A council has defended its decision to reject expansion proposals of an airport despite the threat of a costly planning appeal.
North Somerset Council voted overwhelmingly to reject Bristol Airport's plans in February 2020.
The hearing began earlier after Bristol Airport challenged the decision.
Council leader Don Davies (Independent) said: "This unfortunately is used by big business the world over to try and cow members to do things for profit."
"This airport is not owned locally, it's owned by a Canadian pension scheme and what is the motivation for the appeal?
"They barely got eight million passengers per annum previous to the planning application.
"They have permission for up to 10 million passengers so there was a 12 percent window of expansion there already.
"It is ironic that a country like Canada was wrecked ... by the heat dome - but they can't see the impact of the expansion on the environment here in north Somerset," Mr Davies added.
The expansion will mean capacity will rise to 12 million passengers per year which the airport says will create new jobs and support the local economy.
Critics protesting outside the hearing venue in Weston said more flights would increase global warming.
Witnesses will range from Bristol Airport executives, industry experts, environmental campaigners and parish councillors.
If the decision is overturned, there will be more flights and extra car parking spaces to grow the business.
The hearing which began at 10:00 BST saw a representative for the airport put forward its case.
Counsel for Bristol Airport, Michael Humphries QC said: "The government has made clear the importance it attaches to airports and their expansion.
"The merits of government policy are not a matter of debate for this local planning inquiry.
"The expansion of the airport does not cut across climate change ambitions that we all share.
"It is consistent with and complements them."
Ahead of the hearing, the airport's procurement manager Susannah Caws said: "Would you stop going on holiday?
"Would you stop flying? If I asked whether they would ever stop flying because of the carbon footprint I'm not sure anybody would.
"All we can do is do everything we can to reduce our carbon footprint where possible.
"People will always fly and it's how we mitigate that where possible."
She said mitigation would include ensuring all of its vehicles were electric and that its electricity came from renewable sources.
The Parish Councils Airport Association represents 30 parish councils in the area, all of which oppose the plans.
Chairwoman Hilary Burn said: "I commend anybody who moves forward in an environmentally-friendly way.
"Let's not forget the elephant in the room - the new modernised flights, which are coming, which are electric, don't come until 2035.
"We know we have a biodiversity crisis and a climate crisis and we know that we have to act for 2030.
"We have to do our utmost to reduce carbon."
CEO of Bristol Airport, Dave Lees said: "Bristol Airport is important to the region and its recovery and that includes a greener future.
"We want to improve connectivity - that's what businesses are telling us.
"We want to avoid people having to travel up to London - it's new and existing demand from people in our region."
The appeal is expected to last at least two months and will be streamed on North Somerset Council's YouTube channel.