One of the major lessons learned from the storm "is the recognition that climate change is a reality; extreme weather is a reality; it is a reality that we are vulnerable," said New York Gov. Andrew Cuomo (D) in a press conference yesterday.

The governor called for a "fundamental rethinking of our built environment" to ensure the city is more prepared to deal with extreme weather events like Sandy in the future.

"Protecting this state from coastal flooding is a massive, massive undertaking. But it's a conversation I think is overdue," Cuomo said.

 Researchers, however, have been warning of the damage New York City would sustain in the event of severe flooding and sea-level rise for years. A 2009 study by Stony Brook University's Storm Surge Research Group, for instance, estimated that building a barrier network to protect New York City and the surrounding area from storm surges would cost at least $10 billion.

"At the end of the day, I wouldn't be surprised if fixing the city up from this catastrophe costs more than that easily," said Malcolm Bowman, an oceanography professor at Stony Brook and author of the report. "And it could happen again in the next year."

New York has been a leader in studying the impacts of flooding and sea-level rise and has already taken some initial precautions. In response to a fierce storm during the summer of 2007, the city began raising subway entrances and ventilation grates to stop runoff from entering the tunnels. But it has been slow to make long-term preventive measures.

Last year, David Bragdon, former New York City sustainability chief, told the New York's City Council that the city government was looking at a number of "structural and non-structural" coastal protection strategies. But he did not make mention of any major engineering solutions, such as storm surge barriers.

Asked whether Hurricane Sandy had triggered action to take on future adaptation measures, a spokesperson with the mayor's office said in an interview that, for the moment, the city is focused on "dealing with the current situation."

 Turning to a 'bus bridge'
After suffering what New York's Metropolitan Transit Authority (MTA) Chairman Joseph Lhota called "a disaster as devastating as it has ever faced in its history," the New York transit system is starting to reopen.

According to the MTA, the Long Island Rail Road and Metro-North Railroad started offering select service yesterday and the subway system will start to offer limited service on several routes today, supplemented by a shuttle bus where necessary.

Hurricane Sandy caused an immense amount of damage to New York's metropolitan area, but the damage would have likely been worse if city managers hadn't pre-emptively shut down the subway, blocked grates and built makeshift dams to hold back water in vulnerable stations.

In the aftermath, with all subway lines still closed, Mayor Michael Bloomberg gave orders to allow yellow cabs to pick up multiple passengers. "We're encouraging this ride sharing," Bloomberg said at a press conference Tuesday.

To help ease traffic, which is expected to worsen as more and more people return to work, Gov. Cuomo said there would be a "bus bridge" running express service between Brooklyn and Manhattan.

These types of temporary measures the city has put in place in the wake of the storm are practices that could reduce congestion and greenhouse gas emissions on a daily basis in future, said Michael Kodransky, global research manager at the New York-based Institute for Transportation and Development Policy.