ALBERT

Beschreibung: In the future, Earth will be warmer, precipitation events will be more extreme, global mean sea level will rise, and many arid and semi-arid regions will be drier. Human modifications of landscapes will also occur at an accelerated rate as developed areas increase in size and population density. We now have gridded global forecasts, being continually improved, of the climatic and land-use changes (C&LUC) that are likely to occur in the coming decades. Aside from a few exceptions, however, consensus forecasts do not exist for how these C&LUC will likely impact Earth-surface processes and hazards. In some cases we have the tools to forecast the geomorphic responses to likely future C&LUC. Fully exploiting these models and utilizing these tools will require close collaboration among Earth-surface scientists and Earth-system modelers. This paper assesses the state-of-the-art tools and data that are being used or could be used to forecast changes in the state of Earth's surface as a result of likely future C&LUC. We also propose strategies for filling key knowledge gaps, emphasizing where additional basic research and/or collaboration across disciplines is necessary. The main body of the paper addresses cross-cutting issues, including the importance of nonlinear/threshold-dominated interactions among topography, vegetation, and sediment transport, as well as the importance of alternate stable states and extreme, rare events for understanding and forecasting Earth-surface response to C&LUC. Five supplements delve into different scales or process zones (global-scale assessments, and fluvial, aeolian, glacial/periglacial, and coastal process zones) in detail.

Beschreibung: Coastal responses to sea level rise (SLR) include inundation of wetlands, increased shoreline erosion, and increased flooding during storm events. Hydrodynamic parameters such as tidal ranges, tidal prisms, tidal asymmetries, increased flooding depths and inundation extents during storm events respond non-additively to SLR. Coastal morphology continually adapts towards equilibrium as sea levels rise, inducing changes in the landscape. Marshes may struggle to keep pace with SLR and rely on sediment accumulation and the availability of suitable uplands for migration. Whether hydrodynamic, morphologic or ecologic, the impacts of SLR are inter-related. To plan for changes under future sea levels, coastal managers need information and data regarding the potential effects of SLR to make informed decisions for managing human and natural communities. This review examines previous studies that have accounted for the dynamic, nonlinear responses of hydrodynamics, coastal morphology and marsh ecology to SLR by implementing more complex approaches rather than the simplistic “bathtub” approach. These studies provide an improved understanding of the dynamic effects of SLR on coastal environments and contribute to an overall paradigm shift in how coastal scientists and engineers approach modeling the effects of SLR, transitioning away from implementing the “bathtub” approach. However, it is recommended that future studies implement a synergetic approach that integrates the dynamic interactions between physical and ecological environments to better predict the impacts of SLR on coastal systems.

Beschreibung: Water vapor is the most important greenhouse gas in the atmosphere although changes in carbon dioxide constitute the “control knob” for surface temperatures. While the latter fact is well recognized, resulting in extensive spaceborne and ground based measurement programs for carbon dioxide [et~al.(1996), Chin, and Whorf, et~al.(2009), Suto, Nakajima, and Hamazaki, et~al.(2014), Cai, Yang, Zheng, Duan, and Lu], the need for an accurate characterization of the long-term changes in upper tropospheric and lower stratospheric (UTLS) water vapor has not yet resulted in sufficiently extensive long-term international measurement programs (although first steps have been taken). Here we argue for the implementation of a, long-term balloon-borne measurement program for UTLS water vapor covering the entire globe that likely will have to be sustained for hundreds of years.

Beschreibung: Words are integral to thinking and communicating. Words also carry old baggage. The Anthropocene necessitates new thinking and communication at the human-nature interface. Words like progress, natural, and thresholds are pervasive in both scientific and policy discourse, but carry baggage that will likely slow understanding of the Anthropocene and appropriate adaptation. The dynamic systems thinking with emergent properties of ecology needs to replace the efficiency and growth framework of economics. Diversity and resilience are productive and less historically burdened words.

