Anthony C. Janetos

Implications of Limiting CO2 Concentrations for Land Use and Energy

The Power of Green Carbon dioxide is produced both by fossil fuel burning and by deforestation and other land-use changes. Limiting both sources of CO2 is necessary if we are to curb global warming. Wise et al. (p. 1183) use an integrated assessment model to explore the consequences of limiting atmospheric CO2 concentrations at levels between 450 and 550 parts per million through a combination of fossil-fuel emissions reductions and land-use modification. Land-use modification strategies reduce the cost of limiting atmospheric CO2 concentrations, but can make crop prices rise and transform human diets, for example, when people consume less beef and other carbon-intensive protein sources. The rate at which crop productivity is improved has a strong influence on emissions from land-use change. Thus, the technology used for growing crops is potentially as important for limiting atmospheric CO2 as are approaches like CO2 capture and storage. Technologies for growing crops are potentially as important for limiting the concentration of atmospheric CO2 as are those for capture and storage. Limiting atmospheric carbon dioxide (CO2) concentrations to low levels requires strategies to manage anthropogenic carbon emissions from terrestrial systems as well as fossil fuel and industrial sources. We explore the implications of fully integrating terrestrial systems and the energy system into a comprehensive mitigation regime that limits atmospheric CO2 concentrations. We find that this comprehensive approach lowers the cost of meeting environmental goals but also carries with it profound implications for agriculture: Unmanaged ecosystems and forests expand, and food crop and livestock prices rise. Finally, we find that future improvement in food crop productivity directly affects land-use change emissions, making the technology for growing crops potentially important for limiting atmospheric CO2 concentrations.

Strategies of female mate choice: A theoretical analysis

SummaryFemales of many species face a difficult sampling problem while searching for a mate. How do they find the best male possible when the constraints of time, memory, and mobility prevent them from visiting all the males in the population?Five possible solutions are examined: random mating a fixed-threshold criterion, a fixed-threshold with last-chance option, an optimal one-step decision strategy, and the best-of-n-males strategy. Random mating is the worst strategy whenever the female gets more than one chance to mate. The two fixed-threshold strategies approach equal effectiveness as n increases but are always below the optimal one-step decision strategy. However, the best-of-n-males strategy always yields the highest expectation of fitness in a mate. The difference is especially great when n≳5.Plotting the average fitness of males chosen vs n, the number of males examined, yields a negatively accelerating curve. Since the cost of searching will be an increasing function of n, the two curves can be combined to yield an optimum n: the point where the difference between the curves is greatest.The one field study (Brown 1978) that addresses these problems in detail reveals that female mottled sculpins choose males on a relative, rather than absolute, basis, as theory suggests they should.

A Synthesis of Information on Rapid Land-cover Change for the Period 1981–2000

Abstract This article presents a synthesis of what is known about areas of rapid land-cover change around the world over the past two decades, based on data compiled from remote sensing and censuses, as well as expert opinion. Asia currently has the greatest concentration of areas of rapid land-cover changes, and dryland degradation in particular. The Amazon basin remains a major hotspot of tropical deforestation. Rapid cropland increase, often associated with large-scale deforestation, is prominent in Southeast Asia. Forest degradation in Siberia, mostly related to logging activities, is increasing rapidly. The southeastern United States and eastern China are experiencing rapid cropland decrease. Existing data do not support the claim that the African Sahel is a desertification hotspot. Many of the most populated and rapidly changing cities are found in the tropics.

A New Biology for the 21st Century

An editorial on A New Biology for the 21st Century: A Critical Role for Ecologists for Frontiers Magazine.

Using remote sensing to assess Russian forest fire carbon emissions

Russian boreal forests are subject to frequent wildfires. The resulting combustion of large amounts of biomass not only transforms forest vegetation, but it also creates significant carbon emissions that total, according to some authors, from 35–94 Mt C per year. These carbon emissions from forest fires should be considered an important part of the forest ecosystem carbon balance and a significant influence on atmospheric trace gases. In this paper we discuss a new method to assess forest fire damage. This method is based on using multi-spectral high-resolution satellite images, large-scale aerial photography, and declassified images obtained from the space-borne national security systems. A normalized difference vegetation index (NDVI) difference image was produced from pre- and post-fire satellite images from SPOT/HRVIR and RESURS-O/MSU-E images. A close relationship was found between values of the NDVI difference image and forest damage level. High-resolution satellite data and large-scale aerial-photos were used to calibrate the NDVI-derived forest damage map. The method was used for mapping of forest fire extent and damage and for estimating carbon emissions from burned forest areas.

