ENV2073_f10_e1_soln - 1. The graph is consistent with the...

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1. The graph is consistent with the theory of anthropogenic global warming. This theory is based on the “greenhouse effect.” The idea is that human emissions of CO 2 and other “greenhouse gases” are causing the atmosphere to absorb more infrared light as it leaves the earth towards space. As we emit greenhouse gases, more of the outgoing energy is re- directed to earth’s surface, which causes the planet to heat up. However, if this theory is correct, then we ought to see *cooling* occurring in the upper atmosphere (the stratosphere) as the energy is “bounced” back to earth’s surface. This is, in fact, what the graph shows -- a cooling trend between the 1970s and the early 21 st century. Note that there are two short- term deviations from the overall trend, each lasting about two years, and each caused by a major volcanic eruption, which serves to warm the stratosphere and cool the lower atmosphere. However, these volcanic eruptions merely cause some “noise” in the prevailing trend of stratospheric cooling. The overall trend of stratospheric cooling is consistent with the theory that human emissions of greenhouse gases are causing the planet to warm. One could argue, based on the graph, that the “flattening” of the temperature trend in the final few years could be an indicator that stratospheric cooling has slowed or stopped, and therefore the theory of human-induced warming is questionable. This would be a reasonable argument, but I still think that the overall trend of stratospheric cooling since the 1970s is pretty clear, so I would still say that the graph supports the theory of anthropogenic climate change. 2. Dear Friend, Thanks for asking me about Ms Angle’s stance on global warming. I would have to disagree with the quotes that Ms Angle has made about global climate change, and it is my opinion that her stance is not sound. First of all, there is clearly plenty of scientific evidence that the earth has been heating up over the past 100 years or so. This warming trend is shown by multiple lines of scientific evidence like surface thermometer records, records of sea level rise, records of glacial retreat, and records of annual melting of sea ice. Based on all this, there is clearly sound science to demonstrate that the earth is warming. But I think what Ms Angle probably meant is that we don’t have sound science to
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ENV2073_f10_e1_soln - 1. The graph is consistent with the...

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