UNITED NATIONS (Reuters) - The Obama administration will work with the United Nations to reach a climate change deal acceptable to the world community by the end of 2009, U.N. Secretary-General Ban Ki-moon said on Thursday.

Speaking to reporters after a two-day trip to Washington earlier this week, Ban said he and the new American leader agreed completely on the urgency of tackling the problem of global warming.

“President Obama and I share a fundamental commitment -- 2009 must be the year of climate change. That means reaching a comprehensive agreement in Copenhagen by year’s end,” the U.N. chief said at a monthly news conference.

“With U.S. leadership, in partnership with the United Nations, we can and will reach a climate change deal that all nations can embrace,” he added.

The U.N. hopes to have a new global treaty on climate change in place at a conference in Copenhagen in December. Some experts warn that the world will face more droughts, floods and rising seas if global warming is not addressed soon.

Ban will attend the G20 leaders’ summit in London next month amid fears that the issue could be pushed far down the agenda by the global economic crisis and the need to restore faith in shattered financial markets.

The U.N. chief had planned to invite Obama and other leaders to New York this month for what was dubbed a “mini summit” on climate change, hoping that the U.S. president would use the occasion to announce a reversal on the issue.

Former U.S. President George W. Bush was criticized in much of the developed world for rejecting the U.N. Kyoto Protocol, which set binding targets for reducing the greenhouse gas emissions that contribute to global warming.

The mini summit was shelved because of the unlikelihood that the U.S. president would attend and the realization that the issue would be raised by the G20 in London, according to diplomats and U.N. officials.

Ban also said on Thursday that he would urge the G20 nations to honor their commitments to help the world’s poorest and most vulnerable countries and push ahead with investments in environmentally friendly initiatives.

“President Obama and I further agreed that ‘green’ investments must be a major part of any global stimulus plan,” he said. “If we are going to spend such tremendous sums of money, let us be smart about it.”

British Prime Minister Gordon Brown, who is hosting the April 2 summit, supports the idea, according to Ban. Britain also has dismissed objections from countries like Russia who want the summit to focus exclusively on the financial crisis.

“We must not allow the financial turmoil to distract us from meeting the challenges of climate change and development,” said a British government document obtained by Reuters on Wednesday.