Earth, sea, and sky
How Effective Are US Renewable Energy Subsidies in Cutting Greenhouse Gases?
Brian Murray et al.
American Economic Review, May 2014, Pages 569-574
Abstract:
The federal tax code provides preferential treatment for the production and use of renewable energy. We report estimates of the subsidies' effects on greenhouse gases (GHG) emissions developed in a recent National Research Council (NRC) Report. Due to lack of estimates of the impact of tax provisions on GHG emissions, new modeling studies were commissioned. The studies found, at best, a small impact of subsidies in reducing GHG emissions; in some cases, emissions increased. The NRC report also identified the need to capture the complex interactions among subsidies, pre-existing regulations, and commodity markets.
----------------------
Impact of natural disaster on public sector corruption
Eiji Yamamura
Public Choice, forthcoming
Abstract:
This paper uses inter-country panel data from 1990 through 2010 to examine how the occurrence of natural disasters affects corruption within the public sector. For a closer analysis, disaster is classified into various categories, including general floods, other floods, tropical storms, other storms, earthquakes, volcanic eruptions, and landslides. Furthermore, this paper explores whether natural disasters have different impacts on corruption levels in developed and developing countries. The study reveals a number of novel findings. (1) Natural disasters that cause substantial damage increase public sector corruption in both developing and developed countries. (2) Natural disasters have a greater impact on public sector corruption in developed countries than in developing countries. (3) In developed countries, natural disaster frequency has a significant impact on the level of corruption. Hence, foreseeable disasters increase corruption in general. In developed countries, an incentive may exist to live within disaster-prone areas because of the potential for disaster compensation payments.
----------------------
Increasing Storm Tides in New York Harbor, 1844-2013
S.A. Talke, P. Orton & D.A. Jay
Geophysical Research Letters, forthcoming
Abstract:
Three of the nine highest recorded water levels in the New York Harbor (NYH) region have occurred since 2010 (Mar. 2010, Aug. 2011, and Oct. 2012), and eight of the largest twenty have occurred since 1990. To investigate whether this cluster of high waters is a random occurrence or indicative of intensified storm tides, we recover archival tide gauge data back to 1844 and evaluate the trajectory of the annual maximum storm tide (AMST). Approximately half of long-term variance is anti-correlated with decadal-scale variations in the North Atlantic Oscillation (NAO), while long-term trends explain the remainder. The 10-year storm-tide has increased by 0.28 m. Combined with a 0.44 m increase in local sea-level since 1856, the 10-year flood-level has increased by approximately 0.72 ± 0.25 m, and magnified the annual probability of overtopping the typical Manhattan seawall from less than 1% to about 20-25%.
----------------------
The Impact of a Carbon Tax on Manufacturing: Evidence From Microdata
Ralf Martin, Laure de Preux & Ulrich Wagner
Journal of Public Economics, forthcoming
Abstract:
We estimate the impact of a carbon tax on manufacturing plants using panel data from the UK production census. Our identification strategy builds on the comparison of outcomes between plants subject to the full tax and plants that paid only 20% of the tax. Exploiting exogenous variation in eligibility for the tax discount, we find that the carbon tax had a strong negative impact on energy intensity and electricity use. No statistically significant impacts are found for employment, revenue or plant exit.
----------------------
Mechanisms of Reef Coral Resistance to Future Climate Change
Stephen Palumbi et al.
Science, 23 May 2014, Pages 895-898
Abstract:
Reef corals are highly sensitive to heat, yet populations resistant to climate change have recently been identified. To determine the mechanisms of temperature tolerance, we reciprocally transplanted corals between reef sites experiencing distinct temperature regimes, and tested subsequent physiological and gene expression profiles. Local acclimatization and fixed effects, such as adaptation, contributed about equally to heat tolerance and are reflected in patterns of gene expression. In less than two years, acclimatization achieves the same heat tolerance that we would expect from strong natural selection over many generations for these long-lived organisms. Our results show both short-term acclimatory and longer-term adaptive acquisition of climate resistance. Adding these adaptive abilities to ecosystem models is likely to slow predictions of demise for coral reef ecosystems.
----------------------
Arnaud Costinot, Dave Donaldson & Cory Smith
NBER Working Paper, April 2014
Abstract:
A large agronomic literature models the implications of climate change for a variety of crops and locations around the world. The goal of the present paper is to quantify the macro-level consequences of these micro-level shocks. Using an extremely rich micro-level dataset that contains information about the productivity -- both before and after climate change -- of each of 10 crops for each of 1.7 million fields covering the surface of the Earth, we find that the impact of climate change on these agricultural markets would amount to a 0.26% reduction in global GDP when trade and production patterns are allowed to adjust.
