Day three of COP29, the global U.N. climate conference, highlighted how challenging it will be for the world to transition away from fossil fuels. As some countries are making new commitments to reduce emissions and ramp up clean energy production, others are advocating for the continued use of fossil fuels.

Joining the United Kingdom and United Arab Emirates, Brazil announced its Nationally Determined Contribution (NDC) plans on Wednesday. NDCs are each country's plan for achieving the goals outlined in the Paris Climate Agreement. Brazil has pledged to reduce its carbon emissions by 59% to 67% by 2035.

"Cutting emissions by 67% by 2035 could put Brazil on a pathway to reach net-zero by 2050," said Karen Silverwood-Cope, climate director of WRI Brasil.

Brazil is hosting next year's COP, and Silverwood-Cope said the country has "a responsibility to lead by example and aim high."

But Silverwood-Cope also pointed out that Brazil's NDC does not include a plan for reducing fossil fuel emissions. Instead, they are pledging to increase biofuel production. Biofuel is produced from renewable biological sources, including plants and algae. In Brazil, biofuel primarily comes from soybean oil. As a country with a history of mass deforestation, the loss of vegetation and forests for energy is controversial.

"Instead of saying that they're going to reduce oil consumption in the country, they are betting on biofuels," said Silverwood-Cope.

She said Brazil plans to use denigrated land for biofuel production. Deingrated land is land that has already been deforested.

As Brazil announced its new, stronger climate pledge, another South American country moved in the opposite direction by literally walking out of the conference.

Argentinian President Javier Milei ordered the country's COP29 representatives to withdraw from the conference and return home. Milei, the country's newly-elected, far-right president, has a history of climate change denial.

Despite the drama, delegates came to some agreements, including using more nuclear power as an alternative to fossil fuels.

The United States, El Salvador, Kazakhstan, Kenya, Kosovo, Nigeria and Türkiye endorsed a declaration calling for tripling the use of nuclear energy by 2050.

Italy also voiced its support for more nuclear energy and touted its ongoing investment in nuclear fusion research. Unlike current nuclear reactors, nuclear fusion doesn't create radioactive waste. Despite billions of dollars in research funding, the technology has yet to be developed commercially.

"We must use all available technologies. Not only renewables, but also gas, biofuels, hydrogen, CO2 capture, and, in the future, nuclear fusion," said Italian President Giorgia Meloni. "Italy is at the forefront on nuclear fusion."

-ABC News' Charlotte Slovin

If negotiating international agreements to slow down and reverse the global climate crisis wasn't challenging enough, the delegates at COP29, the U.N. climate conference in Azerbaijan, are facing the grim reality that the world is moving in the wrong direction when it comes to fossil fuels.

According to the latest Global Carbon Budget report from the Global Carbon Project, carbon emissions from fossil fuels have hit a record high in 2024. The study projects that carbon dioxide (CO₂) emissions will reach 37.4 billion tonnes, up 0.8% from 2023.

For almost three decades, international leaders have been attending COP conferences and discussing the urgent need to reduce greenhouse gas emissions. However, despite these efforts, the Global Carbon Project says, "There is still no sign that the world has reached a peak in fossil CO2 emissions."

"The impacts of climate change are becoming increasingly dramatic, yet we still see no sign that burning of fossil fuels has peaked," wrote Pierre Friedlingstein of Exeter's Global Systems Institute in a press statement.

He added, "Until we reach net zero CO2 emissions globally, world temperatures will continue to rise and cause increasingly severe impacts."

Although the past decade has seen a decline in emissions from deforestation and land-use changes, emissions this year are rising compared to 2023, influenced by extreme drought conditions linked to the 2023-2024 El Niño climate event, according to the study. Despite this increase, land-use emissions have actually declined by 20% over the past decade thanks to reforestation and afforestation efforts.

Efforts to stop burning coal for energy are slowing down the year-over-year increase in those emissions, but they are still rising, albeit modestly. The study estimates that global coal emissions will increase by 0.2%. China and India are seeing increases of 0.2% and 4.5%, respectively, while the United States and the European Union are seeing declines of 3.5% and 15.8%.

Overall, the study found that China's emissions (32% of the worldwide total) for 2024 are expected to increase by 0.2% compared to 2023. India (8% of the worldwide total) is projected to grow emissions by 4.6% from the previous year. The European Union (7% of the worldwide total) should see a 3.8% decline year-to-year and the United States (13% of the worldwide total) is looking at a 0.6% decrease compared to 2023.

It's important to remember that many products purchased and used in the U.S. and Europe are made in places like China and India. Hence, their emissions reflect the manufacturing of goods for other countries.

According to the research, this trend worsens the cumulative impact of CO₂ in the atmosphere, projected to reach 422.5 parts per million (ppm) in 2024, representing a 52% increase compared to pre-industrial levels.

There is some good news in the data. The study finds that many countries have succeeded in reducing their fossil fuel carbon emissions or slowing down their growth. However, it's not enough to put the world on a path to net zero.

"There are many signs of positive progress at the country level, and a feeling that a peak in global fossil CO2 emissions is imminent, but the global peak remains elusive," wrote Glen Peters of the CICERO Center for International Climate Research in a statement. "Climate action is a collective problem, and while gradual emission reductions are occurring in some countries, increases continue in others."

