But for those organizing this summit, it had already become increasingly clear this would be a difficult G7 when nobody could find America's Sherpa.
Sherpa is the nickname given to each senior bureaucrat who represents each leader in the negotiations that precede the summit and continue after the leaders arrive.
Trump initially appointed Kenneth Juster as his Sherpa. But in the run-up to the G7, Juster was given new duties and never replaced. So the Sherpas of the world's most economically powerful democracies arrived in Sicily not knowing who would speak for the U.S. president at their table. Canadian Prime Minister Justin Trudeau has called climate change one of the world's greatest threats. But with the world's biggest economy threatening to pull out of the Paris accord, he would not criticize the president's decision when pressed at his summit closing news conference
"I'm not going to lecture another country on what they should do," Trudeau told reporters. "It is explicitly written in the communique that we respect President Trump's choice to reflect further on their engagement around climate change and the Paris accord."
A second Canadian official says Trudeau's careful approach wasn't just for public consumption. The official says the prime minister took a conciliatory tone during the climate discussions.
Trudeau, this official says, focused on fact-based arguments in the private meetings and steered away from personal or ideological ones. Trudeau, along with Japanese Prime Minister Shinzo Abe, arguably has the best relationship with the president. The official said Trudeau's approach was designed to allow Canada to act as a bridge between Trump and the European leaders.
It didn't convince Trump to stay in the Paris accord, but it may have secured the Paris accord a mention in the summit declaration. As late as Saturday morning, the Canadian official said there was resistance to even mention the accord in the G7 statement. Canadian officials believe their efforts helped to earn that small victory.
'Trying to stop them from doing damage'
But the failure to reach consensus on climate was clearly the biggest disappointment for the pro-Paris leaders. As for Trump, he described the summit as a resounding success in an end-of-summit speech to U.S. military personnel stationed in Italy.
"It was a tremendously productive meeting where I strengthened American bonds. We have great bonds with other countries," Trump told the troops.
Those bonds will be severely tested if Trump does abandon the Paris accord this week or tries to drastically scale back the U.S.'s climate targets. A third Canadian official said there was always significant doubt that they could sway Trump to the G7 climate consensus. But this official described the goal for handling the U.S. delegation as being closer to containment than agreement.
"It's not really about compromise. It's about trying to stop them from doing damage," said the third official.
The hope is that the risk to the climate deal isn't as dire as it appears. Multiple Canadian officials take solace in comments by U.S. officials who say Trump's views on climate change are "evolving."
Italian Prime Minister Paolo Gentiloni praised Trump's contribution to the overall discussion, saying he found the president "very curious with a capacity and willingness to participate and learn." In sharp contrast, German Chancellor Angela Merkel described the entire climate discussion as "difficult" and "dissatisfying."
The reality is the G7 leaders left this summit with no clear indication of what Trump will do. The hope is that the views of the man who once tweeted that climate change was a hoax invented by the Chinese have evolved enough to keep him in the Paris accord.
If the president's latest tweets are to be believed, we'll find out if that's true next week.