----------------------
Implications of Shale Gas Development for Climate Change
Richard Newell & Daniel Raimi
Environmental Science & Technology, forthcoming
Abstract:
Advances in technologies for extracting oil and gas from shale formations have dramatically increased U.S. production of natural gas. As production expands domestically and abroad, natural gas prices will be lower than without shale gas. Lower prices have two main effects: increasing overall energy consumption, and encouraging substitution away from sources such as coal, nuclear, renewables, and electricity. We examine the evidence and analyze modeling projections to understand how these two dynamics affect greenhouse gas emissions. Most evidence indicates that natural gas as a substitute for coal in electricity production, gasoline in transport, and electricity in buildings decreases greenhouse gases, although as an electricity substitute this depends on the electricity mix displaced. Modeling suggests that absent substantial policy changes, increased natural gas production slightly increases overall energy use, more substantially encourages fuel-switching, and that the combined effect slightly alters economy wide GHG emissions; whether the net effect is a slight decrease or increase depends on modeling assumptions including upstream methane emissions. Our main conclusions are that natural gas can help reduce GHG emissions, but in the absence of targeted climate policy measures, it will not substantially change the course of global GHG concentrations. Abundant natural gas can, however, help reduce the costs of achieving GHG reduction goals.
----------------------
Kelly Twomey Sanders & Michael Webber
Environmental Research Letters, April 2014
Abstract:
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.
----------------------
Hurricane strikes and local migration in US coastal counties
B. Ouattara, E. Strobl
Economics Letters, July 2014, Pages 17–20
Abstract:
We examine the effects of hurricane shocks on key migration variables in US coastal counties. Results show that hurricane strikes increase outward migration rate and that these migrants were somewhat wealthier; but that there was no impact on inward migration.
----------------------
Rodica Lindenmaier et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
There is a pressing need to verify air pollutant and greenhouse gas emissions from anthropogenic fossil energy sources to enforce current and future regulations. We demonstrate the feasibility of using simultaneous remote sensing observations of column abundances of CO2, CO, and NO2 to inform and verify emission inventories. We report, to our knowledge, the first ever simultaneous column enhancements in CO2 (3–10 ppm) and NO2 (1–3 Dobson Units), and evidence of δ13-CO2 depletion in an urban region with two large coal-fired power plants with distinct scrubbing technologies that have resulted in ∆NOx/∆CO2 emission ratios that differ by a factor of two. Ground-based total atmospheric column trace gas abundances change synchronously and correlate well with simultaneous in situ point measurements during plume interceptions. Emission ratios of ∆NOx/∆CO2 and ∆SO2/∆CO2 derived from in situ atmospheric observations agree with those reported by in-stack monitors. Forward simulations using in-stack emissions agree with remote column CO2 and NO2 plume observations after fine scale adjustments. Both observed and simulated column ∆NO2/∆CO2 ratios indicate that a large fraction (70–75%) of the region is polluted. We demonstrate that the column emission ratios of ∆NO2/∆CO2 can resolve changes from day-to-day variation in sources with distinct emission factors (clean and dirty power plants, urban, and fires). We apportion these sources by using NO2, SO2, and CO as signatures. Our high-frequency remote sensing observations of CO2 and coemitted pollutants offer promise for the verification of power plant emission factors and abatement technologies from ground and space.
----------------------
Abnormal Daily Temperature and Concern about Climate Change Across the United States
Jeremy Brooks et al.
Review of Policy Research, May 2014, Pages 199–217
Abstract:
The relatively low level of concern about climate change among Americans has important implications for climate policy. While many studies have examined individual characteristics associated with climate change attitudes, fewer studies have considered the effects of environmental conditions on such attitudes. Here, we use two national samples of American adults to explore the impact of abnormal daily temperatures on levels of concern about climate change. We test the hypotheses that (1) abnormally warm temperatures, and (2) both abnormally warm and abnormally cool temperatures are associated with higher levels of concern. Using a generalized ordinal logit, we find that the quadratic form of deviation from mean temperature on the date of the survey is significantly associated with higher levels of concern, thus supporting the second hypothesis. We discuss several theoretical frameworks that may explain this result including availability bias, mental models, and implicit stimuli, and the implications for climate policy.
----------------------
William Anderegg & Gregory Goldsmith
Environmental Research Letters, May 2014
Abstract:
Despite overwhelming scientific consensus concerning anthropogenic climate change, many in the non-expert public perceive climate change as debated and contentious. There is concern that two recent high-profile media events — the hacking of the University of East Anglia emails and the Himalayan glacier melt rate presented in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change — may have altered public opinion of climate change. While survey data is valuable for tracking public perception and opinion over time, including in response to climate-related media events, emerging methods that facilitate rapid assessment of spatial and temporal patterns in public interest and opinion could be exceptionally valuable for understanding and responding to these events' effects. We use a novel, freely-available dataset of worldwide web search term volumes to assess temporal patterns of interest in climate change over the past ten years, with a particular focus on looking at indicators of climate change skepticism around the high-profile media events. We find that both around the world and in the US, the public searches for the issue as 'global warming,' rather than 'climate change,' and that search volumes have been declining since a 2007 peak. We observe high, but transient spikes of search terms indicating skepticism around the two media events, but find no evidence of effects lasting more than a few months. Our results indicate that while such media events are visible in the short-term, they have little effect on salience of skeptical climate search terms on longer time-scales.
