«DIRECT TESTIMONY OF JAMES E. HANSEN Q. Please state your name and business address. A. My name is James E. Hansen. My business address is 2880 ...»
It can be argued, as E.O. Wilson has suggested, that the world beyond the 21st century, post fossil fuel domination and post the human population peak, could have an environment that is more tolerant of all species. It is difficult to project how many of the species of creation will survive the bottleneck in the 21st century (Figure 28), but surely the number will be much smaller if the stresses include business-as-usual climate change.
Realization that we are already near ‘dangerous’ climate change, for sea level rise and other effects, has a bright side. It means that we must curtail atmospheric CO2 and other climate forcings more sharply than has generally been assumed. Thus various problems that had begun to seem almost inevitable, such as acidification of the ocean, cannot proceed much further, if we are to avoid other catastrophes. If the needed actions are taken, we may preserve most species.
Q. Are there other criteria, besides sea level and species extinction, for “danger”?
24 A. There are many regional effects of global warming. Large natural weather and climate fluctuations make it difficult to identify global warming effects, but they are beginning to emerge. If we follow business-as-usual, the southernmost parts of our country are likely to have much less tolerable climate. Fresh water shortages could become a frequent problem in parts of the country, especially those dependent on snowpack runoff, as spring comes earlier and summers are longer, hotter and drier, and forest fires will be an increasing problem. Other parts of the country, and in some cases the same places, will experience heavier rain, when it occurs, and greater floods. The tier of semi-arid states, from West Texas through the Dakotas, is subject to the same expected increase of hydrologic extremes, but overall they are likely to become drier and less suited for agriculture, if we follow business-as-usual and large global warming ensues.
Given that effects of global warming on regional climate are already beginning to emerge, the regional climate criterion also implies that further global warming much above the present level is likely to be deleterious.
Q. Is it still possible to avoid dangerous climate change?
A. It is possible, but just barely. Most climate forcings are increasing at a rate consistent with, or even more favorable (slower), than the ‘alternative scenario’ which keeps warming less than 1°C. CO2 is the one climate forcing that is increasing much more rapidly than in the alternative scenario, and if CO2 emissions continues on their current path CO2 threatens to become so dominant that it will be implausible to get the net climate forcing onto a path consistent with the alternative scenario. Furthermore, as I have discussed, there are reasons to believe that even the smaller warming of the alternative scenario may take us into the dangerous range of climate change. It is likely that we will need to aim for global warming even less than 1°C.
Q. Why are CO2 and coal the focus of climate concerns?
A. Figure 29a shows one crucial fact. When a pulse of CO2 is added to the atmosphere by burning fossil fuels, half of the CO2 disappears from the air within about 25 years, being taken up by carbon sinks, principally the ocean. However, uptake then slows as the CO2 added to the ocean exerts a ‘back pressure’ that inhibits further uptake. About one-fifth of the initial increase is still present in the atmosphere after 1000 years. Complete removal of the pulse depends upon formation of carbonate sediments on the ocean floor, a very slow process. It is this long atmospheric lifetime that makes CO2, on the long run, the principal climate forcing for humanmade climate change.
Q. Why do you focus especially on coal?
A. Part of the reason is the size of the coal carbon reservoir, shown in Figure 29b. The coal reservoir is larger than either oil or gas. The amount of CO2 already emitted to the atmosphere, shown by the purple portions of the bar graphs, is about 50% from coal, 35% from oil and 15% from gas. On the long run, coal will be even much more important.
Proven and estimated reserves of these fossil fuels are uncertain, and the amounts shown in Figure 29b for oil and coal both could be substantially over-estimated. Many experts believe that we are already at a point of having used approximately half of the economically recoverable reserves of oil. In that case we are already at approximately the point of ‘peak oil’ production and oil use will soon begin to noticeably decline because of resource constraints.
Uncertainties in the oil and gas reserves have little qualitative effect on the climate discussion, however. The reasons are, first, that remaining oil and gas, used at any feasible rate, 25 can at most only take atmospheric CO2 to approximately 450 ppm. Second, it is impractical to avoid the use of readily extractable oil and gas, and most of the CO2 resulting from that oil and gas will be emitted to the atmosphere, because it is emitted by small sources where it is impractical to capture the CO2.
Coal reserves are also uncertain and it is likely that the estimates in Figure 29b, even the smaller estimate of EIA (Energy Information Agency), are too high. Nevertheless, there is more CO2 in coal than in the other conventional fossil fuels. Indeed, there is enough CO2 in coal to take the Earth far into the ‘dangerous’ zone of climate change, to doubled atmospheric CO2 and even beyond.
The second critical fact about coal is that it is possible to imagine coal being used only at power plants to generate electricity, with the CO2 emissions captured and sequestered, with the carbon put back underground where it came from. Indeed, the elementary carbon cycle facts summarized in Figure 29 dictate the solution to the global warming problem.
Q. Can a solution to global warming be defined?
A. An outline of a practical solution can be defined readily (Figure 30). By far the most important element in this solution, indeed 80% of the solution, is phase-out of coal use except at power plants where the CO2 is captured and sequestered. This requirement is dictated by the fundamental facts of the carbon cycle summarized in Figure 29.
The steps needed to achieve termination of CO2 emissions from coal use are: (1) a moratorium in developed countries on construction of new coal-fired power plants until the technology is ready for carbon-capture and sequestration, (2) a similar subsequent moratorium in developing countries, (3) a phase-out over the next several decades of existing old-technology coal plants, with replacement by coal-fired plants that capture and sequester the CO2, energy efficiencies, renewable energies, or other sources of energy that do not emit CO2.
