Week of 12/30/07

Dear EarthTalk: Green groups don't seem to discuss human population growth, but I think the biggest issue confronting the planet is the collective demand we put upon it. And what is the difference in impact between population growth in Third World countries, which are poor, against that in the U.S., where we consume and waste so much more?

—Ronald Marks, via e-mail

Human population is expected to exceed nine billion by 2050, the result an ever increasing number of poor people suffering from malnutrition, lack of clean water, overcrowding, inadequate shelter, and AIDS and other diseases. Pictured here: Living conditions today in Srinagar, Kashmir, India.
© Getty Images

The global rate of human population growth peaked around 1963, but the number of people living on Earth—and sharing finite resources like water and food—has grown by more than two-thirds since then, topping out at over 6.6 billion today. Human population is expected to exceed nine billion by 2050. Environmentalists don't dispute that many if not all of the environmental problems—from climate change to species loss to overzealous resource extraction—are either caused or exacerbated by population growth.

"Trends such as the loss of half of the planet's forests, the depletion of most of its major fisheries, and the alteration of its atmosphere and climate are closely related to the fact that human population expanded from mere millions in prehistoric times to over six billion today," says Robert Engelman of Population Action International.

According to Population Connection, population growth since 1950 is behind the clearing of 80 percent of rainforests, the loss of tens of thousands of plant and wildlife species, an increase in greenhouse gas emissions by some 400 percent and the development or commercialization of as much as half of the Earth's surface land. The group expects that half of the world's population will be exposed to "water-stress" or "water-scarce" conditions feared to "intensify difficulties in meeting
consumption levels, and wreak devastating effects on our delicately balanced ecosystems" in the coming decades.

In less developed countries, lack of access to birth control, as well as cultural traditions that encourage women to stay home and have babies, lead to rapid population growth. The result is ever increasing numbers of poor people across Africa, the Middle East, Southeast Asia, and elsewhere suffering from malnourishment, lack of clean water, overcrowding and inadequate shelter, and AIDS and other diseases.

And while population numbers in most developed nations are leveling off or diminishing today, high levels of consumption make for a huge drain on resources. Americans, who represent only four percent of world population, consume 25 percent of all resources. Industrialized countries also contribute far more to climate change, ozone depletion and overfishing than developing countries. And as more and more residents of developing countries get access to Western media, or immigrate to the U.S., they want to emulate the consumption-heavy lifestyles they see on their televisions and read about on the Internet.

Given the overlap of population growth and environmental problems, many would like to see a change in U.S. policy on global family planning. In 2001, George W. Bush instituted what some call the "global gag rule," whereby foreign organizations that provide or endorse abortions are denied funding support. Environmentalists consider that stance to be shortsighted, that support for family planning is the most effective way to check population growth and relieve pressure on the planet's environment accordingly.

CONTACTS: Population Action International; Population Connection

Dear EarthTalk: How much of an effect, if any, does the carbon dioxide in carbonated beverages have on global warming?

—Michael Holmes, Shenandoah, VA

Cans and bottles of sodas emit very little CO2 directly when opened, but the production and distribution of single-serving beverages of all kinds generate untold millions of tons of greenhouse gases and other pollutants every year, while also wasting billions of gallons of fresh water. And once the drinks have been consumed, all those cans and plastic bottles have to go somewhere.
© Getty Images

A typical 12-ounce can of soda contains up to six grams (.013 pounds) of carbon dioxide (CO2) gas, which either escapes into the atmosphere from the liquid upon opening, or from your body after you consume the contents. So yes, drinking carbonated beverages does contribute to your "carbon footprint," but only ever so slightly.

To provide some context, every time you burn a gallon of gas driving from point A to B in your car, about 20 pounds of carbon dioxide wafts skyward (if you find this hard to believe, visit the U.S. Department of Energy's fuel economy website at: www.fueleconomy.gov/feg/co2.shtml). So, extrapolating out, a typical car commute to work produces upwards of 700 times the greenhouse gases as drinking that can of Coke.

But cans and bottles of carbonated (or non-carbonated) drinks are still no friends of the environment. The production and distribution of single-serving beverages of all kinds generates untold millions of tons of greenhouse gases and other pollutants every year, while also wasting billions of gallons of fresh water. And once the drinks have been consumed, all those cans and plastic bottles have to go somewhere.

Some communities are diligent enough to capture more than half of all such containers for recycling—an activity which itself generates significant amounts of greenhouse gases—but that still means that more than 40 billion cans are ending up in landfills each year, or even worse, as litter, according to data compiled by the non-profit Container Recycling Institute (CRI).

Each un-recycled can or bottle then must be replaced by an equivalent one made from virgin materials. CRI reports that just the manufacture of these replacement aluminum cans each year generates about 3.5 million tons of greenhouse gas emissions, while also causing other environmental damage from the extraction of the bauxite from which aluminum is made. Even a larger amount of resources are used (petroleum-based in this case) and greenhouse gases emitted from the significant number of plastic single-serving drink bottles that are thrown away and not recycled each year.

Consumers can take a bite out of all this resource waste and pollution by remembering that, first and foremost, water is the least costly and healthiest beverage of all (on virtually all personal and ecological counts). And water drawn from the kitchen faucet requires no disposable packaging or shipping to get there, thanks to the highly efficient water-delivery systems that have been in place in developed countries in the vast majority of communities for a very long time.

For those who cannot get by without their soft drinks—carbonated or otherwise—the best way to lower that carbon footprint is to buy them in large containers and parse out servings in cups or glasses. A typical two-liter (67.6 ounce) plastic soda bottle holds five and a half times the liquid of a 12-ounce container and over four times that of a 16-ounce container, so it is easy to imagine the resource savings over time.

CONTACTS: Container Recycling Institute; fueleconomy.gov