Prince Harry took a £6,000 private helicopter to Birmingham for his royal engagement this week.
And the move from the Duke of Sussex came just two days before he spoke about climate change at a meeting with environmentalists.
The royal hired the private helicopter for his trip to Birmingham on Monday, where he opened a memorial in the city's Cannon Hill Park.
The Mirror reports he used an AgustaWestland A109S Grand Chopper, which comes with a custom interior and leather seats.
Harry was in the city to dedicate a memorial as a focus of remembrance for those killed in the two separate attacks on the Bardo Museum in Tunis on March 18, and a hotel beach resort in Sousse on June 26.
The Duke of Sussex also visited the Institute of Translational Medicine and the Scar Free Foundation Centre for Conflict Wound Research based at the QE.
But two days later, Harry urged school kids to "wake up" to the prospect of climate change.
He said at an event at Wembley: "Climate change is a humanitarian issue and one where we've been far too slow in waking up to the issues and acting on the damaging impact our ways of living are having on the world.
"We now have the facts, the science, the technology and the ability to save not just our planet, but ourselves."
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Taking the flight would have saved the prince just under 40 minutes but the emissions are up to five-times higher.
Alternatively, he could have caught the train using a first class ticket for just £34, reports The Sun .
Harry and Meghan had previously caught a train to Bristol last month after snow caused them to cancel plans for another private flight.
Friends of the Earth had previously criticised the Duchess of Sussex for taking a private jet with Amal Clooney from New York.
A spokesperson told the Mail Online: “Private air travel obviously comes with a huge carbon footprint.
"Perhaps for future trips the Duchess could consider less carbon-intensive modes of travel.”
William and Kate routinely use helicopters for public visits, most recently to Blackpool on Wednesday.
Kensington Palace told The Sun: “Travel decisions are based on a number of factors, including effective use of time, security and minimising the impact on others, while ensuring the full schedule can be delivered.”
While in the city, addressing an audience of about 200 family and friends of the victims, Harry said: "In memory of all those who lost their lives.
"And to the families whose lives were changed forever by these events.
"I would like to pay my deepest respects to you and officially dedicate this memorial to your loved ones."
The park site in Birmingham was selected in consultation with the families due to its central location, its "seclusion and tranquillity" and as "being a place of public prominence", the Foreign and Commonwealth Office (FCO) said previously.
The memorial has been designed by George King Architects and overlooks the park's boating lake.
The centrepiece of the memorial is a sculpture titled Infinite Wave, made up of 31 individual stainless steel rods, each representing the Britons who lost their lives.
From the side, the memorial also takes the shape of a dove of peace taking flight, while concentric rings of stone and turf ripple outwards.
The FCO developed the memorial, consulting with families on the design and location.
In 2016, Harry attended a service at Westminster Abbey for the victims, and gave a reading.
After meeting the relatives, the Duke went on to visit the Scar Free Foundation for Conflict Wound Research at the Queen Elizabeth Hospital.
