No description available.

This work has contributed to the understanding of dominant runoff generation at the large catchment scale and to the understanding of the relationships between landscape properties and hydrological behaviour. The developed models were used to estimate the climate change impact on the hydrology in the study catchment. A multivariate geochemical tracer survey was carried out in North Esk catchment in north east Scotland. A generic typology was developed using multivariate statistical methods to characterise the hydrochemical tracer response. Upland headwater runoff was dominant downstream in winter and provided significant flows during base flow periods in summer. These insights were complemented by a conjunctive analysis of long-term river flow data and a one year stable isotope survey. Integrative metrics of transit times, hydrometric responses, and catchment characteristics were explored for relationships at the large catchment scale. The evaluation that the associated soils and bedrocks, themselves controlling the flow path distribution, have a strong influence on the integrated hydrological catchment response. The empirically-based understanding of dominant runoff generation processes in the North Esk uplands and lowlands were used in a stepwise rainfall-runoff model development. Tracers were directly incorporated to reduce structural and parameter uncertainty. The integration of tracers helped reduce parameter uncertainty. These tracer-aided models increased confidence for using them to explore the effects of environmental change. Climate change impacts in the catchment where explored by forcing the models with projected climate change forcing from the UK Climate Projections 2009. The results revealed landscape-specific changes in the hydrological response with increased summer drought risk in the lowlands and diminishing snow influence and increased winter floods in the uplands. The spatial integration mediated the extremes observed in the subcatchments.

<p> Yellow-cedar is a long-lived conifer of the North Pacific Coastal Temperate Rainforest region that is thought to be undergoing a continued natural range expansion in southeast Alaska. Yellow-cedar is locally rare in northeastern portions of the Alexander Archipelago, and the fairly homogenous climate and forest conditions across the region suggest that yellow-cedar&rsquo;s rarity could be due to its local migrational history rather than constraints on its growth. Yellow-cedar trees in northern range edge locations appear to be healthy, with few dead trees; additionally, yellow-cedar tend to be younger than co-dominant mountain and western hemlock trees, indicating recent establishment in existing forests.</p><p> To explore yellow-cedar&rsquo;s migration in the region, and determine if the range is expanding into unoccupied habitat, I located 11 leading edge yellow-cedar populations near Juneau, Alaska. I used the geographic context of these populations to determine the topographic, climatic, and disturbance factors associated with range edge population establishment. I used those same landscape variables to model suitable habitat for the species at the range edge. Based on habitat modeling, yellow-cedar is currently only occupying 0.8 percent of its potential landscape niche in the Juneau study area. Tree ages indicate that populations are relatively young for the species, indicating recent migration, and that most populations established during the Little Ice Age climate period (1100 &ndash; 1850).</p><p> To determine if yellow-cedar is continuing to colonize unoccupied habitat in the region, I located 29 plots at the edges of yellow-cedar stands to measure regeneration and expansion into existing forest communities. Despite abundant suitable habitat, yellow-cedar stand expansion appears stagnant in recent decades. On average, seedlings only dispersed 4.65 m beyond stand boundaries and few seedlings reached mature heights both inside and outside of existing yellow-cedar stands. Mature, 100 &ndash; 200-year-old trees were often observed abruptly at stand boundaries, indicating that most stand boundaries have not moved in the past ~150 years. When observed, seedlings were most common in high light understory plant communities and moderately wet portions of the soil drainage gradient, consistent with the species&rsquo; autecology in the region.</p><p> Despite an overall lack of regeneration via seed, yellow-cedar is reproducing via asexual layering in high densities across stands. Layering may be one strategy this species employs to slowly infill habitat and/or persist on the landscape until conditions are more favorable for sexual reproduction. This study leads to a picture of yellow-cedar migration as punctuated, and relatively slow, in southeast Alaska. Yellow-cedar&rsquo;s migration history and currently limited spread at the northeastern range edge should be considered when planning for the conservation and management of this high value tree under future climate scenarios.</p>

This study analyzes temporal trends and periodicity in seventy years of publicly available stream discharge and climate data for the Winooski River Basin of northern Vermont as well as lake level data for adjacent Lake Champlain. We also use random sampling and manual, point-based classification of recent and historical aerial imagery to quantify land use change over the past seventy years in the 2,704 km2 Winooski River Basin of northern Vermont. We find a general increase in annual precipitation, discharge, and mean lake level with time in the basin; discharge increases 18% over the period of record while precipitation increases by 14%. Over the last 70 years, mean annual temperature has increased at the Burlington Vermont station by 0.78 degrees Celsius (1.4 degrees Fahrenheit). Four sets of aerial photographs, taken at intervals of 12 to 29 years between 1937 and 2003 at thirty randomly selected sites, demonstrate that actively cleared land area has decreased by 14%, while forested land and impervious surfaces increased by 10% and 5%, respectively. Spectral analysis of precipitation, discharge and lake level data show a ~7.6 year periodicity, which is in phase with the North Atlantic Oscillation (NAO); higher than average precipitation and discharge are most likely when the NAO is in a positive mode. The NAO relationship demonstrates that discharge is largely controlled by precipitation; anthropogenic changing climate and changing land use over the past 70 years appear to have subtly changed the seasonality of discharge and caused an increase in base flow.

