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A holistic approach to climate targets
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An assessment of allowable carbon emissions that factors in multiple climate targets finds smaller permissible emission budgets than those inferred from studies that focus on temperature change alone.
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A new, global, multi-annual (2000–2007) burnt area product at 1 km resolution Vol. 35
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This paper reports on the development and validation
of a new, global, burnt area product. Burnt areas are
reported at a resolution of 1 km for seven fire years (2000 to
2007). A modified version of a Global Burnt Area (GBA)
2000 algorithm is used to compute global burnt area. The
total area burnt each year (2000– 2007) is estimated to be
between 3.5 million km2 and 4.5 million km2
. The total
amount of vegetation burnt by cover type according to the
Global Land Cover (GLC) 2000 product is reported.
Validation was undertaken using 72 Landsat TM scenes
was undertaken. Correlation statistics between estimated
burnt areas are reported for major vegetation types. The
accuracy of this new global data set depends on vegetation
type.
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Are there basic physical constraints on future anthropogenic emissions of carbon dioxide?
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Here, it is shown both theoretically and observationally how the evolution of the human system can be considered from a surprisingly simple thermodynamic perspective in which it is unnecessary to explicitly model two of the emissions drivers: population and standard of living. Specifically, the human system grows through a self-perpetuating feedback loop in which the consumption rate of primary energy resources stays tied to the historical accumulation of global economic production—or p × g—through a time-independent factor of 9.7 ± 0.3 mW per inflation-adjusted 1990 US dollar. This important constraint, and the fact that f and c have historically varied rather slowly, points towards substantially narrowed visions of future emissions scenarios for implementation in GCMs.
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Asymmetric effects of economic growth and decline on CO2 emissions
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Letter to Editor: Excerpt: "Why does economic decline not have an effect on CO2 emissions that is symmetrical with the effect of economic growth? There are various reasons that this may occur, but the asymmetry is probably due to the fact that economic growth produces durable goods, such as cars and energy-intensive homes, and infrastructure, such as manufacturing facilities and transportation networks, that are not removed by economic decline and that continue to contribute to CO2 emissions even after growth is curtailed."
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Carbon debt and carbon sequestration parity in forest bioenergy production
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The capacity for forests to aid in climate change mitigation efforts is substantial but will ultimately depend on their management. If forests remain unharvested, they can further mitigate the increases in atmospheric CO2 that result from fossil fuel combustion and deforestation. Alternatively, they can be harvested for bioenergy production and serve as a substitute for fossil fuels, though such a practice could reduce terrestrial C storage and thereby increase atmospheric CO2 concentrations in the near-term. Here, we used an ecosystem simulation model to ascertain the effectiveness of using forest bioenergy as a substitute for fossil fuels, drawing from a broad range of land-use histories, harvesting regimes, ecosystem characteristics, and bioenergy conversion effi- ciencies. Results demonstrate that the times required for bioenergy substitutions to repay the C Debt incurred from biomass harvest are usually much shorter (< 100 years) than the time required for bioenergy production to substitute the amount of C that would be stored if the forest were left unharvested entirely, a point we refer to as C Sequestration Parity. The effectiveness of substituting woody bioenergy for fossil fuels is highly dependent on the factors that determine bioenergy conversion efficiency, such as the C emissions released during the har- vest, transport, and firing of woody biomass. Consideration of the frequency and intensity of biomass harvests should also be given; performing total harvests (clear-cutting) at high-frequency may produce more bioenergy than less intensive harvesting regimes but may decrease C storage and thereby prolong the time required to achieve C Sequestration Parity.
Keywords: bioenergy, biofuel, C cycle, C sequestration, forest management
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Climate Change Impact: Food Systems, Food Security, and Global Linkages
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Food systems both impact and are affected by climate change. Emissions come not only from farming, but also from the processing, manufacturing, distribution, storage, sale, and preparation of food, and the disposal of food wastes. Likewise, climate change influences not just agriculture, but activities that occur throughout this larger system. In this talk, Dr. Peters will address the fundamental concepts of food systems and food security. He will explain how scientists estimate climate emissions from individual supply chains and from whole food systems. He will also consider case study examples of strategies for reducing emissions viewed both from the production and consumer ends of the food system.
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Webinars
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Climate: Sawyer predicted rate of warming in 1972
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Excerpt: "In four pages Sawyer summarized what was known about the role of carbon dioxide in enhancing the natural greenhouse effect, and made a remarkable prediction of the warming expected at the end of the twentieth century.He concluded that the 25% increase in atmospheric carbon dioxide predicted to occur by 2000 corresponded to an increase of 0.6 °C in world temperature..... In fact the global surface temperature rose about 0.5 °C between the early 1970s and2000. Considering that global temperatures had, if anything, been falling in the decades leading up to the early 1970s, Sawyer’s prediction of a reversal of this trend, and of the correct magnitude of the warming, is perhaps the most remarkable long-range forecast ever made.
Despite huge efforts, and advances in the science, the scientific consensus on the amount of global warming
expected from increasing atmospheric carbon dioxide concentrations has changed little from that in Sawyer’s time.
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CO2 emissions from forest loss
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Deforestation is the second largest anthropogenic source of carbon dioxide to the atmosphere, after fossil fuel combustion. Following a budget reanalysis, the contribution from deforestation is revised downwards, but tropical peatlands emerge as a notable carbon dioxide source.
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Combined climate and carbon-cycle effects of large-scale deforestation
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The prevention of deforestation and promotion of afforestation have often been cited as strategies to slow global warming. Deforestation releases CO2 to the atmosphere, which exerts a warming influence on Earth’s climate. However, biophysical effects of deforestation, which include changes in land surface albedo, evapotranspiration, and cloud cover also affect climate. Here we present results from several large-scale deforestation experiments performed with a three-dimensional coupled global carbon-cycle and climate model. These simulations were performed by using a fully three-dimensional model representing physical and biogeo- chemical interactions among land, atmosphere, and ocean. We find that global-scale deforestation has a net cooling influence on Earth’s climate, because the warming carbon-cycle effects of de- forestation are overwhelmed by the net cooling associated with changes in albedo and evapotranspiration. Latitude-specific deforestation experiments indicate that afforestation projects in the tropics would be clearly beneficial in mitigating global-scale warming, but would be counterproductive if implemented at high latitudes and would offer only marginal benefits in temperate regions. Although these results question the efficacy of mid- and high-latitude afforestation projects for climate mitigation, forests remain environmentally valuable resources for many reasons un-related to climate.
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commentary: the case for mandatory sequestration
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the fact that cumulative carbon dioxide emissions are more important than annual emission rates calls for a fresh approach to climate change mitigation. one option would be a mandatory link between carbon sequestration and fossil fuel extraction. FROM THE TEXT: With current emissions around 10 billion tonnes of carbon per year, and over three trillon tonnes still available in fossil fuel reserves (4,11), emissions need to fall,on average, by over 2% per year from now on to avoid releasing the trillionth tonne.The longer emissions are allowed to rise, the faster they will have to fall thereafter to stay within the same cumulative total.
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