Current Controversies

By Joanna Santa Barbara and Ron Shirtliff | 2021-10-01 12:00:00

How Many People Can Earth Support? A Long-lived Controversy

(Joanna Santa Barbara)

For one side of this controversy, let’s hear from William Rees, professor emeritus of human ecology and ecological economics at the University of British Columbia, famous for his work on the Carbon footprint. There are “way too many people using vastly too much energy and material resources and dumping too much waste.” In this statement, Rees picks up the two major dimensions of the problem: the number of humans multiplied by the rate of consumption of energy and materials and production of waste. He recommends that we “(e)nact polices that lead, fairly and without coercion, to a smaller global population, such as education, access to birth control and economic independence for women. The challenge is great, given that models show about two billion people could live comfortably indefinitely within the biophysical means of nature.”

On the other side of the controversy are thinkers who pick up the consumption side of the problem. Some of them say that the Earth could support even more people (projections go up to 11 billion by the end of this century) if we collectively consumed a lot less. Having everyone eat a plant-based diet would allow the Earth to support more humans on the land available for agriculture.

This leads quickly to the point that it is the consumption of energy and materials by the global richest 10 percent that does the damage. Since most readers are in that 10 percent, it will be a relief to know that it isn’t necessary to eliminate us to enable the Earth to support its coming population, but merely that we cut our consumption drastically. So the redistribution of wealth is part of this picture.

Finally, if you were a whooping crane or Eastern Box Turtle (endangered species in Canada), how many humans would you like to have on Earth? Our arguments about this matter are almost entirely anthropocentric, with little attention to the other species we continually displace and extinguish.

The number of people on the planet is not the issue, but the number of consumers and the scale and nature of their consumption, says David Satterthwaite, a senior fellow at the International Institute for Environment and Development in London. He quotes Gandhi: “The world has enough for everyone’s need, but not enough for everyone’s greed.”

Satterthwaite goes on to say that if we look at an individual’s lifestyle, the differences between wealthy and non-wealthy are even more dramatic. There are many low-income urban dwellers whose consumption is so low that they contribute almost nothing to greenhouse gas emissions.

People living in high-income nations must play their part if the world is to sustain a large human population so a world with a human population of 11 billion might put comparatively little extra strain on our planet’s resources. But the world is changing. Low-income urban centres may not continue on low-carbon development trajectories.

The real concern would be if the people living in these areas decided to demand the lifestyles and consumption rates currently considered normal in high-income nations; something many would argue is only fair. If they do, the impact of urban population growth could be much larger.

Doctor Joanna Santa Barbara is an activist in New Zealand

Can Trees Save Us from Global Overheating?

(Ron Shirtliff)

Can we use photosynthesis to remove carbon from the atmosphere and store it in wood and soil for many years? We are pouring carbon into the air by burning coal and oil, which nature has sequestered in the Earth for millennia. Nature mostly had used trees and other vegetation in past eras to accumulate these concentrations of carbon. The plants that collected it from the air were similar to the vegetation of our modern era. Trees today are still drawing carbon dioxide and storing it in their wood, roots, and foliage.

Many, including the Intergovernmental Panel on Climate Change, have logically proposed that if the atmosphere contains too much carbon dioxide, we can use trees to absorb it. We would need an extra trillion trees to add to the three trillion currently alive. By drawing carbon dioxide out of the atmosphere and storing it in useful materials — wood, and carbon-enriched soil, we can reach net-zero carbon emissions in the near future.

Complex calculations have been made. A trillion trees would require some one billion hectares of appropriate land. A trillion extra trees could potentially capture some 205 gigatonnes of carbon and might cost some $300 billion to plant and maintain — a small price to save our planet: the amount that the world spends on the military every two months.

But, aside from the cost, planting a trillion trees is quite a challenge. Where to plant them? We would need about one billion hectares of appropriate land that is not already forested, not in agricultural use and not taken up by urban developments. The Arctic looked attractive; there is ample space there, but the area basically supports only slow-growing varieties like Black Spruce. This slow-growing tree will not capture as much carbon as quickly as trees grown in tropical areas.

And, as research has found, there is a more challenging problem. In the Arctic, snow cover reflects many of the sun’s rays, thus reducing the warming of the planet. Introducing trees can counter this albedo effect and warm the Arctic, potentially releasing quantities of methane, a potent greenhouse gas, from the permafrost.

Iain Hartley, Professor of Terrestrial Ecosystems Science at U of Exeter, thinks that reforestation of areas which have snow on the ground for significant time periods, is not useful as a method of reducing carbon in the atmosphere. Such areas tend to be warmed by the vegetation and may increase rather than decrease global warming. Does much does this rule apply to such places as Toronto, where it does snow, but everyone enjoys trees?

Yes, let’s plant more trees! But unfortunately, we must not count on them to remove much of the carbon from the atmosphere. The coal and oil we have burned in the last 200 years is the product of millions of years of photosynthesis. We have rapidly released that accumulated carbon into the in our industrial age; we cannot create enough new forests to undo that mistake in the few years we have left before our world temperature rises dangerously.

Bill Gates’ book, How to Avoid a Climate Disaster, emphasizes that it would require 50 acres of tropical forest to absorb the carbon emissions of one average American in a lifetime. At this rate, to absorb the total American carbon footprint would use up half the world’s landmass, not counting the rest of the world.

Gates thinks it’s more important to preserve the existing forests. Right! Let’s stop deforestation! And turn to page seven for another angle on this controversy.

Ron Shirtliff is a retired Professor of English at Ryerson University.