Capturing Carbon?The amount of carbon dioxide (CO2) in the atmosphere has been rising steadily since the beginning of the industrial age. As one of the most important ‘greenhouses gases’, atmospheric CO2 is a major contributor to global warming. Recent initiatives to slow the rate of warming, such as the Kyoto protocol, focus on reducing emissions (eg. from factories and automobiles).
But what if we could simply store the excess CO2 for centuries until some other solution is found? New technologies are making it possible to ‘capture’ excess carbon from the atmosphere and store it in geological reservoirs or perhaps even the deep sea. Could this buy us precious time in which to adopt cleaner energy sources or would we simply be leaving a time-bomb for future generations? Scientists are not yet able to say what environmental impact this so-called “carbon sequestration” would have. In the meantime, the political and economic stakes are high and the debate has become a passionate one.
The Intergovernmental Oceanographic Commission of UNESCO (IOC) with the Scientific Committee on Oceanic Research (SCOR) have set up an Advisory Panel on ocean carbon dioxide, in order to ensure that decision-makers and the general public have access to an unbiased picture of worldwide research on ocean carbon sequestration. A major symposium on “The Ocean in a High CO2 World” has recently been scheduled for March 2004 to pool present scientific knowledge in order to determine whether – and at what levels – increasing carbon dioxide will affect the oceans, with their marine life and coral reefs.
In this interview, Patricio Bernal, Executive Secretary of UNESCO’s IOC, sets out some of the issues.
Is there a proven link between climate and carbon?
We know from glacier records that there is a correlation between carbon levels in the atmosphere and climate. At the start of the last Ice Age some 50,000 years ago for example, atmospheric CO2 levels were low. Today, the climate is going through a naturally warm period; this, combined with the burning of fossil fuels and biomass, as well as land-use changes, over the past two centuries, has sent atmospheric CO2 concentration in the atmosphere to levels never seen before.(i) Present carbon levels are now higher than this planet has experienced for at least the last 20 million years. Human activity is releasing something like 7 Gigatons of carbon per year into the atmosphere. And the excess carbon is not going to disappear. Even if all the countries around the world were to implement the 1997 Kyoto Protocol, which calls for them to bring CO2 emissions down to below 1990 levels by 2012, it would not solve the problem of the existing excess, although it would limit the future accumulation of CO2 which in itself would be a major achievement.
What does this mean?
We are heading for an increase in hurricanes, floods, droughts and other disturbed weather patterns, together with a rise in sea-level and the melting of glaciers and permafrost which store two-thirds of the Earth’s freshwater reserves. The difficulty for scientists today is to distinguish the effects of the naturally occurring cyclical disturbances caused by El Niņo and La Niņa oscillation, for example, from those caused by global warming.
But why store carbon in the oceans?
Faced with the stark reality, even the International Panel on Climate Change has admitted that we may have to consider what it calls ‘carbon management strategies’ to complement reductions in greenhouse gas emissions. One option is to store the excess carbon on land; this is already being done in deep geological formations, abandoned mines and the like.
But it is the oceans that have the greatest natural capacity to absorb and store carbon. On an annual basis, the surface of the ocean absorbs about 30% of the carbon in the atmosphere, less during El Niņo years. But over very long timescales, of thousands of years, as much as 85% is absorbed by the oceans. The ocean contains an estimated 40,000 billion tons of carbon, as compared to 750 billion tons in the atmosphere and about 2200 billion tons on land. This means that, were we to take all the atmospheric CO2 and put it in the deep ocean, the concentration of CO2 in the ocean would change by less than 2%.
Experiments have shown that, up to a depth of 3000 m, liquid CO2 tends to rise to the surface because it is less dense than the surrounding seawater. At 3000 m, on the other hand, it turns into a solid, ice-like substance that is denser than the surrounding water. One method being considered is that of injecting liquid CO2 into the sea floor. Another is to store it in disaffected oil wells.
The trouble is that, even if theories abound – including that CO2 stored at a depth of 3000 m would not come in contact with the atmosphere for 200 years – it is all conjecture. We simply don’t know what the consequences would be over the long term. The IOC’s main concern is making sure that sound, unbiased scientific findings are available to the general public and policymakers to address these issues when decisions will have to be made.
One of the principle scientific concerns is what will happen naturally if we do nothing to reduce atmospheric CO2 levels: the pH of the surface ocean will decrease, causing the water to become more acidic. This will affect the chemistry of the surface ocean where most marine organisms live. We don’t yet understand how the ecosystem will respond to this slow, natural invasion of CO2. This concern has led some scientists to suggest that it may be less damaging to take CO2 out of the atmosphere and inject it directly into the deep ocean where only a small fraction of marine organisms live. The problem is that these organisms living in the deep ocean would be particularly affected because of the rapid change in their environment and the fact that their slow metabolisms make it very difficult for them to adjust to changes.
And what would be the effect on the atmosphere if, some 100 or 200 years from now, an enormous quantity of accumulated CO2 buried in the deep ocean began to slowly leak back into the surface ocean and into the atmosphere?
What else are you ‘watching’?
Iron fertilization research, for example. In many parts of the ocean, phytoplankton growth is limited by the lack of an essential micro-nutrient, iron. A number of private companies are trying to stimulate phytoplankton growth to up to 30 times the natural rate so as to create what might be termed ocean carbon sinks, much along the same principle as the forests being promoted as carbon sinks on land. The concept is not a new one. Oceanographer John Martin became famous in the 1970s by declaring ‘Give me a ton of iron and I’ll produce the next Ice Age’.
