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1:18:31 Institute of Physics (IOP) English 2011

Electronic Properties of Bilayer Graphene, from High to Low Energies

  • Published: 2011
  • Publisher: Institute of Physics (IOP)
  • Language: English
1:18:00 Institute of Physics (IOP) English 2011

Raman Spectra of Graphene and Carbon Nanotubes

  • Published: 2011
  • Publisher: Institute of Physics (IOP)
  • Language: English
54:08 Institute of Physics (IOP) English 2011

Recent Progress in Graphene Synthesis and Applications

  • Published: 2011
  • Publisher: Institute of Physics (IOP)
  • Language: English
1:01:25 Institute of Physics (IOP) English 2011

Graphene Update

  • Published: 2011
  • Publisher: Institute of Physics (IOP)
  • Language: English
04:03 Institute of Physics (IOP) English 2013

Bioenergy: how much can we expect for 2050?

Estimates of global primary bioenergy potentials in the literature span almost three orders of magnitude. We narrow that range by discussing biophysical constraints on bioenergy potentials resulting from plant growth (NPP) and its current human use. In the last 30 years, terrestrial NPP was almost constant near 54 PgC yr−1, despite massive efforts to increase yields in agriculture and forestry. The global human appropriation of terrestrial plant production has doubled in the last century. We estimate the maximum physical potential of the world's total land area outside croplands, infrastructure, wilderness and denser forests to deliver bioenergy at approximately 190 EJ yr−1. These pasture lands, sparser woodlands, savannas and tundras are already used heavily for grazing and store abundant carbon; they would have to be entirely converted to bioenergy and intensive forage production to provide that amount of energy. Such a high level of bioenergy supply would roughly double the global human biomass harvest, with far-reaching effects on biodiversity, ecosystems and food supply. Identifying sustainable levels of bioenergy and finding ways to integrate bioenergy with food supply and ecological conservation goals remains a huge and pressing scientific challenge.
  • Published: 2013
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:53 Institute of Physics (IOP) English 2013

Soil microbial respiration from observations and Earth System Models

Soil microbial respiration (Rh) is a large but uncertain component of the terrestrial carbon cycle. Carbon–climate feedbacks associated with changes to Rh are likely, but Rh parameterization in Earth System Models (ESMs) has not been rigorously evaluated largely due to a lack of appropriate measurements. Here we assess, for the first time, Rh estimates from eight ESMs and their environmental drivers across several biomes against a comprehensive soil respiration database (SRDB-V2). Climatic, vegetation, and edaphic factors exert strong controls on annual Rh in ESMs, but these simple controls are not as apparent in the observations. This raises questions regarding the robustness of ESM projections of Rh in response to future climate change. Since there are many more soil respiration (Rs) observations than Rh data, two 'reality checks' for ESMs are also created using the Rs data. Guidance is also provided on the Rh improvement in ESMs.
  • Published: 2013
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:20 Institute of Physics (IOP) English 2018

Climate effects of non-compliant Volkswagen diesel cars

On-road operations of Volkswagen light-duty diesel vehicles equipped with defeat devices cause emissions of NOx up to 40 times above emission standards. Higher on-road NOx emissions are a widespread problem not limited to Volkswagen vehicles, but the Volkswagen violations brought this issue under the spotlight. While several studies investigated the health impacts of high NOx emissions, the climatic impacts have not been quantified. Here we show that such diesel cars generate a larger warming on the time scale of several years but a smaller warming on the decadal time scale during actual on-road operations than in vehicle certification tests. The difference in longer-term warming levels, however, depends on underlying driving conditions. Furthermore, in the presence of defeat devices, the climatic advantage of 'clean diesel' cars over gasoline cars, in terms of global-mean temperature change, is in our view not necessarily the case.
  • Published: 2018
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:56 Institute of Physics (IOP) English 2013

Connecting plug-in vehicles with green electricity through consumer demand

The environmental benefits of plug-in electric vehicles (PEVs) increase if the vehicles are powered by electricity from 'green' sources such as solar, wind or small-scale hydroelectricity. Here, we explore the potential to build a market that pairs consumer purchases of PEVs with purchases of green electricity. We implement a web-based survey with three US samples defined by vehicle purchases: conventional new vehicle buyers (n = 1064), hybrid vehicle buyers (n = 364) and PEV buyers (n = 74). Respondents state their interest in a PEV as their next vehicle, in purchasing green electricity in one of three ways, i.e., monthly subscription, two-year lease or solar panel purchase, and in combining the two products. Although we find that a link between PEVs and green electricity is not presently strong in the consciousness of most consumers, the combination is attractive to some consumers when presented. Across all three respondent segments, pairing a PEV with a green electricity program increased interest in PEVs—with a 23% demand increase among buyers of conventional vehicles. Overall, about one-third of respondents presently value the combination of a PEV with green electricity; the proportion is much higher among previous HEV and PEV buyers. Respondents' reported motives for interest in both products and their combination include financial savings (particularly among conventional buyers), concerns about air pollution and the environment, and interest in new technology (particularly among PEV buyers). The results provide guidance regarding policy and marketing strategies to advance PEVs and green electricity demand.
  • Published: 2013
  • Publisher: Institute of Physics (IOP)
  • Language: English
02:17 Institute of Physics (IOP) English 2018

Feed conversion efficiency in aquaculture: do we measure it correctly?

