A star-studded Paris summit

It is not unusual that climate conferences start off with resounding speeches and fervent appeals. But what set this first day of the climate conference in Paris apart from other such events was the fact that these appeals were delivered not by environment ministers, but by some 150 heads of state and government.

"It is on your shoulders that the hopes of all humanity rest," French President Francois Hollande told his counterparts from around the world.

And US President Barack Obama urged fellow world leaders to "rise to the moment."

Even German Chancellor Angela Merkel, in general less emotional, said that concluding a universal climate change agreement in Paris was "a question of the future of humanity."

Merkel's statement

The chancellor also said there was a need for "far-reaching" decarbonization of the global economy - a statement climate activists said should be taken with a grain of salt.

"When chancellor Merkel says we must decarbonize and get off coal, oil and gas, we support that," said Kumi Naidoo, head of Greenpeace International.

"But the detail that we want to hear is that we can get to that point by 2050," Naidoo added.

Merkel spoke of decarbonization "by the end of the century."

She also called for a climate agreement that was "ambitious, fair and binding."

"I found it interesting that Merkel said she wants to see a review of national pledges to reduce greenhouse gas emissions before 2020," said Christoph Bals of the NGO Germanwatch. "The position of the European Union has been that the first review should take place only in 2023. By calling for an earlier date, Merkel is putting pressure on the EU to improve on its climate targets for the decade starting in 2020."

A different view from China?

For his part, Chinese President Xi Jinping said it was "imperative" to respect the differences among countries and that developing nations should not be denied their "legitimate needs" to grow.

But Xi also talked about "win-win situations" in following low-carbon growth paths.

Germanwatch's Bals interpreted this as a positive change from the rhetoric used in past climate conferences.

"China used to say that fighting climate change is a burden that others should bear," Bals said. "Saying that through technology transfer it can be turned into an opportunity means putting a whole new spin on things."

"At the climate conference in Copenhagen in 2009, China said emissions would continue throughout the century," Greenpeace's Naidoo said. "Now they have made a commitment that emissions will peak by 2030 at the latest - and that is a pretty big shift."

'Let's get to work'

President Obama reaffirmed the US's commitment to help developing nations embark on low-carbon growth paths, and pledged $50 million (47 million euros) to a fund supporting the world's poorest countries.

"We embrace our responsibility," Obama said, acknowledging the US' role in climate change as the world's second largest emitter of greenhouse gases after China, and ending his statement with an appeal to negotiators to "get to work."

Overall, Bals said, "there was little of substance in Obama's speech."

Concepts to speed up negotiations

The getting to work that Obama called for was facilitated by a move of the French presidency to get procedural questions addressed prior to the event's formal opening, enabling true negotiations to start right away.

Bals called this an "innovative" approach that might prevent negotiators from spending "two or three days" on tactical maneuvering.

The longtime observer of climate conferences added that, though many of Monday's statements might not have contained many surprising or specific elements, they should not be seen as mere "showcase speeches."

"The delegations will be held to what their leaders have said," Bals said, "and if a delegate says something contradictory, the presiding chair can refuse this position for backtracking on a leader's statement."

The aim is to present a consolidated text on Thursday. But many take this as an ambitious goal, and a lot of obstacles have to be overcome to achieve it.