Adnams is adding three new beers to its portfolio, including one it claims is Europe's first carbon-neutral brew.
The brewer calculated the amount of carbon generated throughout the supply chain, from growing the hops to packaging, to reduce the product's total emissions.
Through a combination of energy efficient brewing, lightweight bottling, locally-grown raw materials and a small amount of off-setting, Adnams says producing East Green will not create a carbon footprint.
The 4.3% abv golden ale will be exclusive to Tesco for six months, priced £1.79 for 50cl, to keep it competitive with other beers in the fixture.
Andy Wood, Adnams' managing director, said if the beer sold as well as Broadside, its most popular beer, it would be the equivalent of taking 65 cars off the road a year.
Dan Jago, Tesco category director for beers, wines and spirits, said: "It is refreshing to see a company like Adnams bringing exciting products to shelf that promote environmental sustainability.
"With the launch of this initiative, we are enabling our customers to make considered, informed decisions in the BWS aisles. We are doing all we can to reduce the environmental impact of our industry, and we will continue to work with innovative companies like Adnams to create environmentally-conscious produce."
Adnams is also rolling out two lower strength beers in a bid to recruit new ale drinkers. Continuing the ethical theme, an as yet unnamed 4% abv dark ale will be introduced later this month, with a percentage of its sales being donated to charity.
The second is Lighthouse, a 3.4% abv brew which was first sold in the 1980s as Adnams pale ale. The brewer's sales director Rob Flanagan said: "This is one of our old recipes and it used to win lots of awards when it was sold as a seasonal ale. We have done lots of work understanding the 4% abv and lower category and we think there is an opportunity. These beers are about being introduced to Adnams. They are great beers, but less challenging."