Assessing Evapotranspiration Estimates from the Global Soil Wetness Project Phase 2 (GSWP-2) Simulations

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).We assess the simulations of global-scale evapotranspiration from the Global Soil Wetness Project Phase 2 (GSWP-2) within a global water-budget framework. The scatter in the GSWP-2 global evapotranspiration estimates from various land surface models can constrain the global, annual water budget fluxes to within ±2.5%, and by using estimates of global precipitation, the residual ocean evaporation estimate falls within the range of other independently derived bulk estimates. However, the GSWP-2 scatter cannot entirely explain the imbalance of the annual fluxes from a modern-era, observationally-based global water budget assessment, and inconsistencies in the magnitude and timing of seasonal variations between the global water budget terms are found. Inter-model inconsistencies in evapotranspiration are largest for high latitude inter-annual variability as well as for inter-seasonal variations in the tropics, and analyses with field-scale data also highlights model disparity at estimating evapotranspiration in high latitude regions. Analyses of the sensitivity simulations that replace uncertain forcings (i.e. radiation, precipitation, and meteorological variables) indicate that global (land) evapotranspiration is slightly more sensitive to precipitation than net radiation perturbations, and the majority of the GSWP-2 models, at a global scale, fall in a marginally moisture-limited evaporative condition. Finally, the range of global evapotranspiration estimates among the models is larger than any bias caused by uncertainties in the GSWP-2 atmospheric forcing, indicating that model structure plays a more important role toward improving global land evaporation estimates (as opposed to improved atmospheric forcing).NASA Energy and Water-cycle Study (NEWS, grant #NNX06AC30A), under the NEWS Science and Integration Team activities

A Healthy Diet of Preemption: The Power of the FDA and the Battle Over Restricting High Fructose Corn Syrup From Food and Beverages Labeled \u27Natural\u27

America is unhealthy. America faces an obesity epidemic. The food consumed by Americans is making them fat. Americans, bombarded every single day by negative headlines like these, are becoming more and more health conscious. This newfound commitment to health is reflected in the food and beverages Americans purchase

Regional climate change of the greater Zambezi River Basin: A hybrid assessment

Projections of regional changes in seasonal surface-air temperature and precipitation for the eastern and western Zambezi River Basin regions are presented. These projections are cast in a probabilistic context based on a numerical hybridization technique of the MIT Integrated Global System Model. Unconstrained emissions send the majority of outcomes in spring precipitation to a drying by 2050, although the total distribution spans both precipitation increases and decreases. From climate policy, the distributions' range collapse considerably and the distributions' mode lies near zero precipitation change. For surface air temperature, the most notable effect of climate policy is to reduce the mode value of warming as well as the occurrence of the most extreme increases

Assessing the likelihood of regional climate change over the Nile River basin and northern Africa: A hybrid assessment

Projections of regional changes in surface air temperature and precipitation for the greater Nile River basin and northern Africa are presented. The probabilistic projections are obtained through a technique that combines projections of the MIT Integrated Global System Model with climate-change patterns of the Intergovernmental Panel on Climate Change. Overall, the most consistent response to climate policy is seen in the distributions of temperature change. For precipitation, the predominant climate stabilization response is to reduce the likelihood of modal change. To quantify risks of climate change, the study data can be vetted through a chain of impact models

The Association of Large-Scale Climate Variability and Teleconnections on Wind Energy Resource over Europe and its Intermittency

In times of increasing importance of wind power in the world’s energy mix, this study focuses on a better understanding of the influences of large-scale climate variability on wind power resource over Europe. The impact of the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), the El Niño Southern Oscillation (ENSO) and the Atlantic Multidecadal Oscillation (AMO) are investigated in terms of their correlation with wind power density (WPD) at 80 m hub height. These WPDs are calculated based on the MERRA Reanalysis data set covering 31 years of measurements. Not surprisingly, AO and NAO are highly correlated with the time series of WPD. This correlation can also be found in the first principal component of a Principal Component Analysis (PCA) of WPD over Europe explaining 14% of the overall variation. Further, cross-correlation analyses indicates the strongest associated variations are achieved with AO/NAO leading WPD by at most one day. Furthermore, the impact of high and low phases of the respective oscillations has been assessed to provide a more comprehensive illustration. The fraction of WPD for high and low AO/NAO increases considerably for northern Europe, whereas the opposite pattern can be observed for southern Europe. Similar results are obtained by calculating the energy output of three hypothetical wind turbines for every grid point over Europe. Thus, we identified a high interconnection potential between wind farms in order to reduce intermittency, one of the primary challenges in wind power generation. In addition, we observe significant correlations between WPD and AMO

