I have come here today, as the leader of the world’s largest economy and its second-largest emitter, to say that the United States recognizes our role in creating the problem, and we embrace our responsibility to help solve it.
That is the nub of climate politics — culpability and responsibility — and illuminates why conservatives have resisted acknowledging climate change for so long.
Nothing is more repulsive to the nativist sentiment that currently has Donald Trump atop the polls than the notion that America is (partially) to blame for a problem that falls hardest on the global poor — and thus that America has a moral obligation to help the poor adapt to what changes are inevitable and prevent those that aren't. People inclined to build walls to keep out the foreign poor are unlikely to accede to sacrifices on their behalf.
What's worse, the US has inflicted this harm by getting wealthy, by industrializing with fossil fuels. This connection, discovered long after fossil fuels were enmeshed in the economy, is a blunt reminder of interdependence and unintended consequences to a demographic that has mythologized rugged independence and the untainted virtue of American capitalism.
Nativist conservatives rebel at any effort to assign the US blame or responsibility for ills in the world, which they see as unpatriotic. That's what all the history curriculum fights are about. Conservative psychology is averse to ambiguity and nuance, so for ideological conservatives America is either God's chosen country, a force for good, or not. Any discussion of American culpability or responsibility is interpreted as an argument for the latter.
But acknowledging the scientific facts on climate change is the first step in a chain of reasoning that inevitably leads to the realization articulated by Obama. It's built into the structure of the situation.
That's why the core of nativist voters on the right are unlikely ever to acknowledge those facts.
Here's the full speech: