According to the UN Population Division, the average annual global growth rate peaked at just over 2 percent between 1965 and 1970. Since then, it has been steadily falling and currently stands at about 1 percent. By 2050, the UN projects that it will have fallen to an estimated 0.3 percent.
Now a team of US and Austrian researchers have shown that slowing population growth could deliver up to 30 percent of the cuts deemed necessary by 2050 to prevent dangerous climate change. The findings appear in the Proceedings of the National Academy of Sciences.
These findings are significant because many environmental campaign groups tend to overlook, or worse still ignore, the impact of population growth on climate change.
The UK-based Optimum Population Trust, OPT, a charity that is concerned about the impact of population growth on the environment, believes the planet is already populated beyond its capacity. OPT believes that the optimum human population that can be sustained in the long-term is around three billion people. Responding to the paper, chief executive Simon Ross said: We welcome this analysis of the links between global population and climate change. We believe this paper supports our assertions that reproductive health is an environmental issue, as well as a humanitarian and developmental one, he told BBC News.
The good news, however, is that an increasing number of people may not necessarily lead to a similar rise in emissions. Thats because changing population dynamics exert a subtle influence. Specifically, the number of people aged over 60 is increasing, and the UN predicts that it will almost triple, from 737m in 2009 to in excess of two billion by 2050.
Older households travel less, and the reduced contribution to the labour force means that the overall economy grows more slowly. As a result, the overall use of energy within the economy goes down. And that means emissions go down too.
Thats not to say that demographic shifts, falling birth rates and an older population will solve the problem. The OPT argues that we can only be successful in halting the looming environmental catastrophe through a combination of lower overall population growth, reduced per capita consumption and better use of technology.