I made this image of the Empire State Building from 23rd Street last Monday. The all-green lighting of the Empire State Building symbolizes the three-day Large Cities Climate Summit in Manhattan on how to address climate change. The global summit of leaders, including former President Bill Clinton and NYC mayor Michael Bloomberg convened this week to exchange ideas on this timely issue. The summit is attended by mayors and governors of more than 30 international localities, along with chief executives from a number of international companies. Big cities like NYC must play a key role in reversing climate change - they cover less than 1 percent of the earth's surface, but are largely responsible for polluting it, contributing 80 percent of greenhouse gas emissions. Greenhouse gases, including carbon dioxide, methane and other gases, essentially trap energy from the sun. In a city like New York, the operation of buildings that consume electricity, natural gas, fuel oil and steam contributes an overwhelming majority of emissions. At the conference, delegates will "share best practices, identify collaborative projects and chart future actions relative to reversing dangerous climate change and realizing economic development benefits." There will be discussions on building greener cities, using renewable energy sources, transforming waste into energy and how to engage the private sector along the way. Recently, Mayor Bloomberg introduced his 23-year plan to make the city of 8.2 million people sustainable over the long term. It is projected that by 2030, there will be another million people living in NYC.