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The rebound effect is overplayed
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Increasing energy efficiency brings emissions savings. Claims that it backfires are a distraction, say Kenneth Gillingham and colleagues.
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The timing of climate change
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An innovative assessment of climate change calculates the year in which ongoing warming will surpass the limits of historical climate variability. Three experts explain this calculation’s significance compared with conventional approaches, and its relevance to Earth’s biodiversity.
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Integrated assessment of global water scarcity over the 21st century under multiple climate change mitigation policies
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Water scarcity conditions over the 21st century both globally and regionally are assessed in the context of climate change and climate mitigation policies, by estimating both water availability and water demand within the Global Change Assessment Model (GCAM), a leading community- integrated assessment model of energy, agriculture, climate, and water. To quantify changes in future water availabil- ity, a new gridded water-balance global hydrologic model – namely, the Global Water Availability Model (GWAM) – is developed and evaluated. Global water demands for six ma- jor demand sectors (irrigation, livestock, domestic, electricity generation, primary energy production, and manufacturing) are modeled in GCAM at the regional scale (14 geopolitical regions, 151 sub-regions) and then spatially downscaled to 0.5◦ × 0.5◦ resolution to match the scale of GWAM. Using a baseline scenario (i.e., no climate change mitigation pol- icy) with radiative forcing reaching 8.8 W m−2 (equivalent to the SRES A1Fi emission scenario) and three climate pol- icy scenarios with increasing mitigation stringency of 7.7, 5.5, and 4.2 W m−2 (equivalent to the SRES A2, B2, and B1 emission scenarios, respectively), we investigate the ef- fects of emission mitigation policies on water scarcity. Two carbon tax regimes (a universal carbon tax (UCT) which in- cludes land use change emissions, and a fossil fuel and in- dustrial emissions carbon tax (FFICT) which excludes land use change emissions) are analyzed. The baseline scenario results in more than half of the world population living un- der extreme water scarcity by the end of the 21st century. Additionally, in years 2050 and 2095, 36 % (28 %) and 44 % (39 %) of the global population, respectively, is projected to live in grid cells (in basins) that will experience greater water demands than the amount of available water in a year (i.e., the water scarcity index (WSI) > 1.0). When comparing the climate policy scenarios to the baseline scenario while main- taining the same baseline socioeconomic assumptions, water scarcity declines under a UCT mitigation policy but increases with a FFICT mitigation scenario by the year 2095, particu- larly with more stringent climate mitigation targets. Under the FFICT scenario, water scarcity is projected to increase, driven by higher water demands for bio-energy crops.
water: supply; demand; tax; scarcity
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TOO EARLY TO TELL, OR TOO LATE TO RESCUE? ADAPTIVE MANAGEMENT UNDER SCRUTINY
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“The Forest Service’s definition of adaptive management does not emphasize experimentation but rather rational planning coupled with trial and error learning. Here ‘adaptive’ management has become a buzzword, a fash- ionable label that means less than it seems to promise.”
Kai Lee, 1999 KEY FINDINGS
• A new approach to the research-management relations is required.The natural tension between the two arenas can produce strengthened relations and improved learning, particularly with focussed input from lead scientists and AMA coordinators.
• The AMA research effort is an important complement to PNW Research Station direction and priorities.The AMAs represent an additional research setting, one that offers important opportunities to test, validate, and possibly revise standards and guides contained within the NWFP.
• The AMA research must be grounded in a local sense of priority and need, established by strong links between management and research.At the same time, designing research to maximize its applicability across the whole AMA system is also productive.
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Adaptive management of biological systems: A review
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Adaptive Management (AM) is widely considered to be the best available approach for managing biolog- ical systems in the presence of uncertainty. But AM has arguably only rarely succeeded in improving bio- diversity outcomes. There is therefore an urgent need for reflection regarding how practitioners might overcome key problems hindering greater implementation of AM. In this paper, we present the first structured review of the AM literature that relates to biodiversity and ecosystem management, with the aim of quantifying how rare AM projects actually are. We also investigated whether AM practitioners in terrestrial and aquatic systems described the same problems; the degree of consistency in how the term ‘adaptive management’ was applied; the extent to which AM projects were sustained over time; and whether articles describing AM projects were more highly cited than comparable non-AM articles. We found that despite the large number of articles identified through the ISI web of knowledge (n = 1336), only 61 articles (<5%) explicitly claimed to enact AM. These 61 articles cumulatively described 54 separate projects, but only 13 projects were supported by published monitoring data. The extent to which these 13 projects applied key aspects of the AM philosophy – such as referring to an underlying conceptual model, enacting ongoing monitoring, and comparing alternative management actions – varied enormously. Further, most AM projects were of short duration; terrestrial studies discussed biodiversity conservation significantly more frequently than aquatic studies; and empirical studies were no more highly cited than qualitative articles. Our review highlights that excessive use of the term ‘adaptive man- agement’ is rife in the peer-reviewed literature. However, a small but increasing number of projects have been able to effectively apply AM to complex problems. We suggest that attempts to apply AM may be improved by: (1) Better collaboration between scientists and representatives from resource-extracting industries. (2) Better communication of the risks of not doing AM. (3) Ensuring AM projects ‘‘pass the test of management relevance’’.
