Add spaces: Thenetresultisthehurricane,onaverage,veerstothenorthandrecurvestothenortheastifitlastslongenoughttodoso.

Answer: The net result is the hurricane, on average, veers to the north and recurves to the northeast if it lasts long enought to do so.

Add spaces: Itisthisfactorwhichcausesthedisintegrationofagrouporafamilyoramarriage.

Answer: It is this factor which causes the disintegration of a group or a family or a marriage.

Add spaces: Asanactivistinleft-wingpoliticsIhavebeentouchedbyeachofthemoderndoomsdaymovementsIlistedearli-er,exceptfortheice-agemovement,which,asofthiswriting,hasn'thadtimetocatchonyet.

Answer:
As an activist in left-wing politics I have been touched by each of the modern doomsday movements I listed earli- er, except for the ice-age movement, which, as of this writing, hasn't had time to catch on yet.