A COMPELLING WAY OF VIEWING human progress, of equal appeal to those with roots in 19th century liberalism and those inclined to Marx's "scientific" socialism, is to see it as a triumphal march toward a purely hydrogen energy economy--or, if you prefer, a carbon-free economy. This is just how a collection of scholars looked at the world when they were assembled a few years ago by the American Academy of Arts and Sciences to produce a special issue of Daedalus magazine on the global environment.
Setting the stage for the special issue, its editor Jesse Ausubel, director of the program for the human environment at Rockefeller University in New York City, reminded readers that it is the conversion of hydrogen in hydrocarbon fuels that accounts for most of their energy yield. Since hydrogen produces about four times as much energy per quantity H oxidized as per unit C, wrote Ausubel, "Wood weighs in heavily [with] ten effective Cs for each H. Coal approaches parity with one or two Cs per H, while oil improves to two H per C, and a molecule of natural gas (methane) is a carbon-trim CH 4 ."
From this perspective, in a utopian carbon-free future, all energy might come from some combination of fission, fusion, and fuel cells. And nowadays, the advanced industrial economies, relying mainly on natural gas, can be seen as traversing their carbon-trim phase on the way to that goal. But countries like China and India are struggling at a stage in some ways akin to the worst and least efficient phases of Europe's Industrial Revolution, two centuries back. To a remarkable extent, the peasants and farmers who make up most of their huge populations rely on biomass (woody matter, dung, and crop residues) for their fuel, while their modernizing industrial sectors run on coal.
Almost entirely because of that dependence on coal and biomass, China and India together contribute nearly one-fifth of the carbon dioxide the human race pumps into the atmosphere yearly. And since CO 2 is by far the most important greenhouse gas thought to be warming the world, China and India already are a major ingredient in climate-change scenarios. If China continues to grow at the remarkable rates registered since 1980, it will surpass the United States as the leading source of CO 2 emissions by the middle of the next century. And should India enter into a similar take-off phase of breakneck economic growth, it will not be far behind.
So, if countries like the United States want to mitigate risks of climate change, after cleaning up for themselves and getting their own houses in order, the next-best thing they can do is help China and India do the same.
This, then, is the subject of IEEE Spectrum 's special report: what can China and India realistically hope to do in the next two or three decades to reduce reliance on coal and get on the road to decarbonization, whether by burning coal more cleanly and efficiently or by adopting alternative energy technologies? And what can the advanced industrial countries do to help?
Why should anyone care?
After water, the carbon released in the production and use of energy is the largest mass flow connected with human activity. Annual carbon emissions are estimated at 6 billion tons, or roughly 1 ton per person on earth. To be sure, the ratio of carbon used to energy produced has improved by 40 percent since the middle of the last century, representing an average decline of about 0.3 percent per year. But because of both economic and demographic growth, the total amount of carbon emitted into the atmosphere has gone on increasing and at present rates would roughly double in the next 40 or 50 years.
Why should this matter? Surely the relationship between carbon dioxide emissions and climate is highly speculative? Aren't the temperature records and climate models on which projections are based full of ambiguities and holes? For every scientist who thinks people are making the world warmer, is there not another who believes the opposite?
The short answer to all those questions is No. Scientists who flatly disbelieve human activity is warming the world are a tiny minority among those studying the subject. The link between changes in levels of greenhouse gases (GHG) and climate change is firmly established. And temperature records and climate models are becoming more precise with every passing year.
In 1995, the Intergovernmental Panel on Climate Change (IPCC) reported for the first time that a human fingerprint could be detected in the world's persistent warming trend. The IPCC is a global network of scientists set up under United Nations auspices in 1988 to provide authoritative assessments of knowledge as it evolves. The panel concluded that "the balance of evidence suggests a discernible human influence on global climate."
Since 1995, the evidence has mounted that the world is heating up alarmingly, and that such changes in the world's climate correlate closely with concentrations of carbon dioxide in the atmosphere. Accelerated melting of glaciers and ice sheets in the Arctic, Greenland, and Antarctica, changes in wildlife habitats reported from many parts of the earth, weather irregularities consistent with predictions from the best climate models--all this and more are omens of difficulties to come. Hanging in the balance: patterns of agricultural productivity, sea levels and coastal economic systems, forests, and species.