New York City announced Tuesday it plans to replace a portion of its city-owned fleet of fossil-fuel sedans with plug-in electric cars like the Nissan Leaf and Chevrolet Volt by 2025. The plan is to swap out 2,000 vehicles, or almost a quarter of the city's entire fleet, over the next decade. Mayor Bill de Blasio's office said the announcement was timed to coincide with the Paris climate talks currently underway.

After the conversion is finished, New York City could have the largest number of municipal electric vehicles in the country, if not the world, the mayor's office boasted. "A cleaner, greener fleet is yet another step toward our ambitious but necessary sustainability goals, including an 80 percent reduction in all emissions by 2050," de Blasio said in a statement. "Cities are setting the pace on climate action — and with our city and our planet's very future at stake, we need national leaders in Paris to take note and take action."

The plan would not apply to emergency vehicles, like police cruisers and city-owned ambulances, which account for roughly half of the city's 11,000 fleet of sedans and SUVs. The police and fire department vehicles "have more exacting performance requirements than most current [electric vehicle] technologies offer," the city's plan reads.

"In general, current mass-market EVs have range constraints and require long charge times that mean they can't be deemed 'pursuit rated,'" she added in an email to The Verge. "Teslas will have to come down in price or other manufacturers will need to offer longer-range, faster-charge batteries that are sufficiently power-dense to allow for the speeds and acceleration required in emergency response. Additionally, emergency services/police are most likely to use vehicles for multiple shifts per day, which limits recharging time."

Under the plan, New York City-owned vehicles operated by agencies like the Parks and Transportation departments would be swapped out for electric vehicles as they are phased out. The conversion is expected to cut the city's vehicle emissions by 50 percent by 2025 and 80 percent by 2035.

Challenges remain, such as finding space for charging stations and updating facilities to accommodate electric vehicles. A task force will be set up "to address these infrastructure siting barriers and to identify sufficient siting opportunities for EV chargers throughout the city," the city says. A law passed in 2013 requires new parking garages to provide charging stations for 20 percent of its parking spaces.

Earlier, De Blasio announced a plan to reduce greenhouse emissions produced by privately owned buildings by 80 percent by 2050. Before that, though, he wants to cut building emissions by about one million metric tons through retrofits in roughly 1,000 buildings a year by 2025.

New York City is racing against other larges cities to convert its gas-guzzling fleets to electric. Governing magazine declared 2015 the "Year of the Electric Municipal Fleet." Indianapolis is exploring saving millions through conversions —although it is experiencing problems with city employees overloading circuits while charging their cars. And Los Angeles Mayor Eric Garcetti announced in September that 160 electric vehicles and 128 plug-in hybrids would be leased to the city's fleet.