For the first time in human history , more than half the world 's population is living in cities , which now produce approximately 70 percent of global greenhouse gas emissions . That puts cities on the frontlines of the battle against climate change -- and more and more cities are leading the charge . In New York , we began a frontal attack on climate change in 2007 with the release of our sustainability blueprint , PlaNYC -- and since then we 've made major progress . For instance , we are well on our way to meeting our goal of reducing our greenhouse gas emissions by 30 percent by 2030 . For coastal cities like New York , the risks of climate change are especially serious : sea levels are expected to rise by another two and a half feet in the next 40 years , making storm surges even more powerful and dangerous . And intense storms are likely to increase as the ocean 's temperatures continue to rise . But it 's not just storms . Droughts and heat waves may be longer and more intense for urban populations everywhere in the years to come . Around the world , city leaders are not wasting time debating the science of climate change or waiting around for international treaties to be signed ; we are taking action . There 's simply too much to do and too much at stake . For the past two years , I have been chairman of the C40 Cities Climate Leadership Group , which includes some of the biggest and most innovative cities in the world . Thanks to C40 's research , we know that C40 Cities have taken more than 4,700 actions to reduce greenhouse gas emissions and adapt to the possible effects of climate change . In fact , C40 has the potential to reduce emissions by more than one billion tons a year by 2030 — which is equivalent to making both Canada and Mexico entirely carbon-neutral . In New York City , our actions to reduce our carbon footprint include planting more than a half-million new trees ; banning the use of the most polluting forms of heating oil ; and launching a major bike sharing initiative . The strict codes we 've adopted for energy-efficiency in major commercial and residential buildings have the potential to reduce our greenhouse gas emissions by at least five percent and save New Yorkers more than $ 750 million per year in energy costs . But our work to make our city more energy efficient is only half the battle . Last fall , Hurricane Sandy made all too clear how vitally important it is to build stronger and more sustainable infrastructure that can withstand extreme weather events . That 's why in June , we launched a long-term plan specifically focused on protecting our city from the effects of climate change.e . For instance , we 're working to strengthen dune systems and beaches across the city . Our plan includes surge barriers to prevent flooding and a strong network of bulkheads , floodwalls , levies , and other protections in vulnerable places along the waterfront . We are working with private companies and regulators to strengthen critical infrastructure against severe weather -- including our power , telecommunications , and transportation systems . And we 're also raising construction standards to ensure new buildings can withstand extreme weather . In developing this plan , we looked around the world to identify best practices and innovative new solutions -- and that 's the power of the C40 network . It creates a forum for cities to share best practices and resources -- and even to collaborate with other cities and institutions . For instance , C40 has now formed partnerships with the World Bank and other international organizations that have expertise and resources , which are helping cities take bolder actions more quickly . In addition , C40 has focused on the research and data collection necessary to assess our progress , because I firmly believe in the maxim : If you ca n't measure it , you ca n't manage it . Mayors are pragmatists , not partisans ; innovators , not ideologues . We are responsible for delivering results , not debating politics . And as the world becomes increasingly more urban , the importance of bold local action -- particularly on climate change -- will continue to grow .
New York City Mayor Bloomberg is chairman of C40 Cities Climate Leadership Group . City leaders are taking action , not debating climate science , says Mayor . Hurricane Sandy emphasized construction of stronger infrastructure . New York is preparing for future disasters and cutting costs .