Beschreibung: Though climate models exhibit broadly similar agreement on key long-term trends, they have significant temporal and spatial differences due to inter-model variability. Such variability should be considered when using climate models to project the future marine Arctic. Here we present multiple scenarios of 21 st -century Arctic marine access as driven by sea ice output from 10 CMIP5 models known to represent well the historical trend and climatology of Arctic sea ice. Optimal vessel transits from North America and Europe to the Bering Strait are estimated for two periods representing early-century (2011–2035) and mid-century (2036–2060) conditions under two forcing scenarios (RCP 4.5/8.5), assuming Polar Class 6 and open-water vessels with medium and no ice-breaking capability, respectively. Results illustrate that projected shipping viability of the Northern Sea Route (NSR) and Northwest Passage (NWP) depends critically on model choice. The eastern Arctic will remain the most reliably accessible marine space for trans-Arctic shipping by mid-century, while outcomes for the NWP are particularly model-dependent. Omitting three models (GFDL-CM3, MIROC-ESM-CHEM, MPI-ESM-MR), our results would indicate minimal NWP potential even for routes from North America. Furthermore, the relative importance of the NSR will diminish over time as the number of viable central Arctic routes increases gradually toward mid-century. Compared to vessel class, climate forcing plays a minor role. These findings reveal the importance of model choice in devising projections for strategic planning by governments, environmental agencies, and the global maritime industry.

Beschreibung: Successful climate change mitigation will involve not only technological innovation, but innovation in how we understand the societal and individual behaviors that shape the demand for energy services. Traditionally, individual energy behaviors have been described as a function of utility optimization and behavioral economics, with price restructuring as the dominant policy lever. Previous research at the macro-level has identified economic activity, power generation and technology, and economic role as significant factors that shape energy use. However, most demand models lack basic contextual information on how dominant social phenomenon, the changing demographics of cities, and the socio-cultural setting within which people operate, affect energy decisions and use patterns. Here we use high-quality Suomi-NPP VIIRS nighttime environmental products to: (1) observe aggregate human behavior through variations in energy service demand patterns during the Christmas and New Year's season and the Holy Month of Ramadan; and (2) demonstrate that patterns in energy behaviors closely track socio-cultural boundaries at the country, city, and district-level. These findings indicate that energy decision-making and demand is a socio-cultural process as well as an economic process, often involving a combination of individual price-based incentives and societal-level factors. While nighttime satellite imagery has been used to map regional energy infrastructure distribution, tracking daily dynamic lighting demand at three major scales of urbanization is novel. This methodology can enrich research on the relative importance of drivers of energy demand and conservation behaviors at fine scales. Our initial results demonstrate the importance of seating energy demand frameworks in a social context.

Beschreibung: Despite advances in our understanding of the processes driving contemporary sea level rise, the stability of the Antarctic ice sheets and their contribution to sea level under projected future warming remains uncertain due to the influence of strong ice-climate feedbacks. Disentangling these feedbacks is key to reducing uncertainty. Here we present a series of climate system model simulations that explore the potential effects of increased West Antarctic Ice Sheet (WAIS) meltwater flux on Southern Ocean dynamics. We project future changes driven by sectors of the WAIS, delivering spatially and temporally variable meltwater flux into the Amundsen, Ross and Weddell embayments over future centuries. Focusing on the Amundsen Sea sector of the WAIS over the next 200 years, we demonstrate that the enhanced meltwater flux rapidly stratifies surface waters, resulting in a significant decrease in the rate of Antarctic Bottom Water (AABW) formation. This triggers rapid pervasive ocean warming (〉1°C) at depth due to advection from the original site(s) of meltwater input. The greatest warming predicted along sectors of the ice sheet that are highly sensitized to ocean forcing, creating a feedback loop that could enhance basal ice shelf melting and grounding line retreat. Given that we do not include the effects of rising CO 2 - predicted to further reduce AABW formation - our experiments highlight the urgent need to develop a new generation of fully-coupled ice sheet climate models, that include feedback mechanisms such as this, to reduce uncertainty in climate and sea level projections.

Beschreibung: Key Points Demographic limitations involve acute aspects of public policy. Demographic controls cannot be effectively implemented under current Western values. Traditions of social freedom will have to be altered.

Beschreibung: Key Points Liberal values in rich democracies are threatened by population growth in poor countries. The most likely repressive policy response will be barriers to immigration. Fertility reduction in high-fertility countries requires increased access to contraception.