----------------------
Greater Sensitivity to Drought Accompanies Maize Yield Increase in the U.S. Midwest
David Lobell et al.
Science, 2 May 2014, Pages 516-519
Abstract:
A key question for climate change adaptation is whether existing cropping systems can become less sensitive to climate variations. We use a field-level data set on maize and soybean yields in the central United States for 1995 through 2012 to examine changes in drought sensitivity. Although yields have increased in absolute value under all levels of stress for both crops, the sensitivity of maize yields to drought stress associated with high vapor pressure deficits has increased. The greater sensitivity has occurred despite cultivar improvements and increased carbon dioxide and reflects the agronomic trend toward higher sowing densities. The results suggest that agronomic changes tend to translate improved drought tolerance of plants to higher average yields but not to decreasing drought sensitivity of yields at the field scale.
----------------------
Increasing CO2 threatens human nutrition
Samuel Myers et al.
Nature, forthcoming
Abstract:
Dietary deficiencies of zinc and iron are a substantial global public health problem. An estimated two billion people suffer these deficiencies, causing a loss of 63 million life-years annually. Most of these people depend on C3 grains and legumes as their primary dietary source of zinc and iron. Here we report that C3 grains and legumes have lower concentrations of zinc and iron when grown under field conditions at the elevated atmospheric CO2 concentration predicted for the middle of this century. C3 crops other than legumes also have lower concentrations of protein, whereas C4 crops seem to be less affected. Differences between cultivars of a single crop suggest that breeding for decreased sensitivity to atmospheric CO2 concentration could partly address these new challenges to global health.
----------------------
The Costs and Consequences of Clean Air Act Regulation of CO2 from Power Plants
Dallas Burtraw et al.
American Economic Review, May 2014, Pages 557-562
Abstract:
US climate policy is unfolding under the Clean Air Act. Mobile source and construction permitting regulations are in place. Most important, EPA and the states will determine the form and stringency of the regulations for power plants. Various approaches would create an implicit price on emitting greenhouse gases and create valuable assets that would be distributed differently among electricity producers, consumers, and the government. We compare a tradable performance standard with several cap-and-trade policies. Distributing asset values to fossil-fueled producers and consumers has small effects on average electricity prices but imposes greater social cost than a revenue-raising policy.
----------------------
Half of the world's population experience robust changes in the water cycle for a 2 °C warmer world
Jan Sedláček & Reto Knutti
Environmental Research Letters, April 2014
Abstract:
Fresh water is a critical resource on Earth, yet projections of changes in the water cycle resulting from anthropogenic warming are challenging. It is important to not only know the best estimate of change, but also how robust these projections are, where changes occur, which variables will change, and how many people are affected by it. Here we synthesize the changes in the water cycle, based on results of the latest climate model intercomparison (CMIP5). Several variables of the water cycle, such as evaporation and relative humidity, show robust changes over more than 50% of the land area already with an anthropogenic global warming of 1 °C. A warming of 2 °C shows more than half of the world's population to be directly affected by robust local changes in the water cycle, and everybody experiences a robust change in at least one variable of the water cycle. While the physical changes are widespread, the affected people are concentrated in a few hot-spots mainly in Asia and Central Africa. The occurrence of these hot-spots is driven by population density, as well as by the early emergence of the anthropogenic signal from variability in these areas. Large uncertainties remain in projections of soil moisture and runoff changes.
----------------------
The poleward migration of the location of tropical cyclone maximum intensity
James Kossin, Kerry Emanuel & Gabriel Vecchi
Nature, 15 May 2014, Pages 349–352
Abstract:
Temporally inconsistent and potentially unreliable global historical data hinder the detection of trends in tropical cyclone activity. This limits our confidence in evaluating proposed linkages between observed trends in tropical cyclones and in the environment. Here we mitigate this difficulty by focusing on a metric that is comparatively insensitive to past data uncertainty, and identify a pronounced poleward migration in the average latitude at which tropical cyclones have achieved their lifetime-maximum intensity over the past 30 years. The poleward trends are evident in the global historical data in both the Northern and the Southern hemispheres, with rates of 53 and 62 kilometres per decade, respectively, and are statistically significant. When considered together, the trends in each hemisphere depict a global-average migration of tropical cyclone activity away from the tropics at a rate of about one degree of latitude per decade, which lies within the range of estimates of the observed expansion of the tropics over the same period. The global migration remains evident and statistically significant under a formal data homogenization procedure, and is unlikely to be a data artefact. The migration away from the tropics is apparently linked to marked changes in the mean meridional structure of environmental vertical wind shear and potential intensity, and can plausibly be linked to tropical expansion, which is thought to have anthropogenic contributions.
