One of the underpinnings of 21st century climate forecasts is the projected growth of population. More people means more carbon emissions. Those of us who grew up in the 1970s remember hearing about the Population Bomb, the coming crisis of overpopulation that would wipe out the planet’s ecology and leave everyone crowded and starving. As with all eco-panics the Population Bomb turned out to be a bust. Birth rates started dropping around the world faster than expected and population growth projections began coming down as well. The UN still predicts global population will keep growing over the coming century, passing 9.7 billion in 2050 and reaching 10.9 billion by 2100. But a new study has revisited the topic, taking into account the effects of rising income and education in developing countries. They too foresee 9.7 billion people mid-century but after that it’s all downhill, and the world ends up with only 8.8 billion in 2100. That’s a lot fewer mouths, and a lot less carbon.
In fact, it’s about 20 percent less carbon than the usual UN forecasts. Without anyone even trying to reduce emissions. Which brings us to another key point about modeling.
We’ve written many times about the grossly exaggerated RCP8.5 emission scenario. Its faulty prognostications are based on assuming people will use far more fossil energy over the coming century than anyone thinks possible, and there will be far more income growth than is likely (though it would be nice if it happened). Now we can add exaggerated population projections to the list of alarmist tricks. Even if people moderate their use of fossil fuels and emissions per person don’t rise, the sheer fact of there being more people would keep pushing emissions up. But in all likelihood there won’t be more people, at least after the mid-century peak. There will be fewer people and fewer emissions. One more reason why we should ignore the worst-case scenario doom-sayers.