|Abstracts on Global Climate Change|
Electron tomography of nanoparticle clusters: Implications for atmospheric lifetimes and radiative forcing of soot
van Poppel, LH Friedrich, H Spinsby, J Chung, SH Seinfeld, JH Buseck, PR
GEOPHYSICAL RESEARCH LETTERS 32:24 -
Nanoparticles are ubiquitous in nature. Their large surface areas and consequent chemical reactivity typically result in their aggregation into clusters. Their chemical and physical properties depend on cluster shapes, which are commonly complex and unknown. This is the first application of electron tomography with a transmission electron microscope to quantitatively determine the three-dimensional (3D) shapes, volumes, and surface areas of nanoparticle clusters. We use soot (black carbon, BC) nanoparticles as an example because it is a major contributor to environmental degradation and global climate change. To the extent that our samples are representative, we find that quantitative measurements of soot surface areas and volumes derived from electron tomograms differ from geometrically derived values by, respectively, almost one and two orders of magnitude. Global sensitivity studies suggest that the global burden and direct radiative forcing of fractal BC are only about 60% of the value if it is assumed that BC has a spherical shape.
Global warming is changing the dynamics of Arctic host-parasite systems
Kutz, SJ Hoberg, EP Polley, L Jenkins, EJ
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES 272:1581 2571-2576
Global climate change is altering the ecology of infectious agents and driving the emergence A disease in people, domestic animals, and wildlife. We present a novel, empirically based, predictive model for the impact of climate warming on development rates and availability of an important parasitic nematode of muskoxen in the Canadian Arctic, a region that is particularly vulnerable to climate change. Using this model, we show that warming in the Arctic may have already radically altered the transmission dynamics of this parasite, escalating infection pressure for muskoxen, and that this trend is expected to continue. This work establishes a foundation for understanding responses to climate change of other host-parasite systems, in the Arctic and globally.
Earlier winter wheat heading dates and warmer spring in the US Great Plains
Hu, Q Weiss, A Feng, S Baenziger, PS
AGRICULTURAL AND FOREST METEOROLOGY 135:1-4 284-290
Phenological change of plants is an indication of local and regional climate change, independent of the instrumentation records and associated bias/error. Although some phenological changes have been identified for native and perennial species and used to infer climate change in various regions of the world, little has been known for changes in agricultural plants/crops. In this study, heading or flowering dates of winter wheat cultivar Kharkof are examined from 70 years of data at six locations in the U.S. Great Plains. Results indicate a consistent trend of earlier heading or flowering dates across all sites, but rates of the trend differ (from 0.8 to 1.8 days per 10-year). Because the heading or flowering date is governed primarily by temperatures, the earlier heading or flowering dates indicate warming temperatures in the spring. Further examinations reveal increase in spring daily minimum temperatures. Findings of this study add a diverse species to the plant community for detecting the “fingerprint” of regional and global climate change. (c) 2006 Elsevier B.V. All rights reserved.
Fish use and size of eelgrass meadows in southeastern Alaska: A baseline for long-term assessment of biotic change
Johnson, SW Thedinga, JF
NORTHWEST SCIENCE 79:2-3 141-155
Eelgrass meadows at six sites in southeastern Alaska were sampled for fish assemblages and mapped to establish a baseline of information for long-term assessment of biotic change. All sites were sampled in spring 2001, 2002, and 2003: four of the sites were also sampled in winter 2003. A total of 44 seine hauls from all sampling periods yielded 58,902 fish comprising 45 species. Fish abundance in spring differed significantly among sites but not among years. The most abundant commercially important or forage fish species captured were chum salmon, Pacific herring. pink salmon, coho salmon, and Pacific sand lance: mean size of each of these species was <= 100 mm FL. For those sites sampled seasonally in 2003, fish were significantly more abundant in spring than in winter. At each site, three different species accounted for most (>= 69%) of the total catch. Size of eelgrass meadows varied annually; maximum percent change in area ranged from -13% to +27%. Eelgrass density ranged from 336 shoots/m(2) to 1,544 shoots/m(2), and dry biomass ranged from 36 g/m(2) to 71 g/m(2). Periodic re-sampling of the eelgrass sites established in this study will allow resource managers to track long-term and large-scale changes in fish communities and habitat that may result from shoreline development or global climate change.