----------------------
Global distribution and risk to shipping of very extreme sea states (VESS)
V.J. Cardone et al.
International Journal of Climatology, forthcoming
Abstract:
The impact of extreme sea states on offshore infrastructure is of intense interest in the ocean engineering community at the present time. In this study, a new quality-controlled database of global satellite-derived estimates of significant wave height (HS) and surface marine wind speed from seven missions spanning the period August 1991–March 2010, known as GlobWave, is scanned to yield over 5000 ocean basin specific orbit segments with peak HS > 12 m. This population was subsequently distilled to a population of 120 individual storms [so-called very extreme sea states (VESS) storms], in which there was at least one altimeter estimate of HS > 16 m. The highest HSs were observed in the Northern Hemisphere with ten orbit segments in the North Atlantic Ocean (NAO) with a peak HS of >18 m followed by four segments in the North Pacific Ocean (NPO). Only three HS peaks >18 m were seen in the entire Southern Oceans. Three of the >5000 orbit segments had a peak HS >20 m with the highest at 20.6 m. The number of VESS storms detected is greatest in the NAO (the smallest basin), a result that appears to be consistent with general circulation studies of extratropical cyclogenesis frequency and intensity in general atmospheric circulation models. A new continuous 33-year global wave hindcast (GROW2012) based on a new atmospheric reanalysis wind field product appears to provide unbiased estimates of the probability of exceedance of VESS in extratropical storms and small-basin dependent biases (0.5–1.5 m) of peak HS greater than ∼16 m. GROW2012 was, therefore, applied with a voyage simulator for nine trade routes to assess the risk of a merchant vessel that does not avail itself of weather routing of encountering VESS. The highest monthly exceedance probabilities (MEPs) at the VESS threshold of 14 m are found in the NAO and NPO at ∼0.1% during winter months. The alternative statistical distribution of the MEP of the single maximum peak sea state to be expected for a voyage for any month (MEPm) shows that the highest MEPm is for the month of December in the NAO along the great circle route between the middle US East Coast and entrance to English Channel and in the NPO along the Yokohama–Seattle route, at about 3%. Still, the overall probability of a vessel encountering sea states that may contain waves capable of catastrophic damage over a 33-year lifetime is quite small with mean number of hours of exposure to a vessel typically less than ∼3 h for six of the nine routes and a maximum of 10 h for two of the routes.
----------------------
Kaitlin Keegan et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
In July 2012, over 97% of the Greenland Ice Sheet experienced surface melt, the first widespread melt during the era of satellite remote sensing. Analysis of six Greenland shallow firn cores from the dry snow region confirms that the most recent prior widespread melt occurred in 1889. A firn core from the center of the ice sheet demonstrated that exceptionally warm temperatures combined with black carbon sediments from Northern Hemisphere forest fires reduced albedo below a critical threshold in the dry snow region, and caused the melting events in both 1889 and 2012. We use these data to project the frequency of widespread melt into the year 2100. Since Arctic temperatures and the frequency of forest fires are both expected to rise with climate change, our results suggest that widespread melt events on the Greenland Ice Sheet may begin to occur almost annually by the end of century. These events are likely to alter the surface mass balance of the ice sheet, leaving the surface susceptible to further melting.
----------------------
Elevated CO2 further lengthens growing season under warming conditions
Melissa Reyes-Fox et al.
Nature, forthcoming
Abstract:
Observations of a longer growing season through earlier plant growth in temperate to polar regions have been thought to be a response to climate warming. However, data from experimental warming studies indicate that many species that initiate leaf growth and flowering earlier also reach seed maturation and senesce earlier, shortening their active and reproductive periods. A conceptual model to explain this apparent contradiction, and an analysis of the effect of elevated CO2 — which can delay annual life cycle events — on changing season length, have not been tested. Here we show that experimental warming in a temperate grassland led to a longer growing season through earlier leaf emergence by the first species to leaf, often a grass, and constant or delayed senescence by other species that were the last to senesce, supporting the conceptual model. Elevated CO2 further extended growing, but not reproductive, season length in the warmed grassland by conserving water, which enabled most species to remain active longer. Our results suggest that a longer growing season, especially in years or biomes where water is a limiting factor, is not due to warming alone, but also to higher atmospheric CO2 concentrations that extend the active period of plant annual life cycles.
