Climate Science PDFs
Climate Science PDFs Collection
- Humans and Nature Duel Over the Next Decade’s Climate
- 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.
- WWF : A CLOSING WINDOW OF OPPORTUNITY - GLOBAL GREENHOUSE REALITY 2008
- Scientific evidence accumulating since the IPCC’s Fourth Assessment Report reveals that global warming is accelerating, at times far beyond projections outlined in earlier studies, including the latest IPCC Report. New modelling studies are providing updated and more detailed indications of the impacts of continued warming. The emerging evidence is that important aspects of climate change seem to have been underestimated and the impacts are being felt sooner. For example, early signs of change suggest that the less than 1°C of global warming that the world has experienced to date may have already triggered the first tipping point of the Earth’s climate system – a seasonally ice-free Arctic Ocean. This process could open the gates to rapid and abrupt climate change, rather than the gradual changes that have been projected so far.
- Phylogenetic and functional diversity in large carnivore assemblages
- Large terrestrial carnivores are important ecological components and promi- nent flagship species, but are often extinction prone owing to a combination of biological traits and high levels of human persecution. This study com- bines phylogenetic and functional diversity evaluations of global and continental large carnivore assemblages to provide a framework for conser- vation prioritization both between and within assemblages. Species-rich assemblages of large carnivores simultaneously had high phylogenetic and functional diversity, but species contributions to phylogenetic and func- tional diversity components were not positively correlated. The results further provide ecological justification for the largest carnivore species as a focus for conservation action, and suggests that range contraction is a likely cause of diminishing carnivore ecosystem function. This study high- lights that preserving species-rich carnivore assemblages will capture both high phylogenetic and functional diversity, but that prioritizing species within assemblages will involve trade-offs between optimizing contempor- ary ecosystem function versus the evolutionary potential for future ecosystem performance. Carnivora, predation, ecosystem function, conservation priorities, biodiversity
- Analysis of monotonic greening and browning trends from global NDVI time-series
- Remotely sensed vegetation indices are widely used to detect greening and browning trends; especially the global coverage of time-series normalized difference vegetation index (NDVI) data which are available from 1981. Seasonality and serial auto-correlation in the data have previously been dealt with by integrating the data to annual values; as an alternative to reducing the temporal resolution, we apply harmonic analyses and non-parametric trend tests to the GIMMS NDVI dataset (1981–2006). Using the complete dataset, greening and browning trends were analyzed using a linear model corrected for seasonality by subtracting the seasonal component, and a seasonal non-parametric model. In a third approach, phenological shift and variation in length of growing season were accounted for by analyzing the time-series using vegetation development stages rather than calendar days. Results differed substantially between the models, even though the input data were the same. Prominent regional greening trends identified by several other studies were confirmed but the models were inconsistent in areas with weak trends. The linear model using data corrected for seasonality showed similar trend slopes to those described in previous work using linear models on yearly mean values. The non-parametric models demonstrated the significant influence of variations in phenology; accounting for these variations should yield more robust trend analyses and better understanding of vegetation trends.
