w/d/i/a/d/p/e/e/r/s
widespread
d/n/d/e/s/u
sudden
n/i/t/o/r/a/v/e/l/n/m/e/n
environmental
n/p/a/l/o/t/a/x/e/i/n
explanation
w/o/d/n/u/l/r/e/f
wonderful
i/s/a/h/i/o/n/t/r
historian
e/n/l/u/y/k/l/i
unlikely
p/p/o/o/n/a/u/i/t/l
population
c/u/r/e/t/n/y
century