----------------------
Ben Kravitz et al.
Environmental Research Letters, April 2014
Abstract:
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.
----------------------
Extinction and recolonization of coastal megafauna following human arrival in New Zealand
Catherine Collins et al.
Procedings of the Royal Society: Biological Sciences, 7 July 2014
Abstract:
Extinctions can dramatically reshape biological communities. As a case in point, ancient mass extinction events apparently facilitated dramatic new evolutionary radiations of surviving lineages. However, scientists have yet to fully understand the consequences of more recent biological upheaval, such as the megafaunal extinctions that occurred globally over the past 50 kyr. New Zealand was the world's last large landmass to be colonized by humans, and its exceptional archaeological record documents a vast number of vertebrate extinctions in the immediate aftermath of Polynesian arrival approximately AD 1280. This recently colonized archipelago thus presents an outstanding opportunity to test for rapid biological responses to extinction. Here, we use ancient DNA (aDNA) analysis to show that extinction of an endemic sea lion lineage (Phocarctos spp.) apparently facilitated a subsequent northward range expansion of a previously subantarctic-limited lineage. This finding parallels a similar extinction–replacement event in penguins (Megadyptes spp.). In both cases, an endemic mainland clade was completely eliminated soon after human arrival, and then replaced by a genetically divergent clade from the remote subantarctic region, all within the space of a few centuries. These data suggest that ecological and demographic processes can play a role in constraining lineage distributions, even for highly dispersive species, and highlight the potential for dynamic biological responses to extinction.
----------------------
Evolution of land surface air temperature trend
Fei Ji et al.
Nature Climate Change, forthcoming
Abstract:
The global climate has been experiencing significant warming at an unprecedented pace in the past century. This warming is spatially and temporally non-uniform, and one needs to understand its evolution to better evaluate its potential societal and economic impact. Here, the evolution of global land surface air temperature trend in the past century is diagnosed using the spatial–temporally multidimensional ensemble empirical mode decomposition method. We find that the noticeable warming (>0.5 K) started sporadically over the global land and accelerated until around 1980. Both the warming rate and spatial structure have changed little since. The fastest warming in recent decades (>0.4 K per decade) occurred in northern mid-latitudes. From a zonal average perspective, noticeable warming (>0.2 K since 1900) first took place in the subtropical and subpolar regions of the Northern Hemisphere, followed by subtropical warming in the Southern Hemisphere. The two bands of warming in the Northern Hemisphere expanded from 1950 to 1985 and merged to cover the entire Northern Hemisphere.
----------------------
Public Support for Policies to Reduce Risk After Hurricane Sandy
Michael Greenberg et al.
Risk Analysis, forthcoming
Abstract:
A phone survey was conducted in New Jersey in 2013 four months after the second of two major devastating tropical storms (Sandy in 2012 and Irene in 2011). The objective was to estimate public support for restricting land uses in flood zones, requiring housing to be built to resist storm waters, and otherwise increasing mitigation and resilience. Respondents who supported these mitigation and resilience policies disproportionately were concerned about global climate change, trusted climate scientists and the federal government, and were willing to contribute to a redevelopment program through taxes, bonds, and fees. They also tended to have collectivist and egalitarian worldviews. Half of the respondents supported at least four of the seven risk-reducing policies. How their support translates into public policy remains to be seen. Lack of willingness to personally fund these policies is an obstacle.
----------------------
North Sea Storminess from a Novel Storm Surge Record since AD 1843
Sönke Dangendorf et al.
Journal of Climate, May 2014, Pages 3582–3595
Abstract:
The detection of potential long-term changes in historical storm statistics and storm surges plays a vitally important role for protecting coastal communities. In the absence of long homogeneous wind records, the authors present a novel, independent, and homogeneous storm surge record based on water level observations in the North Sea since 1843. Storm surges are characterized by considerable interannual-to-decadal variability linked to large-scale atmospheric circulation patterns. Time periods of increased storm surge levels prevailed in the late nineteenth and twentieth centuries without any evidence for significant long-term trends. This contradicts with recent findings based on reanalysis data, which suggest increasing storminess in the region since the late nineteenth century. The authors compare the wind and pressure fields from the Twentieth-Century Reanalysis (20CRv2) with the storm surge record by applying state-of-the-art empirical wind surge formulas. The comparison reveals that the reanalysis is a valuable tool that leads to good results over the past 100 yr; previously the statistical relationship fails, leaving significantly lower values in the upper percentiles of the predicted surge time series. These low values lead to significant upward trends over the entire investigation period, which are in turn supported by neither the storm surge record nor an independent circulation index based on homogeneous pressure readings. The authors therefore suggest that these differences are related to higher uncertainties in the earlier years of the 20CRv2 over the North Sea region.
