This endurance swimmer crossed the Red Sea to highlight the plight of the coral reefs

“I was looking down at some of the most amazing coral reefs in the world. There were turtles and manta rays and sharks and small little goldfish and big parrotfish and coral in purple and green and yellow. It's amazing. But we run the risk now of losing all of this if we carry on the way we're going.”

So says Lewis Pugh, the endurance swimmer, who’s just become the first person ever to swim across the Red Sea, to highlight the plight of the oceans and, in particular, coral reefs, which are the “nurseries of the ocean”.

Timed to coincide with the COP27 UN climate summit in Sharm El-Sheik, Pugh, a UN Patron of the Oceans, swam 123 kilometres in 16 days from Tiran Island, Saudi Arabia and all along the coast of the tourist resort hosting the summit, to Hurghada on the opposite side of the Red Sea in Egypt.

He tackled strong winds for 10 days and encountered sharks and container ships in the shipping lanes leading to the Suez Canal, but he also swam through the Marine Protected Area of Ras Mohammed National Park.

Last year, Pugh spoke to the World Economic Forum after completing a gruelling 12-day swim across the Ilulissat Icefjord in Greenland. Here, he explains what the Red Sea Swim was like and his message to COP27 leaders.

When I was swimming in the Arctic in Greenland, the water was around zero degrees centigrade. It's unbelievably cold. And when you swim in the Red Sea, the water is incredibly hot, sometimes close to 30 degrees centigrade. The risks in the Arctic are that you're going to get hypothermia and in the Red Sea you're going to get the complete opposite: hyperthermia. So that was the main danger. The warm water just saps you of all your strength and energy. The views are amazing, but it actually just saps you of everything.

I see the polar regions and the coral reefs as the two ground zeros of the climate crisis: it's just so evident. I've spent 35 years swimming in the world's oceans and these are the two places where we're seeing the climate crisis just moving so quickly. In the Arctic I'm seeing melting glaciers and the melting of the Greenland ice sheet, and less and less sea ice in the Arctic.

Not only were we dealing with very hot water and sharks - and I had to cross a very busy shipping lane with tankers and container ships in front of us all the time - but the wind was unrelenting. Day after day, it was coming from the side, so these waves were hitting me and twisting my body backwards and forwards. I would wake up in the morning and open my cabin door and just say, ‘Oh, no, not not another day of wind’ - for 10 days solid. That's what makes it so difficult, because you've got the wind channelling down the Gulf of Aqaba and the Gulf of Suez, and there's no way of avoiding it.

It was such a great opportunity because now I could take world leaders to the scene of the crime. My message has been, ‘Please leave the conference room, come down to the beach, put your heads in the water and just see what we risk if we carry on the trajectory we're on’. These coral reefs are some of the most resilient in the world. But the science is very stark. If we heat the planet by 1.5 degrees centigrade, we will lose 70% of the coral. If we heat the planet by 2 degrees centigrade, we lose 99% of the world's coral. And we're currently on track for way past that. So every single fraction of a degree now matters.

Coral reefs are the nurseries of the oceans. A quarter of life in our oceans lives in coral. This would be the first time in human history we run the risk of losing a whole ecosystem. I go to the COP conferences and hear the discussions and people are saying, ‘Well, you know, maybe we can stop it at 2 degrees centigrade or maybe 2.5 degrees,’ as if these differences don't matter. Look what's happening now and we've only heated the planet by about 1.2 degrees. Look at the wildfires across Europe. Look at what happened in Pakistan. Over 50 million people were displaced without a home. So there's an urgency and it's conveyed by what's happening down here in the coral reefs of the world.

I don't think many people realized just what we would lose. I'm just talking about what's happening in the oceans and coral reefs. But all of them are at tipping points: the polar regions, the forests, coral reefs, birds, insects. And the cumulative impact of all these tipping points is deeply worrying. The Ilulissat glacier in Greenland is now moving at a speed of 40m per day in summer. Every single year we have more storms, more floods, more droughts. It's almost as if glaciers are now moving quicker than our world leaders. So our response has got to be much quicker, much more urgent.

We are way past the point now where we should be talking endlessly about things. Yes we need to plan and prepare. We need to have short-term, medium-term, long-term goals. We now need delivery. I think this is what is frustrating people and especially frustrating the youth. On my expedition, we had a number of people who were in their early twenties. They were not born when these discussions began and they're angry. They are bitterly disappointed that we haven't delivered. And they see the future as extremely bleak. We need to turn the ship around and we need all hands on deck. Business leaders, political leaders, religious leaders, community leaders from every single sector of society.

All of us have now got to put our shoulder to the wheel. This is going to impact every single person on the planet. It'll impact every single future generation and the whole of the animal kingdom. When you swim across the Red Sea and you see all these animal species, all these tropical fish, there's so many of them. But we are the only animal species on this planet that has the capacity to destroy all of them. And it's happening in one generation.

I get asked all the time when I go to COP, ‘Do you have hope?’ Hope is a dangerous word because hope leads to an abdication of responsibility. You hope that some other government is going to cut its emissions, to stop polluting the environment. We've got to earn hope and we earn hope by taking action every single day. I want world leaders to wake up every morning and ask themselves a very simple question: ‘What can I do today to help solve this crisis?’ And then you need to take that action today. If you're a world leader now, you're facing so many different issues. And if you can't deal with it today, then tomorrow you need to do a double shift, because otherwise this crisis will outpace us. I'm 52 years old, and in my lifetime, we've lost nearly 70% of the world's wildlife. It's a desperate situation.

When you swim across the Red Sea, you have to swim across a shipping lane that takes all the ships to and from the Suez Canal in convoy. It's really difficult to judge the speed of a ship, especially in rough water. I swam as fast as I could past one container ship, not realizing that on the other side, there was another ship overtaking. Suddenly I was caught in the middle and as this was happening, a shark came underneath us. Luckily, my team saw the shark, I jumped onto the boat and then these big container ships came past me.

I love sharks. When you see a shark, it's a sign of a healthy ocean and they are crucially important in the ecosystem. But obviously, when you're doing a swim, you don't want to have sharks too close to you. There are about 40 different species of sharks in the Red Sea and four of them that you have to be really careful of: hammerheads, oceanic white tips, oceanic black tips and tiger sharks. And this was a hammerhead. It was one of those moments which you'll never forget in your life.

If you look at the geography of the Red Sea, it’s very long and almost enclosed. It has incredibly warm water that sometimes spikes way above 30 degrees, so if you were to take coral from other parts of the world, for example, the Great Barrier Reef and put it in the Red Sea temperature, it would die straight away. But over millennia, this coral has learned to adapt to the warm waters. Scientists think this will be the last coral left alive on current trajectories. So it's so important that we protect this coral. I've been urging the Egyptian government to enlarge the protected areas along this part of the Red Sea.

When I swam across Ras Mohammed National Park, the contrast was so great. As I took a swimming stroke, I looked up and on land, it's just arid desert and it's so hot. You put your head in the water and underneath you is so much life and the colours are so vibrant. It showed me just how crucially important these Marine Protected Areas are. I've been urging world leaders to carry on with this commitment of protecting at least 30% of the world's oceans by 2030. So far, about 120 nations have made this commitment - over half of the world. But we need all the remaining nations to join.