New York City's $19.5 billion plan to adapt to climate change may be the world's most ambitious. But Mayor Michael Bloomberg is hardly alone in trying to find ways to prepare his city for rising seas and extreme weather as the global fight to limit warming to 2 degrees Celsius fades.
Roughly 20 percent of cities around the globe have developed adaptation strategies, according to a 2011 estimate by researchers at the Massachusetts Institute of Technology. In the United States, city, county and state governments have developed more than 100 adaptation plans, a separate count by the Georgetown Climate Center found. And through a UN-financing initiative, wealthy nations have poured $11 billion into developing countries to help on adaptation in the past few years.
Experts interviewed by InsideClimate News said that unlike Bloomberg's plan—which detailed 250 climate adaptation strategies and put a price tag on most of them—few other cities have outlined specific actions or provided concrete details on how government agencies should implement initiatives or pay for them.
"A lot of them tend to be an overarching, big vision document," or focus on a single, massive project, like a floodwall, said JoAnn Carmin, a professor in urban studies and planning at MIT. "In some cases, there's no clear work plan in place."
A lack of funding to pay for comprehensive analysis, a focus on other municipal priorities and a shortage of qualified staff is often to blame, she said. And unlike New York, which has its own panel of climate change scientists tapped from some of the best research universities, local governments rarely have access to data on the specific risks that global warming poses to their particular city.
Still, adaptation strategies around the world are maturing as cities and countries build on initial efforts. And no place embodies that trend better than New York City, said Jessica Grannis, a staff attorney for the Georgetown Climate Center.
"It's a huge step forward in terms of the quality of adaptation plans that are coming up"—one that could provide a useful framework as other cities create and refine their own strategies, she said.
The world could end up spending between $49 billion and $171 billion a year through 2030 on adaptation, according to UN figures. Some scientists put the figure at up to three times that amount.
Here's a sampling of cities with some of the world's most comprehensive initiatives.
New York City: Launched on June 11, 2013, by Mayor Bloomberg. The plan was developed in response to superstorm Sandy, which pummeled 1,000 miles of the Atlantic coastline last October and cost $19 billion in damage and economic losses to the city of 8.2 million people.
"A Stronger, More Resilient New York," proposes more than 250 initiatives to reduce the city’s vulnerability to coastal flooding and storm surge. About 80 percent of the $19.5 billion plan will go to repairing homes and streets damaged by Sandy, retrofitting hospitals and nursing homes, elevating electrical infrastructure, improving ferry and subway systems and fixing leaky drinking water systems. The rest will go to building and researching floodwalls, restoring swamplands and sand dunes, and other coastal flood protections.
The 438-page plan was based on hyper-local climate models specific to New York City. The models come from the Intergovernmental Panel on Climate Change's (IPCC) upcoming Fifth Assessment Report, which can project future climate in more detail and on a smaller scale than previous models.
London: Adopted in October 2011 by Mayor Boris Johnson. The adaptation strategy was developed in response to rising concerns about persistent flooding, drought and extreme heat waves in the city.
The mayor's office kicked off the initiative in early 2010 by calling on London's 8.1 million residents to share ideas and expertise in an online forum. "Either we can grow gills, or we'll need to think of other ways of adapting," Johnson said in a promotional video. The website still maintains an active discussion.
The final report, "Managing Risks and Increasing Resilience," analyzes the threat of global warming impacts to the city and identifies the residents and infrastructure that are most vulnerable. It also proposes 34 initiatives to protect and strengthen the city, including three key actions: managing the risk of surface water flooding, increasing the amount of parks and vegetation in the city, and retrofitting more than one million homes by 2015 to improve water and energy efficiency.
London's adaptation plan is based on national climate change projections from 2009 created by the UK's official center for climate change research, the Met Office Hadley Center. Unlike New York, the city doesn't detail the expected cost to implement the proposed initiatives. London’s separate flood risk management plan for the Thames River, however, would cost the city about $2.3 billion in its first 25 years.