Cities Prepare for Extreme Weather Events in a Changing Climate
by Abby Dockter, Institute of the Environment
It was 104 degrees Fahrenheit in Las Cruces, NM, when Lisa LaRocque, the city’s sustainability officer, described her plans to protect citizens from the most extreme negative impacts of climate change. LaRocque had seen the data for historical weather patterns in Las Cruces, a small city of slightly more than 100,000 people in the southern part of the state. Those patterns showed the extremes in temperature and precipitation were getting wider, but what did that mean for life in Las Cruces?
City officials weren’t going to wait around to find out. Las Cruces was one of four small to mid-sized U.S. cities—Miami, OK; San Angelo, TX; and Boulder, CO, were the others—that participated in a project, co-led by Institute of the Environment researchers, to address local climate-related risks based on critical thresholds for extreme weather events.
Looking at Weather, Understanding Climate
A critical threshold is the point when weather goes from being a nuisance to being a problem, explained Gregg Garfin, deputy director for science translation and outreach in the Institute of the Environment and a co-investigator for the project. A critical threshold is a trigger point for concern or action for a city to avoid a crisis, whether that is a severe flood, a drought, or an extreme heat event.
Climate change experts met with city officials in each of the four locations to find out what extreme weather events caused the most concern. Then researchers analyzed local climate data and used projections from climate models to show how frequently those extreme events might occur in the future, compared to the past.
The critical thresholds approach connects weather, which is experienced over short periods of time—hours to days—to climate, which is a cumulative look at weather patterns over multiple decades. The project formed “a bridge between imminent risks and the way those risks might change in the future,” Garfin said.
Knowing that the temperature is going to rise 2 degrees in the next 50 years is not necessarily helpful for someone in the Public Works Department or a public health worker, said Sascha Petersen, a founder of the climate strategies company Adaptation International, and co-investigator on the project. “But if we say the number of summer days over 100 degrees is going to double in the next few decades, then that’s something more tangible. Emergency responders can think about how many more staff they’re going to need during that time.”
Officials from many city departments attended meetings on critical thresholds for extreme weather events, and in Las Cruces, staff from the office of Sen. Martin Heinrich also attended. Las Cruces climate projections were compared with the last 50 years of historical data collected from the weather station at New Mexico State University. The climate models illustrate a range of projections depending on the amount of emissions of heat-trapping gases in the atmosphere: projections with less warming for a world that reduces emissions, and different projections for a world that does not.
The results show an increasing number of days with extreme heat, more warm nights, and more of them in a row. The projections do not anticipate a dramatic change in precipitation patterns for Las Cruces, although the growing season is expected to lengthen. After 2040, the model anticipates at least one day per year with two and a half inches of rainfall, and experiencing a flood every year would make a difference for the city of Las Cruces. These changes would impact agriculture, human health, water supply, and the demand for air conditioning and its draw on the power grid.
For LaRocque, the critical threshold project contextualized climate change in her area. “It wasn’t just about climate change in the abstract, and it wasn’t about polar bears,” she said. “We could see what might be getting worse, and we could see whether or not we were prepared for that.”
For managers like LaRocque, data are not enough. “I needed a plan that was engaging and pragmatic and relevant to different departments,” she said.
Each of the four participating cities was offered a $10,000-$15,000 grant to implement its own strategy for reducing the impacts of extreme weather events.
Las Cruces officials and community members chose to create a rainwater harvesting project and a green infrastructure plan, which helped them secure an additional $400,000 Community Development Block Grant and other capital funds to create a cool natural walking corridor in a low- to middle-income neighborhood.
Storm precipitation usually runs off rooftops and streets and into storm drains before emptying into local retention ponds, carrying whatever pollutants it picked up on the way. Green infrastructure creates unpaved spaces where water collects to support trees and vegetation, which in turn provide shade and help reduce the urban heat island effect.
“We treat storm water as a nuisance instead of an amenity,” LaRocque said. “We have neglected using nature’s services, and they are very helpful. By harvesting stormwater to increase the tree shade canopy, nature is mitigating the impacts of extreme heat. My goal is to try to show win-win solutions.”
Other cities used the implementation grant differently. Miami, Oklahoma, chose to provide extreme weather education to eighth graders in public schools, including assembling emergency preparedness kits to prepare for weather-related emergencies. Leaders in San Angelo, Texas, installed a rainwater collection system in the downtown Bosque Park and continue to offer opportunities for the public to learn about rainwater harvesting systems.
LaRocque said the support and research grant were key to facilitating her and her colleagues’ ongoing efforts to improve the long-term quality of life in Las Cruces. “Partnerships with scientists, municipalities, and community are critical in finding workable solutions,” she said.
Petersen, who works with many communities on their climate adaptation strategies, agrees. “This project is breaking down those silos that show up between city departments,” he said. “Communication and collaboration creates a great foundation for taking action, which is really what we need—more action.”
Adaptation International, Climate Assessment for the Southwest, and the UA Institute of the Environment led the critical thresholds project in partnership with Southern Climate Impacts Planning Program, ISET-International, Western Water Assessment, and Atmos Research. The project was funded by the National Oceanic and Atmosphere Administration’s Sectoral Applications Research Program grant.