- Future climate change driven sea-level rise: secondary consequences from human displacement for island biodiversity
- Sea-level rise (SLR) due to global warming will result in the loss of many coastal areas. The direct or primary effects due to inundation and erosion from SLR are currently being assessed; however, the indirect or secondary ecological effects, such as changes caused by the displacement of human populations, have not been previously evaluated. We examined the potential ecological consequences of future SLR on >1,200 islands in the Southeast Asian and the Pacific region. Using three SLR scenarios (1, 3, and 6 m elevation, where 1 m approximates most predictions by the end of this century), we assessed the consequences of primary and secondary SLR effects from human displacement on habi- tat availability and distributions of selected mammal species. We estimate that between 3–32% of the coastal zone of these islands could be lost from primary effects, and consequently 8–52 million people would become SLR refugees. Assuming that inundated urban and intensive agricultural areas will be relocated with an equal area of habitat loss in the hinterland, we project that secondary SLR effects can lead to an equal or even higher percent range loss than primary effects for at least 10–18% of the sample mammals in a moderate range loss scenario and for 22–46% in a maximum range loss scenario. In addition, we found some species to be more vulnerable to secondary than primary effects. Finally, we found high spatial variation in vulnerability: species on islands in Oceania are more vulnerable to primary SLR effects, whereas species on islands in Indo-Malaysia, with potentially 7–48 million SLR refugees, are more vulnerable to secondary effects. Our findings show that primary and secondary SLR effects can have enormous consequences for human inhabitants and island biodiversity, and that both need to be incorporated into ecological risk assessment, conservation, and regional planning. Keywords: conservation priorities, extinction risk, global change, human migration, human settlements, Indo-Malaysia, insular biodiversity, range contractions, sea-level change
- Wild Pollinators Enhance Fruit Set of Crops Regardless of Honey Bee Abundance
- The diversity and abundance of wild insect pollinators have declined in many agricultural landscapes. Whether such declines reduce crop yields, or are mitigated by managed pollinators such as honey bees, is unclear. We found universally positive associations of fruit set with flower visitation by wild insects in 41 crop systems worldwide. In contrast, fruit set increased significantly with flower visitation by honey bees in only 14% of the systems surveyed. Overall, wild insects pollinated crops more effectively; an increase in wild insect visitation enhanced fruit set by twice as much as an equivalent increase in honey bee visitation. Visitation by wild insects and honey bees promoted fruit set independently, so pollination by managed honey bees supplemented, rather than substituted for, pollination by wild insects. Our results suggest that new practices for integrated management of both honey bees and diverse wild insect assemblages will enhance global crop yields.
- Vulnerability of terrestrial island vertebrates to projected sea-level rise
- Sea-level rise (SLR) from global warming may have severe consequences for biodiversity; however, a baseline, broad- scale assessment of the potential consequences of SLR for island biodiversity is lacking. Here, we quantify area loss for over 12 900 islands and over 3000 terrestrial vertebrates in the Pacific and Southeast Asia under three different SLR scenarios (1 m, 3 m and 6 m). We used very fine-grained elevation information, which offered >100 times greater spatial detail than previous analyses and allowed us to evaluate thousands of hitherto not assessed small islands. Depending on the SLR scenario, we estimate that 15–62% of islands in our study region will be completely inundated and 19–24% will lose 50–99% of their area. Overall, we project that between 1% and 9% of the total island area in our study region may be lost. We find that Pacific species are 2–3 times more vulnerable than those in the Indomalayan or Australasian region and risk losing 4–22% of range area (1–6 m SLR). Species already listed as threatened by IUCN are particularly vulnerable compared with non-threatened species. Under a simple area loss–species loss proportion- ality assumption, we estimate that 37 island group endemic species in this region risk complete inundation of their current global distribution in the 1 m SLR scenario that is widely anticipated for this century (and 118 species under 3 m SLR). Our analysis provides a first, broad-scale estimate of the potential consequences of SLR for island biodiver- sity and our findings confirm that islands are extremely vulnerable to sea-level rise even within this century. Keywords: climate change, conservation, endemic species, island biogeography, range contractions, sea-level rise, threatened species, vertebrates
- Pervasive Externalities at the Population, Consumption, and Environment Nexus
- Growing concerns that contemporary patterns of economic development are unsustainable have given rise to an extensive empirical literature on population growth, consumption increases, and our growing use of nature’s products and services. However, far less has been done to reach a theoretical understanding of the socio-ecological processes at work at the population- consumption-environment nexus. In this Research Article, we highlight the ubiquity of externalities (which are the unaccounted for consequences for others, including future people) of decisions made by each of us on reproduction, consumption, and the use of our natural environment. Externalities, of which the “tragedy of the commons” remains the most widely discussed illustration, are a cause of inefficiency in the allocation of resources across space, time, and contingencies; in many situations, externalities accentuate inequity as well. Here, we identify and classify externalities in consumption and reproductive decisions and use of the natural environment so as to construct a unified theoretical framework for the study of data drawn from the nexus. We show that externalities at the nexus are not self-correcting in the marketplace. We also show that fundamental nonlinearities, built into several categories of externalities, amplify the socio-ecological processes operating at the nexus. Eliminating the externalities would, therefore, require urgent collective action at both local and global levels.
