Scientific and Institutional Considerations for the Monitoring and Management of Planet Earth
Planet Earth is bounded and finite. The Earth system is comprised of a set of subsystems whose interactions are complex; a significant number of those subsystems are now dominated by human forcing. Many Earth subsystems have timescales that are long compared to current decision-making infrastructures. If we are to maintain or improve the aggregate quality of human life on our home planet, then we must at least attempt to place bounds on possible futures of the Earth system, and come to at least first order understanding of our management options. These efforts in turn can illuminate priorities for allocating our knowledge production resources and can guide the development and deployment of new Earth management technologies. The current state and future states of the Earth system can be thought of as a position in some state space that is defined by a vector whose components are a set of proxies for the states of Earth subsystems. Such proxies might include the NINO3 SST, the variance by country of per capita GDP, amphibian counts in the Sierra Nevada etc. The characteristics of these proxies include that they are reasonably easy to sample, that they capture deep information about how Earth is functioning at the time of sampling, and that they also include some information about how we might expect the Earth system to evolve in the near- to intermediate future. Just as the invention of coal burning altered Earth's trajectory through this state space, we should anticipate similar potential for technologies that are now in development. The Earth sciences, in partnership with other sciences and policy makers, will be called upon to characterize Earth sub-systems and their interactions. Advancement in systems modeling, uncertainty and risk, and efficient monitoring systems are essential elements of an Earth management infrastructure that reduces risk and increases resilience.
Natural Carbonation of Peridotite and Applications for Carbon Storage
Natural carbonation of peridotite in the Samail Ophiolite of Oman is surprisingly rapid and could be further enhanced to provide a safe, permanent method of CO2 storage through in situ formation of carbonate minerals. Carbonate veins form by low-temperature reaction between peridotite and groundwater in a shallow weathering horizon. Reaction with peridotite drives up the pH of the water, and extensive travertine terraces form where this groundwater emerges at the surface in alkaline springs. The potential sink for CO2 in peridotite is enormous: adding 1wt% CO2 to the peridotite in Oman could consume 1/4 of all atmospheric carbon, and several peridotite bodies of comparable size exist throughout the world. Thus carbonation rate and cost, not reservoir size, are the limiting factors on the usefulness of in situ mineral carbonation of peridotite for carbon storage. The carbonate veins in Oman are much younger than previously believed, yielding average 14C ages of 28,000 years. Age data plus estimated volumes of carbonate veins and terraces suggest 10,000 to 100,000 tons per year of CO2 are consumed by these peridotite weathering reactions in Oman. This rate can be enhanced by drilling, hydraulic fracture, injecting CO2-rich fluid, and increasing reaction temperature. Drilling and hydraulic fracture can increase volume of peridotite available for reaction. Additional fracture may occur due to the solid volume increase of the carbonation reaction, and field observations suggest that such reaction-assisted fracture may be responsible for hierarchical carbonate vein networks in peridotite. Natural carbonation of peridotite in Oman occurs at low pCO2, resulting in partial carbonation of peridotite, forming magnesite and serpentine. Raising pCO2 increases carbonation efficiency, forming of magnesite + talc, or at complete carbonation, magnesite + quartz, allowing ∼30wt% CO2 to be added to the peridotite. Increasing the temperature to 185°C can improve the reaction rate by a factor of more than 100,000. Thermal modeling suggests that after an initial heating stage, CO2-rich fluids injected at relatively low temperature can be heated by exothermic carbonation reactions, offsetting diffusive heat loss to maintain optimal temperatures for rapid carbonation without additional energy input. With these enhancements, in situ carbonation could consume more than 1 billion tons of CO2 per cubic kilometer of peridotite per year. Costs associated with this method include drilling, hydraulic fracture, initial heating, CO2 capture and transport, fluid injection and monitoring. The techniques for drilling, fracture and injection are routinely used by oil companies. Compared with other carbon storage methods, in situ mineral carbonation has several advantages. It offers permanent storage that is safer and easier to monitor than storage of CO2-rich fluids in porous underground reservoirs or in the ocean. It may also be less costly than ex situ mineral carbonation, which requires quarrying and transportation of peridotite, grinding and heat treatment, reactions in pressure vessels at elevated temperature, production of catalysts, and disposal of carbonated material. An alternative method, carbonation by reaction of offshore peridotite with shallow seawater rather than CO2-rich fluids, would consume less CO2, but would avoid the costs of CO2 capture and transport inherent in other CCS methods. Drilling to depths where rocks are already close to the optimal carbonation temperature would avoid pre-heating costs and circulate water by thermal convection rather than pumping fluids.
