Complex sentence: The timing of the carry reversal in 2008 contributed substantially to the credit crunch which caused the 2008 global financial crisis, though relative size of impact of the carry trade with other factors is debatable.
Split into simpler sentences: The timing of the carry reversal in 2008 contributed substantially to the credit crunch which caused the 2008 global financial crisis. Though, relative size of impact of the carry trade with other factors is debatable.