Globally, demand for food animal products is rising. At the same time, we face mounting, related pressures including limited natural resources, negative environmental externalities, climate disruption, and population growth. Governments and other stakeholders are seeking strategies to boost food production efficiency and food system resiliency, and aquaculture (farmed seafood) is commonly viewed as having a major role in improving global food security based on longstanding measures of animal production efficiency. The most widely used measurement is called the 'feed conversion ratio' (FCR), which is the weight of feed administered over the lifetime of an animal divided by weight gained. By this measure, fed aquaculture and chickens are similarly efficient at converting feed into animal biomass, and both are more efficient compared to pigs and cattle. FCR does not account for differences in feed content, edible portion of an animal, or nutritional quality of the final product. Given these limitations, we searched the literature for alternative efficiency measures and identified 'nutrient retention', which can be used to compare protein and calories in feed (inputs) and edible portions of animals (outputs). Protein and calorie retention have not been calculated for most aquaculture species. Focusing on commercial production, we collected data on feed composition, feed conversion ratios, edible portions (i.e. yield), and nutritional content of edible flesh for nine aquatic and three terrestrial farmed animal species. We estimate that 19% of protein and 10% of calories in feed for aquatic species are ultimately made available in the human food supply, with significant variation between species. Comparing all terrestrial and aquatic animals in the study, chickens are most efficient using these measures, followed by Atlantic salmon. Despite lower FCRs in aquaculture, protein and calorie retention for aquaculture production is comparable to livestock production. This is, in part, due to farmed fish and shrimp requiring higher levels of protein and calories in feed compared to chickens, pigs, and cattle. Strategies to address global food security should consider these alternative efficiency measures.
  • Published: 2018
  • Publisher: Institute of Physics (IOP)
  • Language: English
04:01 Institute of Physics (IOP) English 2017

General framework for fluctuating dynamic density functional theory

We introduce a versatile bottom-up derivation of a formal theoretical framework to describe (passive) soft-matter systems out of equilibrium subject to fluctuations. We provide a unique connection between the constituent-particle dynamics of real systems and the time evolution equation of their measurable (coarse-grained) quantities, such as local density and velocity. The starting point is the full Hamiltonian description of a system of colloidal particles immersed in a fluid of identical bath particles. Then, we average out the bath via Zwanzig's projection-operator techniques and obtain the stochastic Langevin equations governing the colloidal-particle dynamics. Introducing the appropriate definition of the local number and momentum density fields yields a generalisation of the Dean–Kawasaki (DK) model, which resembles the stochastic Navier–Stokes description of a fluid. Nevertheless, the DK equation still contains all the microscopic information and, for that reason, does not represent the dynamical law of observable quantities. We address this controversial feature of the DK description by carrying out a nonequilibrium ensemble average. Adopting a natural decomposition into local-equilibrium and nonequilibrium contribution, where the former is related to a generalised version of the canonical distribution, we finally obtain the fluctuating-hydrodynamic equation governing the time-evolution of the mesoscopic density and momentum fields. Along the way, we outline the connection between the ad hoc energy functional introduced in previous DK derivations and the free-energy functional from classical density-functional theory. The resultant equation has the structure of a dynamical density-functional theory (DDFT) with an additional fluctuating force coming from the random interactions with the bath. We show that our fluctuating DDFT formalism corresponds to a particular version of the fluctuating Navier–Stokes equations, originally derived by Landau and Lifshitz. Our framework thus provides the formal apparatus for ab initio derivations of fluctuating DDFT equations capable of describing the dynamics of soft-matter systems in and out of equilibrium.
  • Published: 2017
  • Publisher: Institute of Physics (IOP)
  • Language: English
02:38 Institute of Physics (IOP) English 2018

The asymmetric response of Yangtze river basin summer rainfall to El Niño/La Niña

The Yangtze river basin, in South East China, experiences anomalously high precipitation in summers following El Niño. This can lead to extensive flooding and loss of life. However, the response following La Niña has not been well documented. In this study, the response of Yangtze summer rainfall to El Niño/La Niña is found to be asymmetric, with no significant response following La Niña. The nature of this asymmetric response is found to be in good agreement with that simulated by the Met Office seasonal forecast system. Yangtze summer rainfall correlates positively with spring sea surface temperatures in the Indian Ocean and northwest Pacific. Indian Ocean sea surface temperatures are found to respond linearly to El Niño/La Niña, and to have a linear impact on Yangtze summer rainfall. However, northwest Pacific sea surface temperatures respond much more strongly following El Niño and, further, correlate more strongly with positive rainfall years. It is concluded that, whilst delayed Indian Ocean signals may influence summer Yangtze rainfall, it is likely that they do not lead to the asymmetric nature of the rainfall response to El Niño/La Niña.
  • Published: 2018
  • Publisher: Institute of Physics (IOP)
  • Language: English
04:05 Institute of Physics (IOP) English 2014

