Monthly Archives: April 2015

Wind to Blame for North American Drought

Thomas L. Delworth, Fanrong Zeng, Anthony Rosati, Gabriel Vecchi, Andrew Wittenberg. A link between the hiatus in global warming and North American drought. Journal of Climate 2015

Portions of western North America have experienced prolonged drought over the last decade. This drought has occurred at the same time as the global warming hiatus – a decadal period with little increase in global mean surface temperature. We use climate models and observational analyses to clarify the dual role of recent tropical Pacific changes in driving both the global warming hiatus and North American drought. When we insert observed tropical Pacific wind stress anomalies into coupled models, the simulations produce persistent negative sea surface temperature anomalies in the eastern tropical Pacific, a hiatus in global warming, and drought over North America driven by SST-induced atmospheric circulation anomalies. In our simulations the tropical wind anomalies account for 92% of the simulated North American drought during the recent decade, with 8% from anthropogenic radiative forcing changes. This suggests that anthropogenic radiative forcing is not the dominant driver of the current drought, unless the wind changes themselves are driven by anthropogenic radiative forcing. The anomalous tropical winds could also originate from coupled interactions in the tropical Pacific or from forcing outside the tropical Pacific. The model experiments suggest that if the tropical winds were to return to climatological conditions, then the recent tendency toward North American drought would diminish. Alternatively, if the tropical winds were to persist, then the impact on North American drought would continue; however, the impact of the enhanced Pacific easterlies on global temperature diminishes after a decade or two due to a surface reemergence of warmer water that was initially subducted into the ocean interior.

Paper is here (fee).


Concurrent Exposure to Arsenic and Fluoride

González-Horta C, Ballinas-Casarrubias L, Sánchez-Ramírez B, Ishida MC, Barrera-Hernández A, Gutiérrez-Torres D, Zacarias OL, Saunders RJ, Drobná Z, Mendez MA, García-Vargas G, Loomis D, Stýblo M, Del Razo LM. A Concurrent Exposure to Arsenic and Fluoride from Drinking Water in Chihuahua, Mexico. International Journal of Environmental Research and Public Health. 2015 Apr 24;12(5):4587-4601.

Inorganic arsenic (iAs) and fluoride (F-) are naturally occurring drinking water contaminants. However, co-exposure to these contaminants and its effects on human health are understudied. The goal of this study was examined exposures to iAs and F- in Chihuahua, Mexico, where exposure to iAs in drinking water has been associated with adverse health effects. All 1119 eligible Chihuahua residents (>18 years) provided a sample of drinking water and spot urine samples. iAs and F- concentrations in water samples ranged from 0.1 to 419.8 µg As/L and from 0.05 to 11.8 mg F-/L. Urinary arsenic (U-tAs) and urinary F- (U-F-) levels ranged from 0.5 to 467.9 ng As/mL and from 0.1 to 14.4 µg F-/mL. A strong positive correlation was found between iAs and F- concentrations in drinking water (rs = 0.741). Similarly, U-tAs levels correlated positively with U-F- concentrations (rs = 0.633). These results show that Chihuahua residents exposed to high iAs concentrations in drinking water are also exposed to high levels of F-, raising questions about possible contribution of F- exposure to the adverse effects that have so far been attributed only to iAs exposure. Thus, investigation of possible interactions between iAs and F- exposures and its related health risks deserves immediate attention.

“Faith Leaders” have Blind Faith on “Climate Change”

This article reminds me of fact that we live in a time when people like to feel like they are thinking. Someone else actually does the thinking for them. They just go along because it leaves a good feeling in the room and they love it. But ask them to think about what they are thinking (e.g. presuppositions), then the reaction is very different indeed, usually very hostile (here against Mr. Morano).

But in any case the actual climate at any scale is a dynamic system, always adjusting, always changing. There is no “normal” climate from which it changes into something else. And from Godel’s incompleteness theorems we learn that the whole is greater than the sum of the parts which seriously limits what any mathematical model can tell us about the climate system as a whole.

