This article was originally published on Huffington Post.

The Paris Agreement is cause for celebration. After years of struggle, it sets a new course on global climate action. Now, four months after 196 countries came together in Paris, it's time for leaders to roll up their sleeves and determine how to move from commitments to action.

As these government representatives gather on April 22 at the United Nations to formally sign the Agreement, the moment is ripe to ask what must happen next to turn the vision of a low-carbon future into reality.

There isn't a moment to lose.

Ever since Paris, a parade of new data points to the perils of delay: 2015 was once again the hottest year in the modern meteorological record. March 2016 was not just record hot, but jaw-droppingly so. It also marked the 11th consecutive month of record-breaking heat globally. The extent of Arctic sea ice (the measure of how much of the far north is melting) also broke the record in January and just skirted the record in February and March. A new climate model indicates that the West Antarctic ice sheet could melt faster than previously thought, fueling sea level rise. A nearly two-decade-long drought around the Mediterranean is the worst in 900 years.

Against this backdrop, many nations are stepping up with climate action. The UN summit gives world leaders the opportunity to show they are serious about shifting course. What should we look for?

Countries Take the Lead

Many national governments are leading. From new solar projects in Morocco and India to plans to offer enhanced national climate commitments by Argentina and Indonesia, momentum toward low-carbon is building.

China and the United States, the world's two biggest carbon polluters, have committed to formally join the Paris Agreement as soon as possible this year. Apart from the message this sends to the rest of the world, these two countries together account for 38 percent of global greenhouse gas emissions.

Once at least 55 Parties join and 55 percent of emissions are covered, the Paris Agreement will go into force. UN Secretary-General Ban Ki-moon has called for leaders to sign and join the Agreement as soon as possible. Entry into force will show not only political will, but also put in motion the key elements of the Paris Agreement, including the ambition mechanism to increase action over time.

What mix of countries will be needed to get us across the 55-55 threshold? WRI's Paris Agreement Tracker offers a way to keep track of actual commitments and experiment with different configurations of countries and emissions to see which combinations could get us over the global goal.

What More Needs to Happen This Year?

Moving from commitment to action will take hard work and political will.

While every country's capabilities are different, all need to develop very clear roadmaps for how they will put their NDCs - their Nationally Determined Contributions, or commitments to deal with climate change - into action. To make sure their NDCs can be effective, countries should get specific about their plans for renewable energy, urban infrastructure, forest management, landscape restoration and other strategies to mitigate the impact of climate change.

Most NDCs are statements of intent rather than detailed, least-cost plans. Designing the policies and programs that underlie the delivery of the NDCs is not easy, and will require the best expertise. International efforts to support such processes will need to be coordinated to prevent a tangles of overlapping technical assistance offerings

Countries will also need to determine how they can align their commitments to tackle climate change with the needs of the world's most vulnerable as spelled out in the Sustainable Development Goals. That is going to require clear plans for national investment and associated financing..

To actually make it possible for action on the ground, countries with climate finance pledges must get down to the nitty-gritty of what those pledges mean: what they add up to and how they can help meet the goal of mobilizing $100 billion a year in climate finance by 2020. Effective rules to track climate finance can help countries make longer-term plans for how to use the money.

More broadly, investors must show they are in line with the Agreement's aim to ensure financial flows are consistent with low greenhouse gas emissions and climate-resilient development. Financial institutions need to shift funding away from high-carbon sectors and towards climate solutions.

Progress Before Marrakesh

We will need significant movement between now and the next global climate meeting in Marrakesh later this year, especially by putting in place the nuts-and-bolts details that will bring the Paris Agreement to life. The Agreement has the potential to spur action at the national level, improve tracking and reporting of climate commitments, encourage greater ambition and make certain that countries have the resources and capacity necessary to effect the change we need. We need world leaders to drive action, with more finance ministers getting engaged as the world starts to implement the Paris Agreement.

We are at a unique and urgent moment. Climate impacts are mounting and the door to make progress is closing. It's time to go all in. If we want change, we must transform our economies, our energy and our ways of doing business. The framework is set. Time to get to work.