Internal variability of Earth's energy budget simulated by CMIP5 climate models

We analyse a large number of multi-century pre-industrial control simulations from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) to investigate relationships between: net top-of-atmosphere radiation (TOA), globally averaged surface temperature (GST), and globally integrated ocean heat content (OHC) on decadal timescales. Consistent with previous studies, we find that large trends (~0.3 K dec−1) in GST can arise from internal climate variability and that these trends are generally an unreliable indicator of TOA over the same period. In contrast, trends in total OHC explain 95% or more of the variance in TOA for two-thirds of the models analysed; emphasizing the oceans' role as Earth's primary energy store. Correlation of trends in total system energy (TE ≡ time integrated TOA) against trends in OHC suggests that for most models the ocean becomes the dominant term in the planetary energy budget on a timescale of about 12 months. In the context of the recent pause in global surface temperature rise, we investigate the potential importance of internal climate variability in both TOA and ocean heat rearrangement. The model simulations suggest that both factors can account for O (0.1 W m−2) on decadal timescales and may play an important role in the recently observed trends in GST and 0–700 m (and 0–1800 m) ocean heat uptake.
  • Published: 2014
  • Publisher: Institute of Physics (IOP)
  • Language: English
04:03 Institute of Physics (IOP) English 2017

Carbon tax effects on the poor: a SAM-based approach

A SAM-based price model for Mexico is developed in order to assess the effects of the carbon tax, which was part of the fiscal reform approved in 2014. The model is formulated based on a social accounting matrix (SAM) that distinguishes households by the official poverty condition and geographical area. The main results are that the sector that includes coke, refined petroleum and nuclear fuel shows the highest price increase due to the direct impact of the carbon tax; in addition, air transport and inland transport are the most affected sectors, in an indirect manner, because both employ inputs from the former sector. Also, it is found that welfare diminishes more in the rural strata than in the urban one. In the urban area, the carbon tax is regressive: the negative impact of carbon tax on family welfare is greater on the poorest families.
  • Published: 2017
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:29 Institute of Physics (IOP) English 2014

The Haber Bosch–harmful algal bloom (HB–HAB) link

Large-scale commercialization of the Haber–Bosch (HB) process is resulting in intensification of nitrogen (N) fertilizer use worldwide. Globally N fertilizer use is far outpacing that of phosphorus (P) fertilizer. Much of the increase in N fertilizers is also now in the form of urea, a reduced form of N. Incorporation of these fertilizers into agricultural products is inefficient leading to significant environmental pollution and aquatic eutrophication. Of particular concern is the increased occurrence of harmful algal blooms (HABs) in waters receiving nutrient enriched runoff. Many phytoplankton causing HABs have physiological adaptive strategies that make them favored under conditions of elevated N : P conditions and supply of chemically reduced N (ammonium, urea). We propose that the HB-HAB link is a function of (1) the inefficiency of incorporation of N fertilizers in the food supply chain, the leakiness of the N cycle from crop to table, and the fate of lost N relative to P to the environment; and (2) adaptive physiology of many HABs to thrive in environments in which there is excess N relative to classic nutrient stoichiometric proportions and where chemically reduced forms of N dominate. The rate of HAB expansion is particularly pronounced in China where N fertilizer use has escalated very rapidly, where soil retention is declining, and where blooms have had large economic and ecological impacts. There, in addition to increased use of urea and high N : P based fertilizers overall, escalating aquaculture production adds to the availability of reduced forms of N, as does atmospheric deposition of ammonia. HABs in both freshwaters and marginal seas in China are highly related to these overall changing N loads and ratios. Without more aggressive N control the future outlook in terms of HABs is likely to include more events, more often, and they may also be more toxic.
  • Published: 2014
  • Publisher: Institute of Physics (IOP)
  • Language: English
02:38 Institute of Physics (IOP) English 2016

Alleviating inequality in climate policy costs: an integrated perspective on mitigation, damage and adaptation

Equity considerations play an important role in international climate negotiations. While policy analysis has often focused on equity as it relates to mitigation costs, there are large regional differences in adaptation costs and the level of residual damage. This paper illustrates the relevance of including adaptation and residual damage in equity considerations by determining how the allocation of emission allowances would change to counteract regional differences in total climate costs, defined as the costs of mitigation, adaptation, and residual damage. We compare emission levels resulting from a global carbon tax with two allocations of emission allowances under a global cap-and-trade system: one equating mitigation costs and one equating total climate costs as share of GDP. To account for uncertainties in both mitigation and adaptation, we use a model-comparison approach employing two alternative modeling frameworks with different damage, adaptation cost, and mitigation cost estimates, and look at two different climate goals. Despite the identified model uncertainties, we derive unambiguous results on the change in emission allowance allocation that could lessen the unequal distribution of adaptation costs and residual damages through the financial transfers associated with emission trading.
  • Published: 2016
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:53 Institute of Physics (IOP) English 2013

Changing the spatial location of electricity generation to increase water availability in areas with drought: a feasibility study and quantification of air quality impacts in Texas

The feasibility, cost, and air quality impacts of using electrical grids to shift water use from drought-stricken regions to areas with more water availability were examined. Power plant cooling represents a large portion of freshwater withdrawals in the United States, and shifting where electricity generation occurs can allow the grid to act as a virtual water pipeline, increasing water availability in regions with drought by reducing water consumption and withdrawals for power generation. During a 2006 drought, shifting electricity generation out of the most impacted areas of South Texas (~10% of base case generation) to other parts of the grid would have been feasible using transmission and power generation available at the time, and some areas would experience changes in air quality. Although expensive, drought-based electricity dispatch is a potential parallel strategy that can be faster to implement than other infrastructure changes, such as air cooling or water pipelines.
  • Published: 2013
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:55 Institute of Physics (IOP) English 2018

