Climate Change Projections for Kansas
Global climate change is likely to touch the lives of all Kansans during this century if greenhouse gas levels in the atmosphere are not controlled. The climate in Kansas is projected to become warmer by 2100, with substantial differences between eastern and western Kansas, according to Johannes Feddema, University of Kansas climate scientist in the Department of Geography.
Feddema spoke at the 2008 K-State Research and Extension Annual Conference in Manhattan, Kansas. He reported results from a study that he and his colleague Nathaniel Brunsell did for the Climate and Energy Project of the Land Institute in Salina, Kansas.
The full report on this study, and the figures included in this article (cited as Brunsell and Feddema, 2008), can be found at:
To make the projections in this study, Feddema and Brunsell tested 21 climate models approved by the U.N.’s Intergovernmental Panel on Climate Change (IPCC) against actual Kansas historical climate data from 1950-2000, then chose the three models that best reflected the variability of the Kansas climate. Next, they ran the models to create projections for 2010-2100, according to a “middle of the road” IPCC assumption about increases of greenhouse gases in the atmosphere.
The projections in the report are only projections, not predictions, Feddema stressed. If greenhouse gas emissions are controlled and mitigation efforts are put in place to reduce atmospheric levels, then the projected changes can be altered.
If greenhouse gas emissions are not reduced and the IPPC’s “middle of the road” scenario occurs, here are the projected climate changes for Kansas as a whole for the remainder of this century:
Western Kansas will become warmer and drier. Soil moisture will decrease, putting more pressure on irrigation. During the summer, the need for water by plants will increase as much as eight inches because of rising temperatures.
Eastern Kansas will become warmer. Precipitation will be slightly greater, but the higher temperatures will likely more than offset any increases in precipitation due to the increase in evaporation rates. The result will actually be an overall drying effect. Less water will be available for rivers and reservoirs in winter, and plant stress will increase in summer.
Temperatures in Kansas will rise in all seasons, in all parts of the state, by an average of 2 to 4 degrees Fahrenheit (F). Southwest Kansas could see a rise as steep as 8 degrees F.
· Higher summer temperatures will create more heat waves. The number of cooling degree days (the days that people run their air conditioning) will increase by about 50%. Higher summer nighttime temperatures will also stress livestock and crops.
· Freezing days will decrease during the winter. By 2060, winter temperatures will mostly stay above freezing. The number of heating degree days (the days that people run their heaters) will decrease by about 25%. The lack of hard freezes means that insects will thrive and diseases will increase among plants, animals, and humans. Mosquitoes and ticks will thrive.
What does this mean for Kansans?
It will probably cost less to heat your home in the winter, but you will pay for more air conditioning in the summer. Air conditioning is less energy-efficient than heating, so more energy will be wasted.
Higher temperatures intensify human health problems – heart disease, respiratory diseases (like asthma), and the spread of epidemic disease. In urban areas, heat waves also lead to increased deaths especially among the elderly and other vulnerable populations.
Higher summer nighttime temperatures are bad for crops – for example, wheat needs cool nighttime temperatures. Hot nights lead to plant stress, which leads to yield loss. Higher temperatures also stress livestock and alter the species composition of rangeland grasses.
Some have asked: Isn’t a longer growing season and more carbon dioxide (CO2) better for crops? Not necessarily. The benefits are canceled out by the problems. The longer growing season comes with increased temperatures, and higher temperatures increase plants’ need for water – but precipitation will remain about the same. As a result, evapotranspiration will increase, and soil moisture will gradually decrease.
In Kansas, crop yield depends on water availability, not on CO2 levels. Increased CO2 levels do not help plants unless there is adequate soil moisture, moderate temperatures, and additional levels of nutrients in the soil.
It should also be mentioned that USDA research has shown that weeds thrive extremely well under high CO2 conditions. Tests have also shown that herbicides such as glyphosate don’t work as effectively in higher CO2 environments.
Precipitation patterns and intensity will become more variable.
Why do models project that storms will become more intense? The reason lies in the projected changes in global temperature patterns. When a warmer atmosphere melts more of the polar ice caps, temperature extremes between the poles and the equator start to even out. The lack of contrast between cold and warm air slows global air circulation patterns. High pressure systems will stay in place longer. Weather systems will get trapped over one area for extended periods of time.
Precipitation Amounts and Soil Water Availability
Temperatures will rise and evaporation rates will increase, resulting in the need for additional water. Annual precipitation amounts will not increase to meet this need, however.
What does this mean for Kansans?
Increased temperatures will create drying, which will result in a slight decrease in soil moisture surplus during winter. This means reduced water flow into rivers and reservoirs.
Water deficit (a measure of water need that has to be made up by irrigation) will increase significantly during the summertime, especially in western Kansas. Water availability will be the key to how plants, animals, and even humans respond to climate change.
Feddema’s entire presentation at the 2008 K-State Research and Extension Annual Conference can be found at:
-- Steve Watson, CASMGS Communications