Climate mitigation and the future of tropical landscapes

Land-use change to meet 21st-century demands for food, fuel, and fiber will depend on many interactive factors, including global policies limiting anthropogenic climate change and realized improvements in agricultural productivity. Climate-change mitigation policies will alter the decision-making environment for land management, and changes in agricultural productivity will influence cultivated land expansion. We explore to what extent future increases in agricultural productivity might offset conversion of tropical forest lands to crop lands under a climate mitigation policy and a contrasting no-policy scenario in a global integrated assessment model. The Global Change Assessment Model is applied here to simulate a mitigation policy that stabilizes radiative forcing at 4.5 W m−2 (approximately 526 ppm CO2) in the year 2100 by introducing a price for all greenhouse gas emissions, including those from land use. These scenarios are simulated with several cases of future agricultural productivity growth rates and the results downscaled to produce gridded maps of potential land-use change. We find that tropical forests are preserved near their present-day extent, and bioenergy crops emerge as an effective mitigation option, only in cases in which a climate mitigation policy that includes an economic price for land-use emissions is in place, and in which agricultural productivity growth continues throughout the century. We find that idealized land-use emissions price assumptions are most effective at limiting deforestation, even when cropland area must increase to meet future food demand. These findings emphasize the importance of accounting for feedbacks from land-use change emissions in global climate change mitigation strategies.

UNDERSTANDING CLIMATIC IMPACTS, VULNERABILITIES, AND ADAPTATION IN THE UNITED STATES: BUILDING A CAPACITY FOR ASSESSMENT

Based on the experience of the U.S. National Assessment, we propose a program of research and analysis to advance capability for assessment of climate impacts, vulnerabilities, and adaptation options. We identify specific priorities for scientific research on the responses of ecological and socioeconomic systems to climate and other stresses; for improvement in the climatic inputs to impact assessments; and for further development of assessment methods to improve their practical utility to decision-makers. Finally, we propose a new institutional model for assessment, based principally on regional efforts that integrate observations, research, data, applications, and assessment on climate and linked environmental-change issues. The proposed program will require effective collaboration between scientists, resource managers, and other stakeholders, all of whose expertise is needed to define and prioritize key regional issues, characterize relevant uncertainties, and assess potential responses. While both scientifically and organizationally challenging, such an integrated program holds the best promise of advancing our capacity to manage resources and the economy adaptively under a changing climate.

Greenhouse Gas Policy Influences Climate via Direct Effects of Land-Use Change

AbstractProposed climate mitigation measures do not account for direct biophysical climate impacts of land-use change (LUC), nor do the stabilization targets modeled for phase 5 of the Coupled Model Intercomparison Project (CMIP5) representative concentration pathways (RCPs). To examine the significance of such effects on global and regional patterns of climate change, a baseline and an alternative scenario of future anthropogenic activity are simulated within the Integrated Earth System Model, which couples the Global Change Assessment Model, Global Land-Use Model, and Community Earth System Model. The alternative scenario has high biofuel utilization and approximately 50% less global forest cover than the baseline, standard RCP4.5 scenario. Both scenarios stabilize radiative forcing from atmospheric constituents at 4.5 W m−2 by 2100. Thus, differences between their climate predictions quantify the biophysical effects of LUC. Offline radiative transfer and land model simulations are also utilized to iden...

Active foragers vs. sit-and-wait predators: a simple model

Abstract I propose a simple model for the decision of when to leave a foraging site in a variable environment for a predator that does not deplete its local resources. Active foraging is favored when the cost of moving is small or the difference between good and poor sites is large. The model corresponds to the behavior of two guilds of web-spinning spiders.

Ecosystem Impacts of Geoengineering: A Review for Developing a Science Plan

Geoengineering methods are intended to reduce climate change, which is already having demonstrable effects on ecosystem structure and functioning in some regions. Two types of geoengineering activities that have been proposed are: carbon dioxide (CO2) removal (CDR), which removes CO2 from the atmosphere, and solar radiation management (SRM, or sunlight reflection methods), which reflects a small percentage of sunlight back into space to offset warming from greenhouse gases (GHGs). Current research suggests that SRM or CDR might diminish the impacts of climate change on ecosystems by reducing changes in temperature and precipitation. However, sudden cessation of SRM would exacerbate the climate effects on ecosystems, and some CDR might interfere with oceanic and terrestrial ecosystem processes. The many risks and uncertainties associated with these new kinds of purposeful perturbations to the Earth system are not well understood and require cautious and comprehensive research.