- Al Gore, accepting an Oscar for "An Inconvenient Truth"

Global warming has gone Hollywood, literally and figuratively. The script is plain. As Gore says, solutions are at hand. We can switch to renewable fuels and embrace energy-saving technologies, once the dark forces of doubt are defeated. It's smart and caring people against the stupid and selfish. Sooner or later, Americans will discover that this Hollywood version of global warming (largely mirrored in the media) is mostly make-believe.

Most of the many reports on global warming have a different plot. Despite variations, these studies reach similar conclusions. Regardless of how serious the threat, the available technologies promise at best a holding action against greenhouse gas emissions. Even massive gains in renewables (solar, wind, biomass) and more efficient vehicles and appliances would merely stabilize annual emissions near present levels by 2050. The reason: Economic growth, especially in poor countries, will sharply increase energy use and emissions.

The latest report came last week from 12 scientists, engineers and social scientists at the Massachusetts Institute of Technology. The report, " The Future of Coal," was mostly ignored by the media. It makes some admittedly optimistic assumptions: "carbon capture and storage" technologies prove commercially feasible; governments around the world adopt a sizable charge (a.k.a. tax) on carbon fuel emissions. Still, annual greenhouse gas emissions in 2050 are roughly at today's levels. Without action, they'd be more than twice as high.

Coal, as the report notes, is essential. It provides about 40 percent of global electricity. It's cheap (about a third of the cost of oil) and abundant. It poses no security threats. Especially in poor countries, coal use is expanding dramatically. The United States has the equivalent of more than 500 coal-fired power plants with a capacity of 500 megawatts each. China is building two such plants a week. Coal use in poor countries is projected to double by 2030 and would be about twice that of rich countries (mainly the United States, Europe and Japan). Unfortunately, coal also generates almost 40 percent of man-made carbon dioxide (CO2), a prime greenhouse gas.

Unless we can replace coal or neutralize its CO2emissions, curbing greenhouse gases is probably impossible. Substitution seems unlikely, simply because coal use is so massive. Consider a separate study by Wood Mackenzie, a consulting firm. It simulated a fivefold increase in U.S. electricity from renewables by 2026. Despite that, more coal generating capacity would be needed to satisfy growth in demand.

Carbon capture and storage (CCS) is a bright spot: Catch the CO2and put it underground. On this, the MIT study is mildly optimistic. The technologies exist, it says. Similarly, geologic formations - depleted oil fields, unusable coal seams - provide adequate storage space, at least in the United States. But two problems loom: First, capture and storage adds to power costs; and second, its practicality remains suspect until it's demonstrated on a large scale.

No amount of political will can erase these problems. If we want poorer countries to adopt CCS, then the economics will have to be attractive. Right now, they're not. Capturing CO2and transporting it to storage spaces uses energy and requires costlier plants. On the basis of present studies, the MIT report says that the most attractive plants with CCS would produce almost 20 percent less electricity than conventional plants and could cost almost 40 percent more. Pay more, get less - that's not a compelling argument. Moreover, older plants can't easily be retrofitted. Some lack space for additions; for others costs would be prohibitive.

To find cheaper technologies, the MIT study proposes more government research and development. The study's proposal of a stiff charge on carbon fuel - to be increased 4 percent annually - is intended to promote energy efficiency and create a price umbrella to make CCS more economically viable. But there are no instant solutions, and a political dilemma dogs most possibilities. What's most popular and acceptable (say, more solar) may be the least consequential in its effects; and what's most consequential in its effects (a hefty energy tax) may be the least popular and acceptable.

The actual politics of global warming defies Hollywood's stereotypes. It's not saints vs. sinners. The lifestyles that produce greenhouse gases are deeply ingrained in modern economies and societies. Without major changes in technology, the consequences may be unalterable. Those who believe that addressing global warming is a moral imperative face an equivalent moral imperative to be candid about the costs, difficulties and uncertainties.