Aerial view of flooded homes in New Orleans after Hurricane Katrina, August 2005. Photo: weather.com

By Michele Berger
6 July 2015 (weather.com) – “There are so many different ways that people will feel the impact of climate change,” says David Easterling, Ph.D., of NOAA’s National Center for Environmental Information. Sea-level rise and flooding. Extreme heat and drought. Extreme precipitation events. Which events matter and how much depends on which part of the country you’re referencing, too. In the face of growing evidence about the effects of climate change — recently bolstered by a study from the National Oceanic and Atmospheric Administration showing there’s been no slowdown in global warming, despite the popular “hiatus” theory — the future landscape looks quite different from today. “The warmest day that we’d see in 20 to 30 years, the record temperature at that time would have no precedent,” explains Michael Mann, Ph.D., director of the Penn State Earth System Science Center. “New records would exceed old records and typical conditions [would] start to resemble what we today consider ‘extreme.’” Katharine Hayhoe, Ph.D., a climate scientist based out of Texas Tech University, works with cities on their climate preparedness. She said many local governments are much more aware of and proactive about climate change today. “Ten years ago, it used to be a city wouldn’t really have seen anything happen unless it was a city in Alaska,” she said. “Now, they already have a list of ways they’re being impacted by changing climate. All of the impacts are tied to services or infrastructure.” With that notion as our backdrop, we decided to take a look at which 25 cities across the United States will face the greatest challenges from climate change, resulting in The weather.com Climate Disruption Index. We started with cities with a population greater than 200,000 people, then factored in sea-level rise, extreme precipitation and drought, urban heat islands, and changes to average temperature and precipitation, giving more weight to certain factors. (See below for a full and detailed methodology.) We learned a great deal through this process, namely that where you live, who you are and what you do for a living will likely determine how much certain issues matter to you. “If you’re a farmer, then extreme drought is probably the thing you’re going to care the most about. A reservoir manager cares about extreme flooding,” Mann said, who noted that with a process like this, “there’s almost as much art [to it] as science.” We also learned we’re limited by the datasets available, a notion Thomas Wilbanks, Ph.D., of the Oak Ridge National Laboratory said plagues anyone attempting such an assessment. “Basically,” Wilbanks wrote in an email, “you are struggling with the same issues that the research community is focusing on, trying to do your best with data sources that are far from ideal.” To that end, not all the scientists we spoke with agreed with our methodology or our final list. See the Q&A with Hayhoe and Mann for details about their opinions on this list. Our hope is to spur conversation about climate change and cities, not offer a be-all end-all ranking.

25. Newark, New Jersey

Population: 278,427
Like much of the northeast, from West Virginia and Maryland north, extreme precipitation events are projected to increase significantly. That, coupled with a slight increase in drought, brought this well-known Jersey city onto our list.

24. Anchorage, Alaska

Population: 300,950
In the most extreme scenario, Alaska’s largest city is likely, in general, to get wetter in both winter and springtime, resulting in fewer drought-like conditions. Sea-level rise is also a potential factor, but not as much as for some other cities. [more]

The weather.com Climate Disruption Index