Queen Elizabeth and other senior members of the UK royal family will attend the Cop26 climate conference in Glasgow this November.
The long-serving monarch will attend a diplomatic drinks reception alongside the Prince of Wales and the Duchess of Cornwall, and the Duke and Duchess of Cambridge.
Confirmation that the family will be at the event shows the seriousness with which they take climate breakdown.
Prince William recently announced the winners of his inaugural £50 million ($68m) Earthshot Prize, a competition that aims to find solutions to some of the planet's most pressing environmental questions.
The Duke of Cambridge will address conference, The Telegraph reported. His father, Prince Charles, will also speak.
The Prince of Wales is a lifelong environmentalist and so an apt choice to lead the talks, which will try to persuade international partners to make meaningful progress in the fight against climate change.
Of all these partners, China is by far the biggest polluter, with the biggest challenges to success.
A 2018 poll by Ipos Mori found much of the Chinese population was pro-monarchy. These sentiments go some way to explaining why the senior Windsors are heading to the summit in such numbers.
Their presence was welcome by Bob Ward, of the Grantham Research Institute on Climate Change and the Environment at the London School of Economics.
"The more the UK looks like it's taking this seriously, the more other countries will want to be seen to match that," Mr Ward told The Telegraph.
"So yes, I think it's entirely helpful to have such a strong showing from the royal family. Prince Charles, and increasingly Prince William, have shown a particular interest in this area.
"Prince Charles is definitely recognised around the world as a deep thinker on these issues, and having a track record of having been interested in this for a long, long time.
"So it's not just the symbolism. They are people of substance on these issues.
"It should indicate that the UK is pulling out all diplomatic stops and is committed to doing everything possible to ensure that we leave Glasgow with the Paris Agreement goal of keeping warming to 1.5°C [above pre-industrial levels] within reach."