Gerry McCann said that he was "disappointed" after a hearing at a Lisbon court was delayed but added that he "would come back" to give evidence in the family's libel case against a former detective.
He said: "Obviously we are disappointed.
"If I get the opportunity to be heard, I will certainly come back."
More top news
The study is expected to warn of the impacts of melting ice and permafrost.
Some northern and eastern areas may stay bright and warm but heavy rain or showers will affect most parts.
Police used tear gas and rubber rounds against protesters on Saturday