As discussed in Section 9. 2, the scientific consensus on the causes for climate change appears to be associated with anthropogenic factors, most notably the increased use of fossil fuels since the beginning of the Industrial Revolution. Are you satisfied by the available scientific evidence to support this claim? Why, or why not? Be specific.

Data from Section 9.2

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In this section an attempt will be made to provide a brief and balanced account for the sci- entific understanding of the causes and consequences of climate change. This is done in the following order: A working definition of climate change is offered. A brief discussion is provided on the atmospheric layers and their gaseous chemical ele- ments that are particularly relevant to the understanding of the earth's heat budget-the balance between the incoming heat from the sun and the outgoing heat to outer space. This is done to provide a basic-level understanding of how or in what ways certain gas- eous chemical elements of the atmosphere, collectively known as "greenhouse gases," are instrumental to an increase in the temperature near the earth's surface and, over the long term, contribute to global warming. 3. An attempt is made to examine the evidence for the anthropogenic (human) induced increase of "greenhouse gas" emissions into the atmosphere which have contributed to global warming. This is done through careful examination of the records of atmos- pheric concentrations of certain gaseous molecules (principally CO) before and after the industrial era. 4. An effort is made to delineate the anthropogenic and natural sources that play important roles in the projection of future warming (temperature) trend. Projection of future warm- ing trend is challenging because it requires not only the projection of the future atmos- pheric concentrations of certain gaseous molecules emitted by humans, but also involves converting these gaseous atmospheric concentrations into global average temperature increases using some metrics. As will be evident from the discussion in this section, what makes projection of future warming trend even more complicated is the existence of exog- enous factors (induced by nature and some feedback mechanisms) that may contribute to either the warming and/or cooling of the earth's average surface temperature. 1. 2.