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Human Evolution Out of Africa: The Role of Refugia and Climate Change
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Although an African origin of the modern human species is generally accepted, the evolutionary
processes involved in the speciation, geographical spread, and eventual extinction of archaic
humans outside of Africa are much debated. An additional complexity has been the recent evidence
of limited interbreeding between modern humans and the Neandertals and Denisovans. Modern
human migrations and interactions began during the buildup to the Last Glacial Maximum,
starting about 100,000 years ago. By examining the history of other organisms through glacial
cycles, valuable models for evolutionary biogeography can be formulated. According to one
such model, the adoption of a new refugium by a subgroup of a species may lead to important
evolutionary changes.
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Human land-use-driven reduction of forest volatiles cools global climate
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Human conversion of forest ecosystems to agriculture is a major driver of global change. Conventionally, the impacts of the historical cropland expansion on Earth’s radiation balance have been quantified through two opposing effects: the release of stored carbon to the atmosphere as CO2 (warming) versus the increase in surface albedo (cooling)1. Changing forest cover has a third effect on the global radiation balance by altering emissions of biogenic volatile organic compounds (BVOCs) that control the loadings of multiple warming and cooling climate pollutants: tropospheric ozone (O3 ), methane (CH4 ) and aerosols. Although human land cover change has dominated BVOC emission variability over the past century2–4, the net effect on global climate has not been quantified. Here, I show that the effects of the global cropland expansion between the 1850s and 2000s on BVOC emissions and atmospheric chemistry have imposed an additional net global radiative impact of −0.11 ± 0.17 W m−2 (cooling). This magnitude is comparable to that of the surface albedo and land carbon release effects. I conclude that atmospheric chemistry must be considered in climate impact assessments of anthropogenic land cover change and in forestry for climate protection strategies.
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Humans and Nature Duel Over the Next Decade’s Climate
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Rising greenhouse gases are changing global climate, but during the next few decades natural climate variations will have a say as well, so researchers are scrambling to factor them in.
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Humphrey et al 1989.pdf
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HUE-JOH
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Hydrology, forests and precipitation recycling: a reply to van der Ent et al
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We warmly welcome the debate our article on the relationship between forest cover and water yield has inspired.....We read with general satisfaction their view that: ‘Ellison et al. (2012a) [have] initiated an important shift in thinking of forests as water suppliers, instead of mere water users’.On the other hand, we regret that we are required to point out and correct a number of misplaced criticisms and misrepresentations of our work.
climate change adaptation, ecosystem services, forests, precipitation recycling, water yield
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Hylton, Roberta E
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Identifying human influences on atmospheric temperature
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We perform a multimodel detection and attribution study with climate model simulation output and satellite-based measurements of tropospheric and stratospheric temperature change. We use simulation output from 20 climate models participating in phase 5 of the Coupled Model Intercomparison Project. This multimodel archive provides estimates of the signal pattern in response to combined anthropogenic and natural external forcing (the finger- print) and the noise of internally generated variability. Using these estimates, we calculate signal-to-noise (S/N) ratios to quantify the strength of the fingerprint in the observations relative to fingerprint strength in natural climate noise. For changes in lower stratospheric temperature between 1979 and 2011, S/N ratios vary from 26 to 36, depending on the choice of observational dataset. In the lower troposphere, the fingerprint strength in observations is smaller, but S/N ratios are still significant at the 1% level or better, and range from three to eight. We find no evidence that these ratios are spuriously inflated by model variability errors. After removing all global mean signals, model fingerprints remain identifiable in 70% of the tests involving tropospheric temperature changes. Despite such agreement in the large-scale features of model and observed geographical patterns of atmospheric temperature change, most models do not replicate the size of the observed changes. On average, the models analyzed underestimate the observed cooling of the lower stratosphere and overestimate the warming of the troposphere. Although the precise causes of such differences are unclear, model biases in lower stratospheric temperature trends are likely to be reduced by more realistic treatment of stratospheric ozone depletion and volcanic aerosol forcing.
climate change detection and attribution | climate modeling | multimodel analysis
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Identifying refugia from climate change
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This article highlights how the loose definition of the term ‘refugia’ has led to discrepancies in methods used to assess the vulnerability of species to the current trend of rising global temperatures. The term ‘refugia’ is commonly used without distinguishing between macrorefugia and microrefugia, ex situ refugia and in situ refugia, glacial and interglacial refugia or refugia based on habitat stability and refugia based on climatic stability. It is not always clear which definition is being used, and this makes it difficult to assess the appropriateness of the methods employed. For example, it is crucial to develop accurate fine-scale climate grids when identifying microrefugia, but coarse-scale macroclimate might be adequate for determining macrorefugia. Similarly, identifying in situ refugia might be more appropriate for species with poor dispersal ability but this may overestimate the extinction risk for good dispersers. More care needs to be taken to properly define the context when referring to refugia from climate change so that the validity of methods and the conservation significance of refugia can be assessed.
Keywords
Bioclimatic envelope models, climatic stability, conservation biogeography, cryptic refugia, ecological niche models, extinction risk, interglacial refugia, macrorefugia, microclimate, microrefugia.
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Identifying the World’s Most Climate Change Vulnerable Species: A Systematic Trait-Based Assessment of all Birds, Amphibians and Corals
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Climate change will have far-reaching impacts on biodiversity, including increasing extinction rates. Current approaches to quantifying such impacts focus on measuring exposure to climatic change and largely ignore the biological differences between species that may significantly increase or reduce their vulnerability. To address this, we present a framework for assessing three dimensions of climate change vulnerability, namely sensitivity, exposure and adaptive capacity; this draws on species’ biological traits and their modeled exposure to projected climatic changes. In the largest such assessment to date, we applied this approach to each of the world’s birds, amphibians and corals (16,857 species). The resulting assessments identify the species with greatest relative vulnerability to climate change and the geographic areas in which they are concentrated, including the Amazon basin for amphibians and birds, and the central Indo-west Pacific (Coral Triangle) for corals. We found that high concentration areas for species with traits conferring highest sensitivity and lowest adaptive capacity differ from those of highly exposed species, and we identify areas where exposure-based assessments alone may over or under-estimate climate change impacts. We found that 608–851 bird (6–9%), 670–933 amphibian (11– 15%), and 47–73 coral species (6–9%) are both highly climate change vulnerable and already threatened with extinction on the IUCN Red List. The remaining highly climate change vulnerable species represent new priorities for conservation. Fewer species are highly climate change vulnerable under lower IPCC SRES emissions scenarios, indicating that reducing greenhouse emissions will reduce climate change driven extinctions. Our study answers the growing call for a more biologically and ecologically inclusive approach to assessing climate change vulnerability. By facilitating independent assessment of the three dimensions of climate change vulnerability, our approach can be used to devise species and area- specific conservation interventions and indices. The priorities we identify will strengthen global strategies to mitigate climate change impacts.
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Igniting Inspiration for Women in Fire
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If our use of fire for managing lands is to improve and expand in the United States, it will need to involve more women and diverse perspectives. Thanks to programs like Women-in-Fire Prescribed Fire Training Exchanges (WTREX), more women are participating in and leading controlled burns.
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