Beschreibung: The multi-model ensemble of the Coupled Model Intercomparison Project, Phase 5 (CMIP5) synthesizes the latest research in global climate modeling. The freshwater system on land, particularly runoff, has so far been of relatively low priority in global climate models, despite the societal and ecosystem importance of freshwater changes, and the science and policy needs for such model output on drainage basin scales. Here we investigate the implications of CMIP5 multi-model ensemble output data for the freshwater system across a set of drainage basins in the Northern hemisphere. Results of individual models vary widely, with even ensemble mean results differing greatly from observations and implying unrealistic long-term systematic changes in water storage and level within entire basins. The CMIP5 projections of basin-scale freshwater fluxes differ considerably more from observations and among models for the warm-temperate study basins than for the Arctic and cold-temperate study basins. In general, the results call for concerted research efforts and model developments for improving the understanding and modeling of the freshwater system and its change drivers. Specifically, more attention to basin-scale water flux analyses should be a priority for climate model development, and an important focus for relevant model-based advice for adaptation to climate change.

Beschreibung: We explore potential changes in Greenland ice sheet form and flow associated with increasing ice temperatures and relaxing effective ice viscosities. We define "thermal-viscous collapse" as a transition from the polythermal ice sheet temperature distribution characteristic of the Holocene to temperate ice at the pressure-melting-point and associated lower viscosities. The conceptual model of thermal-viscous collapse we present is dependent on: (i) sufficient energy available in future meltwater runoff, (ii) routing of meltwater to the bed of the ice sheet interior, and (iii) efficient energy transfer from meltwater to the ice. While we do not attempt to constrain the probability of thermal-viscous collapse, it appears thermodynamically plausible to warm the deepest 15 % of the ice sheet, where the majority of deformational shear occurs, to the pressure-melting-point within five centuries. First-order numerical modelling of an end-member scenario, in which prescribed ice temperatures are warmed at an imposed rate of 0.05 K/a, infers a decrease in ice sheet volume of 5 ± 2 % within five centuries of initiating collapse. This is equivalent to a cumulative sea level rise contribution of 33 ± 18 cm. The vast majority of the sea level rise contribution associated with thermal-viscous collapse, however, would likely be realized over subsequent millennia.

Beschreibung: We report on a detailed time series analysis of long total column ozone (TO) records based on multi-satellite observations of daily resolution. We concentrate on three geographic latitudes over and around the Antarctic area, specifically on three circles at 58.5° S, 59.5°S, and 79.5°S. Almost continuous observations are available at the two former latitudes, however data are lacking during the polar winter periods at 79.5°S, because the measurement technique requires sunlight. The methodology is motivated by level-crossing statistics, where subsets of the records above or below particular threshold levels are evaluated. Long term trend reversal at around the turn of the century is already detectable for low TO levels in the raw time series in the “ozone hole” region (79.5°S). In order to overcome the apparent non-stationarities of the time series, we determined daily TO differences (ΔTO) belonging to the same geographic longitudes between the different latitudinal circles. The result is a stable, stationary behavior for small (absolute) ΔTO values in the period January-February-March without any significant detectable trends. The high absolute value ΔTO subsets (September-October-November) indicate a robust trend reversal in the middle of the 1990s. The observed trend reversal in the total column ozone time series is consistent with the temporal development of the stratospheric halogen loading. However, a close correspondence of ozone and halogen turnaround years is not expected because of the statistical uncertainties in the determination of the ozone turnaround, and the many factors contributing to ozone depletion processes.

Beschreibung: Historical examples of demographic change, in China, Italy, Nigeria, Utah, Easter Island, and elsewhere, together with simple mathematics and biological principles, show that stabilizing world population before it is limited by food supply will be more difficult than is generally appreciated. United Nations population projections are wrong because they assume, in spite of the absence of necessary feedbacks, that all nations will converge rapidly to replacement-level fertility and thereafter remain at that level. Education of women and provision of contraceptives have caused dramatic reductions in fertility, but many groups, including some that are well-educated, maintain high fertility. Small groups with persistent high fertility can grow to supplant low-fertility groups, resulting in continued growth of the total population. The global average fertility rate could rise even if each country's fertility rate is falling. In some low-fertility European countries where deaths exceed births, the population continues to grow because of immigration. Producing more than two offspring is normal for all animal species with stable populations, because their populations are limited by resources or predation rather than birth control. It may therefore be appropriate to view the growth of human population as the result not of excess fertility but rather of excess food.

