Unveiling a $15 billion annual investment plan to build a clean energy future, president-elect Barack Obama has said his presidency would mark a 'new chapter'in America's leadership on climate change and would engage vigorously in international negotiations on it. The truth is, the United States cannot meet this (climate) challenge alone. Solving this problem will require all of us working together," Obama said on Tuesday in a surprise video message to the Bipartisan Governors Global Climate Summit in Los Angeles. Besides governors from 22 key US states, top government officials from several countries including India, China, Brazil, Britain, Canada, Indonesia and Australia are participating in the meeting. In a four-minute video message Obama said "My presidency will mark a new chapter in America's leadership on climate change that will strengthen our security and create millions of new jobs in the process". Observing that Washington has too often failed to show the kind of leadership needed to tackle such an important issue, Obama said his administration would start with a federal cap and trade system. "We will establish strong annual targets that set us on a course to reduce emissions to their 1990 levels by 2020 and reduce them an additional 80 percent by 2050," Obama said, according to the transcripts of the message made available by the Obama Transition Office.