The future impact of climate change on inequality in the U.S.

I just finished reading this 2017 article published in the journal Science, by Solomon Hsiang (UC Berkeley) and co-authors, which investigates the economic impact of climate change in the U.S. The headline results are unsurprising:

The combined value of market and nonmarket damage across analyzed sectors—agriculture, crime, coastal storms, energy, human mortality, and labor—increases quadratically in global mean temperature, costing roughly 1.2% of gross domestic product per +1°C on average.

Interestingly, the biggest contributor to economic impact is mortality:

The greatest direct cost for GMST [Global Mean Surface Temperature] changes larger than 2.5°C is the burden of excess mortality, with sizable but smaller contributions from changes in labor supply, energy demand, and agricultural production...

However, what was more interesting was the spatial impacts and their distribution, summarised in the following map:

The counties that suffer the greatest impacts of climate change are those in the South and Midwest, where the mortality impacts are likely to be the greatest due to higher summer temperatures. In contrast, in the North and Northwest, this is offset by lower winter mortality due to milder winters. However, the areas projected to suffer the greatest impacts are also the areas that include most of the poorest counties in the U.S. This is likely to increase inequality over time. As Hsiang et al. explain:

In general (except for crime and some coastal damages), Southern and Midwestern populations suffer the largest losses, while Northern and Western populations have smaller or even negative damages, the latter amounting to net gains from projected climate changes. Combining impacts across sectors reveals that warming causes a net transfer of value from Southern, Central, and Mid-Atlantic regions toward the Pacific Northwest, the Great Lakes region, and New England... Because losses are largest in regions that are already poorer on average, climate change tends to increase preexisting inequality in the United States.

The last thing the U.S. needs is another contributor to income inequality, but it seems like climate change is set to make a bad situation worse.

It would be interesting to do a similar analysis for New Zealand, not necessarily in terms of inequality, but simply looking at the impacts of climate change on mortality. On that research question, we currently know very little. To what extent will increased summer mortality, predominantly in the north of the country, offset lower winter mortality in the south? Does a wetter west and a drier east of the country matter? These and related questions might make a good project for a motivated Masters or Honours student.