Global warming wasn’t the biggest threat in 2007.
No, George Bush hasn’t actually commented on present events in Iraq, probably because he doesn’t believe it’s helpful for ex-presidents to criticize their successors.
But he already described the situation back in 2007, when he gave a speech explaining why he was vetoing a bill passed by the Democratic Congress which would have pulled troops out of Iraq (the first three minutes of the video above are especially relevant).
For those who say “but Bush negotiated the agreement under which Obama ended up completely pulling out of Iraq,” there is no question that everyone involved in those Bush negotiations expected that the next president would forge a new agreement with the Iraqi government when the time came, and that it would involve leaving some residual forces there. But it was clear that Obama had no interest in doing so; he barely participated in the talks and pulled out when the going got the least bit rough.