Over the past year, it's become clear that the way the political and environmental communities are approaching global warming isn't going to solve it. Books by Al Gore and Tim Flannery, for example, admonish people to use less energy and reduce carbon emissions; the Kyoto Protocol calls for an emissions reduction of 5 percent below 1990 levels; and politicians around the world are mandating sizable reductions in carbon emissions by 2050. But without a plan of action that prioritizes tackling emissions from coal plants, such goals are ineffectual--and the politicians will either be in retirement homes or dead by 2050.
At 385 parts per million (ppm), the increased concentration of carbon dioxide in the air today is primarily due to the burning of fossil fuels--coal, oil, and natural gas. In "Implication of 'Peak Oil' for Atmospheric Carbon Dioxide and Climate", NASA research scientist Pushker Kharecha and I show that proven and estimated reserves of oil and gas, used at any feasible rate, would at most take atmospheric carbon dioxide levels to 450 ppm--a threshold level that, if exceeded, will cause dangerous climate change. Coal reserves, however, contain much more stored carbon, and if used in power plants without carbon capture technology, have the potential to at least double the preindustrial atmospheric carbon dioxide amount of 280 ppm.
Most of the carbon dioxide from oil and gas usage is emitted by small sources (i.e., vehicle tailpipes) where it's impractical to capture it. Nor does it seem likely that Saudi Arabia, Russia, the United States, and other major oil producers will decide to leave their oil in the ground. Therefore, the only practical way to prevent carbon dioxide levels from exceeding 450 ppm is to phase out coal power except at plants where carbon emissions are captured and stored.
An outline of a practical way to do this can be readily defined: First, establish a moratorium in developed countries on construction of new coal power plants until effective carbon-capture-and-storage technology is viable; second, establish a similar subsequent moratorium in developing countries; and third, phase out existing coal plants over the next several decades and replace them with energy sources that don't emit carbon, such as wind, solar, and nuclear power, and coal plants with carbon capture and storage. Specifically, developed countries need to stop building coal power plants that don't capture and store carbon by 2012, developing countries need to halt such construction by 2022, and all existing coal power plants without carbon capture must be bulldozed by 2050.
The 10-year delay of the coal power moratorium for developing countries is analogous to the chlorofluorocarbon (CFC) phaseout designed to combat depletion of the ozone layer throughout the 1990s, and it's justified by the primary responsibility of developed countries for the current excess of greenhouse gases in the atmosphere, as well as by the much higher per-capita emissions in developed countries. This phaseout of coal emissions would keep the maximum future atmospheric carbon dioxide level at about 450 ppm.
Adding even one new coal power plant to any national energy grid can make an important difference because of tipping points in the climate system, life systems, and social behavior.
Arctic sea-ice loss is an example of a process in the climate system that can pass a tipping point and proceed rapidly. As the warming global ocean transports more heat into the Arctic, floating sea ice melts and exposes more of the dark ocean surface, which absorbs more sunlight. The ocean stores the added heat, winter sea ice is thinner, and increased melting occurs in following summers. Sadly, based on recent observations, it appears we have already reached the Arctic sea-ice tipping point. However, the feedbacks driving further sea-ice melting aren't "runaway" feedbacks. Sea-ice loss is reversible: If human influence on the climate system is reduced, sea ice can increase rapidly.
A different tipping point in the climate system--and the most threatening--is the potential instability of large ice sheets, especially West Antarctica and Greenland. If disintegration of these ice sheets passes their tipping points, dynamical collapse could proceed out of our control. If it melts completely, West Antarctica alone contains enough water to cause about 20 feet (6 meters) of sea-level rise.
