Climate change is making New York City hotter, wetter and under worst-case scenarios could raise sea levels as much as six feet by the year 2100, a group of independent experts reported to City Hall.
The New York City Panel on Climate Change Tuesday released its 2015 update on how Mayor Bill de Blasio's administration is working to keep communities resilient and bolster infrastructure in the face of climate change.
The price tag of city's comprehensive resiliency plan -- which is unfolding over many years -- is about $20 billion, according to the mayor's office. Much of it is already funded, including parts of the coastal protection efforts. Federal money is also helping foot the bill.
The de Blasio administration has proposed reducing New York City's greenhouse gases by 80 percent by 2050. Scientists blame global emissions as a key contributor to warming of the planet.
Mean temperatures are projected to increase by 4.1 degrees Fahrenheit to 5.7 degrees by the 2050s, and by 5.3 degrees to 8.8 degrees by the 2080s, the panel found. Experts warned that even fluctuations of a few degrees can have profound consequences for the region.
"What seem like maybe small shifts in averages -- average sea level rise increasing, temperature going up by 4 or 5 degrees -- can profoundly influence how frequently we get extreme events, and how severe those severe events are," said panelist Radley Horton of the Columbia University Earth Institute and Center for Climate Systems Research, at a City Hall briefing.
Average annual precipitation is expect to increase from 4 percent to 11 percent by the 2050s, and from 5 percent to 13 percent by the 2080s, using the 1980s baseline period.
The likeliest projections for sea-level rise through the rest of the century are 22 to 50 inches, but the most dire scenarios show a six-foot rise, the report said.
With a sea level base line raised by 5 feet, Horton said, "You turn what's currently a 1-in-100-year flood event into something that happens on average once every 8 years or so."
The panelists also said that heat waves are expected to increase to six per year by the 2080s from the current two per year. According to the National Weather Service, a heat wave is commonly defined as three successive days of temperatures at or above 90 degrees.
Like his predecessor, Michael Bloomberg, de Blasio has focused on long-term planning to tackle the dire effects of climate change.
Among the plans discussed Tuesday that are being put into effect: $335 million for flood protection on the Lower East Side, a project to assess the city's food-supply chain network, and a $100 million program for waterfronts like Coney Island Creek and Staten Island's South Shore.
The administration also provided an update on the city's Cool Roofs program: so far, 6 million square feet of building roofs have been coated with reflective paint to address urban heat. The goal is 1 million a year.
The panel's report was released in the Annals of the New York Academy of Sciences.
Scientists have long warned about the damage being wrought by the heat-trapping greenhouse gasses and how the of human behavior has exacerbated the problem.
"Actually, what we were surprised about," committee co-chair Cynthia Rosenzweig told reporters, "is that there weren't surprises."