The city of Helsinki has revealed a first-of-its kind website meant to empower citizens, businesses and tourists to make more sustainable choices.

The Think Sustainably digital service resembles a regular city guide, but with environmental sustainability as the primary factor.

It is part of the local government's Carbon Neutral Helsinki Initiative, which aims to make the city carbon neutral by 2035 — a change that would involve cutting each resident's carbon footprint to one-quarter of what it is at present.

For business owners, the service presents a checklist of actions they can take to make their enterprise more environmentally sustainable.

These range from simple things like switching to LED lights and offering a vegan menu option to more involved efforts, such as writing and implementing a measurable carbon-reduction plan.

For residents and visitors, the initiative represents a chance to support those businesses that are mitigating their environmental impact. When users open the app or website, they see listings of cafes, restaurants, bars, shops, cultural centres and other venues — the most sustainable among them marked with a green tag.

It also shows whether a company is hitting its full sustainability criteria, as well as what they're missing. A business does not need to meet all of the criteria to be certified sustainable; in the restaurants, bars and cafes category, for instance, they need to hit 10 of 17.

Think Sustainably is designed to make conscious consumerism easier for residents, two-thirds of whom identified the climate crisis as a major concern in a survey last year.

The city's Carbon Neutral Helsinki Initiative director Kaisa-Reeta Koskinen said the service was significant because the shift towards carbon neutrality would require both major structural change and individual everyday action.

"Individual choices matter," she said. "According to recent studies, in order to stop further climate warming, every Finn should reduce their carbon footprint from 10.3 tonnes to 2.5 tonnes by the year 2030."

"If one person in each of the 2.6 million households existing in Finland would reduce their carbon footprint by 20 per cent, we would reach 38 per cent of the goals set for Finland in the Paris climate agreement for reducing emissions."

Helsinki Marketing CEO Laura Aalto described the website as "nudging people and businesses towards more sustainable living".

She said that as a small city, Helsinki could be a "test-bed" for solutions that larger cities could scale up.

"Operating like a city-scale laboratory, Helsinki is eager to experiment with policies and initiatives that would not be possible elsewhere," she said.

"The city is able to effect change in this way because of its compact size, well-functioning infrastructure and well-developed knowledge-economy cluster," she continued. "We hope that others can also learn from our experiments."

Think Sustainably launched as a pilot in June, and so far has 81 participating service providers.

It works through businesses self-reporting rather than independent auditing — an approach that the City of Helsinki said had so far been effective, with businesses more likely to under- than oversell their sustainable actions.

The transparent nature of the system means the public can keep businesses accountable through feedback. Some of the service's high performers include the Amos Rex art museum, the Design Museum, and the Flow Festival, one of the world's first carbon-neutral festivals.

The sustainability criteria — written by think tank Demos Helsinki — varies from category to category. While renewable energy use applies to everyone, restaurants are asked to take actions such as avoiding disposable cutlery and serving ethical seafood, while cultural institutions need to encourage public transport use and shops can sell recycled items, offer repairs or incorporate borrowing.

There are also a few social sustainability criteria, including employing people who may otherwise be difficult to place and publicising accessibility information.

The City of Helsinki has prioritised sustainability in recent years, which is partly why it was named the inaugural European Capital of Smart Tourism in 2018.

The city is the also the first in Europe (and the second in the world, after New York) to commit to reporting to the UN on its implementation of the sustainable development goals.

Ethical creative agency Nice and Serious have created a digital directory of London's zero-waste shops, to guide potential customers to their nearest store, and offer advice on how to reduce reliance on single-use plastics.