Iron is found in dust, which is best carried into the atmosphere in dry, arid conditions. Not surprisingly, it is the Sahara and Sahel deserts that contain most of this dust, which prevailing winds blow over the Atlantic to the Caribbean and north-eastern Latin America.
Scientists estimate that fertilizing the entire Southern Ocean with iron would only reduce atmospheric CO2 levels by about 20–30% over a century. More seriously, it would lead to significant ecological perturbations. When organisms die, their decomposition consumes oxygen. Creating an unnatural abundance of decomposing organisms would lead to low oxygen levels that could be devastating to marine life.
Is it ethical to pursue research in such a controversial area?
The best argument against ocean carbon storage would be to prove that it is environmentally unsound. However, we mustn’t be naīve. Carbon trading is a profitable business. The only thing holding back many potential traders from storing carbon in the ocean tomorrow is the cost of the technology.
What do you think of Greenpeace’s role in putting a stop to an environmental impact assessment in Norwegian waters last August?
It was misguided in my view. I share Greenpeace’s concern that high concentrations of CO2 may harm deep marine organisms (ii). We don’t know today what ultimate effects a slow invasion of CO2 would have on the ecosystem composition and food-chain.
But in preventing a consortium of research institutions from Norway, the USA, Canada, Australia and Japan from carrying out an assessment that might have substantiated Greenpeace’s claims, the environmental group was shooting itself in the foot.
We need to get the debate out into the open. After all, in the final analysis, whether or not the world resorts to ocean carbon storage will be a societal decision.
The Norwegian government has called for more international debate on ocean carbon storage. This is what the Member States of the IOC are trying to promote within the Watching Brief. We have set up the Brief to provide governments, industry and the general public with access to the results of unbiased research. Via the Watching Brief on the web (iii) and as an active observer and participant in research, the IOC is fulfilling an advisory and advocacy role.
The Norwegian government bowed to pressure from the environmentalists out of concern that it might be trespassing international marine law. Does this mean that CO2 is considered a pollutant?
According to the Office for the London Convention (iv), there is no unanimity on the issue of whether fossil fuel-derived CO2 should be regarded as industrial waste. This causes a legal void, since the various treaties and conventions governing dumping in the oceans only refer to ‘industrial wastes’. The London Dumping Convention bodies should look into the matter.
IOC’s Watching Brief also documents the legal aspects of ocean carbon storage. There is a plethora of legal instruments – the United Nations Framework Convention on Climate Change, the United Nations Law of the Sea, Kyoto, etc. – but these government treaties have no power of enforcement; that poses a real problem. The Scientific Group of the London Convention recently developed a Waste Assessment Framework which would require a full environmental impact assessment before a permit could be delivered for CO2 dumping. This is a step in the right direction but it is insufficient.
In the absence of a coercive legal instrument, isn’t there a danger that ocean carbon storage will be seen as a permit to pollute?
Yes, there is a very real danger that it will make us more irresponsible rather than less so. We should be moving towards cleaner fuels at a much faster rate. Everyone knows that, within the next few decades, fossil fuels will begin to run out and we shall be forced to adopt alternative sources of energy. The USA for example depends on fossil fuels for approximately 85% of its energy needs and these are growing every year. Despite the urgency, the proposed target of attributing a 10% market share to renewable energies was still rejected by governments at the World Summit on Sustainable Development in Johannesburg last September.
Industry has invested considerably in research on alternative energy sources. At the Johannesburg Summit, everybody could see a number of BMW hydrogen-powered cars on display. The problem is that industry receives little government support to invest in renewable energies and conversion from petrol-driven to ‘clean’ cars has a huge cost. Governments should be providing incentives, such as tax rebates, and investing in the necessary infrastructure. It’s not a technological problem but a political one. Prototype cars driven by liquid petroleum gas, compressed natural gas, hydrogen (i.e. water vapour) and the like have been around for decades.
Are there grounds for optimism?
Over the centuries, we have engineered an artificial world for ourselves, to the point where more than 60% of the natural landscape is of our own making. The temptation has always been to engineer a new world rather than to respect the boundaries of the existing one.
With ocean carbon storage, we must beware of the same compartmentalized reflexes which have been our undoing in the past. Take the example of DDT. Paul Muller was awarded the Nobel Prize for medicine or physiology in 1948 for discovering the effectiveness of DDT as an insecticide, notably against malaria-bearing mosquitoes. Only after DDT had been put to extensive use was it realized that many species of insects had developed resistance to it and that it had a high toxicity towards fish and animals – upon which DDT was banned in many countries.
Instead of considering our planet as a whole made up of interdependent systems, we are always tempted to look for simple solutions to complex problems. We forget that the atmosphere, land and oceans are three sides of the same triangle, that what we do to one will affect the other two. I do believe we are making progress – physics, chemistry and biology are beginning to be integrated into a single conceptual model to deal with planetary processes - but there is a long way to go.
We must tread carefully with ocean carbon sequestration; take the time. We need to get our science right. As technology progresses, the consequences of our acts are becoming harder to correct – or even to anticipate.
Interview by Maria Hood and Susan Schneegans, first published in UNESCO’s science newsletter, A World of Science vol 1 N°2, January-March 2003. See also: www.unesco.org/science
(i)In the pre-industrial world, atmospheric CO2 concentrations oscillated on roughly 100,000 year cycles between 180 parts per million by volume (ppmv) during glacial periods and 280 ppmv during interglacial periods. We are now at an unprecedented 370 ppmv.
(ii)See for example: http://archive.greenpeace.org/politics/co2/co2dump.pdf
(iv)Convention for the Prevention of Marine Pollution by Dumping Wastes and Other Matters, 1972 and 1996 Protocol