One thousand feet above the world’s largest iceberg, it’s hard to believe what you’re seeing.

It stretches all the way to the horizon – a field of white as far as the eye can see.

Its edge looks thin in comparison, until you make out a bird flying alongside and realise it is, in fact, a cliff of ice hundreds of feet high.

Scientists who have used satellites to track the iceberg’s decades-long meanderings north from Antarctica have codenamed the iceberg A23a.

But up close, numbers and letters don’t do it justice.

It’s a seemingly endless slab of white, fringed by an aquamarine glow – the ocean at its base backlit by a sill of reflective ice below.

Monotonous yet magnificent; we’re flying along the coastline of a nation of ice.

And it’s also hard to believe you’re seeing it at all.

Where it has run aground – 50 miles off the small island of South Georgia – seems impossibly remote.

We’re 800 miles from the Falkland Islands and 900 miles from the icy wastes of Antarctica.

With no runway on South Georgia, there’s only one aircraft that ever flies here.

Once a month or so, a Royal Air Force A400 transport plane based in the Falklands carries out Operation Cold Stare – a maritime surveillance and enforcement flight over the British Overseas Territory that includes the neighbouring South Sandwich Islands.

It’s a smooth, albeit noisy, two-hour flight to South Georgia.

But as the dramatic peaks of the island come into view, the ride – for us inexperienced passengers at least – gets scary.

Gusts off the mountains and steep terrain throw the plane and its occupants around.

Not that that stops the pilots completing their circuit of the island.

We fly over some of its 500,000 square mile marine protected zone designed to protect the greatest concentration of marine mammals and birds on the planet that is found on South Georgia.

Only then do we head out to the iceberg, and even though it’s only a few minutes flying from South Georgia it’s at first hard to see. It’s so big and white it’s indistinguishable from the horizon through the haze.

Until suddenly, its edge comes into view.

It’s immediately apparent the A23a is not too long for this world. Large icebergs hundreds of metres across have already broken off and are drifting closer to South Georgia.

All along its edges, cracks are appearing and arches at its base caverns are being eroded by the warmer ocean here, undercutting the ice, weakening it further.

The iceberg might present a problem for some of South Georgia’s super-abundant penguins, seals and seabirds. A jumble of rapidly fragmenting ice could choke up certain bays and beaches in which colonies of the animals breed.

The trillion tonnes of fresh water melting out of the iceberg could also interfere with the food webs that sustain marine life.

However, the breeding season is coming to an end and icebergs are also known to fertilise oceans with sediment carried from the Antarctic continent.

The impact on shipping is more relevant. There’s not much of it down here. But fishing vessels, cruise ships and research teams ply these waters and smaller lumps of ice called “growlers” are a regular risk.

A23a will create many.

Icebergs this big are too few for scientists to know if they are becoming more frequent or not.

But they are symptomatic of a clearly emerging trend. As our climate warms, Antarctica is slowly melting.

It’s losing around 150 billion tonnes of ice a year – half of it breaking off the continent in the form of icebergs calving from glaciers, the rest melting directly from its vast ice sheets as temperatures gradually rise.

The pace of A23a’s disintegration is far, far faster. It will disappear in months, not millennia.

But watching its edges crumble and slide into the South Atlantic, you can’t help seeing it as the fate of a whole continent in miniature.

Vladimir Putin has said Russia agrees to an end to fighting in Ukraine, but “lots of questions” remain over proposals for a 30-day ceasefire.

Casting doubt over whether a deal can be agreed, the Russian president said a ceasefire must lead to “long-term peace” which “would remove the initial reasons for the crisis”.

Russia has previously said it would not accept Ukraine joining NATO and European peacekeepers in Ukraine.

Moscow has reportedly also presented a “list of demands” to the US to end the war, which would include international recognition of Russia’s claim to Crimea and four Ukrainian provinces.

Ukraine’s president Volodymyr Zelenskyy said Mr Putin’s remarks were “very predictable” and “very manipulative”, adding that the Russian president was preparing to reject the ceasefire proposal he agreed with the US.

