LONDON — Reflecting on energy markets just over one month into Russia’s onslaught in Ukraine, Saudi Arabia’s top energy official said: “Look at what is happening today, who is talking about climate change now?”

Prince Abdulaziz bin Salman’s comments in late March were effectively a rerun of his address to attendees at the COP26 climate conference in Glasgow, Scotland, in November last year when he claimed the world could slash greenhouse gas emissions without swearing off hydrocarbons.

Summarizing his views on energy security and the climate crisis, Abdulaziz told CNBC that the world’s top oil exporter would not shy away from fossil fuel production. “We are pro producing oil and gas, and — hallelujah — pro using coal.”

Russian President Vladimir Putin’s war in Ukraine is now on the cusp of entering its fourth month, amplifying concern about what the conflict means for food, energy and global climate goals.

The G-7 has warned Russia’s invasion has resulted in “one of the most severe food and energy crises in recent history,” threatening those most vulnerable worldwide.

U.N. Secretary-General Antonio Guterres has said the Kremlin’s assault on Ukraine will likely have major implications for global heating targets, particularly as many countries turn to coal or imports of liquefied natural gas as alternative sources to Russian energy.

Guterres described this short-sighted rush to fossil fuels as “madness,” before warning that humanity’s “addiction to fossil fuels is mutually assured destruction.”

Six months from the end of COP26, where negotiators left the U.K. with a sense of incremental progress, the global energy picture has changed dramatically.

In short, Russia’s invasion has put a planned energy transition at a crossroads. The upshot facing policymakers is that the shift away from fossil fuels is vital to avoid a cataclysmic climate scenario.

The U.N. chief has said that instead of countries “hitting the brakes” on the decarbonization of the global economy in the wake of Russia’s invasion, “now is the time to put the pedal to the metal towards a renewable energy future.”

Putin’s invasion of Ukraine has thrust the issue of energy security back toward the top of the political agenda. Indeed, one of the most pressing challenges facing European leaders today is how to sever their dependence on Russian energy while accelerating the fight against the climate crisis.

Complicating this challenge, however, is the fact that many European countries are acutely reliant on Russian oil and gas.

Speaking to CNBC from Kyiv, Ukraine’s top climate scientist Svitlana Krakovska made clear that survival — not energy security — had been the top priority for people living in the country.

“From my side, since I am still here in Ukraine and I see everything here from the very beginning, I would say that our first security is the security of life,” Krakovska said. She has previously told CNBC that the primary driver of the climate emergency and the root cause of Russia’s war both stem from humanity’s fossil fuel dependency.

“The more we continue our dependency on these fossil fuels and the more we postpone [climate] action, the less secure we are,” Krakovska said.

The burning of fossil fuels, such as coal, oil and gas, is the chief driver of the climate crisis and researchers have repeatedly stressed that limiting global heating to 1.5 degrees Celsius will soon be beyond reach without immediate and deep emissions reductions across all sectors.

This temperature limit is recognized as a crucial global target because beyond this level, so-called tipping points become more likely. Tipping points are thresholds at which small changes can lead to dramatic shifts in Earth’s entire life support system.

The world’s governments agreed in the 2015 Paris climate accord to limit global heating to well below 2 degrees Celsius and pursue efforts to limit the temperature rise to 1.5 degrees Celsius. For the latter, the International Energy Agency has warned that no new oil and gas projects are possible.

Krakovska, who heads the applied climatology laboratory at Ukraine’s Hydrometeorological Institute, said that while it was currently difficult to assess the climate impact of Russia’s invasion, there were already clear examples of environmental destruction.

For instance, Krakovska said she had observed with some concern the large swathes of wildfires burning unchecked in Siberia, noting that Russian military units that would usually fight these fires have been relocated to the Ukrainian frontline.

Wildfires in Siberia last month were found to be more than twice the size when compared to the same period in 2021, environmental group Greenpeace told CNBC, citing satellite data. In what is becoming an annual occurrence of climate breakdown, the burning of trees in Siberia unlocks extreme carbon pollution while melting methane-rich permafrost.

“This war actually causes so many devastating consequences and it just exacerbates the climate crisis,” Krakovska said. She reiterated the Ukrainian government’s call for the EU to stop funding Russia’s invasion by imposing an immediate import ban on Russian oil and gas.

To some, Russia’s invasion of Ukraine and the resulting energy crisis should be seen as a harbinger of how countries think about their oil use.

“We can respond so much quicker on the demand side than we can on the supply side — and we are not hearing enough about that,” Michael Lazarus, director of the U.S. office for the Stockholm Environment Institute, a non-profit research firm, told CNBC via video call.

In late March, the IEA published a 10-point plan to reduce oil demand, recommending policies such as reducing speed limits on highways by at least 10 kilometers per hour, working from home as much as three days per week when possible and car-free Sundays for cities.

The energy agency said imposing measures such as these would help to reduce the price pain being felt by global consumers, lessen the economic damage, shrink Russia’s hydrocarbon revenues and help move oil demand toward a more sustainable pathway.

“Even though some efforts are behaviorally or culturally challenging, whether it is changing speed limits or changing the temperature of our houses, these things can happen and what we have seen is the motion of public support,” Lazarus said.

“People want to do something. People want to contribute, and this reduces costs and vulnerabilities for households to invest in energy efficiency and conservation and it helps free up resources for the rest of the world to address this moment” Lazarus said. “This is really the moment for dramatic efforts on the demand side.”

In early April, the world’s leading climate scientists warned that the fight to keep global heating under 1.5 degrees Celsius had reached “now or never” territory.

The U.N.’s Intergovernmental Panel on Climate Change reaffirmed that to keep rising global temperatures under this key threshold, emissions from warming gases must be halved by the end of the decade.

“We have here a contradiction,” Jose Manuel Barroso, chairman of Goldman Sachs International and former president of the European Commission, said at a May 10 event entitled: “The Conflict in Ukraine and Europe’s Clean Energy Transition.”

“While in the medium and long-term everybody agrees that the less dependent on fossil fuels the better. The point is how costly it will be — and so I think there is a risk of backlash. I will even say that there is a risk of having the climate agenda as collateral damage from this war in Ukraine,” Barroso said.

The IPCC is unequivocal on the so-called “cost” of the global fight to secure a livable future: It’s not nearly as expensive as we may think.

“Without taking into account the economic benefits of reduced adaptation costs or avoided climate impacts, global Gross Domestic Product (GDP) would be just a few percentage points lower in 2050 if we take the actions necessary to limit warming to 2°C (3.6°F) or below, compared to maintaining current policies,” IPCC Working Group III Co-Chair Priyadarshi Shukla said on April 4.

— CNBC’s Lucy Handley contributed to this report.