Monday, September 5, 2011

What proof is there that humans are the cause?

Some skeptics may ask for scientific proof that human activities are causing the increase in global average temperatures, and not natural effects. As shown in figures 1 and 2, the global average temperature and CO2 emissions begin to take off around 1900-1910. When compared to levels from the past obtained by ice sampling, tree-ring analysis, and other methods, it can be seen in figure 2 that in the past 100 years, changes have occurred that normally would take hundreds of thousands of years, and corresponds to when the the industrial revolution took place. The concentration of CO2 in the atmosphere is nearly 30% higher than has ever been  seen in history. This evidence leads to the conclusion that natural causes cannot have caused these kinds of changes so rapidly.
Figure 1

Figure 6—Variations in carbon dioxide concentrations in the Earth’s atmosphere over the last 400,000 years. Source: Robert A. Rohde and Global Warming Art.
Figure 2

Figure 3
Figure 3 shows the temperature variation with the CO2 variation from the past 800 thousand years obtained by ice core sampling. The data shows that a change of 100 parts per million (0.01%) of carbon dioxide concentration corresponds with a change of 10 degrees Celsius in average global temperature. Today's high concentration of carbon dioxide (highest ever recorded in over 800 thousand years) will undoubtedly cause drastic changes unless something changes. They also show that human activity causing increases in the carbon dioxide levels, such as the burning of fossil fuels, is causing irreversible changes to the Earth's climate.

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