Climate change as a result of human activity on Earth is a science that has more and more taken on credibility as we track rising global temperatures, ozone depletion, vanishing polar ice, shrinking alpine glaciers, and extreme weather systems that are a departure from recorded meteorological history. Humanity has several choices. We can stay the course continuing to pump out atmospheric-warming pollution and see what happens, or we can try and change humanity’s consumption of fossil fuels, or we can look at ways of re-engineering our environment to mitigate the greenhouse effect. Never before has humanity had to experiment on a global scale to address such a far reaching problem. In 2009, Douglas Fisher wrote an article that appeared in Scientific American, entitled, “Engineering the Planet to Dodge Global Warming.” In it he wrote “The idea of tinkering with planetary controls is not for the faint of heart. Even advocates acknowledge that any attempt to set the Earth’s thermostat is full of hubris and laden with risk.”
Hubris and risk….absolutely. But humans have been tinkering with climate for years. In 1946, an American, Dr. Vincent Schaefer, tried to create artificial clouds by seeding them with silver iodide crystals. There is no certainty that cloud seeding actually works but enough anecdotal evidence has accumulated to make many people around the world attempt cloud seeding. Probably the most famous recent experiment occurred at the 2008 Olympic Games in Beijing, China where the government deployed 32,000 people working with light aircraft, rockets and shells to spread silver iodide crystals or dry ice in clouds 50 km upwind of Beijing. The goal was to prevent rain from interrupting the August 8 opening ceremonies because historical records indicated a 41% chance of precipitation on that date. China spent a lot of money in this effort setting up 26 control stations reporting every 10 minutes on the status of local weather after each seeding event. According to the Beijing Municipal Meterological Bureau 1,104 rain dispersal rockets were fired from 21 sites in the city between 4 p.m. and 11:39 p.m. on the day of the opening ceremonies, successfully intercepting a stretch of rain clouds from moving towards the stadium. Heavy rains were record around Beijing but not during the time of the opening ceremonies.
In 1990, John Firor wrote “The Changing Atmosphere,” a book that described what we were doing to the atmosphere through our own neglect. He described acid rain, ozone depletion, increases in greenhouse gases, and other atmospheric pollutants and what they were doing to degrade the atmosphere. Firor foresaw the need for a coordinated strategy among all nations to tackle this problem. In his book he stated that it was almost impossible to halt the continued pollution of our atmosphere but suggested steps to slow the process.
For Firor one of the most important steps in changing the atmospheric equation was stabilizing human population growth. We, however, continue to propagate the species at an alarming rate. In 2011 the world’s human population will surpass 7 billion. By mid-century it is projected that we will surpass 9.2 billion. If we as a species can slow the current birth rate to zero growth then the population should stabilize at around that number throughout the balance of the century. If we don’t, however, at present growth rates human population could exceed 14 billion according to a recent U.N. study. Part of this sustained population surge will be due in part to longer lifespans with life expectancy of 97 by 2100 and 106 by 2300. Human population growth will change our atmosphere but that is not the re-engineering that is the topic we want to describe here. We’ll deal with human population and the planet’s carrying capacity in a future blog. Short of all members of the human species stopping breathing there are many ways we can begin to re-engineer the atmosphere.
So let’s begin by describing the current atmospheric challenges we face and the technologies that we need to deploy to reverse the effects of fossil fuel addiction and industrial resource consumption.
What gases and pollutants are we talking about?
Carbon dioxide (CO2) is the primary gas that climatologists point to when talking about atmospheric temperature changes. Carbon dioxide concentrations today are higher than at any time in the last half-million years. Since the start of the Industrial Revolution carbon dioxide has been growing from 280 parts per million (ppm) to 382 ppm in 2006, a rise of 36 percent. Since 2006 CO2 continues to rise at a rate of about 1.9 ppmv/year.
Methane (CH4) is the second greenhouse gas that has seen a sharp increase of 148% from pre-industrial levels to today.
Nitrous oxide (N2O) had shown little variance over 11,500 years before the Industrial Revolution but recently in the last few decades of the 20th century it has increased by 18%.