Impact of cutting meat intake on hidden greenhouse gas emissions in an import-reliant city

Greenhouse gas emissions embodied in trade is a growing concern for the international community. Multiple studies have highlighted drawbacks in the territorial and production-based accounting of greenhouse gas emissions because it neglects emissions from the consumption of goods in trade. This creates weak carbon leakage and complicates international agreements on emissions regulations. Therefore, we estimated consumption-based emissions using input-output analysis and life cycle assessment to calculate the greenhouse gas emissions hidden in meat and dairy products in Hong Kong, a city predominately reliant on imports. We found that emissions solely from meat and dairy consumption were higher than the city's total greenhouse gas emissions using conventional production-based calculation. This implies that government reports underestimate more than half of the emissions, as 62% of emissions are embodied in international trade. The discrepancy emphasizes the need of transitioning climate targets and policy to consumption-based accounting. Furthermore, we have shown that dietary change from a meat-heavy diet to a diet in accordance with governmental nutrition guidelines could achieve a 67% reduction in livestock-related emissions, allowing Hong Kong to achieve the Paris Agreement targets for 2030. Consequently, we concluded that consumption-based accounting for greenhouse gas emissions is crucial to target the areas where emissions reduction is realistically achievable, especially for import-reliant cities like Hong Kong.
  • Published: 2018
  • Publisher: Institute of Physics (IOP)
  • Language: English
04:32 Institute of Physics (IOP) English 2015

Energy for water and water for energy on Maui Island, Hawaii

Energy and water systems are interconnected. This work first characterizes 2010 primary energy demand for direct water services and local freshwater demand for energy on Maui Island, Hawaii, then investigates scenarios for future changes in these demands. The goal of this manuscript is to dissect the relationship and trends of energy–water connections to inform policymaking decisions related to water and energy planning. Analysis proceeds by inventorying water and energy flows and adjusting to a 2010 base year, then applying intensity factors for energy or water used at a given stage for a given sector to determine absolute energy and water demands for the isolated system of Maui Island. These bottom-up, intensity-based values are validated against published data where available. Maui consumes about 0.05% of its freshwater for energy (versus >6% for the US on average) and about 32% of its electricity (19% of its on-island primary energy) for direct water services (versus 8% of primary energy for the US on average). These values could change with policy choices like increased instream flows, higher wastewater treatment standards, electricity fuel mix changes, desalination, or increased biofuels production. This letter contributes a granular assessment of both energy for water and water for energy in a single isolated system, highlighting opportunities to address energy–water interdependencies in a context that could be relevant in other communities facing similar choices.
  • Published: 2015
  • Publisher: Institute of Physics (IOP)
  • Language: English
04:00 Institute of Physics (IOP) English 2013

A shorter snowfall season associated with higher air temperatures over northern Eurasia

The temperature sensitivity of the snowfall season (start, end, duration) over northern Eurasia (the former USSR) is analyzed from synoptic records of 547 stations from 1966 to 2000. The results find significant correlations between temperature and snowfall season at approximately 56% of stations (61% for the starting date and 56% for the ending date) with a mean snowfall season duration temperature sensitivity of −6.2 days °C−1 split over the start (2.8 days) and end periods (−3.4 days). Temperature sensitivity was observed to increase with stations' mean seasonal air temperature, with the strongest relationships at locations of around 6 °C temperature. This implies that increasing air temperature in fall and spring will delay the onset and hasten the end of snowfall events, and reduces the snowfall season length by 6.2 days for each degree of increase. This study also clarifies that the increasing trend in snowfall season length during 1936/37–1994 over northern European Russia and central Siberia revealed in an earlier study is unlikely to be associated with warming in spring and fall seasons.
  • Published: 2013
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:21 Institute of Physics (IOP) English 2013

REDD+ readiness: early insights on monitoring, reporting and verification systems of project developers

A functional measuring, monitoring, reporting and verification (MRV) system is essential to assess the additionality and impact on forest carbon in REDD+ (reducing emissions from deforestation and degradation) projects. This study assesses the MRV capacity and readiness of project developers at 20 REDD+ projects in Brazil, Peru, Cameroon, Tanzania, Indonesia and Vietnam, using a questionnaire survey and field visits. Nineteen performance criteria with 76 indicators were formulated in three categories, and capacity was measured with respect to each category. Of the 20 projects, 11 were found to have very high or high overall MRV capacity and readiness. At the regional level, capacity and readiness tended to be highest in the projects in Brazil and Peru and somewhat lower in Cameroon, Tanzania, Indonesia and Vietnam. Although the MRV capacities of half the projects are high, there are capacity deficiencies in other projects that are a source of concern. These are not only due to limitations in technical expertise, but can also be attributed to the slowness of international REDD+ policy formulation and the unclear path of development of the forest carbon market. Based on the study results, priorities for MRV development and increased investment in readiness are proposed.
  • Published: 2013
  • Publisher: Institute of Physics (IOP)
  • Language: English
04:52 Institute of Physics (IOP) English 2013

Are global wind power resource estimates overstated?

