Understanding Long-Term Climate Changes for Kansas City, Missouri INTRODUCTION Weather conditions in Kansas City, Missouri will change as greenhouse gas concentration continues to increase. This report will assist the planning efforts of city officials and staff or other individuals considering the potential impact of climate change on the area. It contains summary information of the local weather response expected under different possible levels of greenhouse gases in the future. The Kansas City Climate Change Story As pointed out in the National Climate Assessment, climate change will tend to amplify existing climate-related risks to people, ecosystems, and infrastructure in the Midwest. Analysis in this report indicates Kansas City can expect to see changes consistent with those expected regionally. While the recent change in temperatures observed in Kansas City is relatively modest, temperature is projected to increase substantially over the remainder of this century. Temperature will increase in all seasons, summers will accumulate more cooling degree-days and winters will accumulate fewer heating degree-days. Heat waves will become more frequent and summer nights will become hotter. Recent and projected increases in precipitation for Kansas City are substantial, with seasonal rainfall increases clear for both spring and fall. In addition, rainfall increase is clear for extreme events including annual maximum of daily, 5-day, and 15-day precipitation. These projected changes in temperature and precipitation extremes can be expected to increase demand for summertime cooling, degrade local air quality, and place additional stress on water supply systems, wastewater and stormwater management systems, and flood control efforts. METHOD This climate change assessment for Kansas City utilizes the same database of projected climate variables used to develop insights into national and regional climate change and associated impacts reported in the third U. S. National Climate Assessment (NCA; Melillo and Coauthors, 2014). The NCA and other assessments explore a variety of potential future climates that each correspond to as many as eight, well-established scenarios of global human greenhouse gas (GHG) emissions adopted by the Intergovernmental Panel on Climate Change (IPCC; Nakicenovic and Coauthors, 2000), a program of the World Meteorological Organization and the United Nations Environment Program. While useful for discerning trends over broad areas, these national and global assessments simply cannot provide the localized information for planning or similar local activities of interest to the tens of thousands of municipalities in the United States. In part to simplify the process, this report provides an assessment of change in local climate conditions through the end of the 21st century for just two emissions scenarios developed for the IPCC and summarized in the NCA. A1FI is a high emissions scenario in which the rate of GHG emissions continues to increase in a manner consistent with that seen for the last two decades. A1B is a moderate emissions scenario in which the rate of increase GHG emissions slows due to a variety of mitigation efforts. 1 Understanding Long-Term Climate Changes for Kansas City, Missouri: A Climate Assessment While A1FI might be considered “business as usual,” voluntary commitments made at the Conference of Parties (COP) in Paris in December of 2015, would put the world on a path closer to A1B, and the agreement to limit warming to +2C (+3.4°F) would be below A1B. This discussion serves to underscore one of the major sources of uncertainty in climate projections, the rate at which GHG (especially from fossil fuels) will be emitted. (More detailed descriptions of handling of uncertainty are provided in Appendix A.) Any changes observed over the last three or four decades, a period when the climate signal associated with increase concentrations of GHG began to emerge from the noise created by weather variability, provide a context within which projected change can be evaluated. When broad spatial patterns of change occur, many municipalities within the same region will experience a common direction of change (warmer vs. cooler, wetter vs. dryer). When local change is significantly different from regional change, the likelihood that local change will continue should be assigned less confidence unless a factor explaining trend differences is determined. Some examples include urbanization, deforestation, and switch from grassland to cropland. Confidence in the direction and rate of projected climate change is important when including consideration of future climate in planning or other decision making activities. ClimateLOOK™ reports, therefore, include a discussion of the level of agreement