It is probably one of the most comprehensive examinations of a rugby match ever carried out.
Welsh fans enjoying an international weekend
Researchers at Cardiff University's Centre for Sustainability (Brass) assessed the economic and environmental impacts of the 2006 Six Nations clash between Wales and Scotland.
The economic scoreline for the Welsh capital was very welcome: Rugby fans spent nearly £15m that weekend.
And 77% of that remained in the Cardiff economy.
But the environmental results, according to the researchers, were a different matter.
Dr Andrea Collins, of Brass, said: "Our research considered how far supporters travelled to Cardiff, whether they used public transport, the amount of food and drink they consumed, overnight accommodation and how much waste was created.
"The energy and resources used by 85,499 rugby supporters that weekend resulted in an ecological footprint equivalent to the area of 3,578 rugby pitches."
Ecological footprinting is a way of showing humans' environmental impacts.
It depicts the amount of productive land that would be needed to sustain human activities like consumption and pollution.
Match 'carbon footprint' = 3,578 rugby pitches
47,000 burgers, pies and pasties eaten over weekend
Average match day drink - six pints of lager, five spirits and four more units of alcohol
67 tonnes of waste, but only 1% recycled
Source: Cardiff University
The more land needed, the less sustainable the activity.
Brass researchers say a footprint the area of 3,578 rugby pitches makes Six Nations matches at the Millennium Stadium unsustainable.
Dr Collins said: "For example, the types of food eaten by fans. All those burgers, pies and pasties require lots of energy to make because they're highly processed.
"They result in a large footprint."
Researchers found that 47,000 burgers, pies, pasties were eaten over the match weekend by fans, and no vegetarian meals or fruit was consumed.
An average supporter drank six pints of lager, five measures of spirits and another four units of other alcohol on the day of the match.
The analysis also found that the Wales v Scotland match produced 67 tonnes of waste, but only 1% of it was recycled.
And to get to the game, fans travelled a staggering 15 million miles.
With the vast majority coming not by train but by car, that added a fair bit to pollution.
Cardiff Council was criticised for promoting car use with its park-and-ride scheme and for not making recycling easier.
Cardiff councillor Elgan Morgan admitted "We have some significant problems with these events and we do need to do more to reduce our footprint and find practical ways to do that."
The researchers said they were not discouraging supporters to enjoy themselves, but they are warning that more and more big games and events will take their toll on the planet unless fans and organisers try to make them more sustainable.