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Earth system sensitivity inferred from Pliocene modelling and data
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Here we use a coupled atmosphere–ocean general circulation model to simulate the climate of the mid-Pliocene warm period (about three million years ago), and analyse the forcings and feedbacks that contributed to the relatively warm temperatures. Furthermore, we compare our simulation with proxy records of mid-Pliocene sea surface temperature. Taking these lines of evidence together, we estimate that the response of the Earth system to elevated atmospheric carbon dioxide concentrations is 30–50% greater than the response based on those fast-adjusting components of the climate system that are used traditionally to estimate climate sensitivity. We conclude that targets for the long-term stabilization of atmospheric greenhouse gas concentrations aimed at preventing a dangerous human interference with the climate system should take into account this higher sensitivity of the Earth system.
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Ecohydrologic separation of water between trees and streams in a Mediterranean climate
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Water movement in upland humid watersheds from the soil surface to the stream is often described using the concept of translatory flow (1,2), which assumes that water entering the soil as precipitation displaces the water that was present previously, pushing it deeper into the soil and eventually into the stream (2). Within this framework, water at any soil depth is well mixed and plants extract the same water that eventually enters the stream. Here we present water-isotope data from various pools throughout a small watershed in the Cascade Mountains, Oregon, USA. Our data imply that a pool of tightly bound water that is retained in the soil and used by trees does not participate in translatory flow, mix with mobile water or enter the stream. Instead, water from initial rainfall events after rainless summers is locked into small pores with low matric potential until transpiration empties these pores during following dry summers. Winter rainfall does not displace this tightly bound water. As transpiration and stormflow are out of phase in the Mediterranean climate of our study site, two separate sets of water bodies with different isotopic characteristics exist in trees and streams. We conclude that complete mixing of water within the soil cannot be assumed for similar hydroclimatic regimes as has been done in the past (3,4) .
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Ecological and Evolutionary Responses to Recent Climate Change
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Ecological changes in the phenology and distribution of plants and animals are occurring in all well-studied marine, freshwater, and terrestrial groups. These observed changes are heavily biased in the directions predicted from global warming and have been linked to local or regional climate change through correlations between climate and biological variation, field and laboratory experiments, and physiological research. Range-restricted species, particularly polar and mountaintop species, show severe range contractions and have been the first groups in which entire species have gone extinct due to recent climate change. Tropical coral reefs and amphibians have been most negatively affected. Predator-prey and plant-insect interactions have been disrupted when interacting species have responded differently to warming. Evolutionary adaptations to warmer conditions have occurred in the interiors of species’ ranges, and resource use and dispersal have evolved rapidly at expanding range margins. Observed genetic shifts modulate local effects of climate change, but there is little evidence that they will mitigate negative effects at the species level.
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Ecological Effects of Prescribed Fire Season: A Literature Review and Synthesis for Managers
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Prescribed burning may be conducted at times of the year when fires were infrequent historically, leading to concerns about potential adverse effects on vegetation and wildlife. Historical and prescribed fire regimes for different regions in the continental United States were compared and literature on season of prescribed burning synthesized. In regions and vegetation types where considerable differences in fuel consumption exist among burning seasons, the effects of prescribed fire season appears, for many ecological variables, to be driven more by fire-intensity differences among seasons than by phenology or growth stage of organisms at the time of fire. Where fuel consumption differs little among burning seasons, the effect of phenology or growth stage of organisms is often more apparent, presumably because it is not overwhelmed by fire-intensity differences. Most species in ecosystems that evolved with fire appear to be resilient to one or few out-of-season prescribed burn(s). However, a variable fire regime including prescribed burns at different times of the year may alleviate the potential for undesired changes and maximize biodiversity.
