The landmark Paris agreement on climate change moved closer to reality Wednesday after 31 countries joined during the United Nations General Assembly.

UN Secretary-General Ban Ki-moon voiced confidence that the accord, through which countries commit to take action to stem the planet's rising temperatures, would come into force by the end of the year.

"The momentum is remarkable," said the outgoing UN chief, who convened a meeting on the Paris accord during the annual UN gathering of leaders.

"When the Paris agreement enters into force this year, it will be a major step forward on our journey for a more secure, more equitable and more prosperous future," Ban said.

The countries that joined the accord on Wednesday included Latin American powerhouses Argentina, Brazil and Mexico as well as major fossil-fuel powers Brunei and the United Arab Emirates.

Also submitting its ratification was Morocco, the host of the next UN climate conference which opens in Marrakesh on November 7.

Foreign Minister Salaheddine Mezouar said that Morocco was "strongly committed" to putting the Paris accord in force in time for the meeting.

The Paris agreement needs ratification from 55 countries that account for at least 55 percent of the planet's greenhouse gas emissions responsible for climate change.

With Wednesday's event, in which leaders ceremonially ratified the accord, a total of 60 countries have joined the Paris accord but they account for less than 48 percent of global emissions.

- Calls for more ambition -

The accord requires all countries to devise plans to achieve the goal of keeping the rise of temperatures within two degrees Celsius (3.6 Fahrenheit) above pre-industrial levels.

But Edgar Gutierrez, the environment and energy minister of Costa Rica, said that the level was not ambitious enough in light of evidence of worse-than-feared climate change, with last month the hottest August on record, extending the global record streak to 16 months.

Gutierrez called for countries to aim for 1.5 Celsius and warned that even a one-year delay in implementing the Paris accord could be too late for the planet.

"Climate change is already dangerous, it has already exceeded the capacity of many countries to adapt to it, we have already lost lives, we are losing species and we have lost lands and buildings," said Gutierrez, speaking on behalf of a troika of climate-vulnerable nations including Ethiopia and the Philippines.

Mattlan Zackhras, a senior official from the Marshall Islands, warned that despite pledges under the Paris accord the planet still looked on track for a rise of three degrees.

"This will wipe out my country and many island-states in the Pacific," he told reporters.

- EU set to seal accord -

Ban's office said that 14 other countries accounting for 12.58 percent of emissions had signaled they would ratify the accord this year, meaning the agreement is virtually certain to come into force, barring a widespread change of heart.

The European Union will enter the agreement "in the next weeks," Miguel Arias Canete, the 28-member bloc's commissioner for climate action and energy, told reporters.

China and the United States, the two largest emitters, gave a major boost to the accord when they signed on during a summit earlier this month between presidents Xi Jinping and Barack Obama.

Amid political opposition from the rival Republican Party, Obama has had to rely on executive actions including regulating power plants to cut emissions in the United States.

The US Senate refused to join the earlier Kyoto Protocol, leading the Democratic Obama administration to insist that the Paris agreement not be a formal treaty that would require Senate ratification.

Secretary of State John Kerry said that the United States "shared our part of the blame" for the years of difficulty in securing global action on climate change.

"It's one of the reasons why President Obama and I have been so focused and so committed to try to make up that difference and help us to get where we are today," Kerry said at the United Nations.

Kerry pointed to the string of record-breaking high temperatures, as well as rising incidence of disease and water scarcities, as reasons to be ambitious in cutting emissions.

"If ever anybody doubted science, all they have to do is watch, feel, sense what is happening in the world today," he said.

Highlights of the Paris Agreement on climate change
Paris (AFP) Sept 21, 2016 - Thirty-one countries on Wednesday ratified a climate rescue pact concluded in Paris last December, bringing the hard-fought international treaty a step closer to taking legal effect.

These are the key points in the Paris Agreement, which needs the official sanction of countries emitting 55 percent of global greenhouse gas emissions to enter into force. The figure to date stands at nearly 48 percent.

- The goal -

Nations agreed to hold global warming to "well below" two degrees Celsius (3.6 degrees Fahrenheit) over pre-Industrial Revolution levels, and to strive for 1.5 C (2.7 F) if possible.

The lower goal was a demand of poor countries and island states at high risk of climate change effects such as sea-level rise and drought.

Many experts say that even 2 C will be a tough ask. Scientists warn that on current emission rates, we are headed for a 4 C warmer world, or 3 C if countries meet their self-determined targets for cutting carbon.

- Getting there -

The world will aim for climate-altering emissions from fossil-fuel burning to peak "as soon as possible", with "rapid reductions" thereafter.

By the second half of this century, says the Paris pact, there must be a balance between emissions from human activities such as energy production and farming, and the amount that can be captured by carbon-absorbing "sinks" such as forests or carbon storage technology.

- Burden-sharing -

Developed countries, which have polluted for longer, should take the lead in absolute emissions cuts. Developing nations which still need to burn coal and oil to power growing populations and economies are encouraged to enhance efforts and "move over time" to cuts.

- Tracking progress -

In 2018, and every five years thereafter, countries will take stock of the overall impact of what they are doing to rein in global warming, according to the text.

In 2020, they will revisit their non-binding carbon-curbing pledges -- submitted to bolster the core agreement.

Some countries had set targets for 2025, and others for 2030, which will be updated five-yearly.

- Finance -

Developed countries "shall provide" funding to help developing countries make the costly shift to green energy and to shore up their defences against climate change impacts.

Rich nations must report every two years on their finance levels -- current and intended.

Not included in the agreement itself, but in a non-binding "decision", reference is made to the $100 billion (90 billion euros) a year that rich countries had pledged in 2009 to muster by 2020 as a "floor", which means it can only go up. The amount must be updated by 2025.

- Climate damage -

Rich nations blamed for their historic contribution to carbon pollution balked at any kind of financial compensation for countries now hit by climate impacts.

But the agreement does recognise the need for "averting, minimising and addressing" losses suffered.