Climate change and coupling of macronutrient cycles along the atmospheric, terrestrial, freshwater and estuarine continuum

This paper provides an introduction to the Special Issue on “Climate Change and Coupling of Macronutrient Cycles along the Atmospheric, Terrestrial, Freshwater and Estuarine Continuum”, dedicated to Colin Neal on his retirement. It is not intended to be a review of this vast subject, but an attempt to synthesize some of the major findings from the 22 contributions to the Special Issue in the context of what is already known. The major research challenges involved in understanding coupled macronutrient cycles in these environmental media are highlighted, and the difficulties of making credible predictions of the effects of climate change are discussed. Of particular concern is the possibility of interactions which will enhance greenhouse gas concentrations and provide positive feedback to global warming.

Detection and attribution of climate change: a regional perspective

The Intergovernmental Panel on Climate Change fourth assessment report, published in 2007 came to a more confident assessment of the causes of global temperature change than previous reports and concluded that ‘it is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent except Antarctica.’ Since then, warming over Antarctica has also been attributed to human influence, and further evidence has accumulated attributing a much wider range of climate changes to human activities. Such changes are broadly consistent with theoretical understanding, and climate model simulations, of how the planet is expected to respond. This paper reviews this evidence from a regional perspective to reflect a growing interest in understanding the regional effects of climate change, which can differ markedly across the globe. We set out the methodological basis for detection and attribution and discuss the spatial scales on which it is possible to make robust attribution statements. We review the evidence showing significant human-induced changes in regional temperatures, and for the effects of external forcings on changes in the hydrological cycle, the cryosphere, circulation changes, oceanic changes, and changes in extremes. We then discuss future challenges for the science of attribution. To better assess the pace of change, and to understand more about the regional changes to which societies need to adapt, we will need to refine our understanding of the effects of external forcing and internal variability

Transient climate change simulations with a coupled atmosphere–ocean GCM including the tropospheric sulfur cycle

The time-dependent climate response to changing concentrations of greenhouse gases and sulfate aerosols is studied using a coupled general circulation model of the atmosphere and the ocean (ECHAM4/OPYC3). The concentrations of the well-mixed greenhouse gases like CO2, CH4, N2O, and CFCs are prescribed for the past (1860–1990) and projected into the future according to International Panel on Climate Change (IPCC) scenario IS92a. In addition, the space–time distribution of tropospheric ozone is prescribed, and the tropospheric sulfur cycle is calculated within the coupled model using sulfur emissions of the past and projected into the future (IS92a). The radiative impact of the aerosols is considered via both the direct and the indirect (i.e., through cloud albedo) effect. It is shown that the simulated trend in sulfate deposition since the end of the last century is broadly consistent with ice core measurements, and the calculated radiative forcings from preindustrial to present time are within the uncertainty range estimated by IPCC. Three climate perturbation experiments are performed, applying different forcing mechanisms, and the results are compared with those obtained from a 300-yr unforced control experiment. As in previous experiments, the climate response is similar, but weaker, if aerosol effects are included in addition to greenhouse gases. One notable difference to previous experiments is that the strength of the Indian summer monsoon is not fundamentally affected by the inclusion of aerosol effects. Although the monsoon is damped compared to a greenhouse gas only experiment, it is still more vigorous than in the control experiment. This different behavior, compared to previous studies, is the result of the different land–sea distribution of aerosol forcing. Somewhat unexpected, the intensity of the global hydrological cycle becomes weaker in a warmer climate if both direct and indirect aerosol effects are included in addition to the greenhouse gases. This can be related to anomalous net radiative cooling of the earth’s surface through aerosols, which is balanced by reduced turbulent transfer of both sensible and latent heat from the surface to the atmosphere.

Risk perception and commitment to reduce global climate change in Spain

An online national survey among the Spanish population (n = 602) was conducted to examine the factors underlying a person’s support for commitments to global climate change reductions. Multiple hierarchical regression analysis was conducted in four steps and a structural equations model was tested. A survey tool designed by the Yale Project on Climate Change Communication was applied in order to build scales for the variables introduced in the study. The results show that perceived consumer effectiveness and risk perception are determinant factors of commitment to mitigating global climate change. However, there are differences in the influence that other factors, such as socio-demographics, view of nature and cultural cognition, have on the last predicted variable.

