Poverty.

Nobody cares about climate change on Alpha Centauri Bb because we don't know of any life capable of suffering there.

Climate change on Earth has the potential to create vast misery, or even make human life untenable. But if we consider only the worst case scenario, we should be more concerned with potential extinction events like asteroid strike, supervolcano, or grey goo.

We can barely find evidence that climate change is having negative effects on people today, and the net effect of increased temperature and CO2 levels on agriculture might well be positive.

If we are going to rely on complex models that make predictions specific to the fraction of a millimeter, it’s only fair to factor risk level and uncertainty into the analysis.

Poverty causes misery today, with uncertainty of zero. If our goal is to improve human welfare, we must recognize that wealth brings the most effective relief. Goal #1 of the UN Millennium Development Goals was to eradicate extreme poverty and hunger. “The target of reducing extreme poverty rates by half was met five years ahead of the 2015 deadline,” largely thanks to liberalized markets.

As populations increase their wealth, they can afford to make choices that benefit them today, and everyone in the long term.