Estimates of the global wind power resource over land range from 56 to 400 TW. Most estimates have implicitly assumed that extraction of wind energy does not alter large-scale winds enough to significantly limit wind power production. Estimates that ignore the effect of wind turbine drag on local winds have assumed that wind power production of 2–4 W m−2 can be sustained over large areas. New results from a mesoscale model suggest that wind power production is limited to about 1 W m−2 at wind farm scales larger than about 100 km2. We find that the mesoscale model results are quantitatively consistent with results from global models that simulated the climate response to much larger wind power capacities. Wind resource estimates that ignore the effect of wind turbines in slowing large-scale winds may therefore substantially overestimate the wind power resource.
  • Published: 2013
  • Publisher: Institute of Physics (IOP)
  • Language: English
01:26 Institute of Physics (IOP) English 2018

Saharan dust plume charging observed over the UK

A plume of Saharan dust and Iberian smoke was carried across the southern UK on 16th October 2017, entrained into an Atlantic cyclone which had originated as Hurricane Ophelia. The dust plume aloft was widely noticed as it was sufficiently dense to redden the visual appearance of the sun. Time series of backscatter from ceilometers at Reading and Chilbolton show two plumes: one carried upwards to 2.5 km, and another below 800 m into the boundary layer, with a clear slot between. Steady descent of particles at about 50 cm s−1 continued throughout the morning, and coarse mode particles reached the surface. Plumes containing dust are frequently observed to be strongly charged, often through frictional effects. This plume passed over atmospheric electric field sensors at Bristol, Chilbolton and Reading. Consistent measurements at these three sites indicated negative plume charge. The lower edge plume charge density was (−8.0 ± 3.3) nC m−2, which is several times greater than that typical for stratiform water clouds, implying an active in situ charge generation mechanism such as turbulent triboelectrification. A meteorological radiosonde measuring temperature and humidity was launched into the plume at 1412 UTC, specially instrumented with charge and turbulence sensors. This detected charge in the boundary layer and in the upper plume region, and strong turbulent mixing was observed throughout the atmosphere's lowest 4 km. The clear slot region, through which particles sedimented, was anomalously dry compared with modelled values, with water clouds forming intermittently in the air beneath. Electrical aspects of dust should be included in numerical models, particularly the charge-related effects on cloud microphysical properties, to accurately represent particle behaviour and transport.
  • Published: 2018
  • Publisher: Institute of Physics (IOP)
  • Language: English
05:27 Institute of Physics (IOP) English 2014

A comparative analysis of the greenhouse gas emissions intensity of wheat and beef in the United States

The US food system utilizes large quantities of liquid fuels, electricity, and chemicals yielding significant greenhouse gas (GHG) emissions that are not considered in current retail prices, especially when the contribution of biogenic emissions is considered. However, because GHG emissions might be assigned a price in prospective climate policy frameworks, it would be useful to know the extent to which those policies would increase the incremental production costs to food within the US food system. This analysis uses lifecycle assessment (LCA) to (1) estimate the magnitude of carbon dioxide equivalent (CO2e) emissions from typical US food production practices, using wheat and beef as examples, and (2) quantify the cost of those emissions in the context of a GHG-pricing regime over a range of policy constructs. Wheat and beef were chosen as benchmark staples to provide a representative range of less intensive and more intensive agricultural goods, respectively. Results suggest that 1.1 ± 0.13 and 31 ± 8.1 kg of lifecycle CO2e emissions are embedded in 1 kg of wheat and beef production, respectively. Consequently, the cost of lifecycle CO2e emissions for wheat (i.e. cultivation, processing, transportation, storage, and end-use preparation) over an emissions price range of 10 and 85 per tonne CO2e is estimated to be between 0.01 and 0.09 per kg of wheat, respectively, which would increase total wheat production costs by approximately 0.3–2% per kg. By comparison, the estimated lifecycle CO2e price of beef over the same range of CO2e prices is between 0.31 and 2.60 per kg of beef, representing a total production cost increase of approximately 5–40% per kg based on average 2010 food prices. This range indicates that the incremental cost to total US food production might be anywhere between 0.63–5.4 Billion per year for grain and 3.70 and 32 Billion per year for beef based on CO2e emissions assuming that total production volumes stay the same.
  • Published: 2014
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:24 Institute of Physics (IOP) English 2013

Strategic incentives for climate geoengineering coalitions to exclude broad participation

Solar geoengineering is the deliberate reduction in the absorption of incoming solar radiation by the Earth's climate system with the aim of reducing impacts of anthropogenic climate change. Climate model simulations project a diversity of regional outcomes that vary with the amount of solar geoengineering deployed. It is unlikely that a single small actor could implement and sustain global-scale geoengineering that harms much of the world without intervention from harmed world powers. However, a sufficiently powerful international coalition might be able to deploy solar geoengineering. Here, we show that regional differences in climate outcomes create strategic incentives to form coalitions that are as small as possible, while still powerful enough to deploy solar geoengineering. The characteristics of coalitions to geoengineer climate are modeled using a 'global thermostat setting game' based on climate model results. Coalition members have incentives to exclude non-members that would prevent implementation of solar geoengineering at a level that is optimal for the existing coalition. These incentives differ markedly from those that dominate international politics of greenhouse-gas emissions reduction, where the central challenge is to compel free riders to participate.
  • Published: 2013
  • Publisher: Institute of Physics (IOP)
  • Language: English
05:35 Institute of Physics (IOP) English 2013

