Dubai, UNITED ARAB EMIRATES — COP28 President Sultan Al-Jaber is facing a backlash over his claim that there is “no science” behind calls for a phase out of fossil fuels — a demand that many believe will ultimately determine the success of the U.N. climate conference.

In comments first reported on Sunday by The Guardian and investigative journalism organization the Centre for Climate Reporting, COP28 president and United Arab Emirates climate chief Al-Jaber suggested a fossil fuel phase out would not allow sustainable development “unless you want to take the world back into caves.”

The remarks, which were made by Al-Jaber during a live online event on Nov. 21, have been described by scientists and advocates as “farcical,” “beyond astonishing” and verging on climate denial.

In a social media post, University of Pennsylvania climate scientist Michael Mann accused Al-Jaber of “making a complete mockery” of the COP28 talks and urged U.N. chief Antonio Guterres to speak out on the issue.

Al-Jaber was seen as a controversial choice to lead COP28 discussions in Dubai given that he also works as the head of the state-run Abu Dhabi National Oil Company.

A spokesperson for COP28 told CNBC that the story regarding Al-Jaber’s comments was “just another attempt to undermine the Presidency’s agenda, which has been clear and transparent and backed by tangible achievements by the COP President and his team.”

They said Al-Jaber has been “unwavering” in saying that keeping global warming to 1.5°C involves action across a number of areas and sectors. “The COP President is clear that phasing down and out of fossil fuels is inevitable and that we must keep 1.5°C within reach. We are not sure what this story was supposedly revealing. Nothing in it is new or breaking news.”

The 1.5 degrees Celsius temperature threshold is widely recognized as crucial because so-called tipping points become more likely beyond this level. Tipping points are thresholds at which small changes can lead to dramatic shifts in Earth’s entire life support system.

Looking ahead, “the COP President is focused on working with parties to deliver a plan that will deliver maximum transition and minimal disruption for everyone in the world,” the spokesperson said. “He has repeatedly communicated our position on fossil fuels and invited all parties to work together and come up with solutions that can achieve alignment, common ground and consensus.”

The spokesperson added that the COP28 host has been “excited with the progress” made so far and for the delivery of a decision on the global stock take. “Attempts to undermine this will not soften our resolve,” they said.

The outcry over Al-Jaber’s comments comes as COP28 gears up for a fight over the future of fossil rules.

For nearly three decades, policymakers representing nearly 200 countries at the U.N.’s annual climate conference have tried to address the chief driver of the climate crisis: the burning of coal, oil and gas.

The language of the final agreement, expected by or around the Dec. 12 end of the conference, will be closely monitored. A “phase out” commitment would likely require a shift away from fossil fuels until their use is eliminated, while a “phase down” could indicate a reduction in their use — but not an absolute end.

There’s also an ongoing debate about whether an agreement should center on “abated” fossil fuels, which are trapped and stocked with carbon capture and storage technologies, or “unabated” fossil fuels, which are largely understood to be produced and used without substantial reductions in the amount of emitted greenhouse gases.

“If we fail with the phase out on fossil fuels then we are not going to be successful on climate mitigation,” Petteri Taalas, secretary general of the U.N.’s World Meteorological Organization, told CNBC in Dubai.

Asked for a response to Al-Jaber’s comments, Taalas said there is “very clear science” behind calls for a fossil fuel phase out.

“This impact of carbon dioxide on atmospheric warming, that’s very basic physics … There’s no question about that.”

U.S. climate envoy John Kerry was also asked to reflect on Al-Jaber’s comments. In an interview with CNBC’s Tania Bryer on Sunday, Kerry replied, “That’s not the argument.”

“The G7 countries voted that there should be a phasing out of unmitigated fossil fuel emissions and what there is science for is keeping 1.5 degrees as your North Star,” Kerry said.

“Every decision we make should be geared to say, ‘does this advance the 1.5 degrees or is it going to be more destructive and take us in the wrong direction?'”

