From our hotel rooms we can look over Shanghai, an enormous, world-class city of modern, architecturally innovative skyscrapers as far as the eye can see. There are cranes everywhere, and the city is getting ready to host the largest World Expo in history next year. Everyone we met, from the Mayor of Shanghai, to company executives, to building materials experts, emphasized with great pride how green building techniques and energy efficiency are integrated into buildings starting in the design phase.

This bustling city is home to more than 20 million people, the largest city in China, and among the largest in the world. It is far from the only city here to experience explosive growth in recent years; there are now 174 cities in China with more than 1 million people. By comparison, the United States has five states that have less than 1 million people.

Although the average Chinese person uses far less energy per person than the typical American, their large steel and cement industries and substantial urban populations mean that China's energy use now exceeds that of the United States. That puts a tremendous obligation on China to address its global warming pollution.

Our congressional delegation has come to China with a message that the United States is finally ready to take a leadership role in solving global warming, but that we must work together with China. Together, our two countries are responsible for 40 percent of global warming emissions and we both have a responsibility to take action.

We have heard from many people we met with, from government officials, to business leaders to energy experts, that China has two faces: the modern urban China and a less developed China where there is less capacity to take action.

Our conversations focused on learning how we can work together with Chinese leaders from around the country. We heard about new energy efficiency standards, the push to produce electric vehicles, commitments to develop more renewable energy, upgrade old coal-fired power plants and reduce greenhouse gas emissions from the biggest polluting industries of steel, cement and glass. When our delegation travels to Beijing later this week, we will ask government leaders whether these developments are being adopted across China in a transparent and enforceable manner.

After two days of meetings, we are encouraged that China recognizes and is beginning to address the immense challenge of global warming. We remain curious as to whether these developments apply to other industrialized areas of China and whether the Chinese government will commit to transparency and concrete action to reduce its emissions.

There is much more to be done here in China, but also in the United States, as we look forward to international negotiations in December in Copenhagen.