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Afforestation Effects on Soil Carbon Storage in the United States: A Synthesis
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Afforestation (tree establishment on nonforested land) is a management option for increasing terrestrial C sequestration and mitigating rising atmo- spheric carbon dioxide because, compared to nonforested land uses, afforestation increases C storage in aboveground pools. However, because terrestrial ecosystems typically store most of their C in soils, afforestation impacts on soil organic carbon (SOC) storage are critical components of eco- system C budgets. We applied synthesis methods to identify the magnitude and drivers of afforestation impacts on SOC, and the temporal and verti- cal distributions of SOC change during afforestation in the United States. Meta-analysis of 39 papers from 1957 to 2010 indicated that previous land use drives afforestation impacts on SOC in mineral soils (overall average = +21%), but mined and other industrial lands (+173%) and wildlands (+31%) were the only groups that specifically showed categorically significant increases. Temporal patterns of SOC increase were statistically significant on former industrial and agricultural lands (assessed by continuous meta- analysis), and suggested that meaningful SOC increases require ≥15 and 30 yr of afforestation, respectively. Meta-analysis of 13C data demonstrated the greatest SOC changes occur at the surface soil of the profile, although par- tial replacement of C stocks derived from previous land uses was frequently detectable below 1 m. A geospatial analysis of 409 profiles from the National Soil Carbon Network database supported 13C meta-analysis results, indicating that transition from cultivation to forest increased A horizon SOC by 32%. In sum, our findings demonstrate that afforestation has significant, positive effects on SOC sequestration in the United States, although these effects require decades to manifest and primarily occur in the uppermost (and per- haps most vulnerable) portion of the mineral soil profile.
Abbreviations: BD, bulk density; CI, confidence interval; MAP, mean annual precipitation; MAT, mean annual temperature; SOC, soil organic carbon.
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Trees on farms: Tackling the triple challenge of 07 mitigation, adaptation and food security
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Policy recommendations
␣␣Increased adoption of agroforestry should be supported through finance for agricultural development and adaptation as well as mitigation.
␣␣Payments for environmental services – including carbon finance – should be geared towards increasing the extent of trees on farms
␣ More support is needed to increase the contribution of tree-based crops to smallholder incomes, thus diversifying income sources and increasing food security in the face of climate change.
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AGU: Human-induced climate change requires urgent action.
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1st paragraph: concentrations of carbon dioxide and other heat-trapping greenhouse gases have increased sharply since the Industrial Revolution. Fossil fuel burning dominates this increase. Human-caused increases in greenhouse gases are responsible for most of the observed global average surface warming of roughly 0.8°C (1.5°F) over the past 140 years.
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A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests
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Of particular concern are potential increases in tree mortality associated with climate- induced physiological stress and interactions with other climate-mediated processes such as insect outbreaks and wildfire. Despite this risk, existing projections of tree mortality are based on models that lack functionally realistic mortality mechanisms, and there has been no attempt to track observations of climate-driven tree mortality globally. Here we present the first global assessment of recent tree mortality attributed to drought and heat stress. Although episodic mortality occurs in the absence of climate change, studies compiled here suggest that at least some of the world’s forested ecosystems already may be responding to climate change and raise concern that forests may become increasingly vulnerable to higher background tree mortality rates and die-off in response to future warming and drought, even in environments that are not normally considered water-limited. This further suggests risks to ecosystem services, including the loss of sequestered forest carbon and associated atmospheric feedbacks. Our review also identifies key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system. Overall, our review reveals the potential for amplified tree mortality due to drought and heat in forests worldwide.
heat, temperature, drought, tree mortality, forest dieoff
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Slow Recovery from Perturbations as a Generic Indicator of a Nearby Catastrophic Shift
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The size of the basin of attraction in ecosystems with alternative stable states is often referred to as “ecological resilience.” Ecosystems with a low ecological resilience may easily be tipped into an alternative basin of attraction by a stochastic event. Unfortunately, it is very difficult to measure ecological resilience in practice. Here we show that the rate of recovery from small perturbations (some- times called “engineering resilience”) is a remarkably good indicator of ecological resilience. Such recovery rates decrease as a catastrophic regime shift is approached, a phenomenon known in physics as “crit- ical slowing down.” We demonstrate the robust occurrence of critical slowing down in six ecological models and outline a possible ex- perimental approach to quantify differences in recovery rates. In all the models we analyzed, critical slowing down becomes apparent quite far from a threshold point, suggesting that it may indeed be of practical use as an early warning signal. Despite the fact that critical slowing down could also indicate other critical transitions, such as a stable system becoming oscillatory, the robustness of the phenom- enon makes it a promising indicator of loss of resilience and the risk of upcoming regime shifts in a system.
Keywords: alternative stable states, catastrophic bifurcations, critical slowing down, early warning signals, resilience, return time.
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