Most major nations — including the United States, the 27 nations of the European Union, China, India, Japan and Brazil — restated earlier pledges to curb emissions by 2020, some by promising absolute cuts, others by reducing the rate of increase from a business-as-usual curve.

In all, 55 developed and developing countries submitted emission reduction plans to the United Nations Framework Convention on Climate Change, the body overseeing global negotiations. Two major nations — Mexico and Russia — had not submitted plans as of Monday evening.

United Nations officials said that the countries that have already filed plans account for 78 percent of greenhouse gas emissions globally.

The so-called Copenhagen Accord was pasted together in the final hours of the United Nations-sponsored climate summit meeting that ended Dec. 19. The skeletal agreement was not formally adopted by the conference, is not binding on the parties and sets no deadline for reaching a formal international climate change treaty.

Yvo de Boer, executive secretary of the United Nations’ climate change office, said that the submissions showed that the commitment to confront climate change on the part of the world’s nations was “beyond doubt,” but he urged countries to do more.

“Greater ambition is required to meet the scale of the challenge,” he said.

Analysts said that even if all nations met their promises, the world would still be on a path to exceed the Copenhagen agreement’s central goal of limiting global warming to less than 3.6 degrees above the pre-industrial era.

“The pledges put on the table to date do not put us on track to meet that goal and will make it very difficult for us politically and technically beyond 2020 to meet that target,” said Alden Meyer, director of strategy and policy at the Union of Concerned Scientists.

Other aspects of the accord remain unresolved, including the question of financial aid for developing nations to adapt to climate changes and develop sustainable growth plans. The wealthy nations pledged nearly $30 billion in short-term support, but there is no mechanism in place to collect or distribute the money. Longer-term aid pledges remain just a concept.

Nonetheless, it was the first time that major developing nations, whose emissions are growing more quickly than the rest of the world’s, put on paper their plans for slowing production of carbon dioxide and other gases that contribute to a warming planet.

China said it would reduce its carbon intensity — the amount of carbon dioxide emitted per unit of economic activity — by 40 to 45 percent by 2020, compared with 2005 levels.

India said its carbon intensity would fall by 20 to 25 percent over the same period.

South Korea set an intensity target of 30 percent below 2005 levels by 2020.

Raekwon Chung, the South Korean ambassador for climate change, said that his nation’s target was set into law in December and that the government was preparing plans to carry it out.

He said South Korea planned to invest 2 percent of its gross domestic product, about $86 billion a year, in green growth programs, including low-carbon energy production, new transportation systems and higher-efficiency building codes.

The major industrialized powers also repeated earlier pledges. The European Union said its 27 members would cut emissions by 20 to 30 percent over 1990 levels by 2020. Japan’s target is 25 percent over the same period.

The United States, in a submission last Thursday, repeated President Obama’s promise to cut emissions “in the range of” 17 percent by 2020 compared with 2005 levels — but only if Congress enacts legislation that meets that goal, a far-from-certain prospect.

Jennifer Morgan, director of the World Resources Institute’s climate and energy program, urged Congress to act quickly on climate change legislation, or risk seeing the United States fall further behind in the competition to develop new low-carbon sources of energy.

“The pledges made by countries like Japan, China, Europe and India show a commitment to collective, transparent action on a scale never seen before,” she said in a statement. “The United States should have no doubt that these countries plan to build their economies with clean energy.”