The U.N. climate change conference in Warsaw ended with a call on nations to offer plans for reducing their greenhouse gas emissions from 2020. The deadline for doing so was set March 31, 2015.

Japan, which has been widely criticized for slashing its emission goal for 2020, must come up with a new longer-term plan within 16 months. We urge the government to quickly launch serious discussions on new ways to cut Japan’s carbon output that reflect the urgent need to combat climate change.

A conference impasse was avoided with a watered-down agreement that urges the parties to the talks to start preparing their “contributions” to a new international framework aimed at reducing emission of carbon dioxide and other heat-trapping gases.

The participants are called on to announce their offer by the end of March 2015 if they are “in a position to do so.” The voluntary reduction plans by the countries will be reviewed for a conference to be held at the end of that year. At that time, the parties hope to agree on a deal that takes effect in 2020.

A standoff between developed countries and emerging economies again characterized the climate talks. The wording of “commitments” was changed to “contributions” at the last minute to placate fast-growing economies like China and India, which insist that they are developing countries and cannot agree to the same commitments as mature economies.

The developed countries say that the meaningful participation of emerging economies, which account for a growing portion of global emissions, will be crucial to any effective framework.

Unlike the 1997 Kyoto Protocol, which set mandatory reduction goals on each of the industrialized nations, a new framework based on voluntary plans by participants is expected to make it easier for more countries to get onboard. On the other hand, the effectiveness of the framework to combat global warming will depend on the voluntary efforts by the parties.

During the Warsaw conference, Japan announced a revised target of reducing its emissions by 3.8 percent from the 2005 levels by 2020, which amounts to a 3 percent increase from the Kyoto Protocol’s base year of 1990. The new target replaced the goal announced by the Democratic Party of Japan-led administration in 2009 to cut emissions by 25 percent by 2020 from 1990 levels.

The government said it was the best Tokyo can promise if it is to be assumed that all of the nation’s nuclear power plants will remain offline — as they are now — following the 2011 Fukushima nuclear disaster.

Still, Japan won’t be able to escape criticism that its revised target gave emerging economies an excuse to say they can limit their emission-reduction efforts because a developed economy like Japan — the world’s fifth largest emitter of carbon dioxide in 2012 — isn’t doing enough.

Japan achieved its Kyoto Protocol commitments mostly through forestry absorption and the purchase of emissions rights from overseas. The amount of emissions fluctuated with the ups-and-downs of the economy.

Earlier plans to reduce Japan’s emissions more sharply were based on its reliance on nuclear power, which in theory does not emit carbon dioxide in the power generation process. But this scenario is no longer viable as even Prime Minister Shinzo Abe, who rejects his predecessor’s nuclear phaseout plan, pledges to reduce Japan’s reliance on nuclear power as much as possible. Renewable energy still accounts for only a tiny portion of the power supply in this country.

A substantial cut in Japan’s greenhouse gas emissions does not appear feasible as long as the government continues what it has been doing so far. The government needs to explore new measures, which could include mandatory energy-saving steps, emissions caps and a stronger carbon tax as it prepares Japan’s contributions for the new framework to fight global warming.