Arctic Stratospheric Geoengineering with Spring or Summer Injections
Placing aerosols into the stratosphere to block out sunlight and cool Earth has been suggested to counteract global warming. Previous computer simulations of schemes to put aerosols continuously into the Arctic or tropical stratospheres produced Northern Hemisphere or global cooling, but a reduction of Asian and African summer monsoon precipitation, which would threaten the food supply for billions of people. If society found it desirable to temporarily cool the Arctic to preserve summer sea ice and Greenland while mitigation and carbon capture and sequestration measures are rapidly implemented, it would not be necessary to place aerosols into the winter stratosphere, as there would be no sunlight to block. The e-folding lifetime for Arctic stratospheric aerosols is only about three months. Here we present the results of new simulations injecting aerosol precursors only in spring or summer, to investigate whether it would be possible to cool the Arctic with a smaller impact on the monsoon than for a continuous cloud. At the same time, the cost of injection of aerosols would be much smaller than for continuous injection. We simulated the injection of 0.75 Tg SO2 per year at 68°N during 1-month and 3-month periods starting on April 1 for 20 years. We also simulated the August, 2008 eruption of the Kasatochi volcano using 1.5 Tg and 3 Tg SO2 injections, which while a one time injection, can also inform us about geoengineering. Preliminary results suggest that by putting enough aerosols into the summer Arctic stratosphere to reduce sunlight and cool the planet cannot avoid summer monsoon impacts.
Biogeologic Carbon Sequestration - a Cost-Effective Proposal
Carbon sequestration has been proposed as a strategy for reducing the impact of carbon dioxide emissions from burning of fossil fuels. There are two main routes: 1) capture CO2 emissions from power plants or other large point sources followed by some form of "burial/sequestration", and 2) extraction of CO2 from the ambient atmosphere (involving substantial concentration relative to atmospheric levels) also followed by burial/sequestration. In either case the goal is to achieve significant long-term isolation of CO2 at an economically sustainable price, perhaps measured by some "market price" for CO2, such as the European carbon futures market, where the price is now (2/3/09) about $14-15/tonne of CO2. The second approach, removal of CO2 from the atmosphere, has the potential benefit of reversing the previous buildup of atmospheric CO2, and perhaps even providing a means to "adjust" terrestrial climate by regulating atmospheric CO2 concentrations. For the present, ideas of planetary "geo-engineering" are not as popular as reducing the impact of continued CO2 emissions. In fact, the energy and capital costs of extraction from a dilute atmosphere appear to make this approach uneconomical. Proposals to fertilize the open ocean suffer from concerns about long term ecosystem effects, to say nothing of a lack of verifiability. There is, however, an approach using biological systems that can not only extract significant amounts of CO2, but can do so cost-effectively. Lakes are known in which primary productivity approaches or exceeds 1gm C/cm2-yr. This equates to removal of 35,000 tonnes of CO2 per km2 per year, with a "market value" of about $500,000/yr. Such productivity only occurs under highly eutrophic conditions, and presumably requires significant nutrient additions. As such it would be unthinkable to pursue this technique on a large scale in extant lakes. If, however, it is possible to produce one or more large artificial lakes under acceptable conditions it is conceivable that this approach to carbon sequestration could prove invaluable in both the near and long term.
Facing the Facts and Living our Values
One of the major challenges for the 21st Century is to establish an energy system that is safe, affordable, sustainable, and environmentally responsible. With current reserves in coal and nonconventional oil, we will not run out of energy in the coming century, but we may pay a price with a climate that heats up with an unprecedented rate of change. Even with current technology, there is a wealth of information and solutions available, and we could benefit much by using this knowledge more effectively than we do now. An example is the McKinsey report on the cost of avoiding CO2 emissions (http://mckinsey.com/clientservice/ccsi/greenhousegas.asp). According to this analysis, the USA can avoid about 40% of its CO2 emissions at zero total cost. About 20% of those emissions can be saved by taking steps that save money and reduce energy consumption. In the process of working on these steps for reducing CO2 emissions, many jobs are created. The energy and climate challenge thus comes with new opportunities. Geoscientists can make a difference by talking about energy and climate, and by helping create awareness for the energy challenge and the associated opportunities. Scientists and engineers are, in general, loath to discuss the issue of values. Yet, despite the logical basis of science, our science and the personal views of scientists can help shape our societal values. This can happen, however, only when scientists articulate their values and stimulate their students and the public to make conscious choices what their values are. Education, whether it is in the classroom, at a community center, church, or service club, can play an important role in making the public aware of the facts that are important for the choices that we need to make at a personal and societal level for our energy use. In order to facilitate this type of communication I have created a public lecture that is available online (http://www.mines.edu/∼rsnieder/Global_Energy.html). As a geoscientist, each of us can make a positive difference by being involved in such education.
