The land cover and carbon cycle consequences of large-scale utilizations of biomass as an energy source

The use of modern biomass for energy generation has been considered in many studies as a possible measure for reducing or stabilizing global carbon dioxide (CO₂) emissions. In this paper we assess the impacts of large-scale global utilization of biomass on regional and grid scale land cover, greenhouse gas emissions, and carbon cycle. We have implemented in the global environmental change model IMAGE the LESS biomass intensive scenario, which was developed for the Second Assessment Report of IPCC. This scenario illustrates the potential for reducing energy related emission by different sets of fuel mixes and a higher energy efficiency. Our analysis especially covers different consequences involved with such modern biomass scenarios. We emphasize influences of CO₂ concentrations and climate change on biomass crop yield, land use, competition between food and biomass crops, and the different interregional trade patterns for modern biomass based energy. Our simulations show that the original LESS scenario is rather optimistic on the land requirements for large-scale biomass plantations. Our simulations show that 797 Mha is required while the original LESS scenario is based on 550 Mha. Such expansion of agricultural land will influence deforestation patterns and have significant consequenses for environmental issues, such as biodiversity. Altering modern biomass requirements and the locations where they are grown in the scenario shows that the outcome is sensitive for regional emissions and feedbacks in the C cycle and that competition between food and modern biomass can be significant. We conclude that the cultivation of large quantities of modern biomass is feasible, but that its effectiveness to reduce emissions of greenhouse gases has to be evaluated in combination with many other environmental land use and socio-economic factors.     

Global models meet global policy: How can global and regional modellers connect with environmental policy makers? What has hindered them? What has helped?

Global modelling has developed over the last two decades largely because of the needs of policymaking, yet it has not yet realized its full potential in assisting policymaking. While the first wave of global models in the 1970s had a clear influence on policy discourse, these models were eventually undermined by attacks on their scientific underpinning. The second wave of global models in the 1990s had a stronger scientific footing than the first wave because they were built on a much larger base of knowledge about the global system. Although the improved scientific credibility of global models has increased their use in policymaking, a more subtle yet important factor has been the direct contact of global model developers with policymakers. Taking an example from the field of climate policy, a global modelling team has conducted formal workshops with a group of international climate policymakers with the aim to increase the relevance of modeling activities to policy issues. This interaction has inspired policyrelevant uses of a global model (IMAGE 2) and spawned the development of a new policy concept ‘Safe Emission Corridors’, which has been discussed in the frame of international climate negotiations. A preliminary conclusion is that both improved scientific credibility and improved interaction between modelers and policymakers are critical ingredients for enhancing the policy-relevance of global models.     

Emission scenarios and global climate protection

This paper evaluates the effectiveness of a wide range of emission scenarios in protecting climate (where ‘protecting climate’ Is used here to mean minimizing ‘dangerous anthropogenic interference with the climate system’ which results in impacts to society and the natural environment). Under baseline (no action) conditions there is a significant Increase in emissions, temperature and climate impacts. Controlling only CO₂ emissions (ie freezing emissions in year 2000 at 1990 levels, and decreasing them afterwards at 1%/yr) and only in Annex I countries, does not significantly reduce the impacts observed under the baseline scenario. However, impacts are substantially reduced when emissions are controlled in both Annex I and non-Annex I countries, and when both CO₂ and non-CO₂ emissions are controlled. It was also found that stabilizing CO₂ in the atmosphere below 450 ppm substantially reduces climate impacts. But in order to follow the pathway to stabilization at 450 ppm specified by the IPCC, global emissions can only slightly increase in the coming decades, and then must be sharply reduced. On the other hand, stabilizing CO₂ in the atmosphere above 450 ppm can have significant impacts, which indicates that stabilization of greenhouse gases in the atmosphere will not necessarily provide a high level of climate protection. Results from these and other scenarios are synthesized and related to climate protection goals through a new concept — ‘safe emission corridors’. These corridors indicate the allowable range of near-term global emissions (equivalent CO₂) which complies with specified short- and long-term climate goals. For an illustrative set of climate goals, the allowable anthropogenic global emissions in 2010 are computed to range from 7.3 to 14.5 GtC/yr equivalent CO₂ (1990 level = approximately 9.6 GtC/ yr); when these limits are set twice as strict (ie divided by two), the allowable range becomes 7.6 to 9.3 GtC/yr. To fall within this lower corridor, global emissions must be lower in 2010 than in 1990.     

Baseline scenarios of global environmental change

This paper presents three baseline scenarios of no policy action computed by the IMAGE 2 model. These scenarios cover a wide range of coupled global change Indicators, including: energy demand and consumption; food demand, consumption, and production; changes in land cover including changes in extent of agricultural land and forest; emissions of greenhouse gases and ozone precursors; and climate change and its impacts on sea level rise, crop productivity and natural vegetation. Scenario information is available for the entire world with regional and grid scale detail, and covers from 1970 to 2100. The scenarios indicate that the coming decades could be a period of relatively rapid global environmental change as compared to the period before and after. The natural vegetation in industrialized regions could be threatened by climate change, but abandonment of agricultural lands could also make new lands available for reforestation and revegetation. The opposite is true for most of Asia and Africa. Here the impacts of climate change on vegetation may not be as significant as in temperate climates, but the demand for food will lead to a significant expansion of agricultural lands at the expense of remaining forests and other natural areas.