Salt lakes in Australia: present problems and prognosis for the future
HYDROBIOLOGIA 552: 1-15
Australia is a land of salt lakes and despite low human population density, many lakes are adversely impacted by a range of factors. Secondary salinisation is the most pernicious force degrading lakes, especially in south-west Western Australia where up to 30% of the landscape is predicted to be affected. Mining also impinges on many salt lakes in this state, mainly through the dewatering of saline groundwater. Exploitation of groundwater for irrigation caused some lakes in Victoria, Australia, to dry, especially the significant Red Rock Complex. Global climate change will result in new water balances in endorheic lakes, with most having less water, particularly the seasonal lakes of southern Australia. This has already happened in Lake Corangamite, Victoria, but the prime reason is diversion of inflowing floodwater. Consequently, the lake has retreated and become salinised compromising its status as a Ramsar site. Various other lakes suffer from enhanced sedimentation, have introduced biota or their catchments are being disturbed to their detriment. Enlightened management should be able to maintain some important lakes in an acceptable condition, but, for most others, the future is bleak.
Marine research in the Latitudinal Gradient Project along Victoria Land, Antarctica
Berkman, PA Cattaneo-Vietti, R Chiantore, M Howard-Williams, C Cummings, V Kvitek, R
SCIENTIA MARINA 69: Suppl. 2 57-63
This paper describes the conceptual framework of the Latitudinal Gradient Project that is being implemented by the New Zealand, Italian and United States Antarctic programmes along Victoria Land, Antarctica, from 72 degrees S to 86 degrees S. The purpose of this interdisciplinary research project is to assess the dynamics and coupling of marine and terrestrial ecosystems in relation to global climate variability. Preliminary data about the research cruises from the R/V “Italica” and R/V “Tangaroa” along the Victoria Land Coast in 2004 are presented. As a global climate barometer, this research along Victoria Land provides a unique framework for assessing latitudinal shifts in ‘sentinel’ environmental transition zones, where climate changes have an amplified impact on the phases of water.
Global assessment of coral bleaching and required rates of adaptation under climate change
Donner, SD Skirving, WJ Little, CM Oppenheimer, M Hoegh-Guldberg, O
GLOBAL CHANGE BIOLOGY 11:12 2251-2265
Elevated ocean temperatures can cause coral bleaching, the loss of colour from reef-building corals because of a breakdown of the symbiosis with the dinoflagellate Symbiodinium. Recent studies have warned that global climate change could increase the frequency of coral bleaching and threaten the long-term viability of coral reefs. These assertions are based on projecting the coarse output from atmosphere-ocean general circulation models (GCMs) to the local conditions around representative coral reefs. Here, we conduct the first comprehensive global assessment of coral bleaching under climate change by adapting the NOAA Coral Reef Watch bleaching prediction method to the output of a low- and high-climate sensitivity GCM. First, we develop and test algorithms for predicting mass coral bleaching with GCM-resolution sea surface temperatures for thousands of coral reefs, using a global coral reef map and 1985-2002 bleaching prediction data. We then use the algorithms to determine the frequency of coral bleaching and required thermal adaptation by corals and their endosymbionts under two different emissions scenarios. The results indicate that bleaching could become an annual or biannual event for the vast majority of the world’s coral reefs in the next 30-50 years without an increase in thermal tolerance of 0.2-1.0 degrees C per decade. The geographic variability in required thermal adaptation found in each model and emissions scenario suggests that coral reefs in some regions, like Micronesia and western Polynesia, may be particularly vulnerable to climate change. Advances in modelling and monitoring will refine the forecast for individual reefs, but this assessment concludes that the global prognosis is unlikely to change without an accelerated effort to stabilize atmospheric greenhouse gas concentrations.
