Population trends: Another influence on climate change

Population change: Another influence on climate change
This is an urbanization map of the U.S., derived from city lights data. Legened: urban = red, peri-urban = yellow. Credit: NASA

Changes in population growth and composition, including aging and urbanization, could significantly affect global emissions of carbon dioxide over the next 40 years, according to a new study out next week.

The research, appearing in (PNAS), was conducted by an international team of scientists from the National Center for Atmospheric Research (NCAR), the International Institute for Applied Systems Analysis (IIASA), and the National Oceanographic and Atmospheric Administration. It was funded by a European Young Investigator's Award, the Hewlett Foundation, and the National Science Foundation, which is NCAR's sponsor.

By mid-century it is estimated that global population could rise by more than three billion people, with most of that increase occurring in urban areas. The study showed that a slowing of , following one of the slower growth paths considered plausible by demographers at the United Nations, could contribute to significantly reducing . The researchers found that such slow growth paths by 2050 could account for 16 to 29 percent of the emissions reductions thought necessary to keep from causing serious impacts. The effect of slower population growth on greenhouse gas emissions would be even larger by the end of the century.

"If global population growth slows down, it is not going to solve the climate problem, but it can make a contribution, especially in the long term," says the study's lead author, Brian O'Neill, an NCAR scientist.

O'Neill's co-author, IIASA scientist Shonali Pachauri, says that slower population growth will have different influences, depending on where it occurs.

Population change: Another influence on climate change
This is a map of the night-time city lights of the world, growing in extent each year. Credit: NASA
"A slowing of population growth in developing countries today will have a large impact on future global population size. However, slower population growth in developed countries will matter to emissions, too, because of higher per capita energy use," says Pachauri.

Scientists have long known that changes in population will have some effect on greenhouse gas emissions, but there has been debate on how large that effect might be.

Urbanization and aging

The researchers sought to quantify how demographic changes influence emissions over time, and in which regions of the world. They also went beyond changes in to examine the links between aging, urbanization, and emissions.

The team found that growth in urban populations could lead to as much as a 25 percent rise in projected carbon dioxide emissions in some developing countries. The increased economic growth associated with city dwellers was directly correlated with increased emissions, largely due to the higher productivity and consumption preferences of an urban labor force.

In contrast, aging can reduce emissions levels by up to 20 percent in some industrialized countries. This is because older populations are associated with lower labor force participation, and the resulting lower productivity leads to lower economic growth.

"Demography will matter to greenhouse gas emissions over the next 40 years," says O'Neill. "Urbanization will be particularly important in many developing countries, especially China and India, and aging will be important in industrialized countries."

The researchers worked with projections showing that population aging will occur in all regions of the world, a result of people living longer and declines in fertility.

Future scenarios of human behavior

The authors developed a set of economic growth, energy use, and emissions scenarios, using a new computer model (the Population-Environment-Technology model, or PET). To capture the effects of future demographic change, they distinguished between household types, looking at age, size, and urban vs. rural location.

In addition, they drew on data from national surveys covering 34 countries and representative of 61 percent of the global population to estimate key economic characteristics of household types over time, including labor supply and demand for consumer goods.

"Households can affect emissions either directly, through their consumption patterns, or indirectly, through their effects on economic growth," O'Neill explains.

The authors also suggest that developers of future emissions scenarios give greater consideration to the implications of urbanization and aging, particularly in the United States, European Union, China, and India.

"Further analysis of these trends would improve our understanding of the potential range of future energy demand and emissions," says O'Neill.

The researchers caution that their findings do not imply that policies affecting aging or urbanization should be implemented as a response to climate change, but rather that better understanding of these trends would help anticipate future changes.


Explore further

Alarming acceleration in CO2 emissions worldwide

Provided by National Center for Atmospheric Research
Citation: Population trends: Another influence on climate change (2010, October 11) retrieved 21 May 2019 from https://phys.org/news/2010-10-population-trends-climate.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
0 shares

Feedback to editors

User comments

Oct 11, 2010
Do these charlatans believe all human life is going to surrender their entire existence to this green scam?

How eager will the free societies of the West be to hand over their liberties and constitutions to some pseudo-scientific global dictatorship?

How much more eager will the Asian and Indian societies be to surrender their new found wealth and independence to these very same creatures?

I say the real "Deniers" are those who deny the nature of human life to free itself from bondage, and the tendency of free nations to overcome and destroy tyrants and usurpers.

If they think they will be able to smuggle their half-formed totalitarian ideology into our societies and reign from afar they are sadly, miserably deluded.

Those who seek to rule as tyrant kings over the new age will find an uncomfortable truth as they slink away in the shadows from their subjects - There is no place to hide, and there is no protection from the weapons we bear.

Oct 11, 2010
This is NOT SCIENCE. GET IT OFF. This is propaganda for POPULATION CONTROL, also known as Eugenics, as practiced by Adolf Hitler, and his friend Margaret Sanger (who later renamed her Population Control organization to a more friendly name: Planned Parenthood).

There is NO THREAT to climate due to population, not humans (in the minority) or other animals (by far in the majority and with far greater protection).

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more