Mr Putin’s comments came as Donald Trump’s envoy Steve Witkoff arrived in Moscow ahead of talks over Ukraine with the Russian president.

Ukraine war latest updates

Speaking on Thursday afternoon, Mr Putin described the situation in Russia’s Kursk region, where Ukrainian troops have pushed into Moscow’s territory, as “completely under our control”.

It appeared the US had persuaded Ukraine to accept the ceasefire, he said, but Ukraine is also interested because of the battlefield situation, with its forces in Kursk fully blocked in the coming days.

“In these conditions, I believe it would be good for the Ukrainian side to secure a ceasefire for at least 30 days,” he said.

He also said there would need to be a mechanism to control possible breaches of the truce.

Another issue he raised was whether Ukraine could use the 30-day ceasefire to continue to mobilise and rearm.

He said he would need to speak to Mr Trump over the terms of any ceasefire.

Mr Putin was speaking alongside Belarus’s President Alexander Lukashenko and the pair said in a joint statement that NATO’s actions regarding the war in Ukraine were fraught with the risk of nuclear conflict.

The two countries also criticised the European Union’s policy towards Russia, labelling it aggressive and confrontational.

Russia’s invasion of Ukraine in early 2022 has left thousands of people dead and injured, millions displaced and towns and cities reduced to rubble.

Moscow’s forces have been advancing since the middle of last year and now control nearly a fifth of Ukraine’s territory.

In his speech Mr Putin said Russian forces were pushing forwards along the entire frontline.

Responding to the comments, Mr Zelenskyy said: “Putin, of course, is afraid to say directly to President Trump that he wants to continue this war, he wants to kill Ukrainians.”

He said Mr Putin’s words were “just another Russian manipulation”.

Mr Trump also responded to the remarks, saying Mr Putin’s statement was not complete and reiterated his willingness to talk to the Russian president, adding: “Hopefully Russia will do the right thing.”

In a news conference with NATO secretary general Mark Rutte, the US president shifted his tone on the alliance, saying it was “stepping up” and praising Mr Rutte for doing “some really good work”.

Mr Rutte said NATO members needed to produce more weapons, stating the alliance was not doing enough and was lagging behind Russia and China.

It comes after Mr Putin donned a camouflage uniform to visit a command post in the Kursk region on Wednesday.

Donald Trump has said he thinks the US will annex Greenland, days after the country’s incoming prime minister said: “We don’t want to be Americans.”

During an Oval Office meeting with NATO secretary general Mark Rutte, the US president was asked about his hopes to annex Greenland.

“I think that will happen,” he said. “I didn’t give it much thought before, but I’m sitting with a man who could be very instrumental.

“You know Mark, we need that for international security. We have a lot of our favourite players cruising around the coast and we have to be careful.”

Mr Trump questioned Denmark’s claim to the autonomous territory, saying Denmark was “very far away” from Greenland despite being part of the country’s kingdom.

“A boat landed there 200 years ago or something. They say they have rights to it,” Mr Trump said. “I don’t know if that’s true. I don’t think it is, actually.”

He said the US already has a military presence in Greenland and added: “Maybe you’ll see more and more soldiers going there.”

It comes after Greenland’s centre-right party won an election in a result seen as a rejection of Mr Trump’s interference in the island’s politics.

The Demokraatit party favours a slow move towards independence from Denmark – with its leader Jens-Frederik Nielsen telling Sky News on the eve of the election “we want to build our own country by ourselves”.

In his White House news briefing Mr Trump claimed the election result was very good for the US and said “the person who did the best is a very good person as far as we’re concerned”.

He previously promised “billions of dollars” in investment and told Greenlanders he would “make you rich”.

Mr Trump also reacted to Vladimir Putin’s remarks about Russia agreeing to an end in fighting in Ukraine, but adding “lots of questions” remain over proposals for a 30-day ceasefire.

The US president said his Russian counterpart’s statement was not complete and reiterated his willingness to talk to him, adding: “Hopefully Russia will do the right thing.”