Every month since June 2023 has eclipsed its own temperature record in a 13-month streak of unprecedented global heat, the Copernicus Climate Change Service (C3S) said.

"This is more than a statistical oddity and it highlights a large and continuing shift in our climate," said the service director, Carlo Buontempo.

"Even if this specific streak of extremes ends at some point, we are bound to see new records being broken as the climate continues to warm."

This was "inevitable" as long as humanity kept adding heat-trapping gases into the atmosphere, he said.

The global average temperature notched last month broke the previous June record set in 2023.

The fresh high came at the midway point of a year marked by climate extremes.

Scorching heat has blanketed swathes of the world from India to Saudi Arabia, the United States and Mexico in the first half of this year.

Relentless rain, a phenomena scientists have also linked to a warmer planet, caused extensive flooding in Kenya, China, Brazil, Afghanistan, Russia and France.

Wildfires have torched land in Greece and Canada and last week, Hurricane Beryl became the earliest category five Atlantic hurricane on record as it barrelled across several Caribbean islands.

- Warmer oceans -

The streak of record-breaking temperatures coincided with El Nino, a natural phenomenon that contributes to hotter weather globally, said Julien Nicolas, a senior scientist at C3S.

"That was part of the factors behind the temperature records, but it was not the only one," he told AFP.

Ocean temperatures have also been hitting new highs.

Record sea surface temperatures in the Atlantic, the Northern Pacific and Indian Ocean also contributed to the soaring heat across the globe.

Sea surface temperatures hit a separate milestone in June -- 15 straight months of new highs, an occurrence Nicolas described as "striking".

The oceans cover 70 percent of the Earth's surface and absorb 90 percent of the extra heat associated with rising climate-warming emissions.

"What happens to the ocean surface has an important impact on the air temperature above the surface and global average temperature as well," he said.

However, the world is about to transition into a La Nina phase, which has a cooling effect.

"We can expect the global (air) temperature to taper down in the next few months," said Nicolas.

"If these record (sea surface) temperatures persist, even as La Nina conditions develop that might lead to 2024 being warmer than 2023. But it's too early to tell," he added.

Global air temperatures in the 12 months to June 2024 were the highest in the data record -- on average 1.64C above pre-industrial levels, Copernicus said.

This doesn't mean the 1.5C warming limit agreed by 196 countries in Paris in 2015 has been breached, because that goal is measured in decades, not individual years.

But last month, Copernicus said there was an 80 percent chance that Earth's annual average temperatures would at least temporarily exceed the 1.5C mark during the next five years.