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population pressures > features > population growth steady as climate heats up

Population growth steady as climate heats up

Posted: 01 Jan 2010

by Robert Engelman

Throughout the first decade of the 21st century, the world has continued to add the equivalent of a new Germany, or nearly 80 million people, every year to the planet's human population . And as the number of people of fertile age in the world continues to grow, there is no sign that annual additions will soon start to decline. Despite this (and changes in the climate which threaten future food supplies) rich country support for family planning has been cut in half. Robert Engelman tells the story and questions whether, under present policies, we will reach 2050 with 9 billion people - or many more.

The world's population surpassed 6.8 billion in early 2009, with no significant slowing in the pace of growth in recent years. Estimates by the United Nations Population Division indicate that humanity has been consistently gaining more than 79 million people - a population almost the size of Germany's - each year since 1999.

World population 1950-2009

During the 1990s, annual additions fell from nearly 90 million people to less than 80 million, feeding optimism that world population might peak not long after the middle of this century. But the recent stability of annual population increments adds to the uncertainty and when - and how - world population growth will end.

U.N. demographers currently offer eight variant projections for the future, with the median and most cited one placing world population slightly above 9.1 billion in 2050. Non-demographers often misinterpret this number, however, as an expert prediction or forecast of what population will be. Rather, all projections are conditional assessments based on current numbers, age structure, and trends and reasonable assumptions about the future. Thus the projections the United Nations offers produce a range of 2050 world population from slightly less than 8 billion to slightly more than 11 billion. The Washington-based Population Reference Bureau (PRB) recently released its own projections, suggesting a population at mid-century of slightly more than 9.4 billion.

The recent leveling out of annual population growth increments, which no demographer had predicted, helps illustrate that there is no way to be sure that population is "likely" or "expected" to peak at roughly 9 billion people at mid-century, or indeed at any particular time in the future.

Annual population increase 1950-2009

Regionally, more than 95 per cent of world population growth is occurring in developing countries, especially in Africa and Asia, regions that account for more than three quarters of the world's current population. Despite perceptions that population growth has stopped or reversed in most of the wealthier countries, however, growth continues in the industrial world as a whole and is likely to keep going, though at modest levels, for some time. Although the populations of Japan, Germany, Russia, and some other East European countries are already declining, U.N. demographers in their median projection do not indicate a population peak among industrial countries as a group until 2036. In the same projection, by mid-century Africa will be adding 21 million people a year to world population and Asia, 5 million.

Family planning aid falling

Today's population growth is occurring midst two important population-related trends, to which current growth rates may be related. First, global assistance for family planning services - provision of contraceptives with counseling on how to use them safely and effectively - in poor countries is falling significantly. Though it was once the main recipient in the foreign assistance category known as population and reproductive health (a category that includes maternal and child health as well as prevention of HIV and other sexually transmitted infections), aid for voluntary family planning has shrunk in recent years to a minor component. Global spending on contraceptive supplies and services totalled just $338 million in 2007, considerably less than half what it was in 1995 - despite a 20 per cent increase in the number of women and men of reproductive age in developing countries.

Ironically, donor spending on the larger category of population and reproductive health has been growing steadily in recent years, a reflection of major boosts among the largest health donors in spending to address the HIV/AIDS pandemic. In percentage terms, partly because of the growth of HIV-related spending, the provision of contraceptive services and goods fell from 55 per cent of donor spending on population and reproductive health in 1995 to just 5 per cent in 2007.

Family planning international assistance

Second, in many countries the fertility rate - the number of children that average women in a particular country have in their lifetimes - is fairly stable at levels significantly above what would be needed to end population growth.16 Both U.N. data and those of ICF Macro, a company that does demographic and health surveys for the U.S. government, show that in many countries fertility is not falling significantly - and certainly not rapidly enough to arrive at "replacement" level (between 2.1 and 3 children, depending mostly on levels of infant and child mortality) by or close to mid-century.

In some cases - in Indonesia, Ghana, and Kenya, for example - fertility appears to have stalled above replacement levels despite having fallen significantly in previous decades. This all but guarantees decades of continued population growth in these countries. In the world's wealthier countries, fertility decline has largely stopped, albeit at low levels, often well below replacement fertility.

In some cases - the United States and Spain, for example - the number of children per woman is actually increasing slightly, or at least it was when data were collected and analysed just before the global economic slowdown began. The net result of these trends, in combination with improvements in life expectancy for people living with HIV, is a human population that is growing somewhat more rapidly than demographers had expected - and that shows no clear sign of realizing any time soon the assumptions on fertility that would yield a 2050 population of 9.1 billion.

Young populations

Due to current demographic momentum stemming from the youthfulness of the world's population and large cohorts of young women entering their childbearing years, only unexpected and near-catastrophic increases in mortality rates or declines in fertility could reverse population growth before 2025 or 2030. Indeed, it is almost certain that the 7 billion mark will be reached in 2012, according to the United Nations. PRB's new World Population Data Sheet projects the world will hit that number even sooner, in the second half of 2011.

After that, the rate of population growth becomes much more uncertain. Demographers tend to assume that all populations, even those with very low incomes, will at some point in this century have fertility rates equal to or below replacement values. Yet trends in many low-income countries raise questions about this assumption.

Demographic and Health Surveys conducted for the U.S. Agency for International Development, for example, measured total fertility in Indonesia at 2.8 children per woman in 1997, at 2.6 in 2002, and at 2.6 again in 2007. In Chad, surveyed fertility was 6.4 in 1996 and 6.3 in 2004.

Since the vast majority of the world's current and projected future population growth takes place in poorer countries, stable fertility rates above replacement level raise an obvious question: What is likely to change in coming years that will produce much more rapid fertility decline in such countries? And without more rapid fertility decline, how likely are demographers' median population projections? Even among environmentalists there is little appreciation of how much demographers' projections of some 9 billion people in 2050 rely on an assumed fertility decline over the next 40 years that may not unfold.

By the same token, these projections rely on an assumption that life expectancy will continue to rise worldwide. This has indeed been a robust demographic trend not just for decades but for centuries. But suppose life expectancy were to stop rising? Climate change, for example, is predicted to have the greatest effect in tropical countries with low incomes and exposure to sea level rise.28 Bangladesh, among the most populous countries in this category, nearly quadrupled its population from 1950 to 2009, growing from an estimated 44 million to 162 million. The country is projected in the U.N. median scenario to gain an additional 80 million people by 2050 - but that assumes that neither climate change nor other types of environmental or health degradation prevent assumed improvements in life expectancy in the country.

For perspective on the importance of assumptions that death rates will continue falling (that is, that people will live longer), U.N. demographers offer a population projection that assumes such rates remain stable-neither falling nor rising-from today's levels. With the same fertility assumptions as in the medium projection, world population would reach only 8.4 billion in 2050, fully 700 million fewer people than in the commonly cited medium projection. That's twice the size of the combined populations of the United States and Canada today.

If death rates actually rise, under the median-variant fertility assumptions the 2050 population would be lower still. This results in a lower world population, but not by means any caring person would approve. If environmental and health conditions and food security deteriorate significantly in a warming and environmentally degrading world, it could become especially hard to predict when and at what level human population will stop growing - and whether lower birth rates or higher death rates play the larger role in reaching that point.

Robert Engelman is Vice President of the Worldwatch Institute. This article is taken from Worldwatch Vital Signs.

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