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The Global Plight of Pollinators
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Wild pollinators are in decline, and managed
honeybees cannot compensate for their loss.
29 MARCH 2013 VOL 339 SCIENCE
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The Greenhouse Is Making the Water-Poor Even Poorer
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How bad will global warming get? The question
has long been cast in terms of how hot
the world will get. But perhaps more important
to the planet’s inhabitants will be how
much rising greenhouse gases crank up the
water cycle. Theory and models predict that
a strengthening greenhouse will increase
precipitation where it is already relatively
high—tropical rain forests, for example—
and decrease it where it is already low, as in
the subtropics.
SCIENCE VOL 336 27 APRIL 2012
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The Greening of Synfuels
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An old, dirty technology to make transportation fuels from coal could
fight global warming, say proponents. The trick is using more biomass
and burying the carbon dioxide that’s generated
18 APRIL 2008 VOL 320 SCIENCE
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The Historical Dynamics of Socio-ecological Traps
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Environmental degradation is a typical unintended
outcome of collective human behavior. Hardin’s
metaphor of the ‘‘tragedy of the commons’’ has become a
conceived wisdom that captures the social dynamics leading
to environmental degradation. Recently, ‘‘traps’’ has gained
currency as an alternative concept to explain the rigidity of
social and ecological processes that produce environmental
degradation and livelihood impoverishment. The trap metaphor
is, however, a great deal more complex compared to
Hardin’s insight. This paper takes stock of studies using the
trap metaphor. It argues that the concept includes time and
history in the analysis, but only as background conditions and
not as a factor of causality. From a historical–sociological
perspective this is remarkable since social–ecological traps
are clearly path-dependent processes, which are causally
produced through a conjunction of events. To prove this point
the paper conceptualizes social–ecological traps as a process
instead of a condition, and systematically compares history
and timing in one classic and three recent studies of social–
ecological traps. Based on this comparison it concludes that
conjunction of social and environmental events contributes
profoundly to the production of trap processes. The paper
further discusses the implications of this conclusion for policy
intervention and outlines how future research might generalize
insights from historical–sociological studies of traps.
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The Holocene`
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Combining nine tree growth proxies from four sites, from the west coast of Norway to the Kola Peninsula of NW Russia, provides a well replicated
(> 100 annual measurements per year) mean index of tree growth over the last 1200 years that represents the growth of much of the northern pine
timberline forests of northern Fennoscandia. The simple mean of the nine series, z-scored over their common period, correlates strongly with mean
June to August temperature averaged over this region (r = 0.81), allowing reconstructions of summer temperature based on regression and variance
scaling. The reconstructions correlate significantly with gridded summer temperatures across the whole of Fennoscandia, extending north across Svalbard
and south into Denmark. Uncertainty in the reconstructions is estimated by combining the uncertainty in mean tree growth with the uncertainty in
the regression models. Over the last seven centuries the uncertainty is < 4.5% higher than in the 20th century, and reaches a maximum of 12% above
recent levels during the 10th century. The results suggest that the 20th century was the warmest of the last 1200 years, but that it was not significantly
different from the 11th century. The coldest century was the 17th. The impact of volcanic eruptions is clear, and a delayed recovery from pairs or multiple
eruptions suggests the presence of some positive feedback mechanism. There is no clear and consistent link between northern Fennoscandian summer
temperatures and solar forcing.
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The Hot Summer of 2010: Redrawing the Temperature Record Map of Europe
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The summer of 2010 was exceptionally warm in eastern
Europe and large parts of Russia. We provide evidence
that the anomalous 2010 warmth that caused adverse
impacts exceeded the amplitude and spatial extent of the
previous hottest summer of 2003. 'Mega-heatwaves' such
as the 2003 and 2010 events broke the 500-yr long
seasonal temperature records over approximately 50% of
Europe. According to regional multi-model experiments,
the probability of a summer experiencing 'megaheatwaves'
will increase by a factor of 5 to 10 within the
next 40 years. However, the magnitude of the 2010 event
was so extreme that despite this increase, the occurrence
of an analogue over the same region remains fairly
unlikely until the second half of the 21st century.
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The Impact of Boreal Forest Fire on Climate Warming
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We report measurements and analysis of a boreal forest fire, integrating the effects of greenhouse gases, aerosols, black carbon deposition on snow and sea ice, and postfire changes in surface albedo. The net effect of all agents was to increase radiative forcing during the first year (34 ± 31 Watts per square meter of burned area), but to decrease radiative forcing when averaged over an 80-year fire cycle (−2.3 ± 2.2 Watts per square meter) because multidecadal increases in surface albedo had a larger impact than fire-emitted greenhouse gases. This result implies that future increases in boreal fire may not accelerate climate warming.
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The impact of climate change on the structure of Pleistocene food webs across the mammoth steppe
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Species interactions form food webs, impacting community structure and, potentially, ecological dynamics. It is likely that global climatic perturbations that occur over long periods of time have a significant influence on species interaction patterns. Here, we integrate stable isotope analysis and network theory to reconstruct patterns of trophic interactions for six independent mammalian communities that inhabited mammoth steppe environments spanning western Europe to eastern Alaska (Beringia) during the Late Pleis- tocene. We use a Bayesian mixing model to quantify the contribution of prey to the diets of local predators, and assess how the structure of trophic inter- actions changed across space and the Last Glacial Maximum (LGM), a global climatic event that severely impacted mammoth steppe communities. We find that large felids had diets that were more constrained than those of co-occurring predators, and largely influenced by an increase in Rangifer abun- dance after the LGM. Moreover, the structural organization of Beringian and European communities strongly differed: compared with Europe, species inter- actions in Beringian communities before—and possibly after—the LGM were highly modular. We suggest that this difference in modularity may have been driven by the geographical insularity of Beringian communities.
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The impact of climate change on mental health
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Climate change will shortly be assuming centre stage when Copenhagen hosts the United Nations Climate Change Conference in early December 2009. In Copenhagen, delegates will discuss the international response to climate change (i.e. the ongoing increase in the Earth’s average surface temperature) and the meeting is widely viewed as the most important of its kind ever held (http://en.cop15.dk/). International agreement will be sought on a treaty to replace the 1997 Kyoto Protocol. At the time of writing it is not known whether agreement will be reached on the main issues of reducing greenhouse gas emissions and financing the impacts of climate change, and it appears that the impact of climate change on mental health is unlikely to be on the agenda. We discuss here how climate change could have consequences for global mental health and consider the implications for future research and policy.
Key words : Climate, mental disorder, mental health, global warming.
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The impact of Miocene atmospheric carbon dioxide fluctuations on climate and the evolution of terrestrial ecosystems
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The Miocene is characterized by a series of key climatic events that led to the founding of the late Cenozoic icehouse mode and the dawn of modern biota. The processes that caused these developments, and particularly the role of atmospheric CO2 as a forcing factor, are poorly understood. Here we present a CO2 record based on stomatal frequency data from multiple tree species. Our data show striking CO2 fluctuations of 600–300 parts per million by volume (ppmv). Periods of low CO2 are contemporaneous with major glaciations, whereas elevated CO2 of 500 ppmv coincides with the climatic optimum in the Miocene. Our data point to a long-term coupling between atmospheric CO2 and climate. Major changes in Miocene terrestrial ecosystems, such as the expansion of grasslands and radiations among terrestrial herbivores such as horses, can be linked to these marked fluctuations in CO2.
atmospheric CO2 fossil plants paleoclimates stomata C4 plants
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