Understanding and Assessing Projected Future Climate Change for Nebraska and the Great Plains

Editor’s Note: Temperature is given in Fahrenheit and precipitation in inches to be consistent with their use in the report that this essay is based on.

Introduction

The Great Plains in general and Nebraska in particular face significant economic, social, and environmental risks due to projected climate change during the remainder of this century (Melillo et al. 2014; Bloomberg et al. 2014; White House 2014). Observations clearly demonstrate that we have already experienced a significant warming of the planet, and the impacts of this warming have been observed worldwide, although the degree of warming, as expected, varies regionally. The body of scientific evidence confirms with a high degree of certainty that human activities in the form of increased concentrations of greenhouse gases since the beginning of the Industrial Revolution are the primary cause for the warming the planet has experienced, especially in recent decades. The projected changes and their rapidity are unprecedented. The implications of these changes for Nebraska and the Great Plains, and the legacy we will leave to our children, our grandchildren, and future generations, therefore, are vital concerns.

The climate of Nebraska, which lies in the Great Plains, is variable, subject to extremes, and can be harsh. For example, portions of the state experienced severe flooding in 2011, and the entire state was engulfed in an extreme drought in 2012, the driest and warmest year on record, when portions of Nebraska recorded maximum daily temperatures exceeding 100°F for 30 days or more. The average annual precipitation gradient across the state, ranging from an average annual total of 36 inches in the extreme southeast to less than 15 inches in the Panhandle, is equal to the precipitation change from the East Coast of the United States to the Missouri River, but is highly variable from year to year. Nebraska’s residents have adapted to its variable weather conditions and will have to continue to adapt to the projected changes in our climate, some of which have already been observed.

This essay is based on a report we prepared last year (Bathke et al. 2014) for the State of Nebraska’s Climate Assessment and Response Committee. The full report (neb) is available online at http://go.unl.edu/climatechange. The Nebraska Climate Assessment and Response Committee was established by the state legis-lature in the early 1990s to provide timely and systematic data collection, analysis, and dissemination about drought and other extreme climatic conditions to the governor and others. It also provides an organizational structure for the state’s drought mitigation plan and advice on requests for federal disaster declarations. In 2013 the Nebraska Legislature passed lb583, a bill that expanded the duties of the committee to include assessing the implication of climate change on key sectors of the state, including water, agriculture, wildlife, ecosystems, energy, and recreation. Our report was based in turn on the recent National Climate Assessment (nca; Melillo et al. 2014) along with our own expert findings and analyses. We refer the reader to the neb and nca reports for more complete details and references than can be presented in this overview essay.

In part 1 we review climate science basics and then discuss what is meant by climate variability and climate change, the differences between them, and the typical sources of climate variability and change. In part 2 we describe climate models and how they are used, including how they differ from, and are similar to, weather forecasting models. We also describe the relationship between global and regional models, and explain the weight of the latter. We devote part 3 to a global perspective on future climate change. In part 4 we discuss past climate change in Nebraska and projected future climate change throughout the remainder of the 21st century. In part 5 we describe possible impacts for Nebraska, with a particular emphasis on how extreme events may change. In part 6 we summarize our findings.

1. Review of Basic Climate Science

Weather versus Climate

The distinction between...