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Ecological extinction and evolution in the brave new ocean
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The great mass extinctions of the fossil record were a major creative force that provided entirely new kinds of opportunities for the subsequent explosive evolution and diversification of surviving clades. Today, the synergistic effects of human impacts are laying the groundwork for a comparably great Anthropocene mass extinction in the oceans with unknown ecological and evolutionary consequences. Synergistic effects of habitat destruction, overfishing, introduced species, warming, acidification, toxins, and massive runoff of nutrients are transforming once complex ecosystems like coral reefs and kelp forests into monotonous level bottoms, transforming clear and productive coastal seas into anoxic dead zones, and transforming complex food webs topped by big animals into simplified, microbially dominated ecosystems with boom and bust cycles of toxic dinoflagel- late blooms, jellyfish, and disease. Rates of change are increasingly fast and nonlinear with sudden phase shifts to novel alternative community states. We can only guess at the kinds of organisms that will benefit from this mayhem that is radically altering the selective seascape far beyond the consequences of fishing or warming alone. The prospects are especially bleak for animals and plants compared with metabolically flexible microbes and algae. Halting and ultimately reversing these trends will require rapid and fundamental changes in fisheries, agricultural practice, and the emissions of green- house gases on a global scale.
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Ecological responses to recent climate change
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There is now ample evidence of the ecological impacts of recent climate change, from polar terrestrial to tropical marine environments. The responses of both flora and fauna span an array of ecosystems and organizational hierarchies, from the species to the community levels. Despite continued uncertainty as to community and ecosystem trajectories under global change, our review exposes a coherent pattern of ecological change across systems. Although we are only at an early stage in the projected trends of global warming, ecological responses to recent climate change are already clearly visible.
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Ecological Restoration in the Light of Ecological History
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Ecological history plays many roles in ecological restoration, most notably as a tool to identify and
characterize appropriate targets for restoration efforts. However, ecological history also reveals deep human
imprints on many ecological systems and indicates that secular climate change has kept many targets
moving at centennial to millennial time scales. Past and ongoing environmental changes ensure that many
historical restoration targets will be unsustainable in the coming decades. Ecological restoration efforts
should aim to conserve and restore historical ecosystems where viable, while simultaneously preparing to
design or steer emerging novel ecosystems to ensure maintenance of ecological goods and services.
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Ecologists Report Huge Storm Losses in China’s Forests
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From delicate orchids and magnolias to rare Chinese yews and Kwangtung pines, the flora of Guangdong
Nanling National Nature Reserve is considered so precious that ecologists call the reserve “a treasure trove of species.” But winter storms have reduced the biological hot spot to a splintered ruin. Snow, sleet, and ice laid waste to 90% of the 58,000- hectare reserve’s forests, says He Kejun, director of Guangdong Forestry
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Economic growth and the human lot
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1st paragraph: In 1974, Richard A. Easterlin, a coauthor of the work by Easterlin et al. (1) in PNAS, published a seminal article (2) that has generated a huge literature. It sought to explain why the happiness score in the United States (and elsewhere) had stayed roughly constant, whereas income per capita had trended up. This evidence has come to be known as the Easterlin Paradox. His explanation was that economic growth has a positive effect on happiness with other things being equal; however, it also raises aspirations, and aspirations have a negative effect. Aspirations are determined by society, particularly reference group income. The combination of these two effects gives rise to a Hedonic Treadmill.
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Economic growth as the limiting factor for wildlife conservation
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The concept of limiting factor includes the lack of welfare factors and the presence of decimating factors. Originally applied to populations and species, the concept may also be applied to wildlife in the aggregate. Because the decimating factor of economic growth eliminates welfare factors for virtually all imperiled species via the principle of competitive exclusion, economic growth may be classified as the limiting factor for wildlife conservation. The wildlife profes- sion has been virtually silent about this limiting factor, suggesting that the pro- fession has been laboring in futility. The public, exhorted by neoclassical economists and political leaders, supports economic growth as a national goal. To address the limiting factor for wildlife conservation, wildlife professionals need to become versed in the history of economic growth theory, neoclassical economic growth theory, and the alternative growth paradigm provided by ecological economics. The Wildlife Society should lead the natural resources professions in developing a position on economic growth.
carrying capacity, competitive exclusion, ecological economics, economic growth, limiting factor, neoclassical economics, niche breadth, steady state economy
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