Separately, former U.S. vice president Al Gore reportedly said Sunday that the UAE’s position as COP28 host was an abuse of public trust.

“They are abusing the public’s trust by naming the CEO of one of the largest and least responsible oil companies in the world as head of the COP,” Gore said, according to Reuters.

At the time of Al-Jaber’s appointment as COP28 president earlier this year, his office said he would play a “crucial role” in building consensus “and driving ambitious climate outcomes.”

A spokesperson for ADNOC, which recently became the first among its peers to bring forward its net-zero ambition to 2045, has previously said: “All of the current energy transition scenarios, including by the IEA, show that some level of oil and gas will be needed into the future.”

Dubai, UNITED ARAB EMIRATES — The head of the International Monetary Fund on Sunday underlined the case for carbon pricing at the COP28 climate summit, saying that the oil and gas industry recognizes “the writing on the wall.”

A long-time proponent of carbon pricing, IMF Managing Director Kristalina Georgieva said this approach creates an incentive for polluters to rapidly decarbonize.

Carbon pricing ascertains the cost that a company needs to pay for its planet-warming emissions and is widely regarded as the most cost-effective and flexible way to cut such pollution.

The IMF recently raised its average price forecast to $85 a ton by the end of the decade, up from a previous forecast of $75. Underlining the scale of the challenge, Georgieva said the current average price is around $20 per ton.

“For those that have adopted a carbon price, how do we get big emitters to accept that we need to accelerate decarbonization?” Georgieva told CNBC’s Dan Murphy at the COP28 conference.

“Well, two things. One, without a carbon price, it won’t happen fast enough. So, we have to move to that incentive,” she said.

“Two, Mother Nature is helping us because countries rich and poor are already experiencing the devastating force of climate change.”

Her comments come as policymakers and business leaders convene in Dubai for the U.N.’s two-week long climate summit, which is scheduled to end on Dec. 12.

The conference is a pivotal opportunity to accelerate climate action, at a time when the world is on track to record its hottest year on record and as extreme weather events take their toll across the globe.

For the IMF chief, COP28 marks an important opportunity for countries to reassess policies that incentivize the use of fossil fuels. She stressed that government subsidies for coal, oil and gas hit $1.3 trillion last year.

“Now we have to pull this gradually and substitute with the other part of the incentive, which is pricing. I want to tell everybody who is willing to listen that a carbon price has [been] proven to work,” Georgieva said, adding that existing schemes — such as the EU’s Emissions Trading System — have registered a rapid reduction of emissions.

“Two, it generates revenues. The same European Union got 175 billion euros ($191 billion) collected from [a] carbon price,” she said.

“Three, it can be fair. It is fair first, because the more you pollute, the more you pay, and the less you pollute, the less you pay. But also, many countries [can] take some of this money and give it back, especially to the vulnerable people.”

Asked about the role of the oil and gas industry at COP28 and how to get Big Oil on side with carbon pricing, Georgieva said, “One of the good news that comes from research is that we are going to see the peak of oil and gas in this decade. Consumption is then going to gradually going down.”

“One of the great news from COP is a commitment to triple renewables in energy within the next years. Where the power of COP has come is by mobilizing the voices of people and that is already happening. I cannot think of any industry that is willing to be the enemy of the people,” she continued.

“I think that oil and gas is seeing the writing on the wall. We see many of the oil-producing countries diversifying quite rapidly and we also see an investment coming from money generated from oil into renewables [at] scale.”

Airlines have seen a drop in bookings in the weeks following the start of Israel’s war against Hamas in the Gaza Strip, and some expect it to cut into their future profits.

According to travel analytics firm ForwardKeys, international flight bookings were 20% below 2019 levels in the three weeks following the attack by the Palestinian militant group Hamas against Israel on Oct. 7, and 5 percentage points below the period of three weeks prior to the attack.

The terrorist attack killed some 1,200 people and saw a further roughly 240 taken hostage, triggering the most ferocious Israeli response that the region has ever seen. Israel’s aerial bombing campaign and subsequent ground offensive in Gaza has killed more than 11,000 people, according to health authorities there.

