Episodic speleothem deposition tracks the terrestrial impact of millennial-scale last glacial climate variability in SW Ireland

Eighty four new U-Th ages are presented for twenty randomly selected broken, displaced and reworked calcite speleothems retrieved from clastic sedimentary fill and from isolated bedding-plane shelves in Crag cave (SW Ireland). The dated pre-Holocene samples span much of the last glacial, ranging in age from 85.15 ± 0.60 to 23.45 ± 0.17 ka. Speleothem deposition requires the presence of liquid water, and because Crag cave is a shallow system, deposition is considered likely only when mean annual air temperatures (MAAT) exceed the freezing point of water. Deposition at this mid-latitude ocean-marginal site occurred episodically during MIS5a through to MIS2, synchronously within dating uncertainties, with the timing of Greenland Interstadials (GI). In the latter part of Marine Isotope Stage 3 (MIS3), deposition was particularly intense, consistent with regional scale climate amelioration inferred previously from radiocarbon ages for sparse MIS3 organic and freshwater surficial deposits in N. Ireland. A brief episode of speleothem deposition at c.23.40 ± 0.22 ka coincides with GI-2, demonstrating the sensitivity of the site to brief climate amelioration episodes in Greenland during MIS2. Conditions favourable for speleothem deposition occurred periodically during the last glacial, indicating temperature changes of at least 10oC between stadials and interstadials at this mid-latitude site. Deposition ceased during Greenland Stadials (GS), including during periods of ice-rafting in the adjacent N. Atlantic Ocean (Heinrich events). Oxygen and carbon isotope ratios of the last glacial speleothems are generally elevated, reflecting non-equilibrium isotope fractionation effects. However, establishment of low 13C values often occurred within a few decades of climate amelioration, indicating that biogenic CO2 production resumed rapidly at this site, particularly during MIS3. Speleothem 18O variability was driven largely by long-term changes in the 18O value of the adjacent North Atlantic surface water, in turn largely reflecting changes in global ice volume. In common with published speleothem datasets, warming episodes in Ireland associated with GI events typically pre-date their timing in the GICC05 and GICC05modelext time scales, but lie comfortably within the maximum counting uncertainties of these ice core age models

New Zealand Agribusiness Success: An Approach to exploring the role of strategy, structure and conduct on firm performance

This paper presents a framework to explore agribusiness success in New Zealand. The framework provides the basis for historical analysis. It draws on existing theory based on the structure-conduct-performance paradigm but expanded to take account of firm strategy and the analysis of value chains.Agribusiness, structure, conduct, performance, history, Agribusiness,

Disasters and Development: Natural Disasters, Credit Constraints and Economic Growth. ESRI WP411. October 2011

We demonstrate, using a simple two‐period equilibrium model of the economy, the potential effects of extreme event occurrences - such as natural or humanitarian disasters - on economic growth over the medium- to long-term. In particular, we focus on the effect of such shocks on investment. We examine two polar cases; an economy in which agents have unconstrained access to capital markets, versus a credit-constrained version, where the economy is assumed to operate in financial autarky. Considering these extreme cases allows us to highlight the interaction of disasters and economic underdevelopment, manifested through poorly developed financial markets. The theoretical analysis shows that the shock of a disaster occurrence could have lasting effects on economic growth only if agents face borrowing constraints. The predictions of our theoretical model are then tested using a panel of data on natural disaster events at the country-year level, covering the period 1979-2007. We find that for countries with low levels of financial sector development, natural disaster events exert a significant negative impact on economic growth. In particular, where access to credit is problematic, the negative effects of disasters on growth are persistent over the medium-term. These results are robust to various checks. Our findings suggest that natural disasters do represent significant threats to economic development in poor countries

A review of Multi-Agent Simulation Models in Agriculture

Multi-Agent Simulation (MAS) models are intended to capture emergent properties of complex systems that are not amenable to equilibrium analysis. They are beginning to see some use for analysing agricultural systems. The paper reports on work in progress to create a MAS for specific sectors in New Zealand agriculture. One part of the paper focuses on options for modelling land and other resources such as water, labour and capital in this model, as well as markets for exchanging resources and commodities. A second part considers options for modelling agent heterogeneity, especially risk preferences of farmers, and the impacts on decision-making. The final section outlines the MAS that the authors will be constructing over the next few years and the types of research questions that the model will help investigate.multi-agent simulation models, modelling, agent-based model, cellular automata, decision-making, Crop Production/Industries, Environmental Economics and Policy, Farm Management, Land Economics/Use, Livestock Production/Industries,

Openly accessed and openly published: a celebration of international high-impact surgical research

Cited by: 0; All Open Access, Gold Open Access, Green Open AccessNon peer reviewe

Openly accessed and openly published: a celebration of international high-impact surgical research

Cited by: 0; All Open Access, Gold Open Access, Green Open AccessNon peer reviewe