Can a country really be carbon neutral? Step forward Bhutan. Yes, despite its position between India and China - two of the most polluting countries in the world - Bhutan is in a carbon deficit. While we usually bemoan expensive visas, we're all for Bhutan's. Not only has it enabled the country to sidestep the culturally erosive blight of overtourism, but roughly a quarter of the fee goes towards strengthening public services in line with eco-credentials. While the country doesn't lack vehicle-oriented infrastructure - the first tarmac road was built in the 60s - its lush, tropical forests help to guzzle more than six million tonnes of carbon per year.

STAY: Gangtey Lodge, Amankora

The Icelandic capital's climate policy is steps ahead of most places on two counts. Firstly, the city has a delightfully low population density. Secondly, Reykjavík runs almost entirely on geothermal energy reserves, which is perhaps unsurprising to those who've ogled Iceland's famous geysers. In 2013, its greenhouse gas emissions stood at 2.3 tonnes per person - a tiny fraction of the 16.5 tonnes attributed to each US dweller.

STAY: Eyja Guldsmeden Hotel

It's a city where New Age hippy types rub shoulders with forward-thinking, Silicon Valley tech magnates: it's little wonder they're carbon-cutting pioneers. It was one of the first cities in America to prohibit the use of plastic carrier bags - a move which is believed to have reduced annual landfill waste by 1.6 million tonnes - and was recognised by Obama as one of the best cities in America to travel car-free. Although you'd be a fool to hire a car in a city so blessed with sweeping cycling routes (48,000 San Francisco locals commute on bicycle), if you do need to hitch a ride more than 60% of the taxis here are electric.

STAY: Hotel Spero

Carbon neutrality by 2035 is the goal for Helsinki. It's one of the most ambitious deadlines in the world - most cities are angling for 2050 or 2040, at a push. Helsinki's Climate Watch tool is a little tiresome to read in one sitting, but it outlines the 147 measures the city's currently enacting to reduce its emissions. It includes things such as the design of pleasant walking routes through the city, the installation of LED street lighting and precisely what proportion of meals served by the public sector (to primary school children and in nursing homes, for instance) are veggie. This Finnish city gets a gold star for transparency.

STAY: Hotel St George

It might only take up 0.03 per cent of the Earth's surface, but Costa Rica's thrumming rainforests represent nearly six per cent of the world's biodiversity - and its government is keen to keep it that way. Thanks to Carlos Manuel Rodriguez, Costa Rica's progressive Minister of Environment and Energy, this Central American haven for holidaymakers is on track to full carbon neutrality by 2050. Under Rodriguez's plans, 70 per cent of Costa Rican buses and 25 per cent of cars will be powered by electricity by 2035, while work on a new nationwide electric train network is scheduled to start in 2022. It's a mightily ambitious plan for such a small country, but a trailblazing one at that.

STAY: Lapa Rios Lodge

Of course this progressive hub - home to Greenpeace and cradled by unspoiled mountains - is years ahead in the carbon race. In its Greenest City Action Plan in 2011, the city rather audaciously pledged to become "the greenest city in the world" by 2020. As well as subsiding electric vehicles, targeting big industrial carbon gluttons and adapting buildings to be more energy efficient, the plan includes admirable focus points on eating locally. Thanks to this, jobs have been boosted in surrounding farmland and inner-city allotments have been carved out in a bid to reduce food miles: good news for conscious travellers with big appetites.

STAY: The Listel Hotel

The much-loved TV show Portlandia might present a comical pastiche of hipster wokeness, but the city's eco efforts are no joke. It has 97 light rail stations, 80 bus lines and a lacework of cycling routes to help tourists access the most hard-to-reach nooks of the city. Half of the neighbourhood's electricity comes from renewable sources and 32 per cent of the office spaces (glassy skyscrapers often being the worst culprits) have the world-recognised ENERGY STAR seal of approval. Despite an ever-increasing population, the city's committed to growing its urban forest too.

STAY: Kimpton RiverPlace Hotel

This year's a big'un for Oslo. In 2016 it pledged to slash emissions by 50 per cent come 2020. While those figures are yet to roll in, the city has stealthily implemented a handful of measures to reach full carbon neutrality by 2050. You might not spot many gimmicks out on the streets (plant walls and vegan cafés aren't at the vanguard of carbon reduction efforts, pleasant though they may be). Yet over the past four years, car-free zones have been introduced, infrastructure for cyclists and pedestrians has levelled up and buses have started chugging along on biogas. It's even earned the title "Electric Vehicle Capital of the World", with 30 per cent of vehicles sold now being electric.

STAY: Amerikalinjen