Whatever results, or lack thereof, flow from the Copenhagen conference on climate change, taxpayers have a right to know: What works best in reducing greenhouse-gas emissions that cause global warming?
After all, a lot of money can be thrown away chasing measures and policies that either won't work or be cost-effective.
One of the very best attempts at measuring effectiveness and cost comes from McKinsey & Co., an international consulting firm that has produced a cost-abatement curve comparing different technologies used today or likely to be ready in the next two decades.
Mixing cost and effectiveness, and choosing approaches that won't materially affect consumers' lifestyles, McKinsey offers a rough guide to how the world might hold the rise in global mean temperatures to below 2 degrees Celsius. Obviously, different measures will be more appropriate for some countries than for others.
At one end of McKinsey's curve comparing the costs of a one-tonne reduction are inexpensive measures, with long-term payback. These include the simplest changes, such as switching incandescent light bulbs to LED ones, improving energy efficiency of appliances and electronics, making more energy-efficient cars and retrofitting buildings with improved insulation. Waste recycling and producing electricity from landfill gases (methane, in particular) are very useful; biofuels from corn (ethanol) is much less so.
Governments in developed countries, including Canada, are already pursuing these policies, because they are cheap and cost-effective over time (except for ethanol, which is more an agricultural subsidy program than a cost-effective response to climate change). These measures also don't rile up consumers and taxpayers.
The much bigger climate-change winners on the McKinsey curve are also the more expensive ones. The five biggest winners in terms of greenhouse-emissions abatement are nuclear power, wind power, solar power, converting pasture land to forest (since trees soak up carbon dioxide) and stopping deforestation. These approaches cost more than light bulb changes and insulation, but they are much more effective in reducing carbon.
At the far end of the McKinsey curve - expensive per tonne reductions - is an approach favoured by Alberta, Canada's largest provincial per capita emitter.
There, the government has set aside $2-billion for carbon sequestration - capturing carbon and burying it. The McKinsey study says, yes, retrofitting coal-fired plants with carbon capture and storage or building new ones with that technology definitely removes carbon but at a high price per tonne.
You can see this in Alberta's first efforts. More than half of the $2-billion has been pledged to two projects that, if they work, will remove only 2.1 million tonnes of carbon, a tiny fraction of Alberta's total emissions.
At this rate of spending, the $2-billion might remove less than 5 per cent of the province's emissions based on Alberta's total emissions today. Of course, when emissions rise as tar sands production grows, so the carbon capture contributions will shrink as a share of the whole.
Carbon sequestration, then, is part of the global attack on climate change, but it's among the least cost-effective measures, based on today's technologies.
McKinsey does not mince words in saying that achieving reductions to keep temperatures from rising beyond 2 degrees will require change on a "huge scale."
Four broad regulations are indispensable: improving energy efficiency standards, providing incentives for emerging technologies, linking agriculture and forestry practices to carbon capture, and pricing carbon.
The hardest measure for politicians is pricing carbon, because it is so politically tricky. Without establishing a price that rises over time, inducing people to switch fuels and products and change lifestyles, no successful attack on greenhouse emissions is possible.
In Canada, most politicians initially shuddered at the politics of carbon pricing. The Liberals under Stéphane Dion put forward a carbon tax as a way of pricing carbon, and were destroyed by the Conservatives' attack machine in the last election.
Now the Conservatives are talking about establishing a cap-and-trade system for carbon emission permits as a way of pricing carbon. But they have delayed everything while waiting for the United States to draft its own carbon legislation.
Ironically, the head of Exxon Mobil has said he prefers a tax to cap-and-trade, as do many of the leaders of Canada's petroleum industry, although they are too politically scared to say so publicly for fear of alienating their friends in the Alberta and Harper governments.