U.N. Secretary-General Antonio Guterres expressed his disappointment with the outcome of the latest United Nations climate change conference, COP25, which closed Sunday in Madrid. There was no strong message requiring parties to the Paris Agreement to upgrade their commitments to reduce greenhouse gas emissions, and talks on some of the rules for implementing the 2015 accord were deferred for another year. Also disappointing was Japan's response to the increasingly serious challenges of climate change. It failed to show any readiness to revamp its own plans for cutting emissions or to review its policy of retaining coal as a major source of power despite international criticism because of the climate impact.

Prior to the conference, the U.N. Environment Programme issued a stern warning that if emissions of greenhouse gases continue at the current pace, global temperatures will rise by up to 3.9 degrees Celsius above pre-industrial levels by the end of the century, causing catastrophic climate effects. The Paris Agreement set a target of containing the temperature increase within 2 degrees — and as close as possible to 1.5 degrees — to avert the devastating impact on the global climate. However, it has been made clear that the temperature rise will add up to 3.2 degrees even if all nations that signed the accord fulfill their voluntary plans to cut emissions. Therefore, the agreement requires the signatories to regularly upgrade their plans.

So far roughly 80 countries have indicated a willingness to cut their emissions beyond what they had pledged earlier. However, the world's major emitters — including the United States, which has pulled out of the Paris accord, China, Russia, India and Japan — remain silent on upgrading their commitments to reduce emissions. The response of the major emitters remain slow even as the world's sense of crisis over climate change grows as more frequent extreme weather conditions and the devastating damage they cause are linked to rising global temperatures. As the world's fifth-largest emitter, Japan must fulfill its duties.