Land cover dynamics following a deforestation ban in northern Costa Rica

Forest protection policies potentially reduce deforestation and re-direct agricultural expansion to already-cleared areas. Using satellite imagery, we assessed whether deforestation for conversion to pasture and cropland decreased in the lowlands of northern Costa Rica following the 1996 ban on forest clearing, despite a tripling of area under pineapple cultivation in the last decade. We observed that following the ban, mature forest loss decreased from 2.2% to 1.2% per year, and the proportion of pineapple and other export-oriented cropland derived from mature forest declined from 16.4% to 1.9%. The post-ban expansion of pineapples and other crops largely replaced pasture, exotic and native tree plantations, and secondary forests. Overall, there was a small net gain in forest cover due to a shifting mosaic of regrowth and clearing in pastures, but cropland expansion decreased reforestation rates. We conclude that forest protection efforts in northern Costa Rica have likely slowed mature forest loss and succeeded in re-directing expansion of cropland to areas outside mature forest. Our results suggest that deforestation bans may protect mature forests better than older forest regrowth and may restrict clearing for large-scale crops more effectively than clearing for pasture.
  • Published: 2013
  • Publisher: Institute of Physics (IOP)
  • Language: English
02:24 Institute of Physics (IOP) English 2018

Global predictability of temperature extremes

Extreme temperatures are one of the leading causes of death and disease in both developed and developing countries, and heat extremes are projected to rise in many regions. To reduce risk, heatwave plans and cold weather plans have been effectively implemented around the world. However, much of the world's population is not yet protected by such systems, including many data-scarce but also highly vulnerable regions. In this study, we assess at a global level where such systems have the potential to be effective at reducing risk from temperature extremes, characterizing (1) long-term average occurrence of heatwaves and coldwaves, (2) seasonality of these extremes, and (3) short-term predictability of these extreme events three to ten days in advance. Using both the NOAA and ECMWF weather forecast models, we develop global maps indicating a first approximation of the locations that are likely to benefit from the development of seasonal preparedness plans and/or short-term early warning systems for extreme temperature. The extratropics generally show both short-term skill as well as strong seasonality; in the tropics, most locations do also demonstrate one or both. In fact, almost 5 billion people live in regions that have seasonality and predictability of heatwaves and/or coldwaves. Climate adaptation investments in these regions can take advantage of seasonality and predictability to reduce risks to vulnerable populations.
  • Published: 2018
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:48 Institute of Physics (IOP) English 2018

A decade of remotely sensed observations highlight complex processes linked to coastal permafrost bluff erosion in the Arctic

Eroding permafrost coasts are likely indicators and integrators of changes in the Arctic System as they are susceptible to the combined effects of declining sea ice extent, increases in open water duration, more frequent and impactful storms, sea-level rise, and warming permafrost. However, few observation sites in the Arctic have yet to link decadal-scale erosion rates with changing environmental conditions due to temporal data gaps. This study increases the temporal fidelity of coastal permafrost bluff observations using near-annual high spatial resolution (<1 m) satellite imagery acquired between 2008–2017 for a 9 km segment of coastline at Drew Point, Beaufort Sea coast, Alaska. Our results show that mean annual erosion for the 2007–2016 decade was 17.2 m yr−1, which is 2.5 times faster than historic rates, indicating that bluff erosion at this site is likely responding to changes in the Arctic System. In spite of a sustained increase in decadal-scale mean annual erosion rates, mean open water season erosion varied from 6.7 m yr−1 in 2010 to more than 22.0 m yr−1 in 2007, 2012, and 2016. This variability provided a range of coastal responses through which we explored the different roles of potential environmental drivers. The lack of significant correlations between mean open water season erosion and the environmental variables compiled in this study indicates that we may not be adequately capturing the environmental forcing factors, that the system is conditioned by long-term transient effects or extreme weather events rather than annual variability, or that other not yet considered factors may be responsible for the increased erosion occurring at Drew Point. Our results highlight an increase in erosion at Drew Point in the 21st century as well as the complexities associated with unraveling the factors responsible for changing coastal permafrost bluffs in the Arctic.
  • Published: 2018
  • Publisher: Institute of Physics (IOP)
  • Language: English
04:21 Institute of Physics (IOP) English 2015

Potential increasing dominance of heterotrophy in the global ocean

Autotrophy is largely resource-limited in the modern ocean. Paleo evidence indicates this was not necessarily the case in warmer climates, and modern observations as well as standard metabolic theory suggest continued ocean warming could shift global ecology towards heterotrophy, thereby reducing autotrophic nutrient limitation. Such a shift would entail strong nutrient recycling in the upper ocean and high rates of net primary production (NPP), yet low carbon export to the deep ocean and sediments. We demonstrate transition towards such a state in the early 22nd century as a response to business-as-usual representative concentration pathway forcing (RCP8.5) in an intermediate complexity Earth system model in three configurations; with and without an explicit calcifier phytoplankton class and calcite ballast model. In all models nutrient regeneration in the near-surface becomes an increasingly important driver of primary production. The near-linear relationship between changes in NPP and global sea surface temperature (SST) found over the 21st century becomes exponential above a 2–4 global mean SST change. This transition to a more heterotrophic ocean agrees roughly with metabolic theory.
  • Published: 2015
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:18 Institute of Physics (IOP) English 2013

Effective information channels for reducing costs of environmentally- friendly technologies: evidence from residential PV markets

