Climate2014, 2(3), 153-167; doi:10.3390/cli2030153 - published 11 August 2014 Show/Hide Abstract
Abstract: We present the detection of the signatures of land use/land cover (LULC) changes on the regional climate of the US High Plains. We used the normalized difference vegetation index (NDVI) as a proxy of LULC changes and atmospheric CO2 concentrations as a proxy of greenhouse gases. An enhanced signal processing procedure was developed to detect the signatures of LULC changes by integrating autoregression and moving average (ARMA) modeling and optimal fingerprinting technique. The results, which are representative of the average spatial signatures of climate response to LULC change forcing on the regional climate of the High Plains during the 26 years of the study period (1981–2006), show a significant cooling effect on the regional temperatures during the summer season. The cooling effect was attributed to probable evaporative cooling originating from the increasing extensive irrigation in the region. The external forcing of atmospheric CO2 was included in the study to suppress the radiative warming effect of greenhouse gases, thus, enhancing the LULC change signal. The results show that the greenhouse gas radiative warming effect in the region is significant, but weak, compared to the LULC change signal. The study demonstrates the regional climatic impact of anthropogenic induced atmospheric-biosphere interaction attributed to LULC change, which is an additional and important climate forcing in addition to greenhouse gas radiative forcing in High Plains region.
Climate2014, 2(3), 133-152; doi:10.3390/cli2030133 - published 26 June 2014 Show/Hide Abstract
Abstract: The impact of heat waves on ischemic heart disease (IHD) mortality and morbidity in Germany during 2001–2010 is analyzed. Heat waves are defined as periods of at least three consecutive days with daily mean temperature above the 97.5th percentile of the temperature distribution. Daily excess mortality and morbidity rates are used. All calculations were performed separately for 19 regions to allow for the investigation of regional differences. The results show that IHD mortality during heat waves is significantly increased (+15.2% more deaths on heat wave days). In stark contrast, no heat wave influence on hospital admissions due to IHD could be observed. Regional differences in heat wave IHD mortality are present, with the strongest impact in Western Germany and weaker than average effects in the Southeastern and Northwestern regions. The increase in mortality during heat waves is generally stronger for females (+18.7%) than for males (+11.4%), and for chronic ischemic diseases (+18.4%) than for myocardial infarctions (+12.2%). Longer and more intense heat waves feature stronger effects on IHD mortality, while timing in season seems to be less important. Since climate change will most likely enhance the number and intensity of heat waves, the obtained results point to public adaptation strategies to reduce the future heat wave impact on mortality.
Climate2014, 2(3), 129-132; doi:10.3390/cli2030129 - published 25 June 2014 Show/Hide Abstract
Abstract: Shifting the presently used baselines of temperature changes during the last 440,000 years to about the lowest recorded temperature (+5 °C) as the baseline, a somewhat different view of climate change during the four Ice Ages emerges. Unlike the presently used baselines, the lowest temperature baseline is sort of the “absolute” one, in the sense that it does not depend on any chosen period during the last 440,000 years. Taking such a temperature as the baseline, the general trend of changes represents approximately the heat input function. Thus, in this view, the warming pulses with a sharp onset are the main feature, rather than a sequence of slow cooling and the subsequent sudden warming, although the basic physics involved in the feedback process may be the same. The interglacial periods are the peaks of the impulsive warming, rather than “returning to the normal condition” or “recovery from the Ice Ages”. In fact, the commonly used baselines represent simply the present conditions, rather than the baseline in climatology.
Climate2014, 2(2), 103-128; doi:10.3390/cli2020103 - published 5 May 2014 Show/Hide Abstract
Abstract: Irrigation provides a needed source of water in regions of low precipitation. Adding water to a region that would otherwise see little natural precipitation alters the partitioning of surface energy fluxes, the evolution of the planetary boundary layer, and the atmospheric transport of water vapor. The effects of irrigation are investigated in this paper through the employment of the Advanced Research (ARW) Weather Research and Forecasting Model (WRF) using a pair of simulations representing the extremes of an irrigated and non-irrigated U.S. Great Plains region. In common with previous studies, irrigation in the Great Plains alters the radiation budget by increasing latent heat flux and cooling the surface temperatures. These effects increase the net radiation at the surface, channeling that energy into additional latent heat flux, which increases convective available potential energy and provides downstream convective systems with additional energy and moisture. Most noteworthy in this study is the substantial influence of irrigation on the structure of the Great Plains Low-level Jet (GPLLJ). The simulation employing irrigation is characterized by a positive 850-mb geopotential height anomaly, a result interpreted by quasi-geostrophic theory to be a response to low-level irrigation-induced cooling. The modulation of the regional-scale height pattern associated with the GPLLJ results in weaker flow southeast of the 850-mb anomaly and stronger flow to the northwest. Increased latent heat flux in the irrigated simulation is greater than the decrease in regional transport, resulting in a net increase in atmospheric moisture and a nearly 50% increase in July precipitation downstream of irrigated regions without any change to the number of precipitation events.
Climate2014, 2(2), 78-102; doi:10.3390/cli2020078 - published 28 April 2014 Show/Hide Abstract
Abstract: The purpose of this study is to conduct an economic valuation of creating a concrete sea dike system as an adaptation measure to counter the impacts of a rise in sea level using a risk cost-benefit analysis framework. It uses an ex-ante approach with risk considerations for storms, floods, and salinity by specifying probability distribution functions in a simulation process, in order to incorporate these risk factors into the analysis. The results showed that the benefits of storms and floods avoided dominated the dike options. The benefit of salinity avoided was also valuable, with annual rice and aquaculture productivity losses avoided of USD 331.25 per ha and USD 915 per ha, respectively. This study evaluated a range of dike options to adapt to climate change in the Vietnamese Mekong Delta, showing high levels of benefits compared to costs. The larger in scale the dike system options were, the higher the expected net present values (ENPVs) were. Of the dike alternatives applicable to the Vietnamese Mekong Delta, considering the impacts of sea level rise of storms, floods and raised salinity in soil from flooding, small scale dikes that can subsequently be increased in height should be a priority choice. The sensitivity analyses showed that the ENPVs of dike options were very sensitive with changes in discount rate but were not sensitive with increases in salinized areas at all. The findings provide evidence to support the necessity of the construction of a concrete sea dike system in the Vietnamese Mekong Delta, given the context of global climate change.
Climate2014, 2(2), 47-77; doi:10.3390/cli2020047 - published 22 April 2014 Show/Hide Abstract
Abstract: Water is critical for sustaining natural and managed ecosystems, and precipitation is a key component in the water cycle. To understand controls on long-term changes in precipitation for scientific and environmental management applications it is necessary to examine whether local land use and land cover change (LULCC) has played a significant role in changing historical precipitation patterns and trends. For the small tropical island of Puerto Rico, where maritime climate is dominant, we used long-term precipitation and land use and land cover data to assess whether there were any detectable impacts of LULCC on monthly and yearly precipitation patterns and trends over the past century. Particular focus was given to detecting impacts from the urban landscape on mesoscale climates across Puerto Rico. We found no statistical evidence for significant differences between average monthly precipitation in urban and non-urban areas directly from surface stations, but, after subdividing by Holdridge Ecological Life Zones (HELZs) in a GIS, there were statistically significant differences (α = 0.05) in yearly average total precipitation between urban and non-urban areas in most HELZs. Precipitation in Puerto Rico has been decreasing over the past century as a result of a decrease in precipitation during periods (months or years) of low rain. However, precipitation trends at particular stations contradict synoptic-scale long-term trends, which suggests that local land use/land cover effects are driving precipitation variability at local scales.