted from the large-scale deforestation practiced at that time. Ruddiman also conjectured that methane was released into the atmosphere when humans started raising livestock and growing rice 5,000 years ago.\n"One of the criticisms [for the original hypothesis] is very basic and it sounds very plausible," Ruddiman said, noting that many experts doubted whether there were enough farmers at that time to have an effect on atmospheric carbon dioxide. Current estimates state that there were around 10 to 20 million people alive about 6,000 years ago, Ruddiman said.\nClaiming that this population was too small to affect the global climate, however, would assume that past populations had the same environmental impact per person as does the modern population. This assumption is "simply not true," Ruddiman said, noting that several archaeological and anthropological studies show that people in antiquity used much more land than people do today.\n"Go back 6,000 years ago, the average farmer would go out into the woods, take an axe, girdle a notch into a tree [to kill it], girdle an acre's worth of trees, they all die ... go away for a few years, come back, set fire to them [and] burn them," Ruddiman said.\nThis slash-and-burn approach gave early farmers a large quantity of fertile soil with plenty of sunlight but it encouraged farmers to simply abandon old fields and clear away more forest, Ruddiman said. Eventually, this method led to a usage of 10 times as much land per-capita as modern populations use.\n"If there were 10 to 20 million people back then, but they had the effect of 10 people [today], that's enough to just become detectable in the carbon dioxide curves, according to our calculations, and become more and more detectable over time," Ruddiman said.\nIn the past, people chose to burn and clear land to such a large extent either because they did not understand how to replenish nutrients or because they simply did not want to do the labor, said co-author Erle Ellis, associate professor at the University of Maryland, Baltimore County.\n"It's a lot easier to burn a forest than build a field," Ellis said, noting that because there was not a land shortage at the time, people used more land for less labor.\nAlthough the study concluded that populations thousands of years ago began the process of altering the climate, "that doesn't change what we've done today," Ellis said.\n"It took them thousands of years to do what we did in five years," Ellis added, referring to the atmospheric release of greenhouse gases that could increase the planet's overall temperature. "What they did was profound but is insignificant to what we've done today"
Read More
D.C. baseball legend Ryan Zimmerman to deliver keynote Valedictory address
By Xander Tilock | 10 hours agoFamously nicknamed “Mr. National” for his many contributions to the Washington, D.C. franchise, Zimmerman is considered one of the most successful alumni in Virginia baseball history.
Administrators and faculty paint conflicting pictures of May 4 encampment clearing
By Cecilia Mould and Finn Trainer | 4 days agoThe details contested between the town halls included the clarity of the University’s tent policy and the presence of suspicious individuals at the encampment.
Faculty Senate calls for an external review of May 4 clearing of encampment
By Priya Kommu | 4 days agoSenators had questions about the lack of direct communication between University administrators and the students and faculty present at the encampment.