Aerosols can effect cloud formation as well as the amount of solar radiation that strikes the earth’s surface. Aerosols can also impact atmospheric temperature. Typical aerosols come from the burning of fossil fuels. Coal-fired power plants produce sulfates that reflect solar radiation and cool the atmosphere. By reducing coal-fired plants suflates in the atmosphere have started to decrease. Another aerosol is soot, again a byproduct of fossil fuel burning as well as the burning of forests for land clearance. Soot, also known as black carbon, tends to be a local atmospheric phenomenon effecting atmospheric temperature and cloud formation. Open pit mining, salt pans and mineral precipitate operations can also contribute organic carbon aerosols into the atmosphere. These precipitates affect air quality quite dramatically and can contribute to global atmospheric changes including cooling and increased cloud formation.
Airborne precipitates and gases are not the only contributors to atmospheric alterations. Land use plays a significant part in changing the reflective capability of our planet and as a result the concentration of radiation-generated heat that gets trapped in the atmosphere. The fraction of solar radiation reflected by a surface or object, often expressed as a percentage is called albedo. Snow has a high albedo. Forests have a low albedo. The oceans have a low albedo. The growth of cities, deforestation and desertification are playing an increasing role in changing our atmosphere.
How can we rework the atmosphere to stabilize it and reverse the impact that greenhouse gases, aerosols, and land-use changes have wrought?
1. The first and foremost is ending our dependence on fossil fuels and immediately reducing the burning of these fuels. One third of our fossil fuel consumption comes from burning oil, natural gas, and coal to generate electricity. Every power plant has the capability to disperse millions of tons of carbon dioxide into the atmosphere annually. Stop the burning of forests to clear them from agricultural use.
2. Decrease carbon emissions from other industrial processes. In the process of creating cement, refining metals, chemicals and fossil fuels we generate many more millions of tons of carbon dioxide. Carbon capture and the reuse of it as an industrial resource can even play a profitable part in the manufacturing process.
3. There are an increasing number of carbon capture and storage technologies being demonstrated today. The most commonly used is deployed at power plant and manufacturing facilities where the flue gas stream is captured. This is a post-combustion process. Two other processes capture carbon dioxide at the pre-combustion and combustion phases within power plants. These current deployed technologies either only capture a fraction of the carbon dioxide stream eminating from plants or cannot be deployed because the retrofits would be prohibitively expensive. This makes reducing carbon dioxide emissions in an economically sustainable way a significant industry problem that governments, through subsidies and tax incentives, may be able to address.
4. Carbon sequestration poses a variety of challenges. Nature’s way of capturing carbon is through photosynthesis. Plants are natural carbon sinks. They take in carbon dioxide and expel oxygen. If only sequestration could be so kind. Through sequestration we capture carbon dioxide either by putting in the ground or in water.
Today, underground sequestration is used by oil companies today as a means of getting additional oil from depleted fields. Pumping carbon dioxide under pressure into oil reservoirs is good business. Because oil reservoirs are porous rock formations overlayed by harder capstones we can find similar geological characteristics in sandstone, shale and other sedimentary rock as well as volcanic rock such as basalt and use these porous formations for sequestration. An interesting consequence of injecting carbon dioxide into basalt formations is the alteration of the rock which turns into limestone.
Sequestering carbon dioxide in water has potential ecological implications. The deep ocean has been considered the ideal place for carbon storage. Liquefied carbon dioxide when injected into the deep ocean (below 3,500 meters) in theory should keep the carbon dioxide permanently trapped. Carbon dioxide in liquid form and subjected to deep ocean pressures turns into clathrate hydrate, an icy substance that in theory cannot be absorbed by ocean water. Experiments in deep ocean carbon sequestration to date have shown mixed success. Sometimes the carbon dioxide stabilizes and sometimes it breaks up in the salt water with potential implications for ocean life. More recently it has been suggested that liquid carbon dioxide can be stored in large polymer containers that are placed in the bottom of the ocean. The target area is in the ocean depths of the Pacific, an area called the abyssal plain. The liquid carbon dioxide would be pumped through pipelines to polymer bags hoding up to 160 million metric tons, equivalent to two day’s of global human output.
Another solution for sequestration has a potential happy ending. Since fossil fuels are a byproduct of carbon sequestration over geological time, we may be able to synthesize fossil fuel production by injecting carbon dioxide deep into the earth’s crust and thereby reproduce the very forces that created fossil fuels naturally. Using gravity we could artificially create a carbon cycle that would give us a continuous supply of fossil fuels for as long as we needed them. Should we be able to develop such technical skill then all the sequestered carbon that we pump into the oceans and underground may prove to be a valuable resource.