There are also tipping points in life systems. Today, as global temperature increases at a rate of about 0.2 degrees Celsius (0.36 degrees Fahrenheit) per decade, isotherms (a line of average temperature) are moving poleward at a rate of about 50-60 kilometers (35 miles) per decade. In response, some species are moving. But many move slowly, and must contend with human-made blockades in their pathways. Disrupted interdependencies among species, some less mobile than others, could lead to collapsing ecosystems and rapid, nonlinear extinctions if climate change continues unabated. Geologic records indicate that mass extinctions occurred several times in Earth's history. New species developed, but that process required hundreds of thousands, even millions of years. If we destroy a large portion of the species on Earth, it will be a far more desolate planet for as many generations of humanity as we can imagine.
On the other hand, reaching a crucial tipping point in social behavior can be positive. If the public stands up in a few places such as Marshalltown, Iowa (where a proposed coal plant with emissions of 5,900,000 tons of carbon dioxide per year and 297,000,000 tons over 50 years could be the straw that broke the camel's back) and successfully opposes the construction of coal power plants that don't include carbon capture and storage, it could also have a cascading effect, helping utilities and politicians realize that the public prefers climate solutions that respect all life on the planet.
Of course, behavioral changes will need to run much more broadly and deeply than simply blocking new coal plants. For better and worse, energy is essential to our way of life. The United States is responsible for more than three times as much of the excess carbon in the air as any other country, and it will continue to be most responsible for the human-made carbon increase for the next few decades. Although China's annual emissions have recently exceeded U.S. emissions, China's per-capita emissions are still only about one-fifth of U.S. per-capita emissions.
China and India have the most to lose from uncontrolled climate change because they have huge populations living near sea level. Conversely then, they also have the most to gain from reduced local air pollution. They must be a part of the solution to global warming, and I believe they will be if developed nations such as the United States take the appropriate first steps.
Quite simply, it makes economic sense for the United States to reduce its carbon emissions now. We will need to learn someday how to exploit the potentials in energy efficiency, renewable energy, nuclear power, and other energy sources that don't produce greenhouse gases. It's an enormous economic advantage if we learn sooner rather than later. Fossil fuels are finite, and we must learn to live without them as they dwindle. Required technology developments in clean coal, biofuels, and advanced nuclear power will produce high-tech jobs and provide a new market for international trade that could allow the United States to recover some of the wealth that it's hemorrhaging to China.
A moderate but rising price on carbon emissions is also essential to wean us off fossil fuel. Otherwise, as oil runs out, we will begin to act like a crazed addict looking for the next fix--cooking the Rocky Mountains to drip oil from tar shale or traveling to extreme environments such as the Arctic National Wildlife Refuge for oil extraction. In addition, we must improve efficiency standards on everything from buildings to vehicles to electronic devices. Regulations on utilities need to be modified so that profits grow when utilities help consumers conserve energy, rather than profits being in proportion to the amount of energy sold.
There's still time. I believe that the plausibility of taking action soon enough depends upon whether citizens become informed and place pressure on the decision-making process. It seems highly unlikely that national governments, which are strongly influenced by fossil-fuel special interests, will exercise the required leadership. Even Germany, among the "greenest" of all nations, is making plans to build coal power plants without carbon capture and storage. Clearly decision makers don't "get it." If they hope to preserve themselves and Earth, the public must become more involved. Strong, specific messages are needed. Rejection of coal power plants that don't capture carbon is such a message.
Another global atmospheric threat was solved with such an approach: When the science suggested that CFCs could potentially destroy the stratospheric ozone layer, there was an immediate moratorium on building CFC factories. Consumers played a big role in reducing demand and annual CFC production immediately stabilized.
If we don't act, the blame will fall squarely on today's adults. We can no longer feign ignorance. We've reached scientific consensus. If we allow the climate to deteriorate and life on Earth to be destroyed, we will be the generation that knew enough, but for selfish reasons declined to take timely action, building more coal power plants in the meantime. In that event, rather than the "greatest generation," how will our epitaph read?
Editor's Note: This essay was adapted from Hansen's testimony before the Iowa Utilities Board regarding a proposal from the Interstate Power and Light Company to build a new coal power plant in Marshalltown, Iowa. He testified as a private citizen.
