British-South African born endurance swimmer, Lewis Pugh, has completed a record-breaking swim in Antarctica to highlight the impact climate change is having on global sea temperatures and to call for the creation of a network of Marine Protected areas (MPAs) around Antarctica.
Lewis, who was appointed as UN Patron of the Oceans in 2013, swam for 10 minutes and 17 seconds in the Antarctic subglacial lake, where water temperatures were recorded at just over 0-degrees.
Lewis also faced the constant threat of the glacial river suddenly emptying through a crack in the ice sheet and falling hundreds of metres to a rock bed below.
Speaking immediately after recovering from the swim, Lewis said: "Today was certainly the most frightening swim of my life.
"Swimming under the Antarctic ice sheet is the most beautiful and terrifying swim I’ve ever done. Every shade of blue and then nearly complete darkness."
However, Lewis has claimed on social media that his remarkable achievement should not have been possible and he was only able to swim in the sub-glacial lakes due to rising global temperatures caused by climate change.
A recent study undertaken by Durham University found that there are 65,000 supra-glacial lakes in East Antarctica, which are formed as melt water collects on the surface of a glacier.
They claim this indicates surface melting is more widespread than previously thought and occurring much further inland and at much higher elevations than previously observed.
After witnessing this first-hand, Lewis has now called on world leaders to “step up or step aside” after being in “no doubt” that we are now facing a global climate emergency.
"I hope that my swim underneath the Antarctic ice sheet will ignite international leaders and lead to the introduction of the Marine Protected Areas this region so critically needs," said Lewis.
"Wherever I looked there were large rivers of water carving their way through the ice sheet. I have no doubt whatsoever that we are now facing a climate emergency.
"We do not have 50 years or 20 years or even 10 years to solve this crisis. We have run out of time. The time for action is now."
Following his Antarctic swim, Lewis will now travel to Moscow to take part in Russia's celebration of the 200th anniversary of the discovery of Antarctica, where he plans to hold talks with some of the country's key decision makers.