The scientist across the table from me was laughing, unusually for a conversation about climate change. "You're in environmental utopia now," he beamed. This being Sweden, he was partly being ironic - but only partly. We downtrodden Brits often look enviously at Scandinavian countries as models of genteel social democracy, and assume likewise that their environmental records must be models for the rest of the world. But, as is so often the case, the truth is a little more complicated.
Take Gothenburg, in southern Sweden, which I was visiting to talk about my book Six Degrees. This is a city that has recently invested vast sums of public money in a combined heat-and-power system, with more than 1,000km of pipes laid to take hot water directly into domestic and commercial buildings. It is an extremely efficient system that hugely reduces emissions from the building sector, where space heating is often the single biggest user of energy. But where does much of the wasted heat come from? Oil refineries, ironically enough - not exactly the last word in sustainability.
Yet Gothenburg wants to be carbon-free by 2050. There are climate-related adverts everywhere, urging car drivers to use the excellent tram system, and extolling the low-carbon virtues of the municipally owned utility Gothenburg Energy. Partly taking its cue from the previous government's aspiration to make Sweden oil-free by 2020, Gothenburg's energy utility has decided to supplement its new natural-gas-fired combined heat-and-power plant with another facility that will use woodchips instead of fossil fuel, lowering net carbon emissions still further. Some biomass is already burned to generate power, but here lies another irony: despite this being a heavily forested country with a substantial timber industry, wood pellets are brought in by ship from Canada.
Gothenburg Energy is also working with a major international corporation on building the first zero-carbon factory anywhere in the world. The client? Volvo. And the factory will be making cars. It all seems a bit contradictory, but this is a country that is even more in thrall to the car than Britain. The local shop is extinct almost everywhere: if you want a litre of milk or a pack of nappies you need to drive to a supermarket. Smaller communities may have a store selling hot dogs and a few daily necessities, but these are always based around the petrol station - seemingly the focal point for modern village life.
Perhaps as a result of this centralised approach to retail, the number of lorries on the roads and the level of transport emissions are rising rapidly. Even in cities with good public transport, there are still plenty of cars: from my 18th-floor hotel room in Gothenburg, I could see miles of interlinked motorways, all clogged with traffic for much of the day.
Nationally, the electricity sector is already fairly low-carbon, with most power generated at nuclear and hydroelectric plants. But other renewables are lagging behind. Windfarms are a rarity in Sweden, and various big schemes have been shelved due to local opposition, despite the climate-change benefits. Sweden is no exception to the general rule that people want electricity, but not electricity generation.
But before we all get quietly smug over here, on an island that was once considered the dirty man of Europe (not least by Swedes, who in the 1980s had to live with all our acid rain), there is a lot that Sweden has got right. This is a country, after all, which introduced a carbon tax way back in 1991, when most of the rest of the world had barely heard of global warming. It is also a country that inverts the usual dynamic between scientists and politicians: recently, when a scientific advisory committee proposed a carbon reduction target to the Swedish government, the environment minister, instead of trying to lower it, demanded more stringent cuts than even the scientists were recommending.
Sweden also seems to have broken the iron link between economic growth and greenhouse-gas emissions: since 1990 its emissions have fallen by 4 per cent, despite a GDP growth of 25 per cent. This is largely due to combined heat-and-power generation schemes such as Gothenburg's, schemes that demonstrate a willingness to pump large sums of public sector cash into energy efficiency.
Travelling back south from the ferry port in Newcastle this week (I had made the trip to Scandinavia by boat and train, for obvious reasons), I was struck once again by the scandalous waste of energy represented by power-station cooling towers in this country, whose only function is to disgorge enormous quantities of heat into the atmosphere. A power station like Drax could heat an entire city, yet all this energy is simply wasted, and instead we burn yet more oil and gas to heat our houses, shops and offices. Sweden may not be the environmental utopia we think, but it has certainly got one thing right.