Beschreibung: Tides exert a major control on the coastal zone by influencing high sea levels and coastal flooding, navigation, sediment dynamics and ecology. Therefore, any changes to tides have wide ranging and important implications. In this paper, we uniquely assess secular changes in 15 regularly used tidal levels (five high water, five low water and five tidal ranges), which have direct practical applications. Using sea level data from 220 tide gauge sites, we found changes have occured in all analysed tidal levels in many parts of the world. For the tidal levels assessed, between 36% and 63% of sites had trends significantly different (at 95% confidence level) from zero. At certain locations, the magnitude of the trends in tidal levels were similar to trends in mean sea level over the last century, with observed changes in tidal range and high water levels of over 5mm/yr and 2mm/yr respectively. More positive than negative trends were observed in tidal ranges and high water levels, and vice versa for low water levels. However we found no significant correlation between trends in mean sea level and any tidal levels. Spatially coherent trends were observed in some regions, including the north-east Pacific, German Bight and Australasia, and we also found that differences in trends occur between different tidal levels. This implies that analysing different tidal levels is important. Because changes in the tide are widespread and of similar magnitude to mean sea level rise at a number sites, changes in tides should be considered in coastal risk assessments.

Beschreibung: How climate controls hurricane variability has critical implications for society but is not well understood. In part, our understanding is hampered by the short and incomplete observational hurricane record. Here we present a synthesis of intense-hurricane activity from the western North Atlantic over the past two millennia, which is supported by a new, exceptionally well-resolved record from Salt Pond, Massachusetts (USA). At Salt Pond, three coarse grained event beds deposited in the historical interval are consistent with severe hurricanes in 1991 (Bob), 1675, and 1635 CE, and provide modern analogs for thirty-two other prehistoric event beds. Two intervals of heightened frequency of event bed deposition between 1400 and 1675 CE (10 events) and 150 and 1150 CE (23 events), represent the local expression of coherent regional patterns in intense-hurricane-induced event beds. Our synthesis indicates that much of the western North Atlantic appears to have been active between 250 and 1150 CE, with high levels of activity persisting in the Caribbean and Gulf of Mexico until 1400 CE. This interval was one with relatively warm sea surface temperatures in the main development region. A shift in activity to the North American east coast occurred ca. 1400 CE, with more frequent severe hurricane strikes recorded from The Bahamas to New England between 1400 and 1675 CE. A warm sea surface temperature anomaly along the western North Atlantic, rather than within the main development region, likely contributed to the later active interval being restricted to the east coast.

Beschreibung: This study performs high-spatial-resolution (12 km) Weather Research and Forecasting (WRF) simulations over a very large domain (7200 km × 6180 km, covering much of North America) to explore changes in mean and extreme precipitation in the mid and late 21st century under Representative Concentration Pathways 4.5 (RCP 4.5) and 8.5 (RCP 8.5). We evaluate WRF model performance for a historical simulation and future projections, applying the Community Climate System Model version 4 (CCSM4) as initial and boundary conditions with and without a bias correction. WRF simulations using boundary and initial conditions from both versions of CCSM4 show smaller biases versus evaluation data sets than does CCSM4 over western North America. WRF simulations also improve spatial details of precipitation over much of North America. However, driving the WRF with the bias-corrected CCSM4 does not always reduce the bias. WRF-projected changes in precipitation include decreasing intensity over the U.S. Southwest, increasing intensity over the eastern United Sates and most of Canada, and an increase in the number of days with heavy precipitation over much of North America. Projected precipitation changes are more evident in the late 21st century than the mid 21st century, and they are more evident under RCP 8.5 than RCP 4.5 in the late 21st century. Uncertainties in the projected changes in precipitation due to different warming scenarios are non-negligible. Differences in summer precipitation changes between WRF and CCSM4 are significant over most of the United States.

