U42A-01 INVITED
Implications of 'Peak Oil' for Atmospheric CO2 and Climate
Unconstrained CO2 emission from fossil fuel burning has been the dominant cause of observed anthropogenic global warming. The amounts of "proven" and potential fossil fuel reserves are uncertain and debated. Regardless of the true values, society has flexibility in the degree to which it chooses to exploit these reserves, especially unconventional fossil fuels and those located in extreme or pristine environments. If conventional oil production peaks within the next few decades, it may have a large effect on future atmospheric CO2 and climate change, depending upon subsequent energy choices. Assuming that proven oil and gas reserves do not greatly exceed estimates of the Energy Information Administration -- and recent trends are toward lower estimates -- we show that it is feasible to keep atmospheric CO2 from exceeding about 450 ppm by 2100, provided that emissions from coal, unconventional fossil fuels, and land use are constrained. Coal-fired facilities without sequestration must be phased out before midcentury to achieve this CO2 limit. It is also important to "stretch" conventional oil reserves via energy conservation and efficiency, thus averting strong pressures to extract liquid fuels from coal or unconventional fossil fuels while clean technologies are being developed for the era "beyond fossil fuels". We argue that a rising price on carbon emissions is needed to discourage conversion of the vast fossil resources into usable reserves, and to keep CO2 below 450 ppm. It is also plausible that CO2 can be returned below 350 ppm by 2100 or sooner, if more aggressive mitigation measures are enacted, most notably a phase-out of global coal emissions by circa 2030 and large- scale reforestation, primarily in the tropics but also in temperate regions.
U42A-02 INVITED
Will peak oil accelerate carbon dioxide emissions?
The relative scarcity of oil suggests that oil production is peaking and will decline thereafter. Some have suggested that this represents an opportunity to reduce carbon dioxide emissions. However, in the absence of constraints on carbon dioxide emission, "peak oil" may drive a shift towards increased reliance on coal as a primary energy source. Because coal per unit energy, in the absence of carbon capture and disposal, releases more carbon dioxide to the atmosphere than oil, "peak oil" may lead to an acceleration of carbon dioxide emissions. We will never run out of oil. As oil becomes increasingly scarce, prices will rise and therefore consumption will diminish. As prices rise, other primary energy sources will become increasingly competitive with oil. The developed world uses oil primarily as a source of transportation fuels. The developing world uses oil primarily for heat and power, but the trend is towards increasing reliance on oil for transportation. Liquid fuels, including petroleum derivatives such as gasoline and diesel fuel, are attractive as transportation fuels because of their relative abundance of energy per unit mass and volume. Such considerations are especially important for the air transport industry. Today, there is little that can compete with petroleum-derived transportation fuels. Future CO2 emissions from the transportation sector largely depend on what replaces oil as a source of fuel. Some have suggested that biomass-derived ethanol, hydrogen, or electricity could play this role. Each of these potential substitutes has its own drawbacks (e.g., low power density per unit area in the case of biomass, low power density per unit volume in the case of hydrogen, and low power density per unit mass in the case of battery storage). Thus, it is entirely likely that liquefaction of coal could become the primary means by which transportation fuels are produced. Since the burning of coal produces more CO2 per unit energy than does the burning of oil, this could lead to an increase in CO2 emissions and an increase in the rate of global warming. If high prices are placed on carbon emissions and/or innovations in the energy and transportation technology sectors result in carbon- neutral transportation fuels that can compete with coal liquefaction, this could help to diminish future CO2 emissions, but it is hard to see how peak oil, amid the abundance of coal, could lead to diminished CO2 emissions. Thus, "peak oil" presents a new challenge to efforts to diminish CO2 emissions.
U42A-03 INVITED
Oil Dependence, Climate Change and Energy Security: Will Constraints on Oil Shape our Climate Future or Vice Versa?
Threats to US and global energy security take several forms. First, the overwhelming dependence on oil in the transport sector leaves the US economy (and others) vulnerable to supply shocks and price volatility. Secondly, the global dependence on oil inflates prices and enhances the transfer of wealth to authoritarian regimes. Finally, the global reliance on fossil fuels more generally jeopardizes the stability of the climate system. These three threats - economic, strategic and environmental - can only be mitigated through a gradual substitution away from fossil fuels (both coal and oil) on a global scale. Such large-scale substitution could occur in response to potential resource constraints or in response to coordinated government policies in which these externalities are explicitly internalized. Here, I make use of a well-known integrated assessment model (MERGE) to examine both possibilities. When resource limits are considered alone, global fuel use tends to shift toward even more carbon-intensive resources, like oil shale or liquids derived from coal. On the other hand, when explicit carbon constraints are imposed, the fuel sector response is more complex. Generally, less stringent climate targets can be satisfied entirely through reductions in global coal consumption, while more stringent targets require simultaneous reductions in both coal and oil consumption. Taken together, these model results suggest that resource constraints alone will only exacerbate the climate problem, while a subset of policy-driven carbon constraints may yield tangible security benefits (in the form of reduced global oil consumption) in addition to the intended environmental outcome.
