This is the third in a series of posts about climate prediction for Missouri. This post reports on a study by Anderson, Gooden, Guinan, Knapp, McManus, and Shulski (2015) that made projections for 5 midwestern cities: Columbia MO, Iowa City IA, Lawrence KS, Lincoln NE, and Oklahoma City OK. I will look only at the results for Columbia.
The Anderson group used a method that is different from what I have seen previously. I am not a climate scientist, so this doesn’t mean the method is improper, it only means that, in trying to report the results using ordinary English, I’m unsure how to describe them. I noted in my previous two posts that climate change is expected to be very sensitive to how humans respond to it. In particular, if we sharply reduce our GHG emissions, it is expected to reduce the amount of climate change, mitigating its effects. If we continue to emit high levels of GHG, or even increase them, it is expected to increase the amount of climate change, exacerbating its effects. Climate scientists have developed a standard suite of scenarios to describe how the world might respond. Some envision reduced emissions, some envision unchanged emissions, and some envision increased emissions.
Every climate projection I have seen has modeled more than one scenario. Typically, scientists have used a high emissions scenario and a low emissions scenario. They have presented results for both scenarios. The Anderson group proceeded differently. They modeled an increased emission scenario (A1fi, the same one used by the Hayhoe group), a less high emission scenario (A2, the same one used by Posey), and a low emission scenario (B1, used by both the Hayoe group and Posey). Then, instead of presenting the results of each, they averaged them. Their rationale in doing so was to present only the “signals that are strongest across a range of circumstances.”
I’m not sure how to describe what this means. Perhaps this reflects the fact that I’m not a climate scientist, but to me it seems a bit like saying that the high temperature during the summer in Columbia averages 83.0°F, while the high in winter averages 41.2°F, therefore the predicted temperature is the average of the two, 62.1°F. While your prediction has a certain methodological validity, what does it mean? Does it represent what it is going to be like in winter? No. In summer? No. If you are planning to visit, does it tell you what clothing to bring? No. If you are planning to build a house, does it tell you how much heating or air conditioning to put in? No, you need to put in enough to handle the coldest and hottest days, not the average day.
It also doesn’t tell you the most likely outcome. There is an implication that somehow the average of the three scenarios represents the most likely eventuality. But it doesn’t. Nobody knows which scenario the future will follow, that’s why studies usually report the results of several.
So, I don’t really know how to describe these results, and they won’t match those of the Hayhoe group or of Posey, as reported in the previous two posts.
Okay, with that said, here is what the Anderson group found. In Columbia, climate change is already underway. The following changes have already occurred:
- There have been changes in daily high and low temperatures, though they vary according to season;
- During heat waves it is staying hotter at night;
- There have been fewer cold waves; and
- There has been an increase in heavy rain events.
In the future:
Columbia’s annual average temperature is projected to increase 2.7°F by 2035 (actually a 30-year average centered on 2035), and 5.5°F by 2065 (actually a 30-year average centered on 2065) (See Figure 1 at right);
- The temperature change is projected to be larger during spring and winter and smaller during summer and fall;
- Annual precipitation is projected to increase by 4.2 inches, but summer precipitation is projected to decrease by half-an-inch.
- Heat waves are expected to get hotter by 6.1°F, with both highs and lows during the heat waves expected to be warmer;
- The number of days on which more than 1.25 inches of rain falls are not projected to increase significantly; however
- The maximum amount of rain that falls during 5-day and 15-day periods is expected to increase by over an inch.
While the specifics of the Anderson group’s projections can’t be compared to the studies by the Hayhoe group or by Posey because of the methodological differences discussed above, it is clear that the general trend of the changes go in similar directions: warmer temperatures, worse heat waves, decreased precipitation during the summer but increased precipitation during other seasons of the year, and an increase in heavy precipitation events.
I will summarize these 3 studies and draw conclusions in the next post.
Anderson, Christopher, Jennifer Gooden, Patrick Guinan, Mary Knapp, Gary McManus, and Martha Shulski. 2015. Climate in the Heartland: Historical Data and Future Projections for the Heartland Regional Network. Downloaded 3/15/16 from http://www.marc.org/Government/GTI/pdf/ClimateintheHeartlandReport.aspx.
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.