Figure 31 defines a specific scenario: developed countries halt construction by 2012 of any coal-fired power plants that do not capture and sequester CO2, developing countries halt such construction by 2022, and all existing coal-fired power plants without sequestration are ‘bull-dozed’ by 2050 (linear decrease of their emissions between 2025 and 2050). The 10-year delay of the moratorium for developing countries is analogous to that allowed by the Montreal Protocol in chlorofluorocarbon phase-out and it is 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.
Figure 32 shows that continued business-as-usual emission of CO2 will more than double the pre-industrial amount of CO2 (280 ppm) in the air, even though we have neglected feedbacks that would likely accompany such large emissions and we have included no emissions from unconventional fossil fuels (tar shale, tar sand, heavy oil, etc.). Figure 33 shows that this specified phase-out of coal emissions keeps the maximum future atmospheric CO2 level at about 450 ppm.
Q. Is it plausible for coal-fired power plants without carbon capture to be phased out?
A. The time scale for action used in calculations for Figures 32 and 33, with moratoriums in developed countries by 2012 and in developing countries by 2022, are conservative, our aim being to show that it is practical to keep CO2 below 450 ppm. However, because it is becoming increasingly likely that an additional 1°C global warming will cause substantial climate impacts, it is highly desirable to take action sooner.
26 I believe that the plausibility of obtaining actions in time depends upon whether citizens become informed and place pressure on the decision-making process. It seems highly unlikely that national governments, which are under the strong influence of fossil fuel special interests, will exercise the required leadership. Even Germany, among the ‘greenest’ of all nations, is making plans to build coal-fired power plants without carbon capture. Clearly decision-makers do not yet ‘get it’. The public must become more involved, if they hope to preserve creation.
Those who argue that it is implausible to ‘bulldoze’ old technology power plants, while energy efficiency and clean energy sources are expanded, might compare the task with the efforts put into World War II. It is a feasible undertaking.
Q. If coal is 80% of the solution, what is the other 20%?
A. There must be a gradually increasing price on carbon emissions. A carbon price is essential to wean us off of our fossil fuel addiction. Without such a phased withdrawal we will soon begin to exhibit the behavior of a desperate addict, attempting to squeeze carbon fuels out of unconventional or remote sources, e.g., ‘cooking’ the Rocky Mountains to drip oil out of tar shale and traveling to extreme environments such as the Arctic National Wildlife Refuge to extract every last drop of oil from the ground.
The irrationality of this behavior is apparent from the realization that fossil fuels are finite. We must learn to live without them as they dwindle. If we begin sooner, we can live with cleaner air and water, preserve creation, and pass on to our children a healthy planet with almost all of the species that we found when we arrived.
Q. A carbon price? Does that mean a tax?
A. It could be a tax, but there are various options, and it does not need to increase the amount of money extracted from citizens by the government. It might include rations that could be bought and sold, cap and trade emission quotas for industries, and other alternatives that stimulate energy and carbon efficiencies, including renewable energies and other forms of energy that do not produce greenhouse gases. This price can start small, the key requirement being certainty that it will continue to rise, because this is the stimulus that the business community needs to make the essential long-term investments. The price must promise to be large enough that it stimulates technology development, but it must not be so large or rise so rapidly that it harms the economy.
It is a truism that a strong economy is needed to afford the investments needed for a clean environment and stable climate. It is desirable to separate the decisions on altering the carbon price from short-term political considerations. One way to achieve this would be via a “Carbon Tsar”, analogous to the Chairman of the Federal Reserve, who would carefully adjust the carbon price so as to optimize economic and environmental gain.
Q. Can coal phase-out and a gradually rising carbon price solve the climate problem?
A. These would need to be accompanied by sensible actions. A gradually rising price is not sufficient for the demand reductions that will be needed to phase off the fossil fuel addiction fast enough. There need to be improved efficiency standards on buildings, vehicles, appliances, lighting, electronic devices, etc. Regulations on utilities need to be modified so that profits grow when the utilities help consumers waste less energy, rather than profits being in proportion to amount of energy sold. The government should be supporting more energy research and development, and more effectively, than it is now.
27 However, the coal phase-out and carbon price are the essential underpinnings. Without these, other actions are nearly fruitless, only yielding a modest slowing of emissions growth.
Q. But are even these enough, if we are so close to a dangerous greenhouse gas level?
A. There are additional actions that could close the gap between where we are and where we need to be to stabilize climate, even if we are slightly overshooting the dangerous level. However, these other actions can close the gap only if we get onto a path to stabilize CO2 in the near future.
Without getting onto a downward path of CO2 emissions, these other actions provide little respite.
The planet is now out of energy balance by something between 0.5 and 1 W/m2. If we reduced human-made climate forcings by that amount, the warming ‘in-the-piepline’ would be eliminated, the forcing leading to a continual warming tendency would be eliminated. Figure 35 shows that there is a large enough climate forcing in pollutant forcings, specifically, tropospheric ozone, especially its precursor methane, and black soot, to offset the present planetary energy imbalance, if we should make major reductions of these pollutants.
Some of these non-CO2 forcings are particularly effective in the Arctic (Hansen et al.
2007b), so it may even be possible to save the Arctic from further ice loss by means of special efforts to reduce these forcings, coupled with stabilization of atmospheric CO2. There are other benefits of such an effort: these pollutants are harmful to human health, being a primary cause of asthma and other respiratory and cardiovascular problems, and they reduce agricultural productivity.
Q. Even if these forcings are reduced, will not the benefits soon be erased by inevitable increases of CO2? It is said that even a 450 ppm limit on CO2 in inconceivable.
A. It is said by whom? Fossil fuel companies, and government energy departments, take it as a godgiven fact that all fossil fuels will be burned because they are there. That may almost be true for the readily mined oil and gas. However, we have shown above (see also Kharecha and Hansen