Consortium for Atlantic Regional Assessment: Information tools for community adaptation to changes in climate or land use
Dempsey, R Fisher, A
RISK ANALYSIS 25:6 1495-1509
To inform local and regional decisions about protecting short-term and long-term quality of life, the Consortium for Atlantic Regional Assessment (CARA) provides data and tools (for the northeastern United States) that can help decisionmakers understand how outcomes of their decisions could be affected by potential changes in both climate and land use. On an interactive, user-friendly website, CARA has amassed data on climate (historical records and future projections for seven global climate models), land cover, and socioeconomic and environmental variables, along with tools to help decisionmakers tailor the data for their own decision types and locations. CARA Advisory Council stakeholders help identify what information and tools stakeholders would find most useful and how to present these: they also provide in-depth feedback for subregion case studies. General lessons include: (1) decisionmakers want detailed local projections for periods short enough to account for extreme events, in contrast to the broader spatial and temporal observations and projections that are available or consistent at a regional level; (2) stakeholders will not use such a website unless it is visually appealing and easy to find the information they want; (3) some stakeholders need background while others want to go immediately to data, and some want maps while others want text or tables. This article also compares what has been learned across case studies of Cape May County, New Jersey, Cape Cod, Massachusetts, and Hampton Roads, Virginia, relating specifically to sea-level rise. Lessons include: (1) groups can be affected differently by physical dangers compared with economic dangers; (2) decisions will differ according to decision makers’ preferences about waiting and risk tolerance; (3) future scenarios and maps can help assess the impacts of dangers to emergency evacuation routes, homes, and infrastructure, and the natural environment; (4) residents’ and decisionmakers’ perceptions are affected by information about potential local impacts from global climate change.
Fossil fuels in the 21st century
AMBIO 34:8 621-627
An overview of the importance of fossil fuels in supplying the energy requirements of the 21st century, their future supply, and the impact of their use on global climate is presented. Current and potential alternative energy sources are considered. It is concluded that even with substantial increases in energy derived from other sources, fossil fuels will remain a major energy source for much Of the 21st century and the sequestration of CO2 will be an increasingly important requirement.
Fates of eroded soil organic carbon: Mississippi basin case study
Smith, SV Sleezer, RO Renwick, WH Buddemeier, R
ECOLOGICAL APPLICATIONS 15:6 1929-1940
We have developed a mass balance analysis of organic carbon (OC) across the five major river subsystems of the Mississippi (MS) Basin (an area of 3.2 X 10(6) km(2)) This largely agricultural landscape undergoes a bulk soil erosion rate of similar to 480 t center dot km(-2)center dot yr(-1) (similar to 1500 x 10(6) t/yr, across the MS Basin), and a,soil organic carbon (SOC) erosion rate of similar to 7 t center dot km(-2 center dot)yr(-1) (similar to 22 x 10(6) t/yr). Erosion translocates upland SOC to alluvial deposits, water impoundments, and the ocean. Soil erosion is generally considered to be a net source of CO2 release to the atmosphere in global budgets. However, our results indicate that SOC erosion and relocation of soil apparently can reduce the net SOC oxidation rate of the original upland SOC while promoting neu replacement of eroded SOC in upland soils that were eroded. Soil erosion at the MS Basin scale is, therefore, a net CO2 sink rather than a source.
Analysing countries’ contribution to climate change: scientific and policy-related choices
den Elzen, M Fuglestvedt, J Hohne, N Trudinger, C Lowe, J Matthews, B Romstad, B de Campos, CP Andronova, N
ENVIRONMENTAL SCIENCE & POLICY 8:6 614-636
This paper evaluates the influence of different policy-related and scientific choices on the calculated regional contributions to global climate change (the “Brazilian Proposal”). Policy-related choices include the time period of emissions, the mix of greenhouse gases and different indicators of climate change impacts. The scientific choices include historical emissions and model representations of the climate system. We generated and compared results of several simple climate models. We find that the relative contributions of different nations to global climate change-from emissions of greenhouse gases alone-are quite robust, despite the varying model complexity and differences in calculated absolute changes. For the default calculations, the average calculated contributions to the global mean surface temperature increase in 2000 are about 40% from OECD, 14% from Eastern Europe and Former Soviet Union, 24% from Asia and 22% from Africa and Latin America. Policy-related choices, such as time period of emissions, climate change indicator and gas mix generally have larger influence on the results than scientific choices. More specifically, choosing a later attribution start date (1990 instead of 1890) for historical emissions, decreases the contributions of regions that started emitting early, such as the OECD countries by 6 percentage points, whereas it increases the contribution of late emitters such as Asia by 8 percentage points. However, only including the fossil CO, emissions instead of the emissions of all Kyoto gases (fossil and land use change), increases the OECD contributions by 21 percentage points and decreases the contribution of Asia by 14 percentage points. (c) 2005 Elsevier Ltd. All rights reserved.
