BEIJING, Dec. 15 -- After a champagne moment in Paris, where a historic climate agreement was reached over the weekend, now comes an even harder mission: implementation.

Envoys from nearly 200 countries on Saturday approved the landmark climate accord at the end of two weeks of make-or-break negotiations. The agreement states that global warming should be capped at two degrees Celsius over pre-industrial levels, while the even more ambitious goal of 1.5 degrees was also put forward as a best case scenario and possible motivator.

The post-2020 agreement marks a shift in global diplomacy on the issue, ending decades of rows between developed and developing nations over how they stave off the effects of climate change.

But the real battle against climate change has just begun, and this time, nations face not bickering and buck-passing around conference tables, but the real challenge of how to ramp up their actions over time to keep the hard-fought provisions in sight.

More than 180 countries, which contribute 95 percent of the world's total carbon emissions, have submitted their own intended nationally determined contributions (INDCs).

Under the Paris accord, every country should participate in global actions against climate change through their own INDCs. From the year 2023, all parties are required to assess their progress in implementing their INDCs. This will allow each nation to reinforce international cooperation in order to ensure the long-term goal of addressing climate change is met.

But even if all the pledges are fully honored, they will set the stage for a world that is about three degrees warmer.

The two-degree threshold is one at which experts hope we can avoid risky climate change.

But according to the UN's World Meteorological Organization, we may already have used up almost one degree of that allocation.

To stick to the two-degree target, countries will not only have to make sure that the Paris climate accord is effectively implemented, but make even more emissions cuts than promised.

In a telephone conversation with U.S. President Barack Obama, Chinese President Xi Jinping called on the two countries to work with all parties to effectively carry out the historic climate accord.

China is willing to work with the United States and other relevant parties to ensure the implementation of the Paris deal and expand bilateral cooperation in tackling climate change, Xi said.

He told French President Francois Hollande the same thing Monday in another phone call, adding that the success of the Paris conference showed that the international community is capable of solving major global issues through cooperation and dialogue.

A sobering fact, and one that all nations must acknowledge, is that the victory in the fight to ward off climate change depends on more than the Paris deal itself.

The success over the weekend is cause for celebration, but a Paris hangover without concrete actions will only spoil the hard-won deal.

Ultimately, it is solid action, rather than high ambition alone, that will keep the two-degree goal alive.