How Many Will We Be? – Are Population Estimates Off the Mark?

[OKIsItJustMe]

http://www.popcouncil.org/mediacenter/newsreleases/2011_PopulationEstimates.asp

News release

How Many Will We Be?
Are Population Estimates Off the Mark?

NEW YORK and WASHINGTON, DC (20 February 2011) — In 2011 the Earth's population will reach 7 billion. The United Nations (UN) reports that the total number of people will climb to 9 billion in 2050, peak at 9.5 billion, stabilize temporarily, and then decline. Despite the confidence with which these projections are presented, in an American Association for the Advancement of Science press briefing and presentation today, the Population Council's John Bongaarts presents evidence that the actual population trajectory is highly uncertain.

What could happen depends on trends in fertility and mortality—and both variables are complex and not easy to forecast.

With respect to fertility, some analysts assume that the very low levels of childbearing now prevailing in Southern and Eastern Europe, where women have fewer than two children on average, will continue in those countries and spread to other parts of the world. But scholars have different expectations of how rapidly and widely that trend will unfold. If fertility remains higher than the UN projects, the world population could exceed 10 billion in 2100.

In terms of mortality, pessimists say that life spans in developed countries are close to the biological limit. However, optimists predict that life expectancy will continue to rise very rapidly, exceeding 100 years before the end of this century. If the optimists are right, the world's population could also exceed 10 billion in 2100. This higher population scenario also has implications for the solvency of social security systems that provide income to the elderly.

"Almost all of the growth in world population will occur in poor countries, particularly in Africa and South Asia," says Bongaarts. "But if we make much larger investments in family planning right now, the number of people could be closer to 8 billion. Such an investment would have a very beneficial impact on human welfare and any environmental issue we care about."

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[GliderGuider]

1. I expect our numbers to peak at 7.5 billion between 2025 and 2030, then start declining.

Mortality and fertility will both be impacted by the effects of the current collision of climate change and peak oil on the global food supply. We'll see a serious decline in net births as a result, going down from today's 80 million per year to zero in 15 to 20 years.

[damntexdem]

2. I predict that the population decline will be more rapid.

And the mortality will have nothing to do with biological limits to human lifespan. There will be a precipitate decline, crash, due to overpopulation and global warming.

[stuntcat]

3. I have dread

what if deaths from starvation/disease/no water just keep on climbing.. what if there's a crash to 4 or 5 billion in a couple of decades? It could happen easy, so much is on the edge right now, everything depending on everything else.

I know some well-fed baby-boomers who will keep laughing at their tvs no matter how many are dying. What I've seen, personal and direct from them, tells me they really are to blame, they are so selfish they don't mind screwing the rest of the world and the future.

[GliderGuider]

4. An article that expands on why I've stopped worrying about overpopulation

Is Peak Population Almost Here?

After 40 years of beating the drum of overpopulation, I've stopped.

I no longer think that overpopulation or the ecological devastation that comes from overconsumption are going to be problems for much longer. I now expect world population to peak between 7.5 and 8 billion people by 2025 or 2030, and then start declining. I also think that the human activity that is currently damaging the natural world is going to start diminishing at the same time.

But I haven't changed my mind for the reasons you might think. It's not that I believe that after all this time, after all this human growth and planetary mutilation we are finally getting a handle on our behaviour. Instead, the reason I believe this "good news" is about to unfold is that we are already in the throes of a collision between climate change and world oil supply limits (aka Peak Oil) that from this moment on is going to progressively destabilize the global food supply.

As our food and energy supplies tighten and then begin to shrink, the engine of population growth will shudder to a halt and our ability to wreak havoc on the world will be drastically curtailed. Whether this will be a good or bad thing is entirely a question of your perspective.

More at the link.

[bhikkhu]

5. They assume limitless food and water

So of course they are off. Reading things like that is like reading economic predictions - they are always wrong, and virtually the whole science in both cases consists of explaining why they were wrong after the fact and then reworking their models. And then being wrong again next time...etc.

Considering that people, like all animals, don't increase in numbers unless there is sufficient food and water, I'd say we have to look at those to see how things will be. It varies from place to place, of course, but for the past 15 years or so we have been unable to provide fresh water to more than 5 billion. That doesn't look like its changing, and rising population without clean water runs into the misery barrier fairly quickly. Of course we could divert water from irrigation, but then the food supply goes down and you run up against the misery barrier on food instead.