An article in the November 1 issue of Science sets out the challenges. Entitled “Advanced Technology Paths to Global Climate Stability: Energy for a Greenhouse Planet,” it was written by a team of 18 scientists and engineers from major universities (including McGill), U.S. government laboratories and agencies, and even Exxon Mobil. The U.S. Department of Energy funded the project.

The level of carbon dioxide in the atmosphere has increased from 275 to 370 parts per million in the past century. Unchecked, it will pass 550 parts per million this century. Climate models and the study of past climate changes indicate that that could warm Earth’s climate as much as it cooled during the last Ice Age. Stabilizing the level of CO2 lower than that will require “Herculean efforts,” the authors conclude.

The world today requires 12 terawatts (12 trillion watts) of power generating capacity, of which 85 percent is fossil-fueled. Power requirements continue to soar as the world’s economy continues to grow. Stabilizing the level of CO2 in the atmosphere by mid-century while permitting the current level of economic growth will require 30 terawatts of carbon-free power production, the study estimates–and we don’t have the technology to achieve that.

Possible sources of carbon-free power include hydrogen, biomass, solar thermal and photovoltaic, wind, hydropower, ocean thermal, geothermal and tidal.

Hydrogen sounds good, but doesn’t exist in geological reservoirs, which means it is usually extracted from hydrocarbons–and per unit of heat generated, more CO2 is produced by making hydrogen from fossil fuel than by burning the fossil fuel directly.

The other sources mentioned currently provide less than one percent of the world’s power, and all suffer from the same problem: low power production per area. For example, producing 10 terawatts of energy using biomass would require more than 10 percent of the Earth’s surface, roughly equivalent to the area covered by all of human agriculture, and a solar array that could produce 10 terawatts would cover a square 470 kilometres on a side. (All the photovoltaic cells shipped from 1982 to 1998 would cover a square only three kilometers on a side.)

Even if we could scale up solar arrays and windmill farms to meet our needs, existing power grids, designed for centralized power plants, couldn’t manage the loads. So another challenge we face this century may be the complete reengineering of our electrical distribution systems.

Another way to harness solar energy is the space solar power satellite, a huge solar array in space that transmits power to Earth by microwave. But getting 10 terawatts of power to Earth by this method would require 660 orbiting solar arrays, each the size of the island of Manhattan. Launch costs, note the study’s authors with admirable understatement, are likely to be “high.”

What about nuclear power? Well, fission, our current method of nuclear energy generation, not only creates radioactive waste and lends itself to the proliferation of nuclear weapons, it’s based on a non-renewable resource, uranium. Meeting the mid-century power needs using fission, the study’s authors estimate, would use up the world’s known reserves in just six to 30 years.

The best hope for a long-term energy solution remains fusion. Fission releases energy through by splitting a large atom (that of uranium); fusion, which powers the sun, releases energy by fusing two small atoms (of forms of hydrogen) together. Fusion powers the sun. Current research has brought fusion power close to the break-even point, at which the amount of energy produced by the fusion reaction is equal to the amount of energy required to bring about the fusion reaction. But fusion power plants are still years away.

The study’s authors believe a massive Apollo-style research and development program will be required to ready new power sources for the world in time to stabilize the CO2 levels in the atmosphere at a reasonable level…and time’s a-wasting.

“Combating global warming by radical restructuring of the global energy system could be the technology challenge of the century,” the authors conclude. “…Stabilizing climate is not easy. At the very least, it requires political will, targeted research and development and international cooperation. Most of all, it requires the recognition that…the fossil fuel greenhouse effect is an energy problem that cannot be simply regulated away.”

Primitive, industrial-revolution technology has gotten us into this mess; it will take advanced, futuristic technology to get us out.

The term “greenhouse effect,” as usually used today, refers to the predicted gradual warming of the Earth due to an increase in various gases in the atmosphere, primarily due to man’s activities. There is considerable debate as to just how serious this warming is going to be–and whether it has begun yet. (Despite the warmth of the ’80s in our part of the world, the most recent and most accurate study of the Earth’s temperature, carried out by satellites over the last decade, shows no evidence of global warming or cooling.)

