The palaeoceanography of the Leeuwin Current : implications for a future world

Long-term progressive changes of the Leeuwin Current are linked to plate and ocean basin ‘geography’ and Cenozoic global climates and palaeoceanography. Suggestions of the presence of a proto-Leeuwin Current as early as late Middle to Late Eocene times (c. 35–42 Ma) cannot be verified by the fossil record of the western margin of Australia. “Leeuwin Current style” circulation around Australia was certainly established by the early Oligocene, in response to palaeogeographic changes in the Tasman Strait. This, followed by tectonic eorganisation of the Indonesian Archipelago throughout the Miocene, provided a palaeogeographic setting, which by the Pliocene was essentially that of today. The subsequent history of the Leeuwin Current comprises climatically-induced changes operating over orbital and sub-orbital temporal scales. Specifically, the advent of Pleistocene-style climates, especially over the last 800 000 years, and their associated interglacial – glacial states provide the two end-member climate-ocean states that have characterised Leeuwin Current activity during that time. Indications of the nature of these contrasting states is provided by: (i) the Last Interglacial (c. 125 Ka) during which sea level was higher by some +4 m, and with higher sea surface temperatures (SSTs) clearly indicating a more ‘active’ Leeuwin Current; and (ii) the Last Glacial Maximum (21 Ka), during which sea level wassome 130 m lower than today, resulting in massive shelf extensions along the coast of Western Australia, ccompanied by reduced Indonesian Throughflow, lower low latitude SSTs and changes in the Western Pacific Warm Water Pool, and with these changes, possibly reduced Leeuwin Current activity. Sub-orbital scale luctuations in current strength are driven by global climate change associated with El Niño – La Niña events as well as regional climatic changes driven by volcanism. These forcing mechanisms operate at time scales well within the reach of human experience, and provide important comparative data for predicting the response of the Leeuwin Current to climate change predicted for this century. Studies of the impact of changes in the vigour of the Leeuwin Current on shallow marine communities are in their infancy. Coupling climate models with geological analogues provide important research agenda for predicting the trajectory of future changes to the Leeuwin Current and their impacts on the marine biota of coastal Western Australia

Working Paper 89 - Come Rain or Shine - Integrating Climate Risk Management into African Development Bank Operations

Climate change is happening now, and further changes during the next decades are inevitable (IPCC, 2007a). During the last century, the global climate warmed by about 0.7°C. At the same time, there were distinct changes in rainfall patterns, an increase in both frequency and severity of extreme weather events, and a rise in sea levels. The impacts of these changes are already being felt, and will intensify as further changes take place. Another 2–4°C rise is projected for the current century, mostly as a result of greenhouse gases that have already been emitted. This means that, although aggressive mitigation of greenhouse gas emissions is crucial to prevent longer term, potentially catastrophic changes, most of the changes projected for the coming decades cannot be avoided.Africa is especially vulnerable. This is clear from the effects of current climate variability and weather extremes – such as floods, droughts and storms – which severely affect economic performance (AfDB, 2003; G8, 2005; Stern et al., 2006; IPCC, 2007b). The poor pay the highest price, because their livelihoods are most affected, and they have fewer resources to help them adapt to the changing climate. Box 1 describes some of the areas where climate change will have its most severe impacts in Africa.African policy-makers and stakeholders are beginning to recognize the need to address adaptation to climate change. There is growing awareness of the setbacks to development and poverty reduction that will result from climate change, threatening the achievement of the Millennium Development Goals (MDGs). This was articulated in the multi-agency document ‘Poverty and Climate Change’ (AfDB, 2003), and more recently at the African Partnership Forum in May 2007 (APF, 2007). Climate change was placed on the agenda of the AU Heads of State Summit for the first time in January 2007, which resulted in the adoption of a Decision and Declaration on Climate Change and Development in Africa and in the endorsement of the Climate Information for Development – Africa (ClimDev Africa) Stakeholders Report and Implementation Strategy (GCOS, 2006).

The change in the distribution of arable weeds in Europe as a consequence of climate change

This study aimed at exploring the future distribution of 25 weeed species, representing different distribution patterns and taxa, at European scale. Using generalized additive models, and data on current climate and species distributions and two different climate scenarios for the period 2051-2080, we developed predictions of the currently suitable area and potential range size changes of 25 European weed species

An approach for assessing human health vulnerability and public health interventions to adapt to climate change.

