"Carbon neutral" sounds pretty straightforward—simply remove as much carbon dioxide from the atmosphere as you put in. The trouble is, civilization began emitting CO2 when humans burned the first lump of coal about 4,000 years ago.
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Ever since, we've been digging up carbon in the form of fossil fuels and sending it skyward. Today the fraction of carbon dioxide in the atmosphere is about 385 parts per million, roughly 30 ppm above the level deemed environmentally sustainable by many scientists and climate experts. If we continue emitting at our current rate, that number will climb to 450 ppm by 2050, putting the planet at serious risk of runaway climate change, with heat-trapping gases causing unprecedented warming. After that, things get pretty scary: Coastlines flood, species disappear, droughts get longer, crops become harder to grow, and people in general become hungrier, thirstier and angrier.
But it's not too late to reverse course. Fortunately, thousands of communities, cities and even whole countries are pursuing real carbon neutrality, enacting legitimate plans to mitigate their greenhouse emissions and, eventually, bring atmospheric CO2 concentrations back to safe levels. Here, we've spotlighted some of the most inspiring. Denmark's Samsø Island, for example, is no mere engineering fantasy. It's already balanced its carbon footprint by adopting wind and solar power and is now working toward offsetting more carbon than it emits. Masdar City in arid Abu Dhabi, meanwhile, is proving that even oil-rich regions with outsize carbon footprints can wean themselves off the black gold. More important, each of these projects is employing energy and conservation strategies well within the reach of any developed nation that really wants to implement them.
These impressive efforts, though, reveal just how far we have to go. The average Maldivian uses so little fossil fuel that the global benefits of a carbon-free Maldives can be undone by just five days of average population growth in the U.S.
Ultimately, carbon neutrality demands a global effort. That means communities from New York to New Delhi must transform—in effect, becoming perfectly balanced biomes: lots of activity, lots of creation and destruction, but without all the CO2 emissions that typically go with it. In other words, carbon neutrality requires a complete rethinking of how we have lived since the Bronze Age. Impossible? There are at least nine ecotopias that are proving otherwise.
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