<p> Tropical precipitation is linked through the moist static energy (MSE) budget to the global distribution of sea surface temperatures (SSTs), and large deviations from the present-day SST distribution have been inferred for past climates and projected for global warming. We use idealized SST perturbation experiments in multiple atmospheric general circulation models (AGCMs) to examine the hydrologic and energetic responses in the zonal mean and in the African Sahel to SST perturbations. We also use observational data to assess the prospects for emergent constraints on future rainfall in the Sahel. </p><p> The tropical zonal mean anomalous MSE fluxes in the NOAA Geophysical Fluid Dynamics Laboratory (GFDL) AM2.1 AGCM due to SST anomalies caused by either historical greenhouse gas or aerosol forcing primarily occur through the time-mean, zonal mean (Hadley) circulation. Away from the Intertropical Convergence Zone (ITCZ), this largely stems from altered efficiency of the Hadley circulation energy transport, i.e. the gross moist stability (GMS). A thermodynamic scaling-based estimate that relates GMS change to the local climatological moisture and temperature change relative to the ITCZ captures most of the qualitative GMS responses. It also yields a heuristic explanation for the well known correlation between low-latitude MSE fluxes and the ITCZ latitude. </p><p> Severe Sahelian drying with uniform SST warming in AM2.1 is eliminated when the default convective parameterization is replaced with an alternate. The drying is commensurate with MSE convergence due to suppressed ascent balanced by MSE divergence due to increased dry advection from the Sahara. These qualitative energetic responses to uniform warming are shared by five other GFDL models and ten CMIP5 models, although they do not translate into quantitative predictors of the Sahel rainfall response. Climatological values and interannual variability in observations and reanalyses suggest that drying in AM2.1 is exacerbated by an overly top-heavy ascent profile and positive feedbacks through cloud radiative properties. Simulations with patterned SST anomalies suggest a major role for mean SST variations in discrepancies among models and potentially in observed decadal variations of Sahelian precipitation.</p>

<p> Climate change has the potential to expose sea turtle nests to higher temperatures, which may negatively impact sea turtle hatchling vigor. In this study, loggerhead and green hatchlings were sampled from the Boca Raton, Florida beach and via lab incubation, and hatchling vigor was determined. Elevated nest temperatures decreased loggerhead and green turtle hatchling performance and corticosterone levels, with the most significant effects found in hatchlings exposed to maximum incubation temperatures above 35 &deg;C during late development. Lab-incubated loggerhead post-hatchling corticosterone levels and growth rates were also determined. The differences seen in corticosterone levels with overall nest incubation temperatures, mean temperatures during early, middle or late stages of development, and its negative correlation with hatchling performance improves our understanding of the underlying physiological mechanisms linking elevated incubation temperatures and sub-lethal physiological effects that may significantly impact hatchling survival, a critical step for sea turtle conservation in south Florida and elsewhere.</p><p>

University of Technology, Sydney. Faculty of Engineering. / This research has analysed the economy-wide impacts of carbon tax as a policy option to reduce the rate of growth of carbon-dioxide emissions from the electricity sector in Australia. These impacts are analysed for energy and non energy sectors of the economy. An energy-oriented Input–Output framework, with ‘flexible’ production functions, based on Translog and Cobb-Douglas formulations, is employed for the analysis of various impacts. Further, two alternative conceptions of carbon tax are considered in this research, namely, based on Polluter Pays Principle (PPP) and Shared Responsibility Principle (SRP). In the first instance, the impacts are analysed, for the period 2005–2020, for tax levels of $10 and $20 per tonne of CO2, in a situation of no a-priori limit on CO2 emissions. The analysis shows that CO2 emissions from the electricity sector, when carbon tax is based on PPP, would be 211 and 152 Mt, for tax levels of $10 and $20, respectively (as compared to 250 Mt in the Base Case scenario, that is, the business-as-usual-case). The net economic costs, corresponding with these tax levels, expressed in present value terms, would be $27 and $49 billion, respectively, over the period 2005-2020. These economic costs are equivalent to 0.43 and 0.78 per cent of the estimated GDP of Australia. Further, most of the economic burden, in this instance, would fall on the electricity sector, particularly coal-fired electricity generators – large consumers of direct fossil fuel. On the other hand, in the case of a carbon tax based on SRP, CO2 emissions would be 172 and 116 Mt, for tax levels of $10 and $20, respectively. The corresponding net economic costs would be $47 (0.74 per cent of GDP) and $84 (1.34 per cent of GDP) billion, respectively, with significant burden felt by the commercial sector – large consumers of indirect energy and materials whose production would contribute to CO2 emissions. Next, the impacts are analysed by placing an a-priori limit on CO2 emissions from the electricity sector – equivalent to 108 per cent of the 1990 level (that is, 138 Mt), by the year 2020. Two cases are analysed, namely, early action (carbon tax introduced in 2005) and deferred action (carbon tax introduced in 2010). In the case of early action, the analysis suggests, carbon tax of $25 and $15, based on PPP and SRP, respectively, would be required to achieve the above noted emissions target. The corresponding tax levels in the case of deferred action are $51 and $26, respectively. This research also shows that the net economic costs, in the case of early action, would be $32 billion (for PPP) and $18 billion (for SRP) higher than those in the case of deferred action. However, this research has demonstrated, that this inference is largely due to the selection of particular indicator (that is, present value) and the relatively short time frame (that is, 2005–2020) for analysis. By extending the time frame of the analysis to the year 2040, the case for an early introduction of carbon tax strengthens. Overall, the analysis in this research suggests that an immediate introduction of carbon tax, based on SRP, is the most attractive approach to reduce the rate of growth of CO2 emissions from the electricity sector and to simultaneously meet economic and social objectives. If the decision to introduce such a tax is deferred, it would be rather difficult to achieve not only environmental objectives but economic and social objectives as well.

