Science Confirms (Again) What Cities Already Know: Climate Change is Happening Now

Getty Images

Getty Images

The continuing drought in the west and wildfires burning in the plains are real world examples—happening right now—of what scientists say is evidence of climate change. Remember the floods in Colorado last year and Hurricane Sandy the year before? Those too are indicative of the kinds of extreme weather events the U.S. will face in the coming years because of climate change. Hotter. Drier. Flooding and rising seas. Cities need to be prepared.

The National Climate Assessment released by President Obama yesterday is the most comprehensive examination of climate change impacts on the U.S. Looking across seven sectors—human health, water, energy, transportation, agriculture, forests and ecosystems—and by region—Northeast, Southeast, Midwest, Great Plains, Southwest, Northwest, Alaska, Hawaii, and the country’s coastal areas, oceans, and marine resources—the report “concludes that the evidence of human-induced climate change continues to strengthen and that impacts are increasing across the country.”

These short NCA videos tell the stories of climate change impacts by sector and region.

As cities build infrastructure and revitalize neighborhoods, downtowns, and riverfronts, they can no longer rely on past forecasts to predict the future. For example, a water utility that looks at only historical rainfall when planning for future capacity needs, will miss the boat. Or need a bigger boat. Looking instead at climatic trends will paint a different, more accurate, picture for local governments. Here are some other key scientific takeaways from the National Climate Assessment:

Temperatures increasing and extreme heat waves

U.S. average temperature has increased by 1.3°F to 1.9°F since 1895, and most of this increase has occurred since 1970. Because human-induced warming is superimposed on a background of natural variations in climate, warming is not uniform over time. Short-term fluctuations in the long-term upward trend are natural and expected. Temperatures are projected to rise another 2°F to 4°F in most areas of the United States over the next few decades.

Heat waves have generally become more frequent across the U.S. in recent decades, with western regions (including Alaska) setting records for numbers of these events in the 2000s. The recent heat waves and droughts in Texas (2011) and the Midwest (2012) set records for highest monthly average temperatures, exceeding in some cases records set in the 1930s, including the highest monthly contiguous U.S. temperature on record (July 2012, breaking the July 1936 record) and the hottest summers on record in several states (New Mexico, Texas, Oklahoma, and Louisiana in 2011 and Colorado and Wyoming in 2012).

Changes in precipitation and extreme rainfall events

Since 1900, average annual precipitation over the U.S. has increased by roughly 5 percent. There is a clear national trend toward a greater amount of precipitation being concentrated in very heavy events, particularly in the Northeast and Midwest, while the Southwest is becoming drier.

Across most of the United States, the heaviest rainfall events have become heavier and more frequent. The amount of rain falling on the heaviest rain days has increased over the past few decades. Since 1991, the amount of rain falling in very heavy precipitation events has been significantly above average. This increase has been greatest in the Northeast, Midwest, and upper Great Plains – more than 30 percent above the 1901-1960 average. There has also been an increase in flooding events in the Midwest and Northeast where the largest increases in heavy rain amounts have occurred.

Sea levels rising

Water expands as it warms, causing global sea levels to rise; melting of land-based ice also raises sea level by adding water to the oceans. Over the past century, global average sea level has risen by about 8 inches. Since 1992, the rate of global sea level rise measured by satellites has been roughly twice the rate observed over the last century, providing evidence of acceleration. Sea level is projected to rise by another 1 to 4 feet in this century.

This is not a partisan issue. These trends have real, everyday consequences for local governments, who are on the front lines when it comes to mitigation and adaptation efforts.

Taking one of the trends above, sea level rise, the stakes couldn’t be higher for local governments. Combined with coastal storms, there is an increased risk of erosion, storm surge damage, and flooding for coastal communities, especially along the Gulf Coast, the Atlantic seaboard, and in Alaska, putting coastal infrastructure, including roads, rail lines, energy infrastructure, airports, port facilities, and military bases, and the nearly five million Americans and hundreds of billions of dollars of property located in areas that are less than four feet above the local high-tide level, increasingly at risk.

Local governments can’t go it alone. The federal government must step up and adopt and enact policies and programs that will support local efforts. The Administration has taken the lead with the President’s Climate Action Plan that created the President’s Task Force on Climate Preparedness and Resilience, comprised of state and local officials to advise the President on ways the federal government can assist local efforts to address and prepare for the impacts of climate change.

NLC and ICLEI USA, under the auspices of the Resilient Communities for America campaign, where 175 mayors and other local elected leaders have pledged to create more resilient cities and towns, will release a policy report next week with nine recommendations on ways the federal government can remove barriers to local resilient investments, modernize federal grant and loan programs to better support local efforts, and develop the information and tools needed to prepare for climate change.

The 1,300 page National Climate Assessment is presented online in an accessible, interactive and graphic manner, which makes it easy for local leaders to dive into for an understanding of how climate change will impact their communities. For communities that have not yet begun climate mitigation efforts, adaptation planning or implemented resilience-building programs, policies and practices, now is the time. Climate change is happening now.

Carolyn Berndt

About the author: Carolyn Berndt is the Principal Associate for Infrastructure and Sustainability on the NLC Federal Advocacy team. She leads NLC’s advocacy, regulatory, and policy efforts on energy and environmental issues, including water infrastructure and financing, air and water quality, climate change, and energy efficiency. Follow Carolyn on Twitter at @BerndtCarolyn.