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Posey Projects Climate Change for St. Louis


In my last post I reported on climate projections for St. Louis and the Midwest by Hayhoe, VanDorn, Naik, and Wuebbles. Here, I will report on climate projections for St. Louis by John Posey, Director of Research for the East West Gateway Council of Governments. His paper focused on temperature and precipitation changes by the middle of this century in the St. Louis Region, and on the types of socio-economic impacts that would be associated with such a change. Because future climate change is expected to be sensitive to how humans respond, he made projections for a high emissions scenario (A2) and a low emissions scenario (B1). Note that while he used a high emission scenario, the scenario he used does not envision emissions as high as the A1fi scenario used by Hayhoe et al.

Please remember that there is uncertainty associated with all climate change projections, and that with projections for the local level the uncertainty is magnified.

Posey’s results are shown in Table 1. He projects a 3.6°F temperature increase by mid-century under the low emissions scenario, and 4.9°F under the high emissions scenario.

Posey Temp Change

(Click on table for larger view.)

Posey projects that St. Louis will experience a slight increase in annual average precipitation, less than 10%. The analyses he conducted were uncertain about whether summer would see a decrease. Posey also projects an increase in heavy precipitation events, though he projects the increase to be small (1 additional heavy precipitation event per year).

Posey identifies 3 main socio-economic impacts that should be expected from climate change in the St. Louis Region. He expects an increase in flooding, heat stress, and energy consumption. In addition, he expects that other challenges might include agricultural stress, problems with roads (road buckling, etc.), and changes in infections disease vectors.

Given that Posey and Hayhoe et all projected for slightly different regions, and that they used different high emissions scenarios, their results seem more or less consistent. Where they differ, they differ in ways we would expect given the differences in their methods. (Posey’s projected temperature increase under the high emissions scenario should be less than Hayoe et al’s, and it is.)

Because of the differences in their methods, you shouldn’t really compare their projections directly, but I know that you’re gonna do it anyway. So, as you do, keep in mind that Hayhoe et al’s projections for extremely hot days were for one of the higher emission scenarios available, and they were for the end of the century, while Posey’s projections used a somewhat less extreme high emissions scenario, and only extended through mid-century.

In the next post, I will report on a study that made climate projections for Columbia, Missouri.

CORRECTION: In the original version of this post, the second to last paragraph stated that the A1fi Scenario used by Hayhoe et al was the highest emission scenario available. That has been corrected to read “one of the higher emission scenarios available.” See Hayhoe’s comment to the blog post for the specifics.

SECOND CORRECTION: In Paragraph 4, the original version of this post said that summer precipitation in St. Louis would decrease. That has been changed to indicate that projected change in summer precipitation is uncertain.


Hayhoe, K, J VanDorn, V. Naik, and D. Wuebbles. 2009. “Climate Change in the Midwest: Projections of Future Temperature and Precipitation.” Technical Report on Midwest Climate Impacts for the Union of Concerned Scientists. Downloaded from http://www.ucsusa.org/global_warming/science_and_impacts/impacts/climate-change-midwest.html#.VvK-OD-UmfA.

Posey, John. 2014. “Climate Change in St. Louis: Impacts and Adaptation Options.” International Journal of Climate Change: Impacts and Responses. Vol 5, #2. Downloaded 1/15/2016 from http://ijc.cgpublisher.com/product/pub.185/prod.233.



  1. John Posey says:

    Thanks for blogging about this. One small clarification. The dynamically downscaled (NARCCAP) projections tended to show a decrease in summer precipitation, while the statistically downscaled projections (USGS) showed an increase. Summer precipitation is probably the area of greatest uncertainty in this region. Otherwise, there was general agreement between the downscaling methods, at least on the direction of change.

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