Climate Change Effects and Water Vulnerability in the Molalla Pudding River Basin, Oregon, USA

The dragonfly communities in Sweden may be affected in many ways. Loss of habitats, habitat alteration or even environmental toxins might have a negative impact on the communities. A new threat to the communities and to the species in general is climate change. In this study I examined whether the dragonfly composition had changed in an area in central Sweden between 1997 and 2010. I did a nestedness matrix to see if the dragonfly composition (only using partivoltine species) was more or less nested in 2010 than it was in 1997, i.e. if there was more unexpected species recorded in the area. I also looked at the surrounding of the lakes and whether the species were considered to be generalist species or specialist species. I found that the dragonfly composition had changed during these 13 years and that the composition was more nested in 1997 than in 2010, i.e. there was more unexpected species in the 2010 survey. I also recorded seven new species for the area and that six species had disappeared. Six species had gone from being generalists to being specialists. The surroundings had not changed significantly and I thus see climate change as a possible explanation to these changes.

<p> The empirical analysis in this dissertation comprises two essays investigating the impacts of climate change on agriculture in Morocco, with an emphasis on climate uncertainty and robust adaptation.</p><p> The first essay in Chapter 4 provides estimates of economic impacts of climate change, and estimates on the extent to which the current Moroccan agricultural development and investment strategy, the Plan Maroc Vert (PMV), could help in agricultural adaptation to climate change and uncertainty.</p><p> We simulated three cases. First, we examined the impacts of PMV on the economy in the absence of climate change and found that it could provide about a 2.4% increase in GDP if the targets could be achieved. Subsequently, we did a separate simulation of the impacts of climate change on the Moroccan economy with no PMV (CC-Only) and found that there would be negative GDP impacts ranging between -0.5% and -3% depending on the climate scenario under the without CO₂ case. Including CO₂ fertilization effects induces a slight change in the distribution of impacts, which range from -1.4% to +0.3%. Finally, we evaluated the extent to which PMV could help mitigate the adverse impacts of climate change, and we found that the gain was quite small ranging between +0.02% and +0.04%.</p><p> The ability of the PMV strategy to mitigate the negative effects of climate change is limited at best, if non-existent. This is due to the scope of the PMV simulations limited to the strategic agricultural crop sectors in Morocco, which jointly represent no more than 35% of aggregate agricultural GDP; whereas the rest of the sectors account for 65%. Additionally, the likelihood of meeting the PMV productivity targets is low in light of our benchmark analysis comparing productivity prior to and after the adoption of GMO technologies.</p><p> The second essay examines the interaction of globalization through trade liberalization and climate change. Our hypothesis was that the more trade is liberalized, the higher the potential to compensate for losses due to climate change.</p><p> Our findings suggest that at the global level, our hypothesis is verified. World welfare gains are highest under a multilateral trade liberalization scenario, which induces a total offset of climate change welfare losses. However, under partial trade liberalization, the welfare gains become very small in comparison with the climate change impacts.</p><p> At the regional level, the results are more nuanced and our hypothesis does not hold for all regions. For instance, and focusing on Morocco as a case study, the net welfare impacts associated with trade liberalization are negative on average. But under the multilateral trade liberalization scenario, Morocco experiences net welfare gains under the SRES A1B and B1, which respectively reached US$ +23 million and US$ +16 million. Although trade liberalization induces net allocative efficiency gains under most scenarios, the large negative terms of trade effects offset most of the gains.</p>