of climate projections generated for a location of interest to regional trends observed over the previous 40 years (1976-2015). When the direction of projected regional trend differs from that of any observed regional trend, the projected trend is characterized as being in “poor agreement.” Conversely, when the projected regional trend agrees with direction, but not the rate, of the observed trend (differ by more than 20 percent) the projected trend is characterized as only being in “good agreement.” Finally, when the projected regional trend agrees with rate and direction of any observed regional trend, the projected trend is characterized as being in “very good agreement.” Users are cautioned that any trend labeled in this report as being in “poor agreement” with the regional observed trend, as described above, are highly suspect. Users should always apply professional judgment and awareness of sensitivity of potential decisions or applications of the results of this report when determining the usefulness of the analysis it contains. CLIMATE OF THE KANSAS CITY AREA Historically, Kansas City lies in a humid continental climate zone, described as temperate with extremes of heat, cold, and precipitation. The Kansas City climate station used in this assessment, as well as the NCA, is located at the Charles B. Wheeler Downtown Airport (Figure 1), and has a period of record from 1893 to present. Since record keeping began at that station, Kansas City has experienced high and low average annual temperatures of 65.1°F and 45.8°F. Annual rainfall is 34.8" and snowfall is 16.2". Monthly temperature reaches peak value in July with average high temperature of 89.2°F. The annual low occurs in January with average minimum of 20.3°F. Rainfall is largest in June with an average of 4.9". The least precipitation occurs in February with an average of 1.3". Figure 1: Location of the Global Historical Climatology Network Station [USW00013988] that provided historical observations used in the NCA and reported in this report. (Google Maps) USW00013988 2 Understanding Long-Term Climate Changes for Kansas City, Missouri: A Climate Assessment Figure 2: U.S. Climate Divisions (NOAA2016a). Extreme daily conditions are inherent in the climate of Kansas City and the surrounding region (referred to as Missouri Climate Division 1; Figure 2). The highest and lowest recorded temperatures differ by over 130° F, with the annual record maximum and minimum temperatures of 112° F and -22° F. The maximum daily rainfall and snowfall are 8.1" and 20.5" (More information on observed trends in the regional precipitation is reported in NOAA Atlas 14 [NOAA 2016b]). Observed regional changes in temperature and precipitation for the 40-year period 1976 ‒ 2015 (Figures 3 and 4) are summarized below: Annual temperature has increased in Missouri by 0.3°F per decade, with the average annual statewide temperature increasing from 53.6°F to 55.8°F (Figure 3a). Annual temperature has increased in Missouri Climate Division 1, by 0.3°F per decade, with the average annual temperature increasing from 52.0°F to 54.2°F (Figure 3b). Annual precipitation has increased in Missouri by 0.54" per decade. Based upon the trend, the average annual statewide precipitation has increased from 40.1" to 44.5" (Figure 4a). Annual precipitation has increased in Missouri Climate Division 1 by 0.25" per decade, with average annual precipitation increasing from 37.5" to 40.0" (Figure 4b). Figure 3a: Recent change in annual temperature for Missouri statewide (Figure source: NOAA National Centers for Environmental Information, Climate At A Glance). 3 Understanding Long-Term Climate Changes for Kansas City, Missouri: A Climate Assessment Figure 3b: Recent observed trends in annual temperature for Missouri Climate Division 1, Northwest Prairie (Fig. 3b; top panel) (Figure source: NOAA National Centers for Environmental Information, Climate At A Glance). Figure 4a and 4b: Recent observed trends in annual precipitation for Missouri statewide (Fig. 4a; middle panel) and Missouri Climate Division 1, Northwest Prairie (Fig. 4b; bottom panel) (Figure source: NOAA National Centers for Environmental Information, Climate At A Glance). 4 Understanding Long-Term Climate Changes for Kansas City, Missouri: A Climate Assessment Figure 5. Projected trends in annual average temperature. Columns show the average by period (left columns, 1976 ‒ 2015; middle columns, 2021 ‒ 2060; right columns, 2061 ‒ 2100) and emissions scenario (black column— observed; blue columns—moderate emissions scenario; red columns— high emissions scenario). Climate Indicator (Annual Average For Period) 1976 - 2015 2021 - 2060 2061 - 2100 Observed A1FI (High) A1B (Mod) A1FI (High) A1B (Mod) Temperature (oF) 56.5 ((High)(High)60.3