Assessments of the potential human health impacts of climate change are needed to inform the development of adaptation strategies, policies, and measures to lessen projected adverse impacts. We developed methods for country-level assessments to help policy makers make evidence-based decisions to increase resilience to current and future climates, and to provide information for national communications to the United Nations Framework Convention on Climate Change. The steps in an assessment should include the following: a) determine the scope of the assessment; b) describe the current distribution and burden of climate-sensitive health determinants and outcomes; c) identify and describe current strategies, policies, and measures designed to reduce the burden of climate-sensitive health determinants and outcomes; d) review the health implications of the potential impacts of climate variability and change in other sectors; e) estimate the future potential health impacts using scenarios of future changes in climate, socioeconomic, and other factors; f) synthesize the results; and g) identify additional adaptation policies and measures to reduce potential negative health impacts. Key issues for ensuring that an assessment is informative, timely, and useful include stakeholder involvement, an adequate management structure, and a communication strategy

CLIMATE CHANGE AND INTERNATIONAL TOURISM: A SIMULATION STUDY

The literature on tourism and climate change lacks an analysis of the global changes in tourism demand. Here a simulation model of international tourism is presented that fills that gap. The current pattern of international tourist flows is modelled using 1995 data on departures and arrivals for 207 countries. Using this basic model the impact on arrivals and departures through changes in population, per capita income and climate change are analysed. In the medium to long term, tourism will grow, however the growth from climate change is smaller than for population and income changes.Tourism demand, climate change, global model

Mountain-pine beetle outbreaks and shifting social preferences for ecosystem services

Conventional wisdom appears to implicate climate change as the root cause of the unprecedented mountain pine beetle (MPB) outbreak currently underway in the western United States. While climate change is undoubtedly a factor, historic changes in public forest management have resulted in greater numbers of large-diameter host trees in MPB habitat. We present a model that integrates standard economic and ecological principles in an attempt to clarify the roles of climate change and public forest management in the current MPB outbreak. Using data on timber sales, climate change and MPB populations, model simulations illustrate how an increased emphasis on non-timber ecosystem services induced a regime shift from climate-independent to climate-dependent disturbance processes, amplifying the current MPB outbreak.mountain pine beetle; climate change; forests

Why would plant species become extinct locally if growing conditions improve?

wo assumptions underlie current models of the geographical ranges of perennial plant species: 1. current ranges are in equilibrium with the prevailing climate, and 2. changes are attributable to changes in macroclimatic factors, including tolerance of winter cold, the duration of the growing season, and water stress during the growing season, rather than to biotic interactions. These assumptions allow model parameters to be estimated from current species ranges. Deterioration of growing conditions due to climate change, e.g. more severe drought, will cause local extinction. However, for many plant species, the predicted climate change of higher minimum temperatures and longer growing seasons means, improved growing conditions. Biogeographical models may under some circumstances predict that a species will become locally extinct, despite improved growing conditions, because they are based on an assumption of equilibrium and this forces the species range to match the species-specific macroclimatic thresholds. We argue that such model predictions should be rejected unless there is evidence either that competition influences the position of the range margins or that a certain physiological mechanism associated with the apparent improvement in growing conditions negatively affects the species performance. We illustrate how a process-based vegetation model can be used to ascertain whether such a physiological cause exists. To avoid potential modelling errors of this type, we propose a method that constrains the scenario predictions of the envelope models by changing the geographical distribution of the dominant plant functional type. Consistent modelling results are very important for evaluating how changes in species areas affect local functional trait diversity and hence ecosystem functioning and resilience, and for inferring the implications for conservation management in the face of climate change

Climate scenarios of sea level rise for the northeast Atlantic Ocean: a study including the effects of ocean dynamics and gravity changes induced by ice melt

Here we present a set of regional climate scenarios of sea level rise for the northeast Atlantic Ocean. In this study, the latest observations and results obtained with state-of-the-art climate models are combined. In addition, regional effects due to ocean dynamics and changes in the Earth’s gravity field induced by melting of land-based ice masses have been taken into account. The climate scenarios are constructed for the target years 2050 and 2100, for both a moderate and a large rise in global mean atmospheric temperature (2 °C and 4 °C in 2100 respectively). The climate scenarios contain contributions from changes in ocean density (global thermal expansion and local steric changes related to changing ocean dynamics) and changes in ocean mass (melting of mountain glaciers and ice caps, changes in the Greenland and Antarctic ice sheets, and (minor) terrestrial water-storage contributions). All major components depend on the global temperature rise achieved in the target periods considered. The resulting set of climate scenarios represents our best estimate of twenty-first century sea level rise in the northeast Atlantic Ocean, given the current understanding of the various contributions. For 2100, they yield a local rise of 30 to 55 cm and 40 to 80 cm for the moderate and large rise in global mean atmospheric temperature, respectively. <br/

Representing climate and extreme weather events in integrated assessment models: A review of existing methods and options for development

The lack of information about future changes in extreme weather is a major constraint of Integrated Assessment Models (IAMs) of climate change. The generation of descriptions of future climate in current IAMs is assessed.We also review recent work on scenario development methods for weather extremes, focusing on those issues which are most relevant to the needs of IAMs. Finally, some options for implementing scenarios of weather extremes in IAMs are considered