----------------------
Climate change and frog calls: Long-term correlations along a tropical altitudinal gradient
Peter Narins & Sebastiaan Meenderink
Proceedings of the Royal Society: Biological Sciences, 22 May 2014
Abstract:
Temperature affects nearly all biological processes, including acoustic signal production and reception. Here, we report on advertisement calls of the Puerto Rican coqui frog (Eleutherodactylus coqui) that were recorded along an altitudinal gradient and compared these with similar recordings along the same altitudinal gradient obtained 23 years earlier. We found that over this period, at any given elevation, calls exhibited both significant increases in pitch and shortening of their duration. All of the observed differences are consistent with a shift to higher elevations for the population, a well-known strategy for adapting to a rise in ambient temperature. Using independent temperature data over the same time period, we confirm a significant increase in temperature, the magnitude of which closely predicts the observed changes in the frogs’ calls. Physiological responses to long-term temperature rises include reduction in individual body size and concomitantly, population biomass. These can have potentially dire consequences, as coqui frogs form an integral component of the food web in the Puerto Rican rainforest.
----------------------
William Shobe, Charles Holt & Thaddeus Huetteman
Journal of Economic Behavior & Organization, forthcoming
Abstract:
We use a set of economic experiments to test the effects of some novel features of California's new controls on greenhouse gas emissions. The California cap and trade scheme imposes limits on allowance ownership, uses a tiered price containment reserve sale, and settles allowance auctions based on the lowest accepted bid. We examine the effects of these features on market liquidity, efficiency, and price variability. We find that tight holding limits substantially reduce banking, which, in turn reduces market liquidity. This impairs the ability of traders to smooth prices over time, resulting in lower efficiency and higher price variability. The price containment reserve, while increasing the supply of allowances available to traders, does not appear to mitigate the effects of tight holding limits on market outcomes. As a result, the imposition of holding limits in the allowance market may have the consequence of increasing the likelihood of the market manipulation that they were intended to prevent. Finally, we find that the choice between lowest accepted bid and highest rejected bid for the allowance auction pricing rule does not have a significant effect on market outcomes.
----------------------
Timothy Considine & Edward Manderson
Energy Economics, July 2014, Pages 291–301
Abstract:
This paper develops an econometric forecasting system of energy demand coupled with engineering-economic models of energy supply. The framework is used to quantify the energy and environmental impacts of renewable and natural gas based electricity power generation in California, considering the role of on-going energy conservation efforts and incorporating different natural gas price scenarios over the forecast horizon (2011–2035). The results indicate that, relative to a business-as-usual scenario of continuing to rely on imported electricity to meet future demand, California’s renewable portfolio standard (RPS) of 33% renewables by 2020 will increase electricity rates by over 10%. However, the RPS will also provide substantial annual savings in carbon dioxide emissions of 40 million metric tons in 2020. Continuing non-price induced energy conservation at the historic rate will only result in a marginal reduction in electricity rates, although lower electricity use means substantial savings are nonetheless achieved in electricity expenditures. In addition, continuing trend energy conservation leads to substantial savings in carbon dioxide emissions. Like the RPS, developing domestic natural gas generation also leads to rate increases and reductions in carbon dioxide emissions (relative to the baseline). However, these impacts are minor compared to the RPS scenario.
----------------------
Anny Cazenave et al.
Nature Climate Change, May 2014, Pages 358–361
Abstract:
Present-day sea-level rise is a major indicator of climate change. Since the early 1990s, sea level rose at a mean rate of ~3.1 mm yr−1. However, over the last decade a slowdown of this rate, of about 30%, has been recorded. It coincides with a plateau in Earth’s mean surface temperature evolution, known as the recent pause in warming. Here we present an analysis based on sea-level data from the altimetry record of the past ~20 years that separates interannual natural variability in sea level from the longer-term change probably related to anthropogenic global warming. The most prominent signature in the global mean sea level interannual variability is caused by El Niño–Southern Oscillation, through its impact on the global water cycle. We find that when correcting for interannual variability, the past decade’s slowdown of the global mean sea level disappears, leading to a similar rate of sea-level rise (of 3.3 ± 0.4 mm yr−1) during the first and second decade of the altimetry era. Our results confirm the need for quantifying and further removing from the climate records the short-term natural climate variability if one wants to extract the global warming signal.
----------------------
Laura Rickard et al.