Integrating risks of climate change into water management

The Working Group II contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change critically reviewed and assessed tens of thousands of recent publications to inform about the assess current scientific knowledge on climate change impacts, vulnerability and adaptation. Chapter 3 of the report focuses on freshwater resources, but water issues are also prominent in other sectoral chapters and in the regional chapters of the Working Group II report as well as in various chapters of Working Group I. With this paper, the lead authors, a review editor and the chapter scientist of the freshwater chapter of the WGII AR5 wish to summarize their assessment of the most relevant risks of climate change related to freshwater systems and to show how assessment and reduction of those risks can be integrated into water management.

Challenging climate change and migration discourse: different understandings of time-scale and temporality in the Maldives

This article draws on ongoing research in the Maldives to explore differences between elite and non-elite perceptions of climate change and migration. It argues that, in addition to variations in perceptions based on diverse knowledge, priorities and agendas, there exists a more fundamental divergence based upon different understandings of the time-scale of climate change and related ideas of urgency and crisis. Specifically, elites tend to focus on a distant future which is generally abstracted from people’s everyday lived realities, as well as utilise the language of a climate change-induced migration ‘crisis’ in their discussions about impacts in a manner not envisaged by non-elites. The article concludes that, rather than unproblematically mapping global, external facing narratives wholesale onto ordinary people’s lives and experiences, there needs to be more dialogue between elites and non-elites on climate change and migration issues. These perspectives should be integrated more effectively in the development of policy interventions designed to help people adapt to the impacts of global environmental change.

Climate change and infectious disease: time for a new normal?

At present, there is a clarion call for action on climate change across the global health landscape. At the recent WHO-sponsored conference on health and climate (held in Geneva, Switzerland, on Aug 27–29, 2014) and the UN Climate Summit (New York, USA, on Sept 23, 2014), participants were encouraged to act decisively to change the current trajectory of climate disruption. Health inequalities, including those related to infectious diseases, have now been pushed to centre stage. This approach represents a step-change in thinking. But as we are urged toward collective action, is it time to rethink our approach to research, especially in relation to climate change and infectious disease?

Towards predictive understanding of regional climate change

Regional information on climate change is urgently needed but often deemed unreliable. To achieve credible regional climate projections, it is essential to understand underlying physical processes, reduce model biases and evaluate their impact on projections, and adequately account for internal variability. In the tropics, where atmospheric internal variability is small compared with the forced change, advancing our understanding of the coupling between long-term changes in upper-ocean temperature and the atmospheric circulation will help most to narrow the uncertainty. In the extratropics, relatively large internal variability introduces substantial uncertainty, while exacerbating risks associated with extreme events. Large ensemble simulations are essential to estimate the probabilistic distribution of climate change on regional scales. Regional models inherit atmospheric circulation uncertainty from global models and do not automatically solve the problem of regional climate change. We conclude that the current priority is to understand and reduce uncertainties on scales greater than 100 km to aid assessments at finer scales.

Transatlantic flight times and climate change

Aircraft do not fly through a vacuum, but through an atmosphere whose meteorological characteristics are changing because of global warming. The impacts of aviation on climate change have long been recognised, but the impacts of climate change on aviation have only recently begun to emerge. These impacts include intensified turbulence and increased take-off weight restrictions. Here we investigate the influence of climate change on flight routes and journey times. We feed synthetic atmospheric wind fields generated from climate model simulations into a routing algorithm of the type used operationally by flight planners. We focus on transatlantic flights between London and New York, and how they change when the atmospheric concentration of carbon dioxide is doubled. We find that a strengthening of the prevailing jet-stream winds causes eastbound flights to significantly shorten and westbound flights to significantly lengthen in all seasons. Eastbound and westbound crossings in winter become approximately twice as likely to take under 5 h 20 min and over 7 h 00 min, respectively. For reasons that are explained using a conceptual model, the eastbound shortening and westbound lengthening do not cancel out, causing round-trip journey times to increase. Even assuming no future growth in aviation, the extrapolation of our results to all transatlantic traffic suggests that aircraft will collectively be airborne for an extra 2000 h each year, burning an extra 7.2 million gallons of jet fuel at a cost of US$ 22 million, and emitting an extra 70 million kg of carbon dioxide, which is equivalent to the annual emissions of 7100 average British homes. Our results provide further evidence of the two-way interaction between aviation and climate change.