Realizing the environmental benefits of solar photovoltaics (PV) will require reducing costs associated with perception, informational gaps and technological uncertainties. To identify opportunities to decrease costs associated with residential PV adoption, in this letter we use multivariate regression models to analyze a unique, household-level dataset of PV adopters in Texas (USA) to systematically quantify the effect of different information channels on aspiring PV adopters' decision-making. We find that the length of the decision period depends on the business model, such as whether the system was bought or leased, and on special opportunities to learn, such as the influence of other PV owners in the neighborhood. This influence accrues passively through merely witnessing PV systems in the neighborhood, increasing confidence and motivation, as well as actively through peer-to-peer communications. Using these insights we propose a new framework to provide public information on PV that could drastically reduce barriers to PV adoption, thereby accelerating its market penetration and environmental benefits. This framework could also serve as a model for other distributed generation technologies.
  • Published: 2013
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:00 Institute of Physics (IOP) English 2017

Irrigation offsets wheat yield reductions from warming temperatures

Temperature increases due to climate change are expected to cause substantial reductions in global wheat yields. However, uncertainty remains regarding the potential role for irrigation as an adaptation strategy to offset heat impacts. Here we utilize over 7000 observations spanning eleven Kansas field-trial locations, 180 varieties, and 29 years to show that irrigation significantly reduces the negative impact of warming temperatures on winter wheat yields. Dryland wheat yields are estimated to decrease about eight percent for every one-degree Celsius increase in temperature, yet irrigation completely offsets this negative impact in our sample. As in previous studies, we find that important interactions exist between heat stress and precipitation for dryland production. Here, uniquely, we observe both dryland and irrigated trials side-by-side at the same locations and find that precipitation does not provide the same reduction in heat stress as irrigation. This is likely to be because the timing, intensity, and volume of water applications influence wheat yields, so the ability to irrigate—rather than relying on rainfall alone—has a stronger influence on heat stress. We find evidence of extensive differences of water-deficit stress impacts across varieties. This provides some evidence of the potential for adapting to hotter and drier climate conditions using optimal variety selection. Overall, our results highlight the critical role of water management for future global food security. Water scarcity not only reduces crop yields through water-deficit stress, but also amplifies the negative effects of warming temperatures.
  • Published: 2017
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:59 Institute of Physics (IOP) English 2014

Explicit feedback and the management of uncertainty in meeting climate objectives with solar geoengineering

Solar geoengineering has been proposed as a method of meeting climate objectives, such as reduced globally averaged surface temperatures. However, because of incomplete understanding of the effects of geoengineering on the climate system, its implementation would be in the presence of substantial uncertainties. In our study, we use two fully coupled atmosphere–ocean general circulation models: one in which the geoengineering strategy is designed, and one in which geoengineering is implemented (a real-world proxy). We show that regularly adjusting the amount of solar geoengineering in response to departures of the observed global mean climate state from the predetermined objective (sequential decision making; an explicit feedback approach) can manage uncertainties and result in achievement of the climate objective in both the design model and the real-world proxy. This approach results in substantially less error in meeting global climate objectives than using a predetermined time series of how much geoengineering to use, especially if the estimated sensitivity to geoengineering is inaccurate.
  • Published: 2014
  • Publisher: Institute of Physics (IOP)
  • Language: English
03:15 Institute of Physics (IOP) English 2018

Deconstructing climate misinformation to identify reasoning errors

Misinformation can have significant societal consequences. For example, misinformation about climate change has confused the public and stalled support for mitigation policies. When people lack the expertise and skill to evaluate the science behind a claim, they typically rely on heuristics such as substituting judgment about something complex (i.e. climate science) with judgment about something simple (i.e. the character of people who speak about climate science) and are therefore vulnerable to misleading information. Inoculation theory offers one approach to effectively neutralize the influence of misinformation. Typically, inoculations convey resistance by providing people with information that counters misinformation. In contrast, we propose inoculating against misinformation by explaining the fallacious reasoning within misleading denialist claims. We offer a strategy based on critical thinking methods to analyse and detect poor reasoning within denialist claims. This strategy includes detailing argument structure, determining the truth of the premises, and checking for validity, hidden premises, or ambiguous language. Focusing on argument structure also facilitates the identification of reasoning fallacies by locating them in the reasoning process. Because this reason-based form of inoculation is based on general critical thinking methods, it offers the distinct advantage of being accessible to those who lack expertise in climate science. We applied this approach to 42 common denialist claims and find that they all demonstrate fallacious reasoning and fail to refute the scientific consensus regarding anthropogenic global warming. This comprehensive deconstruction and refutation of the most common denialist claims about climate change is designed to act as a resource for communicators and educators who teach climate science and/or critical thinking.
  • Published: 2018
  • Publisher: Institute of Physics (IOP)
  • Language: English
02:28 Institute of Physics (IOP) English 2012

Attribution of atmospheric CO2 and temperature increases to regions: importance of preindustrial land use change