-ABC News Climate Unit's Matthew Glasser

If there was a theme for the second day of COP29, the U.N. climate conference in Azerbaijan, it would be mixed messaging from world leaders. As some nations announced ambitious new climate goals, others justified their continued reliance on fossil fuels. The developments come when the world is questioning the United States' future commitment to climate progress in light of President-elect Donald Trump's previous comments about climate change and his selection for EPA administrator.

During his remarks, Azerbaijani President Ilham Aliyev, whose country is hosting the event, defended the use of fossil fuels, calling oil a "a gift of the God" and saying that it is just like any other natural resource. He added that countries "should not be blamed for bringing these resources to the market."

"To accuse us that we have oil is the same like to accuse us that we have more than 250 sunny days in Baku," said Aliyev.

Aliyev also called Western countries hypocrites for decrying oil production and calling for an end to fossil fuel use while still buying oil from countries like Azerbaijan. The European Commission signed an agreement with Azerbaijan in 2022 to receive oil from them when they stopped getting it from Russia. He said double standards are the "modus operandi" for climate talks.

Aliyev's pro-oil statements aren't expected to sidetrack the negotiations. David Waskow, director of international climate action at World Resources Institute, said statements from world leaders "in a sense float above the COP."

But Aliyev's comments added fuel to the criticism that oil-producing states shouldn't be hosting a global climate conference. The United Arab Emirates, another country with significant oil production, hosted last year's event.

Baku is also not an easy place to get to. Conference-goers had to travel by plane because all land routes are closed. A recent study identified that 291 private plane flights to COP28 in Dubai generated 3.8 kilotons of CO2.

How does a nation that touts the excellence of oil and gas end up as the host of an incredibly consequential climate conference?

The answer is entirely procedural. Each year, one of the five U.N. regional groups is selected on a rotational basis to host next year's conference. Group members choose which country will host based on logistics and ability. As a result, champions of climate progress and oil-rich countries are equally likely to host the global climate conference.

Unlike the Azerbaijani president's call to maintain the status quo, U.N. Secretary-General António Guterres stressed the urgency and stakes of controlling global emissions.

"We are in the final countdown to limit global temperature rise to 1.5 degrees Celsius and time is not on our side," the Secretary-General said, urging countries to commit legislatively and financially to the climate response.

He called 2024 "a masterclass in climate destruction," pointing out all of the climate records broken during the year, including the hottest day and months on record, adding that "this is almost certain to be the hottest year on record."

-ABC News' Charlotte Slovin and ABC News Climate Unit's Matthew Glasser

Some of the world's largest greenhouse gas emitters have announced their plans to reduce emissions at the ongoing United Nations climate conference, COP29, in Baku, Azerbaijan.

Although not due until 2025, The United Kingdom, Brazil and the United Arab Emirates released their respective Nationally Determined Contribution (NDC) targets at the conference, marking ambitious plans to reduce their climate impacts.

Under the Paris Agreement, participating countries are required to release their NDCs every five years as part of the goal of limiting global warming to 1.5 degrees Celsius above pre-industrial levels.

"The U.K., Brazil and the UAE are the first major emitters to put forward new national climate commitments, which are the main vehicle for countries to collectively reduce greenhouse gas emissions and avoid catastrophic climate impacts," Melanie Robinson, global director of climate, economics and finance at World Resources Institute said of the announcements.

"Encouragingly, these three nations' new climate targets could put them on a path to reach net-zero emissions by 2050 if their highest ambitions are realized," Robison said.

The U.K. goal aims to reduce the nation's greenhouse gas emissions by at least 81%, compared to their 1990 levels.

The Brazilian government is expected to release its NDC on Wednesday. In a preview announcement, the country said it's committed to reducing net greenhouse gas emissions by 59% to 67%.

"This commitment will allow Brazil to advance towards climate neutrality by 2050, the long-term target of the climate commitment," the government wrote in a statement Monday night. "The NDC results from an extensive assessment of Brazil's emission scenarios. It acknowledges the urgency of combating the climate crisis, addresses the need to build resilience, and sets a roadmap for a low-carbon future for Brazil's society, economy, and ecosystems."

In the UAE's NDC, released last week, the nation sets an emissions reduction target of 47% by 2035, compared to 2019.

"The UAE's third NDC outlines a unified vision for addressing climate change that is aligned and informed by the UAE Consensus adopted at COP28," the UAE wrote in its newest NDC. "The UAE Consensus emphasizes the need for accelerated action across all pillars of the Paris Agreement and serves as a roadmap for enhancing mitigation ambition, scaling up adaptation efforts, and aligning financial flows with low-carbon, climate-resilient development pathways."

"I think when you look at these in the aggregate, what we're seeing is that if these countries really pursue the full extent of what they've committed to, that they would be on track to achieve their net zero targets at mid-century," said David Waskow, director of international climate action at the World Resources Institute, during a press call.

"With all three of them, there's an important question about actually implementing them, and we're going to need to see strong policies and investments," Waskow added.

WRI's Robinson also expressed skepticism about the announcements.

"While these initial 2035 targets look good on paper, they won't move the needle unless countries take bold and immediate steps to turn them into action. The true measure of progress will be whether countries back up their promises with transformative policies and investments that embed climate action at the core of their economic strategies," said Robinson.

-ABC News Climate Unit's Kelly Livingston