Beschreibung: In the context of climate change, both climate researchers and decision-makers deal with uncertainties, but these uncertainties differ in fundamental ways. They stem from different sources, cover different temporal and spatial scales, might or might not be reducible or quantifiable, and are generally difficult to characterize and communicate. Hence, for adaptation strategies and planning to progress, mutual understanding between current and future climate researchers and decision-makers needs to evolve. Iterative two-way dialogue can help to improve the decision-making process and bridge current top-down and bottom-up approaches. One way to cultivate such interactions is by providing venues for these actors to interact and exchange about the uncertainties they face. We use a workshop-seminar series including academic researchers, students, and decision-makers as an opportunity to put this idea into practice and evaluate it. Seminars, case studies and a round table allowed participants to reflect upon and experiment with uncertainties. An opinion survey conducted before and after the workshop-seminar series allowed us to qualitatively evaluate its influence on the participants. We find that the event stimulated new perspectives on communication processes and research priorities, and suggest that similar events may ultimately contribute to the mid-term goal of improving support for decision-making in a changing climate. Therefore, we recommend integrating interdisciplinary bridging events into university curriculum with the goal of exposing researchers, decision-makers and students to these concepts.

Beschreibung: Key Points There are historical antecedents for the Anthropocene idea. The Anthropocene idea has roots in social theory. Rousseau's social theory anticipates the Anthropocene idea.

Beschreibung: The impacts of climate change on Small Island Developing States (SIDS) are leading to discussions regarding decision-making about the potential need to migrate. Despite the situation being well-documented, with many SIDS aiming to raise the topic to prominence and to take action for themselves, limited support and interest has been forthcoming from external sources. This paper presents, analyzes and critiques a decision-making flowchart to support actions for SIDS dealing with climate change linked migration. The flowchart contributes to identifying the pertinent topics to consider and the potential support needed to implement decision-making. The flowchart has significant limitations and there are topics which it cannot resolve. On-the-ground considerations include who decides, finances, implements, monitors and enforces each decision. Additionally, views within communities differ, hence mechanisms are needed for dealing with differences, while issues to address include moral and legal blame for any climate change linked migration, the ultimate goal of the decision-making process, the wider role of migration in SIDS communities and the right to judge decision-making and decisions. The conclusions summarize the paper, emphasizing the importance of considering contexts beyond climate change and multiple SIDS voices.

Beschreibung: The Antarctic ozone hole will continue to be observed in the next 35–50 years, although the emissions of chlorofluorocarbons have gradually been phased out during the last two decades. In this paper, we suggest a geo-engineering approach that will remove substantial amounts of hydrogen chloride (HCl) from the lower stratosphere in fall and hence limit the formation of the Antarctic ozone hole in late winter and early spring. HCl will be removed by ice from the atmosphere at temperatures higher than the threshold under which polar stratospheric clouds (PSCs) are formed if sufficiently large amounts of ice are supplied to produce water saturation. A detailed chemical-climate numerical model is used to assess the expected efficiency of the proposed geo-engineering method, and specifically to calculate the removal of HCl by ice particles. The size of ice particles appears to be a key parameter: larger particles (with a radius between 10 and 100 µm) appear to be most efficient for removing HCl. Sensitivity studies lead to the conclusions that the ozone recovery is effective when ice particles are supplied during May and June in the latitude band ranging from 70 to 90°S and in the altitude layer ranging from the 10 to 26 km. It appears therefore that supplying ice particles to the Antarctic lower stratosphere could be effective in reducing the depth of the ozone hole. In addition, photodegradation of chlorofluorocarbons (CFCs) might be accelerated when ice is supplied due to enhanced vertical transport of this efficient greenhouse gas.