In the days following the attack, major airlines suspended or reduced flights to Israel’s Ben Gurion Airport in Tel Aviv. But air travel demand to and from other countries and regions was noticeably affected, too.

In the three week period before Oct. 7, ticket issuance from the Middle East was just 3% below 2019 levels, according to ForwardKeys data, illustrating the steady recovery of the sector from the Covid-19 pandemic. In the three week period after Oct. 7, by contrast, ticket issuance from the Middle East was 12% lower than 2019 levels, marking a difference of 9 percentage points.

But the biggest drop in terms of international departures was in flight ticket issuance from the Americas, which was actually up 6% from 2019 levels in the three weeks before the attack, and fell to 4% below those levels in the three weeks after, totaling a drop of 10 percentage points.

International arrivals to the Middle East meanwhile plunged by 26 percentage points in that time frame, with the biggest drops by country being Israel, followed by Saudi Arabia, Jordan, and Lebanon. ForwardKeys draws its data from the International Air Transport Association’s industry-wide ticketing database which includes major international carriers, but does not include budget airlines like easyJet or Ryanair.

Stateside, at least one major airline made a profit warning concerning the war.

United Airlines in mid-October said that pricier jet fuel and a halt to its Tel Aviv flights due the Israel-Hamas war would eat into its profits in the last three months of the year. United had more service to Israel than any of the U.S.-based airlines with links from Washington, D.C.; Newark, New Jersey; and San Francisco, accounting for 2% of its capacity.

The fourth-quarter guidance for United was “bleak and worse than our estimates,” Helane Becker, an airline analyst at TD Cowen, wrote in a note following the carrier’s earnings estimate. “Given the projections that this will be a long war we are looking at the lower end of the forecast range and assuming no service by year end.”

The United Arab Emirates’ national airline, Abu Dhabi-based Etihad Airways, continues flying to Israel. It began flying its Abu Dhabi-Tel Aviv route in April of 2021, roughly eight months after the signing of the Abraham Accords, which normalized relations between Israel and the UAE.

“It’s impacting,” Etihad CEO Antonoaldo Neves said of the Israel-Hamas war, speaking to CNBC’s Dan Murphy at the Dubai Airshow on Monday. “Our demand to Israel is still there. But it’s not as big as it was in the past.”

“We keep flying, very safe. I follow up every day, every day. And we just hope it gets over soon. For the sake of everyone involved in this conflict.”

“I’ll not tell you it’s not impacting … And when things are back to normal, I’m sure that everyone’s going to remember that Etihad was not driven only by profits,” Neves said.

“We have our obligation as a transportation company, to be there when we make money and when we make less money. So that’s the approach we take, as long as it’s safe, we’re going to keep flying.”

Dubai’s flagship Emirates Airline, meanwhile, was optimistic about future demand.

“As far as the business is concerned — look, we have been in a part of the world that has seen for the last 35 years a lot of geopolitical issues,” Tim Clark, president of Emirates Airline, told CNBC.

“I won’t be smug and say we’re impervious to issues, because this is a really difficult issue for the Middle East to deal with.”

“But as far as our bookings are concerned, they remain robust,” he said. “We will always get what we call a certain flakiness in the Asian markets where, you know, they get a little bit concerned … But generally, so far, so good, we’re looking very strong.”

Clark pointed to upcoming events that will bring visitors to Dubai like the COP28 climate summit in early December as well as Christmas and New Year.

In a demonstration of its long-term optimism, Emirates Airline on Monday kicked off the first major deal of the 2023 Dubai Airshow with an order for 95 Boeing aircraft at a value of $52 billion.

“A lot of other things are going on in Dubai and Dubai itself is hugely potent city now, global metropolis, which is bringing in business,” he said.

“So with all of that, notwithstanding the difficulties of the Middle East at the moment, I think we will be okay.”

— CNBC’s Leslie Josephs contributed to this report.