Negative feedbacks stabilize the climate over long times of hundreds of thousands or millions of years or more, but feedbacks over years to millennia are mostly positive, amplifying changes. If there is a change in the sun, or CO 2, or something else sufficient by itself to raise the temperature by one degree, this will be amplified to a few degrees by feedbacks. , Points Earned:, 1/1
Correct Answer:, E Your Response:, E 5., You start with some of the right kind of dead material, and heat this material in the right way, perhaps with a little squeezing. As the material changes, you end up with coal, and the name scientists give to the material changes. In order, from coolest (first) to warmest (last) the names given are: , A., Bituminous, anthracite, peat, lignite. B., Peat, lignite, bituminous, anthracite. C., Bituminous, anthracite, lignite, peat. D., Bituminous, lignite, anthracite, peat. E., Bituminous, peat, lignite, anthracite. This is mostly memorization. But the names hide a lot of history, the peat-bog cutters of Ireland, the brown lignites now being mined in Wyoming, the deep-mines and strip-mines of the bituminous coals of western Pennsylvania, West Virginia and elsewhere, and the hard-coal anthracite of the Scranton and Wilkes-Barre region. If you don’t know any of this history, you might consider reading up on it a bit; it is fascinating. , Points Earned:, 1/1 Correct Answer:, B Your Response:, B 6., Some natural resources are renewable—nature produces them fast enough that humans can obtain valuable and useful supplies of a resource without depleting it. Other natural resources are nonrenewable—if we use the resource at a rate fast enough to matter to our economy, the resource will run out because use is much faster than natural production. What do we know about oil and coal?, A., Both oil and coal are renewable resources; they are being made rapidly by natural processes in places such as the Mississippi and Mekong Deltas. B., Coal is a nonrenewable resource, but oil is made more rapidly and so is a renewable resource.C., Both oil and coal are nonrenewable resources, and at current usage rates and prices similar to today, oil will run out in about a century and coal will run out in a few centuries.D., Oil is a nonrenewable resource, but coal is made more rapidly and so is a renewable resource.E., Both oil and coal are nonrenewable resources, and at current usage rates and prices similar to today, both will last a few hundred years before running out. There is lots more coal than oil; oil has this habit of floating on water, thus rising through rocks and escaping to the sea floor where the oil is “burned” for energy by bacteria or other creatures. The size of the resource, in coal, oil, or anything else, depends on the price, and how long the resource lasts depends on rate of use, which is increasing rapidly for fossil fuels. The idea that immense pools of oil are out there, undiscovered but easy to get, is pretty silly—oil companies are really smart, drilled the easy stuff early on, and are now running out of oil that can be drilled and produced at prices close to modern.
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- Fall '08
- Global Warming, Correct Answer, Coal, Pennsylvania, plant material, Points Earned