Glaciers across the globe - including the last ones in Africa - will be unavoidably lost by 2050 due to climate change, the UN says in a report.

Glaciers in a third of UN World Heritage sites will melt within three decades, a UNESCO report found.

Mount Kilimanjaro's last glaciers will vanish as will glaciers in the Alps and Yosemite National Park in the US.

They will melt regardless of the world's actions to combat climate change, the authors say.

The report, which makes projections based on satellite data, comes as world leaders prepare to meet in Egypt for next week's COP27 climate change conference.

About 18,600 glaciers have been identified across 50 UN World Heritage sites. They represent almost 10% of the Earth's glacierised area and include renowned tourist spots and places sacred to local populations.

The retreat and disappearance of glaciers was "among the most dramatic evidence that Earth's climate is warming", the report said.

"We hope we might be wrong, but this is the hard science," said UNESCO project officer Tales Carvalho Resende, one of the authors. "Glaciers are one of the valuable indicators of climate change, because they're visible. This is something we can really see happening."

The remaining glaciers in the other two thirds of UN World Heritage sites could be saved, but only if the world limits global warming to 1.5C, the authors say. Another UN report last week found that the world currently had "no credible pathway" to achieve that.

The projections build upon a previous report which used models to compute how World Heritage site glaciers would change over time.

"What is quite unprecedented in the historical record is how quickly this is happening," said Beata Csatho, a glaciologist from the University of Buffalo, who was not involved in the research.

"In the middle of the 1900s, glaciers were quite stable," she said. "Then there is this incredibly fast retreat."

World Heritage sites listed as having glaciers that will disappear by 2050 are:

The report said that ice loss in World Heritage sites may have caused up to 4.5% of the observed global sea level rise between 2000 and 2020. These glaciers lose 58 billion tonnes of ice every year - equivalent to the total annual volume of water used in France and Spain put together.

Many people also depend on glaciers as their water source for domestic use and agriculture, and their loss could lead to a scarcity of fresh water during the dry seasons, said Prof Duncan Quincey, a glaciology expert at the University of Leeds who was not involved in the research.

"That leads to food security issues because they were using that water to irrigate their crops," said Quincey.

Local communities and indigenous people will bear the brunt of the flooding caused by glacier loss, say the report's authors, urging that early-warning and risk-reduction disaster systems be put in place.

However the most obvious thing we need to do is limit global warming.

"There's a message of hope here," said Carvalho Resende. "If we can manage to drastically cut emissions, we will be able to save most of these glaciers."

"This is really a call to take action at every level - not only at the political level, but at our level as human beings."

• ·Ronna McDaniel WINS fourth term as Republican National Committee chair after hideous leadership battle with Harmeet Dhillon - and will steer GOP to 2024 elections notwithstanding underwhelming midterms
• ·Amazon staff protest climate record and office return
• ·WhatsApp and other messaging apps oppose 'surveillance'
• ·Food prices: Clever technology tackles fleetingages as prices consequentlyar
• ·Top economist calls for 'lenient' migration rules
• ·Disney+ streaming business loses 4m subscribers in first quarter
• ·Royal Mail boss Simon Thompconsequentlyn to step down
• ·Legend of Zelda game sells 10 million copies in three days
• ·Third child strangled by mother suffering from post-componentum psychosis dies three days after his two siblings: Eight-month-old Callan succumbs to injuries after mother's assault at Massach utilizetts home while husband went to pick up food
• ·Number struggling to pay bills consequentlyars by 40%, FCA finds
• ·Vice and Motherboard
• ·Are there 2,000 more GPs than before the pandemic?
• ·German train knife rampage victims are revealed to be girl, 17, and 19-year-old man: Suspect had been released from jail six days earlier 
• ·Colchester City Council investigating Capita over 'serious data breach'
• ·TikTok tracked UK journalist via her cat's account
• ·Train strikes this week to hit FA Chigh final and Epconsequentlym Derby