Global Environmental Change, May 2014, Pages 39–52
Abstract:
Past research suggests that how we perceive risk can be related to how we attribute responsibility for risk-related issues, such as climate change; however, a gap in research lies in exploring possible connections between attribution of responsibility, risk perception, and information processing. Using the Risk Information Seeking and Processing model, this study fills this gap by examining how RISP-based variables are related to information processing and whether attribution of responsibility for mitigating climate change influences communication behaviors that are often predicted by elevated risk perceptions. Undergraduates at two large research universities (N = 572) were randomly assigned to read one of two newspaper articles that emphasized either individual responsibility (by highlighting personal actions) or societal responsibility (by highlighting government policy) for climate change mitigation. Results indicate that subjects in the individual responsibility condition were significantly more likely to process the message in a systematic manner; however, attribution of responsibility did not interact with risk perception to influence systematic processing. Moreover, attitudes toward climate change information and negative affect mediated the relationship between other key variables and systematic processing. These and other findings suggest that strategic communication about climate change may benefit from emphasizing individual responsibility to attract more attention from diverse audiences and to promote deeper thinking about the issue. Additional theoretical implications are presented.
----------------------
Widespread decline of Congo rainforest greenness in the past decade
Liming Zhou et al.
Nature, 1 May 2014, Pages 86–90
Abstract:
Tropical forests are global epicentres of biodiversity and important modulators of climate change1, and are mainly constrained by rainfall patterns. The severe short-term droughts that occurred recently in Amazonia have drawn attention to the vulnerability of tropical forests to climatic disturbances. The central African rainforests, the second-largest on Earth, have experienced a long-term drying trend whose impacts on vegetation dynamics remain mostly unknown because in situ observations are very limited. The Congolese forest, with its drier conditions and higher percentage of semi-evergreen trees, may be more tolerant to short-term rainfall reduction than are wetter tropical forests, but for a long-term drought there may be critical thresholds of water availability below which higher-biomass, closed-canopy forests transition to more open, lower-biomass forests. Here we present observational evidence for a widespread decline in forest greenness over the past decade based on analyses of satellite data (optical, thermal, microwave and gravity) from several independent sensors over the Congo basin. This decline in vegetation greenness, particularly in the northern Congolese forest, is generally consistent with decreases in rainfall, terrestrial water storage, water content in aboveground woody and leaf biomass, and the canopy backscatter anomaly caused by changes in structure and moisture in upper forest layers. It is also consistent with increases in photosynthetically active radiation and land surface temperature. These multiple lines of evidence indicate that this large-scale vegetation browning, or loss of photosynthetic capacity, may be partially attributable to the long-term drying trend. Our results suggest that a continued gradual decline of photosynthetic capacity and moisture content driven by the persistent drying trend could alter the composition and structure of the Congolese forest to favour the spread of drought-tolerant species.
----------------------
Ice plug prevents irreversible discharge from East Antarctica
M. Mengel & A. Levermann
Nature Climate Change, forthcoming
Abstract:
Changes in ice discharge from Antarctica constitute the largest uncertainty in future sea-level projections, mainly because of the unknown response of its marine basins. Most of West Antarctica’s marine ice sheet lies on an inland-sloping bed and is thereby prone to a marine ice sheet instability. A similar topographic configuration is found in large parts of East Antarctica, which holds marine ice equivalent to 19 m of global sea-level rise, that is, more than five times that of West Antarctica. Within East Antarctica, the Wilkes Basin holds the largest volume of marine ice that is fully connected by subglacial troughs. This ice body was significantly reduced during the Pliocene epoch. Strong melting underneath adjacent ice shelves with similar bathymetry indicates the ice sheet’s sensitivity to climatic perturbations. The stability of the Wilkes marine ice sheet has not been the subject of any comprehensive assessment of future sea level. Using recently improved topographic data in combination with ice-dynamic simulations, we show here that the removal of a specific coastal ice volume equivalent to less than 80 mm of global sea-level rise at the margin of the Wilkes Basin destabilizes the regional ice flow and leads to a self-sustained discharge of the entire basin and a global sea-level rise of 3–4 m. Our results are robust with respect to variation in ice parameters, forcing details and model resolution as well as increased surface mass balance, indicating that East Antarctica may become a large contributor to future sea-level rise on timescales beyond a century.
----------------------
Evaluation of extreme climate events using a regional climate model for China
Zhenming Ji & Shichang Kang
International Journal of Climatology, forthcoming
Abstract:
Extreme climate events over China at the end of the 21st century (2080–2099) are investigated using the regional climate model RegCM4. Model performance is validated through comparison between observations and simulations over the period 1985–2005. The results show that RegCM4 can satisfactorily reproduce the spatial distribution of extreme climate events over China. The model simulates temperature extremes more accurately than precipitation. Under the RCP8.5 (high emission) scenario, the number of frost days decreases, and both the heat wave duration index and the growing season length increase dramatically towards the end of the 21st century. Changes in extreme temperature become increasingly pronounced from South to North China, with the most significant changes occurring on the Tibetan Plateau (TP). The proportion of heavy precipitation generally increases, except on the southern TP. The number of very heavy precipitation days increases by 25–50% in Northwest and East China. In winter, the number of consecutive dry days (CDD) decreases in North China and increases in South China. The greatest increases in CDD are found in June, July and August (JJA) in Southwest China. In a future that follows this scenario, drought events may be aggravated in Southwest China, and decrease in North China. In contrast, when repeating these projections under the assumption of the RCP4.5 scenario for emissions, the frequency of extreme climate events is reduced. These results suggest that reductions in greenhouse gas emissions may mitigate the effects of climate change over the coming decades.