Seductive simulations? Uncertainty distribution around climate models
SOCIAL STUDIES OF SCIENCE 35:6 895-922
This paper discusses the distribution of certainty around General Circulation Models (GCMs) - computer models used to project possible global climatic changes due to human emissions of greenhouse gases. It examines the trope of distance underpinning Donald MacKenzie’s concept of ‘certainty trough’, and calls for a more multi-dimensional and dynamic conceptualization of how uncertainty is distributed around technology. The certainty trough describes the level of certainty attached to particular technoscientific constructions as distance increases from the site of knowledge production, and proposes that producers of a given technology and its products are the best judges of their accuracy. Processes and dynamics associated with GCM modeling challenge the simplicity of the certainty trough diagram, mainly because of difficulties with distinguishing between knowledge producers and users, and because GCMs involve multiple sites of production. This case study also challenges the assumption that knowledge producers always are the best judges of the accuracy of their models. Drawing on participant observation and interviews with climate modelers and the atmospheric scientists with whom they interact, the study discusses how modelers, and to some extent knowledge producers in general, are sometimes less able than some users to identify shortcomings of their models.
American risk perceptions: Is climate change dangerous?
RISK ANALYSIS 25:6 1433-1442
Public risk perceptions can fundamentally compel or constrain political, economic, and social action to address particular risks. Public support or opposition to climate policies (e.g., treaties, regulations, taxes, subsidies) will be greatly influenced by public perceptions of the risks and dangers posed by global climate change. This article describes results from a national study (2003) that examined the risk perceptions and connotative meanings of global warming in the American mind and found that Americans perceived climate change as a moderate risk that will predominantly impact geographically and temporally distant people and places. This research also identified several distinct interpretive communities, including naysayers and alarmists, with widely divergent perceptions of climate change risks. Thus, “dangerous” climate change is a concept contested not only among scientists and policymakers, but among the American public as well.
A conceptual model of ecological interactions in the mangrove estuaries of the Florida Everglades
Davis, SM Childers, DL Lorenz, JJ Wanless, HR Hopkins, TE
WETLANDS 25:4 832-842
A brackish water ecotone of coastal bays and lakes, mangrove forests, salt marshes, tidal creeks, and upland hammocks separates Florida Bay, Biscayne Bay, and the Gulf of Mexico from the freshwater Everglades. The Everglades mangrove estuaries are characterized by salinity gradients that vary spatially with topography and vary seasonally and inter-annually with rainfall, tide, and freshwater flow from the Everglades. Because of their location at the lower end of the Everglades drainage basin, Everglades mangrove estuaries have been affected by upstream water management practices that have altered the freshwater heads and flows and that affect salinity gradients. Additionally, interannual variation in precipitation patterns, particularly those caused to El Nino events, control freshwater inputs and salinity dynamics in these estuaries. Two major external drivers on this system are water management activities and global climate change. These drivers lead to two major ecosystem stressors: reduced freshwater flow volume and duration, and sea-level rise. Major ecological attributes include mangrove forest production, soil accretion, and resilience; coastal lake submerged aquatic vegetation; resident mangrove fish populations; wood stork (Mycteria americana) and roseate spoonbill (Platelea ajaja) nesting colonies; and estuarine crocodilian populations. Causal linkages between stressors and attributes include coastal transgression, hydroperiods, salinity gradients, and the “white zone” freshwater/estuarine interface. The functional estuary and its ecological attributes, as influenced by sea level and freshwater flow, must be viewed as spatially dynamic, with a possible near-term balancing of transgression but ultimately a long-term continuation of inland movement. Regardless of the spatio-temporal timing of this transgression, a salinity gradient supportive of ecologically functional Everglades mangrove estuaries will be required to maintain the integrity of the South Florida ecosystem.