Climate Change Attribution Using Empirical Decomposition of Climatic Data

The climate change attribution problem is addressed using empirical decomposition. Cycles in solar motion and activity of 60 and 20 years were used to develop an empirical model of Earth temperature variations. The model was fit to the Hadley global temperature data up to 1950 (time period before anthropogenic emissions became the dominant forcing mechanism), and then extrapolated from 1951 to 2009. After subtraction of the model, the residuals showed an approximate linear upward trend after 1942. Herein we assume that the residual upward warming observed during the second half of the 20th century has been mostly induced by a worldwide rapid increase of anthropogenic emissions, urbanization and land use change. The warming observed before 1942 is relatively small and it is assumed to have been mostly naturally induced by a climatic recovery since the Little Ice Age of the 17th century and the Dalton Minimum at the beginning of the 19th century. The resulting full natural plus anthropogenic model fits the entire 160 year record very well. Residual analysis does not provide any evidence for a substantial cooling effect due to sulfate aerosols from 1940 to 1970. The cooling observed during that period may be due to a natural 60-year cycle, which is visible in the global temperature since 1850 and has been observed also in numerous multisecular climatic records. New solar activity proxy models are developed that suggest a mechanism for both the 60-year climate cycle and a portion of the long-term warming trend. Our results suggest that because current models underestimate the strength of natural multidecadal cycles in the temperature records, the anthropogenic contribution to climate change since 1970 should be around half of that previously claimed by the IPCC [2007]. A 21st Century forecast suggests that climate may warm less than 1^{\circ}C by 2100

Predicting Pleistocene climate from vegetation in North America

International audienceClimates at the Last Glacial Maximum have been inferred from fossil pollen assemblages, but these inferred climates are colder for eastern North America than those produced by climate simulations. It has been suggested that low CO2 levels could account for this discrepancy. In this study biogeographic evidence is used to test the CO2 effect model. The recolonization of glaciated zones in eastern North America following the last ice age produced distinct biogeographic patterns. It has been assumed that a wide zone south of the ice was tundra or boreal parkland (Boreal-Parkland Zone or BPZ), which would have been recolonized from southern refugia as the ice melted, but the patterns in this zone differ from those in the glaciated zone, which creates a major biogeographic anomaly. In the glacial zone, there are few endemics but in the BPZ there are many across multiple taxa. In the glacial zone, there are the expected gradients of genetic diversity with distance from the ice-free zone, but no evidence of this is found in the BPZ. Many races and related species exist in the BPZ which would have merged or hybridized if confined to the same refugia. Evidence for distinct southern refugia for most temperate species is lacking. Extinctions of temperate flora were rare. The interpretation of spruce as a boreal climate indicator may be mistaken over much of the region if the spruce was actually an extinct temperate species. All of these anomalies call into question the concept that climates in the zone south of the ice were extremely cold or that temperate species had to migrate far to the south. An alternate hypothesis is that low CO2 levels gave an advantage to pine and spruce, which are the dominant trees in the BPZ, and to herbaceous species over trees, which also fits the observed pattern. Thus climate reconstruction from pollen data is probably biased and needs to incorporate CO2 effects. Most temperate species could have survived across their current ranges at lower abundance by retreating to moist microsites. These would be microrefugia not easily detected by pollen records, especially if most species became rare. These results mean that climate reconstructions based on terrestrial plant indicators will not be valid for periods with markedly different CO2 levels

Predicting Pleistocene climate from vegetation

International audienceClimates at the Last Glacial Maximum have been inferred from fossil pollen assemblages, but these inferred climates are colder than those produced by climate simulations. Biogeographic evidence also argues against these inferred cold climates. The recolonization of glaciated zones in eastern North America following the last ice age produced distinct biogeographic patterns. It has been assumed that a wide zone south of the ice was tundra or boreal parkland (Boreal-Parkland Zone or BPZ), which would have been recolonized from southern refugia as the ice melted, but the patterns in this zone differ from those in the glaciated zone, which creates a major biogeographic anomaly. In the glacial zone, there are few endemics but in the BPZ there are many across multiple taxa. In the glacial zone, there are the expected gradients of genetic diversity with distance from the ice-free zone, but no evidence of this is found in the BPZ. Many races and related species exist in the BPZ which would have merged or hybridized if confined to the same refugia. Evidence for distinct southern refugia for most temperate species is lacking. Extinctions of temperate flora were rare. The interpretation of spruce as a boreal climate indicator may be mistaken over much of the region if the spruce was actually an extinct temperate species. All of these anomalies call into question the concept that climates in the zone south of the ice were very cold or that temperate species had to migrate far to the south. Similar anomalies exist in Europe and on tropical mountains. An alternate hypothesis is that low CO2 levels gave an advantage to pine and spruce, which are the dominant trees in the BPZ, and to herbaceous species over trees, which also fits the observed pattern. Most temperate species could have survived across their current ranges at lower abundance by retreating to moist microsites. These would be microrefugia not easily detected by pollen records, especially if most species became rare. These results mean that climate reconstruction based on terrestrial plant indicators will not be valid for periods with markedly different CO2 levels

