Media playback is unsupported on your device Media caption John Kerry: "It is urgent that we tackle climate change"

US Secretary of State John Kerry has urged the global community to act against climate change in a keynote speech during a visit to Indonesia.

He said that there was scientific proof of climate change threatening not only the environment, but also the world economy.

He said "the window of time is still open" to prevent the worst consequences, but that it was closing.

The US, along with China, is the biggest emitter of greenhouse gases.

On Saturday, both nations issued a joint statement pledging to do more to curb their carbon dioxide output.

Steps include reducing car emissions and improving the energy efficiency of buildings.

Mr Kerry said that while those nations with bigger emissions had to do more to help solve the problem, "that doesn't mean other nations have a free pass".

Nations with lower emissions must not "repeat the mistakes of the past", he said.

'Point of no return'

Mr Kerry was speaking in Jakarta, his latest stop on a regional tour.

He began his trip in South Korea on Thursday, and arrived in Indonesia on Saturday after visiting China.

It is part of President Obama's "pivot to Asia" policy, begun in 2012, shifting the US foreign policy focus more towards Asia and away from Europe and the Middle East.

In his Jakarta speech, Mr Kerry underscored the way in which climate change is affecting Asian countries.

He also highlighted the possible effects on the global economy, including "potentially catastrophic effects" on the global supply chain.

He warned against "complacency", pointing out that last year carbon dioxide levels in the atmosphere reached their highest ever level.

Image copyright Getty Images Image caption River Citarum near the Indonesian town of Majalaya is one the most polluted waterways in the world

Mr Kerry wants to help broker a global climate treaty in 2015 that will commit the US and other nations to historic reductions in fossil fuel pollution, the BBC's Washington correspondent Kim Ghattas reports.

Environmental groups have criticised the Obama administration for not doing more to reduce US fossil fuel use. Late last year, the US president appointed a new adviser on climate change.

John Podesta, a former White House chief of staff, will help Mr Obama prepare executive actions that bypass Congress, where there is deadlock on the issue.

The talks in Paris next year are aimed at finding a new international climate agreement to succeed the Kyoto Protocol which ends in 2020. The US never ratified the Kyoto agreement, signed in 1997.

Environmental groups have criticised President Barack Obama for not doing more to reduce US carbon dioxide emissions.

On Saturday, the US and China said they would "collaborate through enhanced policy dialogue, including the sharing of information regarding their respective post-2020 plans to limit greenhouse gas emissions".

Last year, a landmark report by the UN's climate panel found scientists were 95% certain that humans were the "dominant cause" of global warming since the 1950s.