However, in a broader sense the greenhouse effect has been at work for eons, which is a good thing, because if it hadn’t been, we probably wouldn’t be here. That’s because the greenhouse effect is what keeps the mean surface temperature high enough (currently it’s 17 degrees) for life to thrive.

About 40 percent of the energy we receive from the sun is shortwave radiation, to which the atmosphere is transparent. This radiation warms the ground, which radiates heat back at a much longer wavelength. Most gases are transparent to this longer-wavelength radiation, but not all. The so-called greenhouse gases, especially carbon dioxide (though others are also involved), absorb it, instead–and heat up, warming the other gases in the atmosphere at the same time.

The amount of carbon dioxide in the air and the mean surface temperature are far from carved in stone. The surface temperature has, in the past, been both so much colder that much of the planet was covered with ice, and so much warmer that even near the poles sub-tropical flora and fauna flourished.

However, the current increase in carbon dioxide is quite rapid, and due almost entirely to human activities, especially the burning of fossil fuels. It’s estimated carbon dioxide levels are 25 percent higher now than they were in 1860. Some scientists predict that by 2050 this increase in carbon dioxide could boost global mean temperatures from two to five degrees.

Considering Saskatchewan winters, that doesn’t sound so bad. But look at some of the possible consequences: shifting weather patterns could bring drought to once-fertile areas (like Saskatchewan?) and heavy rains to fragile deserts; run-off from melting glaciers and the expansion of warming seawater could raise sea levels six feet, inundating low-lying coastal areas and islands; hurricanes could increase in frequency and severity.

Probably some parts of the globe would actually benefit, but the atmosphere is so incredibly complex that there is no way of predicting the precise effect on any area–just as no one can accurately predict the weather more than a few days in advance.

This should mean that all countries have an equal stake in dealing with the problem. While it is generally conceded it is impossible to halt the greenhouse effect, it can be slowed, “simply” by cutting fossil fuel usage.

Of course, that’s not really simple at all. Developed countries such as our own aren’t anxious to give up the comforts and conveniences purchased with high energy usage, and less-developed countries are understandably unhappy with suggestions that they should not be allowed to follow the same industrialized route to prosperity as the developed nations.

Still, there are steps to be taken. Energy conservation techniques such as were all the rage during the 1970s’ energy crisis should be continued and expanded. Just because oil is currently cheap is no reason to burn it profligately. To do so could be costing us a lot more than just a few dollars.

On a broader scale, countries must develop energy sources other than coal and oil. Natural gas, for example, produces half as much carbon dioxide per unit of energy as coal, and solar power, wind power, geothermal power and nuclear power, though they have their own problems, produce no greenhouse gases at all.

Some scientists are already thinking of more direct methods of attacking the problem–and before dismissing them as wildly farfetched and hopelessly expensive, consider the cost of building coastal walls to keep out the rising ocean.

Plant more forests, says George Woodwell, director of the Woods Hole Research Center in Massachusetts. About 1.86 million square kilometres of new forest (4.5 times the area of California) would take care of a third of the carbon dioxide problem (assuming we stop cutting down the forests we already have).

Spread phosphates in the ocean, or use large orbiting reflectors to beam extra sunlight into the polar seas, to promote blooms of phytoplankton, suggests climatologist Roger Revelle of the University of California in San Diego. Phytoplankton use carbon dioxide in photosynthesis, then when they die take it with them to the ocean floor, where it remains for centuries.

Volcanos cool the earth by spewing sulfur dioxide, notes Wallace Broecker, a geochemist at Columbia University; we could load the upper atmosphere with sulfur dioxide, using a fleet of 700 jumbo jets working around the clock for year after year after year. (Aside from the logistical problems, this has one other slight disadvantage: sulfur dioxide promotes acid rain.)

There are other suggestions: painting every roof on every building on Earth white to reflect more sunlight, for example, or building giant orbiting parasols (10 million square kiometres’ worth) to block out the sun, or…

Or maybe we should just look harder for alternatives to fossil fuels and use less of them in the meantime.

Sounds a lot simpler, doesn’t it?