For all the immediate challenges that we gather to address this week -- terrorism, instability, inequality, disease -- there’s one issue that will define the contours of this century more dramatically than any other, and that is the urgent and growing threat of a changing climate.

That's President Obama at the UN Climate summit earlier today (transcript). Even as the US is dropping bombs on ISIS in Syria, Obama is signaling that terrorism is not at the top of his priority list.

It reinforces a point I made last week about Obama's counter-terrorist policy: he has been firm (and in the case of ISIS, over-zealous) in going after terrorists, but he has not hyped the threat. In fact, he has quite deliberately tried to wind back the threat inflation of the previous administration as part of his effort to redirect US foreign and national security policy away from a focus on terrorism (the best explanation I have seen of Obama's approach is this piece by Peter Beinart).

The other lesson to draw from Obama's prioritisation of global challenges is not to confuse media attention with policy focus.

Yes, military action against ISIS is getting a lot of attention, and in my view, the US-led response to the ISIS threat is an over-reaction. But it's not as if Obama is betting the farm on this mission; he's restricting his commitment mostly to air power. So even if America is making a strategic mistake, it is not a big one. And if it relieves pressure on the Kurds and other minorities being persecuted by ISIS, it will even have some humanitarian upside. It also fulfills US (and Australian) moral obligations to a struggling Iraq. We broke the joint, so we ought to play a part in holding it together.

If we're looking for long-term policy impact, it might be worth turning to where Obama says his priority lies: climate change.

His Administration already has a pretty good story to tell on that front. If Obama can cap off the success he's had on domestic environmental legislation with a climate deal with China at the UNFCC conference in Paris late next year (granted, it looks unlikely, though the signs from New York are positive) it would be a spectacular achievement for his presidency. When you add Obama's other major achievements — health care, economic recovery after the worst recession since the 1930s, an an end to two wars, partial reform of the US finance industry — his record looks pretty substantial, and the carping (mine included) about the intervention in Syria and Iraq amounts to very little.