Self-study
In several countries, to slow global warming, many farmers are planting trees on their land because of government incentives. █████ ██████████ █████ ████ ████████ ██████████ ████ ██████████ ███████ ██████ ███████ ████ █████ █████████ ████ ████ ██ ███ ███████████ █ ██████ ██████ ████████ █████████ ████ █████ ██████ ███ █████ ██████ ███████ ████ ███████████ ████ ██████ ████████ ██████████ █████ ██████████ ███ ███████ ██ ██████ ██████ ████████
Summary
The author concludes that government incentives to plant trees will accelerate rather than slow global warming. She bases her conclusion on a study that shows native grasses to be more effective at absorbing carbon dioxide than trees.
Notable Assumptions
The author makes several key assumptions:
(1) The second study is correct. The author bases her conclusion on this study, so if it’s flawed, then the argument is flawed.
(2) Some native grasses would be removed to plant trees. If no native grasses are removed, then even if the trees are less than ideal, they would still help to slow global warming.
(3) There is no factor other than CO2 emissions more important to global warming. If trees remove less CO2 but help with global warming in some other way, the conclusion would no longer follow.
21.
The argument requires the assumption ████
a
trees not only ██████ ██████ ███████ ███ ████ ████ ██
(A) Is too strong to be necessary. We already know that trees don’t help as much as native grasses, so we don’t need further information on why that is the case. As long as trees remove less CO2, they will be less helpful in combating global warming.
b
most farmers do ███ █████ ███ █████ ██ █████ ████ ██████ █████ ██ ██ █████████ ██ ██ ██
(B) is too strong to be necessary. If it said some farmers would not plant trees without an incentive, that would be necessary. We only need to know that at least some grasses will be replaced with trees, and not the exact amount.
c
land that has ████ ██████████ ██████ █████ ████████ ██████ ███████
(C) could strengthen the argument by implying that grasses replaced with trees could not be regrown, but it is too strong to be necessary. Even if the grasses can be regrown, we don’t know if farmers will bother to replant them, or if enough farmers will replant to offset the grasses already lost.
d
some of the █████ ███████ ██ ████████ ██ ███ ██████████ ███ ███████ █████ ██████ ███████ █████ █████████ ██ ███████
If no native grasses are removed, then any trees planted would still help to absorb CO2 and slow global warming, even if they would be less helpful than native grasses.
e
few if any ███████████ ████ ████ ██████████ ██ █████████ ███ ██████ ██ ██████ ███████
(E) could strengthen our argument by implying that native grasses will be removed, but it is too strong to be necessary. Even if certain governments are trying to preserve native grasses, we don’t know if they will be effective, or if other governments will try to preserve their grasses as well.