Beschreibung: A regional nuclear war between India and Pakistan could decrease global surface temperature by 1 to 2°C for 5 to 10 years, and have major impacts on precipitation and solar radiation reaching Earth's surface. Using a crop simulation model forced by three global climate model simulations, we investigate the impacts on agricultural production in China, the largest grain producer in the world. In the first year after the regional nuclear war, a cooler, drier, and darker environment would reduce annual rice production by 30 Mt (29%), maize production by 36 Mt (20%), and wheat production by 23 Mt (53%). With different agriculture managements – no irrigation, auto irrigation, 200 kg/ha nitrogen fertilizer and 10 days delayed planting date, simulated national crop productions reduce 16-26% for rice, 9-20% for maize and 32-43% for wheat during five years after the nuclear war event. This reduction of food availability would continue, with gradually decreasing amplitude, for more than a decade. Assuming these impacts are indicative of those in other major grain producers, a nuclear war using much less than 1% of the current global arsenal could produce a global food crisis and put a billion people at risk of famine.

Beschreibung: This article is a review of the science goals and the activities initiated within the framework of the P ollution and its I mpacts on the S outh A merican C ryosphere ( PISAC ) initiative. Air pollution associated with biomass burning and urban emissions affects extensive areas of South America. We focus on black carbon (BC) aerosol and its impacts on air quality, water availability, and climate, with an emphasis on the Andean cryosphere. BC is one of the key short-lived climate pollutants, which is a topic of growing interest for near-term mitigation of these issues. Limited scientific evidence indicates that the Andean cryosphere has already responded to climate change with receding glaciers and snow cover, which directly affect water resources, agriculture and energy production in the Andean region of South America. Despite the paucity of systematic observations along the Andes, a few studies have detected BC on snow and glaciers in the Andes. These, in addition to existing and projected emissions and weather patterns, suggest a possible contribution of BC to the observed retreat of the Andean cryosphere. Here we provide an overview of the current understanding of these issues from scientific and policy perspectives, and propose strategic expansions to the relevant measurement infrastructure in the region.

Beschreibung: Climate change poses a serious global challenge in the face of rapidly increasing human demand for energy and food. A recent phenomenon in which climate change may play an important role is the acquisition of large tracts of land in the developing world by governments and corporations. In the target countries, land is relatively inexpensive, the potential to increase crop yields is generally high, and property rights are often poorly defined. By acquiring land, investors can realize large profits and countries can substantially alter the land and water resources under their control, thereby changing their outlook for meeting future demand. While the drivers, actors and impacts involved with land deals have received substantial attention in the literature, we propose that climate change plays an important yet underappreciated role, both through its direct effects on agricultural production and through its influence on mitigative or adaptive policy decisions. Drawing from various literature sources as well as a new global database on reported land deals, we trace the evolution of the global land rush and highlight prominent examples in which the role of climate change is evident. We find that climate change – both historical and anticipated – interacts substantially with drivers of land acquisitions, having important implications for the resilience of communities in targeted areas. As a result of this synthesis, we ultimately contend that considerations of climate change should be integrated into future policy decisions relating to large-scale land acquisitions. Copyright © 2015 John Wiley & Sons, Ltd.

Beschreibung: Urbanization, climate, and ecosystem change represent major challenges for managing water resources. Although water systems are complex, a need exists for a generalized representation of these systems to identify important components and linkages to guide scientific inquiry and aid water management. We developed an integrated Structure-Actor-Water framework (iSAW) to facilitate the understanding of and transitions to sustainable water systems. Our goal was to produce an interdisciplinary framework for water resources research that could address management challenges across scales (e.g., plot to region) and domains (e.g., water supply and quality, transitioning and urban landscapes). The framework was designed to be generalizable across all human-environment systems, yet with sufficient detail and flexibility to be customized to specific cases. iSAW includes three major components: structure (natural, built, and social), actors (individual and organizational), and water (quality and quantity). Key linkages among these components include: 1) ecological/hydrologic processes, 2) ecosystem/geomorphic feedbacks, 3) planning, design, and policy, 4) perceptions, information, and experience, 5) resource access and risk, and 6) operational water use and management. We illustrate the flexibility and utility of the iSAW framework by applying it to two research and management problems: understanding urban water supply and demand in a changing climate, and expanding use of green stormwater infrastructure in an arid environment. The applications demonstrate that a generalized conceptual model can identify important components and linkages in complex and diverse water systems and facilitate communication about those systems among researchers from diverse disciplines.