During the last two summer seasons Ethiopia has managed to plant some nine billion tree seedlings of many varieties. According to Environment Forest and Climate Change Commission, the plantation of the forest carried out so far is of immense importance for different reasons.
The commission said the afforestation programs carried out so far have raised the country’s forest coverage to 17 per cent. In addition the country is able to sequester and capture carbon amounting to 92.6Mt from the atmosphere.
Scientists claim that by converting marginal croplands to permanent grasslands or forests, the accompanying increase in biomass and soil organic carbon can offset 20 per cent or more of global fossil fuel emissions.
Policy makers at all levels for their part are seriously considering the potential role of terrestrial ecosystems and geological reservoirs for storing carbon, thereby creating CO2 offsets that could obviate the need for lifestyle-changing reductions in fossil fuel use.
The terrestrial ecosystem activities to generate CO2 offset credits are a distraction from the actual job of mitigating climate change. While there is no question that carbon can be stored in biological sinks, and that care should be taken to foster such sinks and ensure that carbon is not unwontedly and needlessly released via deforestation, the primary focus of climate change mitigation should be on policies that reduce greenhouse gas emissions.
There are several reasons for this. Measurement, monitoring and verification of sink activities is particularly difficult, resulting in high transaction costs that need to be added to the price at which temporary credits will trade. Transaction costs are sufficiently large that most sink projects would no longer be economically viable.
Therefore, tree plantations feature prominently among tools for carbon sequestration typically combines higher productivity and biomass with greater annual transpiration and rainfall interception, particularly for evergreen species such as pines and eucalypts. In addition to influencing water budgets, plantations require additional base cations and other nutrients to balance the stoichiometry of their extra biomass.
In consequence, trade-offs of sequestration with water yield and soil fertility, including nutrient depletion and increased acidity, are likely. The goal of such activities is then to account for the tradeoffs and benefits of carbon sequestration, identifying potential problems and management needs for a sustainable sequestration policy.
Biological activities that sequester carbon create CO2 offset credits that could obviate the need for reductions in fossil fuel use. Credits are earned by storing carbon in terrestrial ecosystems and wood products, although CO2 emissions are also mitigated by delaying deforestation, which accounts for one-quarter of anthropogenic CO2 emissions.
However, non-permanent carbon offsets from biological activities are difficult to compare with each other and with emissions reduction because they differ in how long they prevent CO2 from entering the atmosphere. This is the duration problem. It results in uncertainty and makes it hard to determine the legitimacy of biological activities in mitigating climate change. Measuring, verifying and monitoring the carbon sequestered in sinks greatly increases transaction costs and leads to rent seeking by sellers of dubious sink credits.
Distributed carbon sequestration systems may show adaptability to changing economic as well as climate conditions, since they are locally controlled. Sustainability would be served if both environmental costs and benefits are born locally, thereby providing an incentive to minimize any detrimental environmental consequences.
In doing so, any failure to design a successful approach will be a small-scale failure that can be resurrected locally, rather than a catastrophic failure that leaves entire regions in ecological disaster or does not achieve any climate benefits. Large-scale projects may seem straightforward to implement, but may be more difficult to control.
The challenge for most approaches to agricultural and specifically soil carbon sequestration clearly is the distributed nature of the sequestration and the fragmented and highly variable activities and ecosystem responses. This does not only make verification of net emission reductions laborious, but also poses significant hurdles to implementation in a carbon abatement scheme. For example, the precise amount of carbon accrual to be traded depends on many factors such as what soil management was present before the change in practice, what are the soil type and climate, what practice is implemented and so on. Also, biochar systems deliver vastly different sequestration and emission reductions depending on the baseline conditions, the pyrolysis unit, biomass types and cropping system.
This is even more so the case if stored carbon must be accounted for in perpetuity. Second, while it makes some sense to encourage carbon sinks because they offer a bridge to enable development of technologies with lower fuel emissions such as more efficient vehicles, permitting below-cost sales of sink credits in carbon markets will result in reduced incentives to invest in new technologies. Rent seeking by opportunistic sellers of carbon credits, and even by environmental groups, highlights another important problem: terrestrial sinks remove CO2 from the atmosphere at different rates and store it for varying lengths of time, with both removal rates and storage times embodying significant uncertainty.
This facilitates the marketing of dubious sink offset credits. While this duration problem can readily be solved e.g., taxing emissions and subsidizing removals at the time they occur, given the high transaction costs of including sink activities and the reluctance of countries to make sinks work, the only conclusion is that great care must be taken, and appropriate institutions put in place, before terrestrial ecosystem sink activities can be included in a carbon trading system.
The Government of Canada (2002) had planned to rely on tree planting and improved forest management for meeting some one-third of its Kyoto commitment, but subsequent losses of large swaths of timber to Mountain Pine Beetle and wildfire greatly reduced the expected role of forests.
Proponents of CO2 capture and storage in deep underground aquifers and abandoned oil/gas fields indicate that there is enough available storage to trap decades of CO2 emissions. The costs of this option are unknown as there is a risk of sudden future release of deadly concentrations of CO2—a cost to be evaluated by the willingness of people to pay to avoid such a risk and not unlike that associated with long-term storage of nuclear waste, which could be substantial.
While biological sink activities undoubtedly help mitigate climate change and should not be neglected, it is shown that there are limits to the substitutability between temporary offset credits from these activities and emissions reduction, and that this has implications for carbon trading. A possible solution to inherent incommensurability between temporary and permanent credits is also suggested.
BY HAFTU GEBREZGABIHER
THE ETHIOPIAN HERALD MAY 28/2021