----------------------
Model Simulation and Projection of European Heat Waves in Present-Day and Future Climates
Ngar-Cheung Lau & Mary Jo Nath
Journal of Climate, May 2014, Pages 3713–3730
Abstract:
The synoptic behavior of present-day heat waves (HW) over Europe is studied using the GFDL high-resolution atmospheric model (HiRAM) with 50-km grid spacing. Three regions of enhanced and coherent temperature variability are identified over western Russia, eastern Europe, and western Europe. The simulated HW characteristics are compared with those derived from Climate Forecast System Reanalysis products. Composite charts for outstanding HW episodes resemble well-known recurrent circulation types. The HW region is overlain by a prominent upper-level anticyclone, which blocks the passage of synoptic-scale transients. The altered eddy vorticity transports in turn reinforce the anticyclone. The anticyclone is part of a planetary-scale wave train. The successive downstream development of this wave train is indicative of Rossby wave dispersion. Additional runs of HiRAM are conducted for the “time slices” of 2026–35 and 2086–95 in the climate scenario corresponding to representative concentration pathway 4.5 (RCP4.5). By the end of the twenty-first century, the average duration and frequency of HW in the three European sites are projected to increase by a factor of 1.4–2.0 and 2.2–4.5, respectively, from the present-day values. These changes can be reproduced by adding the mean shift between the present and future climatological temperatures to the daily fluctuations in the present-day simulation. The output from a continuous integration of a coupled general circulation model through the 1901–2100 period indicates a monotonic increase in severity, duration, and HW days during the twenty-first century.
----------------------
Contribution of semi-arid ecosystems to interannual variability of the global carbon cycle
Benjamin Poulter et al.
Nature, forthcoming
Abstract:
The land and ocean act as a sink for fossil-fuel emissions, thereby slowing the rise of atmospheric carbon dioxide concentrations1. Although the uptake of carbon by oceanic and terrestrial processes has kept pace with accelerating carbon dioxide emissions until now, atmospheric carbon dioxide concentrations exhibit a large variability on interannual timescales2, considered to be driven primarily by terrestrial ecosystem processes dominated by tropical rainforests3. We use a terrestrial biogeochemical model, atmospheric carbon dioxide inversion and global carbon budget accounting methods to investigate the evolution of the terrestrial carbon sink over the past 30 years, with a focus on the underlying mechanisms responsible for the exceptionally large land carbon sink reported in 2011 (ref. 2). Here we show that our three terrestrial carbon sink estimates are in good agreement and support the finding of a 2011 record land carbon sink. Surprisingly, we find that the global carbon sink anomaly was driven by growth of semi-arid vegetation in the Southern Hemisphere, with almost 60 per cent of carbon uptake attributed to Australian ecosystems, where prevalent La Niña conditions caused up to six consecutive seasons of increased precipitation. In addition, since 1981, a six per cent expansion of vegetation cover over Australia was associated with a fourfold increase in the sensitivity of continental net carbon uptake to precipitation. Our findings suggest that the higher turnover rates of carbon pools in semi-arid biomes are an increasingly important driver of global carbon cycle inter-annual variability and that tropical rainforests may become less relevant drivers in the future. More research is needed to identify to what extent the carbon stocks accumulated during wet years are vulnerable to rapid decomposition or loss through fire in subsequent years.
----------------------
The risk implications of insurance securitization: The case of catastrophe bonds
Bjoern Hagendorff et al.
Journal of Corporate Finance, April 2014, Pages 387–402
Abstract:
Catastrophe (Cat) bonds are insurance securitization vehicles which are supposed to transfer catastrophe-related underwriting risk from issuers to capital markets. This paper addresses key, unanswered questions concerning Cat bonds and offers the following results. First, our findings show firms that issue Cat bonds exhibit less risky underwriting portfolios with less exposure to catastrophe risks and overall less need to hedge catastrophe risk. These results show that the access to the market for insurance securitization is easiest for firms with less risky portfolios. Second, firms that issue Cat bonds are found to experience a reduction in their default risk relative to non-issuing firms and our results, therefore, demonstrate that Cat bonds provide effective catastrophe hedging for issuing firms. Third, firms with less catastrophe exposure, increase their catastrophe exposure following an issue. Therefore, our paper cautions that the ability to hedge catastrophe risk causes some firms to seek additional catastrophe risk.