U42A-04 INVITED
Hubbert's Peak, The Coal Question, and Climate Change
The United Nations Intergovernmental Panel on Climate Change (IPCC) makes projections in terms of
scenarios that include estimates of oil, gas, and coal production. These scenarios are defined in the Special
Report on Emissions Scenarios or SRES (Nakicenovic et al., 2000). It is striking how different these
scenarios are. For example, total oil production from 2005 to 2100 in the scenarios varies by 5:1 (Appendix
SRES Version 1.1). Because production in some of the scenarios has not peaked by 2100, this ratio would
be comparable to 10:1 if the years after 2100 were considered. The IPCC says "... the resultant 40 SRES
scenarios together encompass the current range of uncertainties of future GHG [greenhouse gas] emissions
arising from different characteristics of these models ..." (Nakicenovic et al., 2000, Summary for Policy
Makers). This uncertainty is important for climate modeling, because it is larger than the likely range for the
temperature sensitivity, which the IPCC gives as 2.3:1 (Gerard Meehl et al., 2007, the Fourth Assessment
Report, Chapter 10, Global Climate Projections, p. 799).
The uncertainty indicates that we could improve climate modeling if we could make a better estimate of future
oil, gas, and coal production. We start by considering the two major fossil-fuel regions with substantial
exhaustion, US oil and British coal. It turns out that simple normal and logistic curve fits to the cumulative
production for these regions give quite stable projections for the ultimate production. By ultimate production,
we mean total production, past and future. For US oil, the range for the fits for the ultimate is 1.15:1 (225-
258 billion barrels) for the period starting in 1956, when King Hubbert made his prediction of the peak year of
US oil production. For UK coal, the range is 1.26:1 for the period starting in 1905, at the time of a Royal
Commission on coal supplies. We extend this approach to find fits for world oil and gas production, and by a
regional analysis, for world coal production. For world oil and gas production, the fit for the ultimate is
640Gtoe (billion metric tons of oil equivalent). This is somewhat larger than the sum of cumulative production
and reserves, 580Gtoe. Because future discoveries are not included in the reserves, it is to be expected
that our fit would be larger. On the other hand, there have been large increases in OPEC reserves that have
not been subject to outside audit, so it is not clear how close the two numbers should be. For world coal, the
sum of the fits for regional ultimate production is 660Gt (billion metric tons). This is considerably less than
the sum of cumulative production and reserves, 1,100Gt, but it is consistent with the British experience,
where until recently, reserves were a large multiple of future production.
The projection is that we will have consumed half of the ultimate world oil, gas, and coal production by 2019.
This means that the current intense development of alternative sources of energy can be justified
independently of climate considerations. When these projections are converted to carbon equivalents, the
projected future emissions from burning oil, gas, and coal from 2005 on are 520GtC. The projected
emissions for the 2005-2100 period are smaller than for any of the 40 SRES scenarios. This suggests that
future scenarios should take exhaustion into account. These projections, if correct, are good news for climate
change.
http://rutledge.caltech.edu
U42A-05
Emissions Scenarios and Fossil-fuel Peaking
Intergovernmental Panel on Climate Change (IPCC) emissions scenarios are based on detailed energy system models in which demographics, technology and economics are used to generate projections of future world energy consumption, and therefore, of greenhouse gas emissions. Built into the assumptions for these scenarios are estimates for ultimately recoverable resources of various fossil fuels. There is a growing chorus of critics who believe that the true extent of recoverable fossil resources is much smaller than the amounts taken as a baseline for the IPCC scenarios. In a climate optimist camp are those who contend that "peak oil" will lead to a switch to renewable energy sources, while others point out that high prices for oil caused by supply limitations could very well lead to a transition to liquid fuels that actually increase total carbon emissions. We examine a third scenario in which high energy prices, which are correlated with increasing infrastructure, exploration and development costs, conspire to limit the potential for making a switch to coal or natural gas for liquid fuels. In addition, the same increasing costs limit the potential for expansion of tar sand and shale oil recovery. In our qualitative model of the energy system, backed by data from short- and medium-term trends, we have a useful way to gain a sense of potential carbon emission bounds. A bound for 21st century emissions is investigated based on two assumptions: first, that extractable fossil-fuel resources follow the trends assumed by "peak oil" adherents, and second, that little is done in the way of climate mitigation policies. If resources, and perhaps more importantly, extraction rates, of fossil fuels are limited compared to assumptions in the emissions scenarios, a situation can arise in which emissions are supply-driven. However, we show that even in this "peak fossil-fuel" limit, carbon emissions are high enough to surpass 550 ppm or 2°C climate protection guardrails. Some indicators are presented that the scenario presented here should not be disregarded, and comparisons are made to the outputs of emission scenarios used for the IPCC reports.