He doesn't take environmentalists seriously, because he finds the value of a seal and a human to be intrinsically different.
He doesn't take global warming seriously, because he believes their $80/ton carbon tax solution to be an economic death sentence.
And so he retaliates. He lowers the value of a seal to nothing, which is less than he truly believes. He denies any and all consequences of living on a warmer planet, which is less than he truly believes.