Beyond Climate and Weather Science: Expanding the Forecasting Family to Serve Societal Needs
The ability to "anticipate" the future is what makes information from the Earth sciences valuable to society - whether it is the prediction of severe weather or the future availability of water resources in response to climate change. An improved ability to anticipate or forecast has the potential to serve society by simultaneously improving our ability to (1) promote economic vitality, (2) enable environmental stewardship, (3) protect life and property, as well as (4) improve our fundamental knowledge of the earth system. The potential is enormous, yet many appear ready to move quickly toward specific mitigation and adaptation strategies assuming that the science is settled. Five important weakness must be addressed first: (1) the formation of a true "climate services" function and capability, (2) the deliberate investment in expanding the family of forecasting elements to incorporate a broader array of environmental factors and impacts, (3) the investment in the sciences that connect climate to society, (4) a deliberate focus on the problems associated with scale, in particular the difference between the scale of predictive models and the scale associated with societal decisions, and (5) the evolution from climate services and model predictions to the equivalent of "environmental intelligence centers." The objective is to bring the discipline of forecasting to a broader array of environmental challenges. Assessments of the potential impacts of global climate change on societal sectors such as water, human health, and agriculture provide good examples of this challenge. We have the potential to move from a largely reactive mode in addressing adverse health outcomes, for example, to one in which the ties between climate, land cover, infectious disease vectors, and human health are used to forecast and predict adverse human health conditions. The potential exists for a revolution in forecasting, that entrains a much broader set of societal needs and solutions. The argument is made that (for example) the current capabilities in the prediction of environmental health is similar to the capabilities (and potential) of weather forecasting in the 1960's.
Building-Scale Atmospheric Modeling for Understanding and Anticipating Environmental Risks to Urban Populations
The innovative use of Computational Fluid-Dynamics (CFD) models to define the building- and street-scale atmospheric environment in urban areas can benefit society in a number of ways. Design criteria used by architectural climatologists, who help plan the livable cities of the future, require information about air movement within street canyons for different seasons and weather regimes. Understanding indoor urban air- quality problems and their mitigation, especially for older buildings, requires data on air movement and associated dynamic pressures near buildings. Learning how heat waves and anthropogenic forcing in cities collectively affect the health of vulnerable residents is a problem in building thermodynamics, human behavior, and neighborhood-scale and street-canyon-scale atmospheric sciences. And, predicting the movement of plumes of hazardous material released in urban industrial or transportation accidents requires detailed information about vertical and horizontal air motions in the street canyons. These challenges are closer to being addressed because of advances in CFD modeling, the coupling of CFD models with models of indoor air motion and air quality, and the coupling of CFD models with mesoscale weather-prediction models. This paper will review some of the new knowledge and technologies that are being developed to meet these atmospheric-environment needs of our growing urban populations.
A Global System of in situ Sensors, Communication Satellites and in situ Actuators Dedicated to the Nearly-Real-Time Detection and Mitigation of Natural Disasters
Most of the ~ 230,000 lives lost in the Indian Ocean Tsunami of December 2004 could have been saved if the victims had had 5 - 15 minutes notice of the tsunami's arrival, provided that the local authorities had had some evacuation plan in place, e.g. running up hill when a klaxon sounded, or retreating to low cost shelters constructed to provide a vertical escape from inundation. Similar structures, equipped with supplies of drinking water, food, blankets, etc., could save countless thousands of people from drowning in flood-prone locations such as Bangladesh or the delta region of Burma, or dying in the aftermath of such events. Given sufficiently rapid communications, a disaster nowcasting system could also order the closing of gas mains, or the powering down of electricity networks, as well as the sounding of klaxons, only tens of seconds before an earthquake wave strikes a major city such as Los Angeles. The central and critical requirement for mitigating natural disasters is two-way communication. Imagine a globally accessible internet collecting event-triggered messages from arrays of sensors (that detect inundation, for example) so they can be analyzed by centralized computer systems in nearly real-time, which then send instructions to alarm systems and actuators in the areas at risk. (Of course, local authorities would have to be involved in planning the local responses to alarms, in constructing rescue facilities, and in educating their populations accordingly). Only a constellation of satellites could provide a communications system with global accessibility and the required robustness. Such an infrastructure would allow the international community to exploit the many common elements in the detection, assessment and response to unfolding disasters. I shall describe some of the elements of such a system, for which I propose the working name CELERITY.