The historical contribution of each country to today's observed atmospheric CO2 excess and higher temperatures has become a basis for discussions around burden-sharing of greenhouse gas reduction commitments in political negotiations. However, the accounting methods have considered greenhouse gas emissions only during the industrial era, neglecting the fact that land use changes (LUC) have caused emissions long before the Industrial Revolution. Here, we hypothesize that considering preindustrial LUC affects the attribution because the geographic pattern of preindustrial LUC emissions differs significantly from that of industrial-era emissions and because preindustrial emissions have legacy effects on today's atmospheric CO2 concentrations and temperatures. We test this hypothesis by estimating CO2 and temperature increases based on carbon cycle simulations of the last millennium. We find that accounting for preindustrial LUC emissions results in a shift of attribution of global temperature increase from the industrialized countries to less industrialized countries, in particular South Asia and China, by up to 2–3%, a level that may be relevant for political discussions. While further studies are needed to span the range of plausible quantifications, our study demonstrates the importance of including preindustrial emissions for the most scientifically defensible attribution.
  • Published: 2012
  • Publisher: Institute of Physics (IOP)
  • Language: English
04:02 Institute of Physics (IOP) English 2012

Human impacts on terrestrial hydrology: climate change versus pumping and irrigation

Global climate change is altering terrestrial water and energy budgets, with subsequent impacts on surface and groundwater resources; recent studies have shown that local water management practices such as groundwater pumping and irrigation similarly alter terrestrial water and energy budgets over many agricultural regions, with potential feedbacks on weather and climate. Here we use a fully-integrated hydrologic model to directly compare effects of climate change and water management on terrestrial water and energy budgets of a representative agricultural watershed in the semi-arid Southern Great Plains, USA. At local scales, we find that the impacts of pumping and irrigation on latent heat flux, potential recharge and water table depth are similar in magnitude to the impacts of changing temperature and precipitation; however, the spatial distributions of climate and management impacts are substantially different. At the basin scale, the impacts on stream discharge and groundwater storage are remarkably similar. Notably, for the watershed and scenarios studied here, the changes in groundwater storage and stream discharge in response to a 2.5 °C temperature increase are nearly equivalent to those from groundwater-fed irrigation. Our results imply that many semi-arid basins worldwide that practice groundwater pumping and irrigation may already be experiencing similar impacts on surface water and groundwater resources to a warming climate. These results demonstrate that accurate assessment of climate change impacts and development of effective adaptation and mitigation strategies must account for local water management practices.
  • Published: 2012
  • Publisher: Institute of Physics (IOP)
  • Language: English
02:02 Institute of Physics (IOP) English 2017

Assessing ExxonMobil's climate change communications (1977–2014)

This paper assesses whether ExxonMobil Corporation has in the past misled the general public about climate change. We present an empirical document-by-document textual content analysis and comparison of 187 climate change communications from ExxonMobil, including peer-reviewed and non-peer-reviewed publications, internal company documents, and paid, editorial-style advertisements ('advertorials') in The New York Times. We examine whether these communications sent consistent messages about the state of climate science and its implications—specifically, we compare their positions on climate change as real, human-caused, serious, and solvable. In all four cases, we find that as documents become more publicly accessible, they increasingly communicate doubt. This discrepancy is most pronounced between advertorials and all other documents. For example, accounting for expressions of reasonable doubt, 83% of peer-reviewed papers and 80% of internal documents acknowledge that climate change is real and human-caused, yet only 12% of advertorials do so, with 81% instead expressing doubt. We conclude that ExxonMobil contributed to advancing climate science—by way of its scientists' academic publications—but promoted doubt about it in advertorials. Given this discrepancy, we conclude that ExxonMobil misled the public. Our content analysis also examines ExxonMobil's discussion of the risks of stranded fossil fuel assets. We find the topic discussed and sometimes quantified in 24 documents of various types, but absent from advertorials. Finally, based on the available documents, we outline ExxonMobil's strategic approach to climate change research and communication, which helps to contextualize our findings.
  • Published: 2017
  • Publisher: Institute of Physics (IOP)
  • Language: English
04:02 Institute of Physics (IOP) English 2018

How big is the energy efficiency resource?

Most economic theorists assume that energy efficiency—the biggest global provider of energy services—is a limited and dwindling resource whose price- and policy-driven adoption will inevitably deplete its potential and raise its cost. Influenced by that theoretical construct, most traditional analysts and deployers of energy efficiency see and exploit only a modest fraction of the worthwhile efficiency resource, saving less and paying more than they should. Yet empirically, modern energy efficiency is, and shows every sign of durably remaining, an expanding-quantity, declining-cost resource. Its adoption is constrained by major but correctable market failures and increasingly motivated by positive externalities. Most importantly, in both newbuild and retrofit applications, its quantity is severalfold larger and its cost lower than most in the energy and climate communities realize. The efficiency resource far exceeds the sum of savings by individual technologies because artfully choosing, combining, sequencing, and timing fewer and simpler technologies can save more energy at lower cost than deploying more and fancier but dis-integrated and randomly timed technologies. Such 'integrative design' is not yet widely known or applied, and can seem difficult because it is simple, but is well proven, rapidly evolving, and gradually spreading. Yet the same economic models that could not predict the renewable energy revolution also ignore integrative design and hence cannot recognize most of the efficiency resource or reserves. This analytic gap makes climate-change mitigation look harder and costlier than it really is, diverting attention and investment to inferior options. With energy efficiency as its cornerstone and needing its pace redoubled, climate protection depends critically on seeing and deploying the entire efficiency resource. This requires focusing less on individual technologies than on whole systems (buildings, factories, vehicles, and the larger systems embedding them), and replacing theoretical assumptions about efficiency's diminishing returns with practitioners' empirical evidence of expanding returns.
  • Published: 2018
  • Publisher: Institute of Physics (IOP)
  • Language: English
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