Fluoride Exposure Increases Risk of Molar Incisor Hypomineralization

“Hypomineralization” is a relatively new term which refers to an abnormality in the translucency of tooth enamel (opacity). Dental fluorosis is just one form. (Click here for more.)

Balmer R, Toumba KJ, Munyombwe T, Duggal MS. A comparison of the presentation of molar incisor hypomineralisation in two communities with different fluoride exposure. European Archives of Paediatric Dentistry: Official Journal of the European Academy of Paediatric Dentistry. 2015 Apr 18.

AIM: To compare the clinical presentation of two cohorts of children diagnosed with molar incisor hypomineralisation (MIH) and living in areas of low and high background fluoridation.

METHODS: The study population comprised 12-year-old children participating in the 2008-2009 National Dental Epidemiological Programme in five regions in Northern England. Participating dentists were trained and calibrated in the use of the modified Developmental Defects of Enamel Index. Children were examined at school under direct vision with the aid of a dental mirror. First permanent molars and incisors were recorded for the presence and type of enamel defects greater than 2 mm. A diagnosis of MIH was ascribed to any child with a demarcated defect in any first permanent molar. Risk ratios for the occurrence of demarcated, diffuse and hypoplastic defects were generated for MIH children in the fluoridated and non-fluoridated area.

RESULTS: 3,233 children were examined. The prevalence of MIH in the fluoridated community was 11 % and in the non-fluoridated community was 17.5 %. Incisors in children with MIH were at greater risk of having demarcated defects (risk ratio 4.0, 3.6-4.5) and diffuse defects (risk ratio 2.2, 2.0-2.5). Molars in children with MIH were at greater risk of diffuse defects (risk ratio 4.4, 3.8-5.0). The teeth of children with MIH living in the fluoridated area were at greater risk of demarcated defects for both incisors (risk ratio 1.6, 1.3-2.0) and molars (risk ratio 1.3, 1.2-1.5) relative to the teeth of MIH children living in the non-fluoridated area.

CONCLUSIONS: Children with MIH were at increased risk of both diffuse and demarcated defects in their incisors. Children with MIH living in the fluoridated area were at increased risk of diffuse and demarcated defects relative to MIH children living in the non-fluoridated area.

Click here for paper (Open Access). 

UAH Version 6 Satellite Data Set Released


Roy W. Spencer, John R. Christy, and William D. Braswell. Version 6.0 of the UAH Temperature Dataset Released: New LT Trend = +0.11 C/decade.  28 April, 2015

Version 6 of the UAH MSU/AMSU global satellite temperature dataset is by far the most extensive revision of the procedures and computer code we have ever produced in over 25 years of global temperature monitoring. The two most significant changes from an end-user perspective are (1) a decrease in the global-average lower tropospheric (LT) temperature trend from +0.140 C/decade to +0.114 C/decade (Dec. ’78 through Mar. ’15); and (2) the geographic distribution of the LT trends, including higher spatial resolution. We describe the major changes in processing strategy, including a new method for monthly gridpoint averaging; a new multi-channel (rather than multi-angle) method for computing the lower tropospheric (LT) temperature product; and a new empirical method for diurnal drift correction. We also show results for the mid-troposphere (“MT”, from MSU2/AMSU5), tropopause (“TP”, from MSU3/AMSU7), and lower stratosphere (“LS”, from MSU4/AMSU9). The 0.026 C/decade reduction in the global LT trend is due to lesser sensitivity of the new LT to land surface skin temperature (est. 0.010 C/decade), with the remainder of the reduction (0.016 C/decade) due to the new diurnal drift adjustment, the more robust method of LT calculation, and other changes in processing procedures.

Wildfire Alters DBP Precursors

Wang JJ, Dahlgren R, Ersan M, Karanfil T, Chow AT. Wildfire alters terrestrial precursors of disinfection byproducts in forest detritus. Environmental Science and Technology. 2015 Apr 20.

