In the 1970s, India began using high-yield crops and the fertilizers required to optimize yield. Today, yield is dropping as infrastructure and policy fail to maintain subsidies for seed or fertilizers. This is an example of A. how crops that were created through genetic modification experience gene weakening and diffusion over time.

B. the downside of the green revolution, wherein developing nations are dependent upon expensive solutions.

C. the downside of plantation agriculture in areas that are neither tropical nor subtropical.

D. population exceeding food supply as predicted by Malthus.

E. desertification and the loss of arable farmland due to lack of proper fertilization and irrigation

Several climate feedback loops to increase temperatures from the last glacial 20,000 years ago to interglacial conditions today. which of the below is a negative feedback loop rather than a positive feedback loop? a. warming temperatures and more rainfall globally at the end of the last glacial period caused increased growth of vegetation which would act to decrease atmospheric carbon dioxide levels. b. warming of the oceans at the end of the last glacial period releases carbon dioxide to the atmosphere (because less carbon dioxide can dissolve in warmer water). c. warming temperatures at the end of the last glacial period resulted in thawing of permafrost over large areas which released carbon dioxide to the atmosphere. d. warming temperatures at the end of the last glacial period caused a reduction in ice covered areas (sea ice, ice sheets and snow) which decreased the earth's albedo.