The impact of climate change on wind and solar resources in southern Africa

Climate change is an issue that requires global attention and co-operation. As climate science develops an understanding of changes to the future climate state, policy makers and engineering project planners beg to know what claims can be made on the subject with a reasonable level of confidence. A common and popular mitigation strategy for reducing emissions is to build away from carbon intensive electricity production to clean energy sources like the energy produced from wind and solar irradiation. These sources themselves are climate dependent. In this study, we present a method to estimate the climate change impact on wind and solar resource potential which builds on previous studies that take a risk-based approach. The assessment combines climate projection output from the Integrated Global Systems Model, which introduces emissions and climate sensitivity uncertainty, with 19 Global Circulation Models available from the Coupled Model Intercomparison Project phase 3. Southern Africa, specifically those in the Southern African Development Community, is used as a case study. We find little agreement between Global Circulation Models and emission scenarios, resulting in a median change close to zero by 2050 in the long-term mean of both wind speed and solar radiation (used as an indicator of change in electricity production potential). Although the extreme possibilities range from about -15 per cent to +15 per cent change, these are associated with low probability. These projected results in the long-term mean climate - and their associated probabilities - stay true to the limitations of state-of-the-art climate system models and are apt to be useful for policy and engineering planning

A Global Land System Framework for Integrated Climate-Change Assessments

Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).Land ecosystems play a major role in the global cycles of energy, water, carbon and nutrients. A Global Land System (GLS) framework has been developed for the Integrated Global Systems Model Version 2 (IGSM2) to simulate the coupled biogeophysics and biogeochemistry of these ecosystems, as well as the interactions of these terrestrial processes with the climate system. The GLS framework has resolved a number of water and energy cycling deficiencies and inconsistencies introduced in IGSM1. In addition, a new representation of global land cover and classification as well as soil characteristics has been employed that ensures a consistent description of the global land surface amongst all the land components of the IGSM2. Under this new land cover classification system, GLS is run for a mosaic of land cover types within a latitudinal band defined by the IGSM2 atmosphere dynamics and chemistry sub-model. The GLS shows notable improvements in the representation of land fluxes and states of water and energy over the previous treatment of land processes in the IGSM1. In addition, the zonal features of simulated carbon fluxes as well as key trace gas emissions of methane and nitrous oxide are comparable to estimates based on higher resolution models constrained by observed climate forcing. Given this, the GLS framework represents a key advance in the ability of the IGSM to faithfully represent coupled terrestrial processes to the climate system, and is well poised to support more robust two-way feedbacks of natural and managed hydrologic and ecologic systems with the climate and socio-economic components of the IGSM2.This study received support from the MIT Joint Program on the Science and Policy of Global Change, which is funded by a consortium of government, industry and foundation sponsors

A hybrid approach to incorporating climate change and variability into climate scenario for impact assessments

Traditional 'delta-change' approach of scenario generation for climate change impact assessment to water resources strongly depends on the selected base-case observed historical climate conditions that the climate shocks are to be super-imposed. This method disregards the combined effect of climate change and the inherent hydro-climatological variability in the system. Here we demonstrated a hybrid uncertainty approach in which uncertainties in historical climate variability are combined with uncertainties in climate predictions to conduct more comprehensive climate change impact assessment to hydropower in Zambezi and Congo River basins. Synthetic ensembles of base-case scenarios of the significant climate variables were generated using frequency domain simulation to represent the uncertainty in natural variability. These were combined with large sets of uncertainties in future climate anomalies, hybrid frequency distributions which are based on the full set of the IPCC AR4 global circulation models. Biophysical modeling of water resource systems in both basins was conducted to study the impact of these scenarios. Results from this study indicate that the use of single base-case approach of delta-change technique could substantially underestimate the potential impact of climate change to hydropower. Particularly, assessments for water resource systems in areas with high natural hydroclimatic variability, careful consideration should be given to the natural variability as the combined effect is more pronounced

The Potential Wind Power Resource in Australia: A New Perspective

Australia is considered to have very good wind resources, and the utilization of this renewable energy resource is increasing. Wind power installed capacity increased by 35% from 2006 to 2011 and is predicted to account for over 12% of Australia’s electricity generation in 2030. This study uses a recently published methodology to address the limitations of previous wind resource analyses, and frames the nature of Australia’s wind resources from the perspective of economic viability, using robust metrics of the abundance, variability and intermittency of wind power density, and analyzes whether these differ with higher wind turbine hub heights. We also assess the extent to which wind intermittency can potentially be mitigated by the aggregation of geographically dispersed wind farms. Our results suggest that over much of Australia, areas that have high wind intermittency coincide with large expanses in which the aggregation of turbine output does not mitigate variability. These areas are also geographically remote, some are disconnected from the east coast’s electricity grid and large population centers, and often are not connected or located near enough to high capacity electricity infrastructure, all of which would decrease the potential economic viability of wind farms in these locations. However, on the eastern seaboard, even though the wind resource is weaker, it is less variable, much closer to large population centers, and there exists more potential to mitigate its intermittency through aggregation.The authors gratefully acknowledge the financial support for this work provided by the MIT Joint Program on the Science and Policy of Global Change through a number of federal agencies and industrial sponsors including US Department of Energy grant DE-FG02-94ER61937

Adaptation Advantage to Climate Change Impacts on Road Infrastructure in Africa through 2100

The African continent is facing the potential of a US$183.6 billion liability to repair and maintain roads damaged from temperature and precipitation changes related to climate change through 2100. As detailed, the central part of the continent faces the greatest impact from climate change with countries facing an average cost of US$22 million annually, if they adopt a proactive adaptation policy and a US$54 million annual average, if a reactive approach is adopted. Additionally, countries face an average loss of opportunity to expand road networks from a low of 22 per cent to a high of 235 per cent in the central region.infrastructure, climate change, roads, cost estimates