Wildfire occurrence and intensity are increasing worldwide causing severe disturbances to forest watersheds used for potable water supply. The effects of wildfire on drinking water quality are not well understood, especially in terms of terrestrial dissolved organic matter (DOM) and DOM-associated formation of disinfection byproducts (DBP). As the forest floor layer is a major source of terrestrial DOM, we investigated characteristics and DBP formation of water extractable organic matter (WEOM) from the 0-5 cm depth of non-burned detritus (control) and burned detritus with black ash (moderate severity) and white ash (high severity) associated with the 2013 Rim Fire in California. Spectroscopic results suggested that the aromaticity of WEOM followed white ash > control > black ash and fluorescence region II (excitation 220-250 nm; emission 330-380 nm) of the emission-excitation-matrix was identified as a potential burn severity indicator. Compared to the control, WEOM from white and black ashes had lower reactivity in forming trihalomethanes (55%-of-control) and haloacetic acids (67%-of-control), but higher reactivity in forming the more carcinogenic haloacetonitrile after chlorination (244%-of-control) and N-nitrosodimethylamine after chloramination (229%-of-control). There was no change in reactivity for chloral hydrate formation, while WEOM from black ash showed a higher reactivity for haloketone formation (150%-of-control). Because wildfire consumed a large portion of organic matter from the detritus layer, there was lower water extractable organic carbon (27%-of-control) and organic nitrogen (19%-of-control) yields in ashes. Consequently, the wildfire caused an overall reduction in water extractable terrestrial DBP precursor yield from detritus materials.

Click here for paper (fee).

Routine Storage Tank Cleaning Necessary to Eliminate Opportunistic Pathogens in Sediments

Struewing I, Yelton S, Ashbolt N. Molecular Survey of Occurrence and Quantity of Legionella spp., Mycobacterium spp., Pseudomonas aeruginosa and Amoeba Hosts in Municipal Drinking Water Storage Tank Sediments. Journal of Applied Microbiology. 2015 Apr 17. doi: 10.1111/jam.12831.

AIM: To examine the occurrence and quantity of potential pathogens and an indicator of microbial contamination in the sediments of municipal drinking water storage tanks (MDWSTs), given the absence of such data across the United States.

METHODS AND RESULTS: Sediment samples (87 MDWST) from eighteen locations across ten states of the U.S. were collected and assayed by qPCR for a range of potential enteric and opportunistic microbial pathogens and a sewage-associated Bacteroides marker. Potential opportunistic pathogens dominated, with the highest detection of occurrence (% positive detection; average cell equivalence [CE]) being Mycobacterium spp. (88.9%; 6.7 ± 8.5 x104 CE g-1 ), followed by Legionella spp. (66.7%; 5.2 ±5.9 x 103 CE g-1 ), Pseudomonas aeruginosa (22.2%; 250 ± 880 CE g-1 ), and Acanthamoeba spp. (38.9%; 53 ± 70 CE g-1 ), with no detected Naegleria fowleri. Most enteric pathogens (Campylobacter jejuni, Escherichia coli 0157:H7, Salmonella enterica, Cryptosporidium parvum and Giardia duodenalis) were not detected, except for a trace signal for Campylobacter spp. There was significant correlation between the qPCR signals of Legionella spp. and Acanthamoeba spp. (R2 =0.61, n=87, P=0.0001). Diverse Legionella spp. including L. pneumophila, L. pneumophila sg1 and L. anisa were identified, each of which might cause legionellosis.

CONCLUSIONS: These results imply that potential opportunistic pathogens are common within MDWST sediments and could act as a source of microbial contamination, but needing downstream growth to be of potential concern.

SIGNIFICANCE AND IMPACT OF THE STUDY: The results imply that opportunistic pathogen risks may need to be managed by regular tank cleaning or other management practices.

Click here for paper (fee).