Aideen M. Foley

Uncertainty in regional climate modelling: A review:

For geographers engaged in activities such as environmental planning and natural resource management, regional climate models are becoming increasingly important as a source of information about the possible impacts of future climate change. However, in order to make informed adaptation decisions, the uncertainties associated with their output must be recognized and taken into account. In this paper, the cascade of uncertainty from emissions scenario to global model to regional climate model is explored. The initial part of the discussion focuses on uncertainties associated with human action, such as emissions of greenhouse gases, and the climate system’s response to increased greenhouse gas forcing, which includes climate sensitivity and feedbacks. In the second part of the discussion, uncertainties associated with climate modelling are explored with emphasis on the implications for regional scale analysis. Such uncertainties include parameterizations and resolutions, initial and boundary conditions inherited from the driving global model, intermodel variability and issues surrounding the validation or verification of models. The paper concludes with a critique of approaches employed to quantify or cater for uncertainties highlighting the strengths and limitations of such approaches.

Spatial variability in the European winter precipitation δ18O‐NAO relationship: Implications for reconstructing NAO‐mode climate variability in the Holocene

This paper investigates the links between precipitation δ 18 O and the North Atlantic Oscillation (NAO) on decadal timescales to identify the optimum locations within Europe at which to compile δ 18 O-based proxy records of past NAO variability. δ 18 O is a commonly used paleoclimate (rainfall and temperature) proxy preserved in natural archives including stalagmites, ice cores, tree rings, and lake sediments. Precipitation δ 18 O data (δ 18 O p ), compiled from Global Network of Isotopes in Precipitation (GNIP) stations in the North Atlantic sector reveal the direction and strength of the δ 18 O p -NAO relationship in mid-latitude, high-latitude, and Mediterranean Europe. The highly significant, positive δ 18 O p -NAO relationship in central Europe is attributed to the strong control of air temperature on δ 18 O p in this region. The δ 18 O p -NAO relationship is strongly negative at high-latitude GNIP sites and weak at Mediterranean sites. Decadal-scale solar irradiance variations correlate with winter δ 18 O p at eight mid-latitude sites.

The dynamics of technology diffusion and the impacts of climate policy instruments in the decarbonisation of the global electricity sector

This paper presents an analysis of climate policy instruments for the decarbonisation of the global electricity sector in a non-equilibrium economic and technology diffusion perspective. Energy markets are driven by innovation, path-dependent technology choices and diffusion. However, conventional optimisation models lack detail on these aspects and have limited ability to address the effectiveness of policy interventions because they do not represent decision-making. As a result, known effects of technology lock-ins are liable to be underestimated. In contrast, our approach places investor decision-making at the core of the analysis and investigates how it drives the diffusion of low-carbon technology in a highly disaggregated, hybrid, global macroeconometric model, FTT:Power-E3MG. Ten scenarios to 2050 of the electricity sector in 21 regions exploring combinations of electricity policy instruments are analysed, including their climate impacts. We show that in a diffusion and path-dependent perspective, the impact of combinations of policies does not correspond to the sum of impacts of individual instruments: synergies exist between policy tools. We argue that the carbon price required to break the current fossil technology lock-in can be much lower when combined with other policies, and that a 90% decarbonisation of the electricity sector by 2050 is affordable without early scrapping.

Quantifying the global carbon cycle response to volcanic stratospheric aerosol radiative forcing using Earth System Models

[1] Large volcanic eruptions can have a significant cooling effect on climate, which is evident in both modern and palaeo data. However, due to the difficulty of disentangling volcanic and other influences in the modern atmospheric CO2 record, and uncertainties associated with palaeo reconstructions of atmospheric CO2, the magnitude of the carbon cycle response to volcanically induced climatic changes is difficult to quantify. In this study, three Earth System Models (SIMEARTH, CLIMBER‐2, and CLIMBER LPJ) are used to simulate the effects of different magnitudes of volcanic eruption, from relatively small (e.g., Mount Pelee, 1902) to very large (e.g., the 1258 ice core event), on the coupled global climate‐carbon cycle system. These models each use different, but justifiable, parameterizations to simulate the global carbon cycle and climate. Key differences include how soil respiration and net primary productivity respond to temperature and atmospheric CO2. All models simulate global surface cooling in response to volcanic events. In response to a Mount Pinatubo‐equivalent eruption, the modelled temperature decrease is 0.3°C to 0.4°C and atmospheric CO2 decreases by 1.1 ppm to 3.4 ppm. The initial response time of climate to volcanic forcing and subsequent recovery time vary little with changes in the size of the forcing. Response times for vegetation and soil carbon are relatively consistent across forcings for each model. However, results indicate that there is significant uncertainty concerning the response of the carbon cycle to volcanic eruptions. Suggestions for future research directed at reducing this uncertainty are given.

Time-scale and state dependence of the carbon-cycle feedback to climate

Climate and atmospheric CO2 concentration are intimately coupled in the Earth system: CO2 influences climate through the greenhouse effect, but climate also affects CO2 through its impact on the amount of carbon stored on land and in the ocean. The change in atmospheric CO2 as a response to a change in temperature (

Evaluation of biospheric components in Earth system models using modern and palaeo observations: the state-of-the-art

\varDelta CO_{2}/\varDelta T

Climate model emulation in an integrated assessment framework: a case study for mitigation policies in the electricity sector

ΔCO2/ΔT) is a useful measure to quantify the feedback between the carbon cycle and climate. Using an ensemble of experiments with an Earth system model of intermediate complexity we show a pronounced time-scale dependence of