On a minimal model for estimating climate sensitivity

In a recent issue of this journal, Loehle (2014) presents a "minimal model" for estimating climate sensitivity, identical to that previously published by Loehle and Scafetta (2011). The novelty in the more recent paper lies in the straightforward calculation of an estimate of transient climate response based on the model and an estimate of equilibrium climate sensitivity derived therefrom, via a flawed methodology. We demonstrate that the Loehle and Scafetta model systematically underestimates the transient climate response, due to a number of unsupportable assumptions regarding the climate system. Once the flaws in Loehle and Scafetta's model are addressed, the estimates of transient climate response and equilibrium climate sensitivity derived from the model are entirely consistent with those obtained from general circulation models, and indeed exclude the possibility of low climate sensitivity, directly contradicting the principal conclusion drawn by Loehle. Further, we present an even more parsimonious model for estimating climate sensitivity. Our model is based on observed changes in radiative forcings, and is therefore constrained by physics, unlike the Loehle model, which is little more than a curve-fitting exercise

Recovery of contaminated wetland soils at the Savannah River Site by natural rainfall: An experimental, toxicological study

This study was conducted at the Department of Energy Savannah River Site in South Carolina. Seepage basins at the SRS F-Area received liquid effluent from the 1950s to 1988. This effluent was typically acidic, containing high amounts of total dissolved ions, low levels of tritium and other radioactive elements, and trace levels of various heavy metals. Sodium (from NaOH), and aluminum (from soil matrix reduction due to acid leachate) were at particularly high levels in the outcropping water. The effluent gradually seeped down to the water table and subsequently outcropped along the edge of a forested wetland bordering Four Mile Creek. A laboratory study was conducted to evaluate the potential for natural remediation of contaminated wetland soils by rainfall. Contaminated soils were collected and leached repeatedly with rainwater. After 6 leachings the leachate was observed to be non-toxic to lettuce seedlings, whereas the initial leachate was very toxic. These results suggest that more detailed studies on leaching as a remediation technique would be beneficial. 6 refs., 2 figs., 3 tabs

Habitat destruction and the extinction debt revisited

A very important analysis of the problem of habitat destruction concluded that such destruction may lead to an extinction debt, which is the irreversible loss of species following a prolonged transient or delay. An error in interpretation of this model led the authors to apply the results to all types of habitat destruction, but in fact the model applies only to an across-the-board decrease in fecundity, not to disturbances. For repeated, spatially random disturbance, a different model applies. For habitat destruction on regional scales (reduction in ecosystem area without disturbance in remnant areas), one must, in contrast, apply species-area relations based on the distribution of different habitat types (e.g., elevational and rainfall gradients, physiographic and edaphic variability). The error in interpretation of the basic model is presented, followed by clarification of model usage and development of a new model that applies to disturbance events

Agreement, Disagreement, and Life: Predicting Outcomes of Borderline Personality using Self and Informant Report

Borderline Personality Disorder (BPD) impacts multiple functional life outcomes, but assessment may be difficult due to distortions in reports arising from the disorder itself. The use of adjunct informant reports shows promise in circumventing the barriers to self-report. Self and informant agreement has typically been low, but positive. I hypothesized this may be due to differences in perspective and available information. In this study, I used classic and novel statistical approaches to analyze agreement between self- and informant-reported BPD features in a community sample of individuals 55-64 years of age recruited as part of the St. Louis Personality and Aging Network. 1,387 participants were included in the final analyses. Optimal methods for combining self- and informant-report are explored in the prediction of clinically-relevant life outcomes. Self-reports and informant-reports were found to show limited, but positive, agreement in the endorsement of BPD criteria and diagnosis. Both reporters’ criteria endorsements were significantly associated with a similar number of relevant life outcomes, but had relatively low overlap (Mean overlap rate = 16%) in which outcomes were associated with any given criterion across both report types. These findings suggest that both self- and informant-reports provide incremental utility in the assessment of BPD features and appear to offer different information about those features

Proper statistical treatment of species-area data

The purpose of this report is to comment on the entire process of analyzing species-area data, particularly as performed by Rydin and Borgegaard (1988). They use three different models to test species-area relations for islands over a 100 year period. Several aspects of their analysis of species-area data could be improved, including their comparison of goodness-of-fit and testing of the expected value of z. The reason that these issues are important (their basic conclusions being correct) is that there is acrimonious debate over the best model to use for species-area curves and over whether the scope coefficient is constant or is an artifact, and because the species-area curve is being used for nature reserve design. The problems pointed out here are common to a large class of allometric-type analyses in ecology. The author attempts to show the potential pitfalls inherent in allometric analyses and demonstrate methods for avoiding these problems

Adaptive significance of root grafting in trees

Root grafting has long been observed in forest trees but the adaptive significance of this trait has not been fully explained. Various authors have proposed that root grafting between trees contributes to mechanical support by linking adjacent root systems. Keeley proposes that this trait would be of greatest advantage in swamps where soils provide poor mechanical support. He provides as evidence a greenhouse study of Nyssa sylvatica Marsh in which seedlings of swamp provenance formed between-individual root grafts more frequently than upland provenance seedlings. In agreement with this within-species study, Keeley observed that arid zone species rarely exhibit grafts. Keeley also demonstrated that vines graft less commonly than trees, and herbs never do. Since the need for mechanical support coincides with this trend, these data seem to support his model. In this paper, the authors explore the mechanisms and ecological significance of root grafting, leading to predictions of root grafting incidence. Some observations support and some contradict the mechanical support hypothesis