By the end of this year, there'll be seven billion people on the planet, a whole billion more than in 1999, according to new UN figures.
In 2011, approximately 135 million people will be born and 57 million will die, a net increase of 78 million people.
And between now and 2050, an estimated 2.3 billion more people will be added — nearly as many as inhabited the entire planet in 1950. By the end of the century, the population will reach 10.1 billion, says the Population Division of the UN's Department of Economic and Social Affairs.
Practically all the growth in the next 40 years - 97 percent - will take place in less developed regions, with just under half in Africa.
By contrast, the populations of more developed countries will remain flat - although they'll age, with fewer working-age adults to support the rest of us on our pensions.
It's an unprecedented global demographic upheaval, says professor David Bloom of the Harvard School of Public Health.
"Although the issues immediately confronting developing countries are different from those facing the rich countries, in a globalized world demographic challenges anywhere are demographic challenges everywhere," he says.
Naturally, there's considerable uncertainty about these projections. For some time, there's been a gradual decline in the number of births per woman - but if we all get a touch more enthusiastic about babies, the figures could be higher.
Depending on birthrate, the ranges for 2050 vary from 8.1 to 10.6 billion, and the 2100 projections vary from 6.2 to 15.8 billion.
Already under a lot of pressure for resources, many developing countries will likely face tremendous difficulties in supplying food, water, housing, and energy to their growing populations, with repercussions for health, security, and economic growth.
"The demographic picture is indeed complex, and poses some formidable challenges. Those challenges are not insurmountable, but we cannot deal with them by sticking our heads in the sand," says Bloom.
"We have to tackle some tough issues ranging from the unmet need for contraception among hundreds of millions of women and the huge knowledge-action gaps we see in the area of child survival, to the reform of retirement policy and the development of global immigration policy. It's just plain irresponsible to sit by idly while humankind experiences full force the perils of demographic change."