Perceptions of climate change at ski resorts in midsouth of Sweden

Climate change as a phenomenon will imply new risks for the ski industry. Intergovernmental Panal on Climate Change presents three future scenarios, during the periods between 1990-2100, in forms of increased temperatures, a rise in the sea level and seasonal variations, variables out of which two have direct impacts on the ski industry. The aim for this study was to explore and compare attitudes towards climate change between five ski resorts located in mid-south of Sweden. This was done through in depth interviews in both face to face and by telephone. The result of the study was that all the chosen ski resorts were aware of climate change as a phenomenon but have not yet recognized its consequences. All ski resorts use methods to maintain skiing i.e. artificial snow production though not because of climate change.

Adaptation to climate change in megacities of Latin America: Regional Learning Network of the research project ClimateAdaptationSantiago (CAS)

The main objective of this publication is to document the current state of urban climate change adaptation practice in Latin America. It is a summary of the three workshops of the Regional Learning Network that was set up under the ClimateAdaptationSantiago project (CAS), encompassing six large Latin American cities (Bogotá, Buenos Aires, Lima, Mexico City, São Paulo and Santiago). It aims to synthesize information on the manifestations and impacts of climate change in those Latin American cities that participated in the network, and above all, governance in the form of concrete actions. The publication is based on information obtained from the participants in the three workshops, but also includes additional scientific input and reflections by the editors. All of this information makes a major contribution to highlighting the different paths these six cities are pursuing in response to climate change. To that end, the publication discusses the various courses of action on climate change adaptation, with the aim of learning from these cases and highlighting practical examples.

An assessment of global economic models for climate change

The project comprises three phases of which Phase I would be implemented over the period September to December 2008. The major objectives of Phase I are, firstly, to establish the scope and feasibility of carrying out a study on the costs/benefits of taking action on climate change adaptation and cost effectiveness of mitigation in the Caribbean compared to a “business as usual” scenario, and secondly, to support initial actions to alert policymakers and key influencing constituencies to the urgency of this challenge.

Sedimentary environments and climate change: a case study (late Miocene, central Crete)

In this study, conditions of deposition and stratigraphical architecture of Neogene (Tortonian, 11-6,7Ma) sediments of southern central Crete were analysed. In order to improve resolution of paleoclimatic data, new methods were applied to quantify environmental parameters and to increase the chronostratigraphic resolution in shallow water sediments. A relationship between paleoenvironmental change observed on Crete and global processes was established and a depositional model was developed. Based on a detailed analysis of the distribution of non geniculate coralline red algae, index values for water temperature and water depth were established and tested with the distribution patterns of benthic foraminifera and symbiont-bearing corals. Calcite shelled bivalves were sampled from the Algarve coast (southern Portugal) and central Crete and then 87Sr/86Sr was measured. A high resolution chronostratigraphy was developed based on the correlation between fluctuations in Sr ratios in the measured sections and in a late Miocene global seawater Sr isotope reference curve. Applying this method, a time frame was established to compare paleoenvironmental data from southern central Crete with global information on climate change reflected in oxygen isotope data. The comparison between paleotemperature data based on red algae and global oxygen isotope data showed that the employed index values reflect global change in temperature. Data indicate a warm interval during earliest Tortonian, a second short warm interval between 10 and 9,5Ma, a longer climatic optimum between 9 and 8Ma and an interval of increasing temperatures in the latest Tortonian. The distribution of coral reefs and carpets shows that during the warm intervals, the depositional environment became tropical while temperate climates prevailed during the cold interval. Since relative tectonic movements after initial half-graben formation in the early Tortonian were low in southern central Crete, sedimentary successions strongly respond to global sea-level fluctuation. A characteristic sedimentary succession formed during a 3rd order sea-level cycle: It comprises mixed siliciclastic-limestone deposited during sea-level fall and lowstand, homogenous red algal deposits formed during sea-level rise and coral carpets formed during late rise and highstand. Individual beds in the succession reflect glacioeustatic fluctuations that are most prominent in the mixed siliciclastic-limestone interval. These results confirm the fact that sedimentary successions deposited at the critical threshold between temperate and tropical environments develop characteristic changes in depositional systems and biotic associations that can be used to assemble paleoclimatic datasets.