U.N. Ssecretary-General Ban Ki-moon greets the crowd at the 2015 Global Citizen Earth Day Concert in Washington, D.C. on April 18, 2015. (UN Photo/Eskinder Debebe)

(CNSNews.com) – More than five years after President Obama and other leaders agreed on a 2020 goal of raising $100 billion each year from public and private sources to help developing countries deal with climate change, the United Nations wants to see action.

Ahead of Earth Day on Wednesday, U.N. Secretary-General Ban Ki-moon is pointing to a meeting next month in New York where he says he will be looking for clear indications from governments and investors as to how the ambitious goal will be reached.

“Climate change is the defining issue of our times,” he told a conference hosted by Bloomberg New Energy Finance last week. “It is also an enormous economic opportunity.”

On Saturday Ban again tackled the subject, at an International Monetary Fund event in Washington.

“We need a credible trajectory for realizing the $100 billion goal per year by 2020, as well as the operationalization of the Green Climate Fund,” he said.

“This was a commitment which was made in 2009 during the Copenhagen climate change summit meeting. We have only mobilized $10 billion as an initial capitalization of this Green Climate Fund. I would really hope that there will be a trajectory, a path, which will be shown to the member-states.”

And at a pre-Earth Day concert on the National Mall in Washington, D.C., on Saturday night, Ban called on concert-goers to raise their voices in support.

“I want to hear from you,” he told the crowd. “It’s our last chance to slow global warming.”

Launched in 2011 as a result of that 2009 decision in Denmark, the Green Climate Fund (GCF) is designed to help developing countries curb “greenhouse gas” emissions and cope with occurrences blamed on climate change, such as rising sea levels.

The aim is to reach $100 billion a year by 2020.

As of April 10, the fund had received pledges from 33 countries, totaling $10.2 billion. That includes a $3 billion pledge by Obama last November, by far the largest contribution promised to date. Some GOP lawmakers have signaled an intention to push back.

The next big date on the international climate calendar is a U.N. climate mega-conference in Paris in November that is meant to deliver a new global agreement.

Ban and U.N. climate officials want clarity on the financing issue, as a confidence booster ahead of the Paris gathering.

Subsidies in the firing line

According to the World Bank, two key ways for governments to free up funding to help achieve the $100 billion target is by “putting a price on carbon” – through carbon taxes or emission trading schemes – and phasing out fossil fuel subsidies.

“With a small percentage of the money that saved by ending subsidies or of the revenue raised from a carbon tax or permit sale going to climate finance, governments could help meet the $100 billion climate finance commitment and other mitigation and adaptation needs,” it said in a report Saturday on the IMF and World Bank spring meetings in Washington.

A coalition of eight countries – Costa Rica, Denmark, Ethiopia, Finland, New Zealand, Norway, Sweden and Switzerland – is targeting the subsidy issue in particular. The coalition, calling itself “Friends of Fossil Fuel Subsidy Reform,” said on Friday governments spent more than $548 billion on fossil fuel subsidies in 2013.

The group noted pointedly that this was more than five times more than the $100 billion target for climate mitigation and adaptation by 2020.

“The elimination of fossil fuel subsidies would make a significant contribution to the goal of keeping average temperatures from rising more than two degrees Celsius above pre-industrial levels,” the coalition added, referring to the goal which world leaders several years ago decided was necessary to avoid what global warming advocates say will be potentially catastrophic effects on the planet.