- NWF:A Letter from Scientists to the United States Congress Urging Action to Address the Threats of Global Warming to Wildlife and Ecosystems
- “We write to you to convey our sense of urgency. Global warming is already causing serious damage and disruptions to wildlife and ecosystems, and reliable projections call for significant additional damage and disruptions. To fulfill the nation’s longstanding commitment to conserving abundant wildlife and healthy ecosystems for future generations, Congress must craft legislation that greatly reduces greenhouse gas pollution and generates substantial dedicated funding to protect and restore wildlife and ecosystems harmed by global warming.” – 612 Scientific Experts Concerned About Global Warming and Its Effect on Wildlife and Natural Resources
- Social Science at the Wildland-Urban Interface: a Compendium of Research Results to Create Fire-Adapted Communities
- Over the past decade, a growing body of research has been conducted on the human dimensions of wildland fire. Building on a relatively small number of foundational studies, this research now addresses a wide range of topics including mitigation activities on private lands, fuels reduction treatments on public land, community impacts and resident behaviors during fire, acceptance of approaches to postfire restoration and recovery, and fire management policy and decisionmaking. As this research has matured, there has been a recognition of the need to examine the full body of resulting literature to synthesize disparate findings and identify lessons learned across studies. These lessons can then be applied to fostering fire-adapted communities—those communities that understand their risk and have taken action to mitigate their vulnerability and increase resilience. This compendium of social science research findings related to fire-adapted communities has resulted from a project funded by the Joint Fire Science Program (JFSP). As part of these efforts, the research team reviewed more than 200 publications of research results. Then the team convened a workshop with 16 scientists with extensive experience in the human dimensions of fire management issues. Workshop participants evaluated collective findings and discussed their application to support fire management activities. In addition to this compendium, project outputs were: 1) a synthesis of published literature specific to eight management questions identified by the JFSP, 2) a list of future research needs, 3) a bibliography, including abstracts, with accompanying subject area guide, and 4) a video featuring the experiences of agency personnel and community leaders in successful collaborative fire planning settings. This video is accompanied by a field guide for use by agency managers to more effectively participate in building fire-safe communities. In the sections that follow, we describe our approach to completing this review and present key findings from the literature. Our discussion is organized around five major topical areas: 1) homeowner/community mitigation, 2) public acceptance of fuels treatments on public lands, 3) homeowner actions during a fire, 4) postfire response and recovery, and 5) wildland fire policy and planning. The compendium concludes with a presentation of management implications and a bibliography of all material in this review.
- Evaluating the Effects and Effectiveness of Post-fire Seeding Treatments in Western Forests
- Key Findings• In studies that evaluated soil erosion in seeded versus unseeded controls, 78 percent revealed that seeding did not reduce erosion relative to unseeded controls. Even when seeding significantly increased vegetative cover, there was insufficient plant cover to stabilize soils within the first two years after fire. •Sixty percent of the studies reported that seeding deterred native plant recovery in the short-term. •Out of 11 papers that evaluated the ability of seeding to curtail non-native plant species invasions, 54 percent stated that seeding treatments were effective and 45 percent stated they were ineffective.• Forty papers and 67 Burned Area Reports dated between 1970 and 2006 revealed an increased use of native species and annual cereal grains/hybrids during seeding treatments over time, with native species dominating seed mixes. • From 2000 to 2007, total Burned Area Emergency Response (BAER) seeding expenditures have increased substantially, reaching an average of $3.3 million per year—a 192 percent increase compared to the average spent over the previous 30 years.
- The rebound effect is overplayed
- Increasing energy efficiency brings emissions savings. Claims that it backfires are a distraction, say Kenneth Gillingham and colleagues.
- The timing of climate change
- 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.
- Integrated assessment of global water scarcity over the 21st century under multiple climate change mitigation policies
- 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
- TOO EARLY TO TELL, OR TOO LATE TO RESCUE? ADAPTIVE MANAGEMENT UNDER SCRUTINY
- “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.
- Adaptive management of biological systems: A review
- 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’’.
- Afforestation Effects on Soil Carbon Storage in the United States: A Synthesis
- 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.
- Trees on farms: Tackling the triple challenge of 07 mitigation, adaptation and food security
- 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.
- AGU: Human-induced climate change requires urgent action.
- 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.
- A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests
- 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
