A global climate pact is again on the horizon, and this time environmentalists say they want to avoid the pitfalls of the past.

The much-hyped 2009 Copenhagen, Denmark, climate conference, where presidents, prime ministers and negotiators ultimately failed to seal the deal on a binding new greenhouse gas emissions treaty, is now the embodiment of the thing to avoid in 2015, activists said yesterday at the opening of a midyear negotiating process.

They said this new deadline, set under the terms of an agreement reached in Durban, South Africa, last year to deliver a new deal binding all major emitters and taking effect by 2020, must look different.

"We should not aim for a big conference summit at the end of this new process in 2015 like what happened in Copenhagen," said Wael Hmaidan, director of Climate Action Network International.

"On the contrary, we need to establish milestones that we need to achieve every year, and we need to make sure that the agreement comes into pieces year after year, and not leave anything to the end to have this big amazing deal which, if we don't reach, we lose everything."

Liz Gallagher, a senior policy adviser at the U.K. think tank E3G, agreed that Copenhagen was "too political for the technocrats and too technical for the politicians, and that led to a kind of shambles of a process."

She, too, called for a steady stream of nitty-gritty agreements raising ambition levels, addressing the threats to tropical forests, raising money for vulnerable countries and other issues to avoid an "all-or-nothing approach" that defined Copenhagen.

"This year will set the tone," Hmaidan said. "It's a very crucial year, this transitional year, and we believe it's not getting as much attention as it should."

Difficult choices loom

At minimum, it's among the most complicated years in recent history. While the "Durban Platform" that nations signed last year establishes an agreement to form an agreement by 2015, the details remain to be sorted out.

India, in particular, has been pushing back against the agreement and any attempt to undo the clear distinctions set out in the 1997 Kyoto Protocol of industrial countries required to curb emissions and developing countries able to voluntarily cut carbon in exchange for money.

In this year's final talks in Doha, Qatar, in November, diplomats may have to decide what countries will agree to enter into a second commitment period of the Kyoto Protocol and whether that phase should last five years or eight years.

They may also have to try to close what's known as the "ambition gap" -- a phrase negotiators use to describe the chasm between emission targets that countries have made with the far tougher goals that scientists say will be needed to avoid catastrophic global warming. Finally, they will have to figure out how to raise the $100 billion annually by 2020 that nations pledged to mobilize for climate mitigation and adaptation.

Denmark's minister of development, Christian Friis Bach, whose country currently holds the rotating presidency of the European Union, said the bloc's top priority this year is continuing the momentum of Durban.

"For us in the E.U., the positions reached in Durban really brought a breakthrough in the international climate talks, and it's important for us to keep that momentum and that constructive spirit," he said. "First and foremost, we have to make sure there is no backtracking to what we decided in Durban."

Christiana Figueres, executive secretary of the U.N. climate change regime, called the beginning of a new process that could lead to a final treaty "very exciting." She, too, called for deliberative decisions -- unlike the heady pronouncements of a global deal that preceded Copenhagen -- saying, "I think we need to temper our excitement also with realism."