This week, the whole world is watching.

It has been a busy week for world leaders, who gathered in the United States to attend a string of UN pow-wows and a G20 summit on global issues ranging from climate change to the financial crisis.

Stepping upon the UN podium one by one, the leaders staked out their countries' positions and grabbed global attention as they shared their wisdom on how to deal with the threats facing mankind.

The whole world is watching - even as the week of multilateral meetings and talks is drawing to a close. The world leaders' words are still echoing, waiting to be matched with deeds.

Curbing climate change: the clock is ticking

Many pledges were made at the climate change summit, but substantial progress should be made, and made quickly, because the Copenhagen conference is less than 80 days away.

Climate change negotiations have stalled on several fronts, including a division between rich and developing nations on what is expected and how much funding the industrialized nations should provide.

That is why a UN climate change summit was held this week to generate political momentum so that a fair, effective and comprehensive global deal can be hammered out in Copenhagen to help stop climate change from worsening and slipping out of control.

Speaking at Tuesday's UN climate change summit, Chinese President Hu Jintao unveiled a number of climate targets and plans of China, including a promise to cut carbon dioxide emissions per unit of gross domestic product by "a notable margin" by 2020 from the 2005 level.

"The principle of common but differentiated responsibilities embodies the consensus of the international community," Hu said.

The Chinese president urged developed countries to fulfill the task of emissions reduction set in the Kyoto Protocol and to support developing countries in countering climate change.

US President Barack Obama admitted the urgency of the issue and said that "the developed nations that caused much of the damage to our climate over the last century still have a responsibility to lead."

However, the American president was vague in terms of what his country could promise and failed to give details. He also attempted to make developing countries shoulder extra obligations beyond what was set in the United Nations Framework Convention on Climate Change and the Kyoto Protocol.

Making his UN debut like Obama, Japan's recently elected Prime Minister Yukio Hatoyama said Japan would cut greenhouse gas emissions by 25 percent below 1990 levels by 2020. However, Japan's precondition is that all economies, including the developing ones, reach a deal on an emissions cut target.

"Failure to reach broad agreement in Copenhagen would be morally inexcusable, economically short-sighted and politically unwise," UN Secretary-General Ban Ki-moon warned.

As climate negotiators gather in Bangkok on September 28 to attend a new round of UN climate change talks to prepare for the Copenhagen conference, the stakes are high.