Tropical forests may dry out and become vulnerable to devastating wild fires
just as global warming accelerates over the coming decade, a senior scientist has warned.
For starters, the underlined portion should include "just" as well, since all the answer options seem to indicate so. A. just as global warming accelerates
"just as" implies that the "dry out" will begin at the same time as "accelerates". While nothing is grammatically wrong with this, it appears logically inconsistent since we would expect warming to cause the drying. Eliminate.B. even as global warming accelerates
"even as" indicates contrast but the "warming" causing "dry out" is logically consistent. Eliminate.C. as global warming accelerated
Tense issue - "accelerated" in past tense is incorrect. The original sentence implies that "dry out" and "accelerate" will happen in parallel (once the acceleration causes drying) and the past tense changes this meaning. Eliminate.D. when global warming accelerates
Correct answer as it gets the chronology correct (at least, does not imply simultaneity) and does not introduce any new errors.E. if global warming accelerated
Same issue as in (C). Also, "if" introduces a condition which changes the meaning. Eliminate.Hope this helps. two