50. What is implied by the phrase our best guess at the moment in the last paragraph of the passage above?
(A) Climate change was aided by the carbon dioxide effect.
(B) Climate change was likely to pose severe challenges for agriculture in the tropics.
(C) Climate change aided by the carbon dioxide effect is probably beneficial in some of the chillier regions of the NorthernHemisphere.
(D) Climate change reduces the dependence on fossil fuels.
(E) Economists are no equal to scientists in terms of climate change.