US president Barack Obama said on Wednesday he was optimistic an elusive deal to contain global warming could be forged at an upcoming crunch summit in Paris, and insisted an ambitious deal would boost a flagging world economy.

In a speech to an Asia-Pacific business conference in the Philippines, Obama said there was still a “lot of work to do” to ensure success at the United Nations summit.

“Nevertheless, I’m optimistic that we can get an outcome that we’re all proud of, because we understand what’s at stake,” Obama said.

The goal of the climate summit in the French capital, which begins on 30 November , is to forge a pact to reduce the greenhouse gas emissions that are blamed for global warming.

The meeting will try to negotiate a pact to keep global warming below 2C over pre-industrial levels.

Scientists warn that unless drastic action is taken quickly, warming temperatures will lead to rising sea levels and natural catastrophes that threaten mankind.

The Paris event represents the first bid for a truly global climate rescue pact since the chaotic 2009 summit in Copenhagen ended in bitter disappointment.

Previous efforts have failed because governments and businesses have struggled to break free from fossil fuel dependency that has driven economic growth since the industrial revolution.

In the latest example, the Republican-run US Senate on Tuesday rejected key rules wanted by Obama’s administration to limit greenhouse gas emissions by power plants.

“There is not a contradiction between growth, development and being good stewards of the planet, they are complementary,” Obama said at the conference, which is taking place ahead of the annual Asia-Pacific Economic Co-operation (APEC) gathering.

“The old rules that said we couldn’t grow our economies and protect our environment at the same time, those are outdated. We can transition to clean energy without squeezing businesses and consumers.”

Obama insisted an ambitious deal in Paris would spur investment, as it would signal to businesses that they should “go all-in on renewable energy technologies”.

“If we can get an agreement done, it could drive new jobs and opportunities, and investment in a global economy that, frankly, needs a boost right now.”

After his speech to the business leaders, Obama led a panel discussion with Chinese tech-billionaire Jack Ma and Aisa Mijeno, a young Filipina engineer turned entrepreneur.

Mijeno explained how she invented a cheap lamp that runs on salt water and can charge a cellphone - part of a bid to provide poor villagers in remote areas of the Philippines with clean electricity.

“Climate change is real, it’s a fact. It’s not a myth that scientists created in order to get funding or grants. It’s real, it’s happening now,” she told Obama.

Mijeno then compared climate change to the stages of cancer, saying the earth was around stage two, where symptoms are beginning to show but can be treated.

“You don’t want to get to stage four,” Obama replied.