Tropical deforestation is estimated to cause about one-quarter of anthropogenic carbon emissions, loss of biodiversity, and other environmental services. United Nations Framework Convention for Climate Change talks are now considering mechanisms for avoiding deforestation (AD), but the economic potential of AD has yet to be addressed. We use three economic models of global land use and management to analyze the potential contribution of AD activities to reduced greenhouse gas emissions. AD activities are found to be a competitive, low-cost abatement option. A program providing a 10% reduction in deforestation from 2005 to 2030 could provide 0.3-0.6 Gt (1 Gt ‫؍‬ 1 ؋ 10 5 g) CO2⅐yr ؊1 in emission reductions and would require $0.4 billion to $1.7 billion⅐yr ؊1 for 30 years. A 50% reduction in deforestation from 2005 to 2030 could provide 1.5-2.7 Gt CO 2⅐yr ؊1 in emission reductions and would require $17.2 billion to $28.0 billion⅐yr ؊1 . Finally, some caveats to the analysis that could increase costs of AD programs are described.carbon sequestration ͉ climate change ͉ reducing emissions from deforestation and ecosystem degradation (REDD) ͉ marginal cost ͉ tropical forest T ropical deforestation is considered the second largest source of greenhouse gas emissions (1) and is expected to remain a major emission source for the foreseeable future (2). Despite policy attention on reducing deforestation, Ϸ13 million ha⅐yr Ϫ1 of forests continue to be lost (3). Deforestation could have the effect of cooling the atmosphere (4), but it also leads to reductions in biodiversity, disturbed water regulation, and the destruction of livelihoods for many of the world's poorest (5). Slowing down, or even reversing, deforestation is complicated by multiple causal factors, including conversion for agricultural uses, infrastructure extension, wood extraction (6-9), agricultural product prices (10), and a complex set of additional institutional and place-specific factors (11).Avoided deforestation (AD) was included alongside afforestation as a potential mechanism to reduce net global carbon emissions in the Kyoto Protocol (KP), but until recently, climatepolicy discussions have focused on afforestation and forest management. Discussions about new financial mechanisms that include AD provide optimism for more effective synergies between forest conservation and carbon policies (11)(12)(13)(14). In 2005, Papua New Guinea and Costa Rica proposed to the United Nations Framework Convention on Climate Change that carbon credits be provided to protect existing native forests (15). The proposal triggered a flurry of discussion on the topic. SoaresFilho et al. (16), for example, suggest that protecting Ϸ130 million ha of land from deforestation in the Amazon could reduce global carbon emissions by 62 Gt (1 Gt ϭ 1 ϫ 10 15 g) CO 2 over the next 50 years.Although the potential for AD activities to help mitigate climate change is widely acknowledged (16,17), there is little information available on what the costs might be globally. This article uses t...

This study develops an optimal control model of carbon sequestration and energy abatement to explore the potential role of forests in greenhouse gas mitigation. The article shows that if carbon accumulates in the atmosphere, the rental price for carbon sequestration should rise over time. From an empirical model, we find that carbon sequestration is costly, but that landowners can sequester substantial amounts of carbon in forests mainly by increasing forestland and lengthening rotations. Forest sequestration is predicted to account for about one-third of total carbon abatement. Tropical forests store over two-thirds of this added carbon. Copyright 2003, Oxford University Press.

This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

In early August 2014, the municipality of Toledo, OH (USA) issued a 'do not drink' advisory on their water supply directly affecting over 400,000 residential customers and hundreds of businesses (Wilson, 2014). This order was attributable to levels of microcystin, a potent liver toxin, which rose to 2.5 mg L1 in finished drinking water. The Toledo crisis afforded an opportunity to bring together scientists from around the world to share ideas regarding factors that contribute to bloom formation and toxigenicity, bloom and toxin detection as well as prevention and remediation of bloom events. These discussions took place at an NSF-and NOAA-sponsored workshop at Bowling Green State University on April 13 and 14, 2015. In all, more than 100 attendees from six countries and 15 US states gathered together to share their perspectives. The purpose of this review is to present the consensus summary of these issues that emerged from discussions at the Workshop. As additional reports in this special issue provide detailed reviews on many major CHAB species, this paper focuses on the general themes common to all blooms, such as bloom detection, modeling, nutrient loading, and strategies to reduce nutrients. KeywordsCyanobacteria, CHAB, Lake Erie, Microcystin, Phosphorus, Nitrogen In early August 2014, the municipality of Toledo, OH (USA) issued a 'do not drink' advisory on their water supply directly affecting over 400,000 residential customers and hundreds of businesses (Wilson, 2014).This order was attributable to levels of microcystin, a potent liver toxin, which rose to 2.5 mg L À1 in finished drinking water. The Toledo crisis afforded an opportunity to bring together scientists from around the world to share ideas regarding factors that contribute to bloom formation and toxigenicity, bloom and toxin detection as well as prevention and remediation of bloom events. These discussions took place at an NSF-and NOAA-sponsored workshop at Bowling Green State University on April 13 and 14, 2015. In all, more than 100 attendees from six countries and 15 US states gathered together to share their perspectives. The purpose of this review is to present the consensus summary of these issues that emerged from discussions at the Workshop. As additional reports in this special issue provide detailed reviews on many major CHAB species, this paper focuses on the general themes common to all blooms, such as bloom detection, modeling, nutrient loading, and strategies to reduce nutrients. ß

This article develops a global timber market model which captures how timber supply reacts to future predicted increases in the demand for timber. Higher future demand is expected to increase prices, increase investments in regeneration, increase establishment of plantations, and expand output. Dynamic market responses imply a greater reliance on plantations in productive regions, allowing large areas of natural forest in low-valued regions to remain largely intact. Sensitivity analysis suggests that price, harvest, and management are most sensitive to the rate of demand increase, the interest rate, the cost of plantations, and access costs of natural forests. Two forest conservation strategies are examined which predict the system-wide implications of forest conservation in Europe and North America. The policies indicate that whereas set asides can induce net conservation, harvests increase elsewhere, particularly in natural forests. Copyright 1999, Oxford University Press.

There is a continuing debate over the role that woody bioenergy plays in climate mitigation. This paper clarifies this controversy and illustrates the impacts of woody biomass demand on forest harvests, prices, timber management investments and intensity, forest area, and the resulting carbon balance under different climate mitigation policies. Increased bioenergy demand increases forest carbon stocks thanks to afforestation activities and more intensive management relative to a no-bioenergy case. Some natural forests, however, are converted to more intensive management, with potential biodiversity losses. Incentivizing both wood-based bioenergy and forest sequestration could increase carbon sequestration and conserve natural forests simultaneously. We conclude that the expanded use of wood for bioenergy will result in net carbon benefits, but an efficient policy also needs to regulate forest carbon sequestration.

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Forests can play a large role in climate change through the sequestration or emission of carbon, an important greenhouse gas; through biological growth, which can increase forest stocks; or through deforestation, which can increase carbon emissions. Carbon is captured not only in tree biomass but also in forest soils. Forest management and public policy can strongly influence the sequestration process. Economic policies can provide incentives for both forest expansion and contraction. Systems that provide prices for carbon sequestration or taxes for emissions can have important effects on emission and sequestration levels. Issues involve carbon additionality, permanence, and leakage. Forest measurement, monitoring, and verification also provide serious challenges. Various economic models are used to estimate the effects of various economic policies on forest carbon stocks. Estimates from the literature of some actual and potential levels of forest carbon are presented.