New research from last week 25/2012
Posted by Ari Jokimäki on June 25, 2012
Oh, those poor women living in semi-arid regions of Alps in Austria. Tree rings, peatland mosses, sunshine in Iran. Tornadoes, glaciers, boreholes, acidified oceans. New. Research. On. Climate.
Tornadoes in Czech Lands
Abstract: “Documentary evidence is employed to present the history of tornadoes in the Czech Lands (recently Czech Republic) in AD 1119–2010. Based on contemporaneous descriptions of events, tornadoes are categorised as proven or probable. They are analysed collectively in terms of their spatio-temporal changes, annual variation, specific features, and impacts according to the Enhanced Fujita (EF) scale. The first documented tornado, on 30 July 1119, did great damage to Vyšehrad Castle in Prague (EF3). Only three other tornadoes were recorded before AD 1500. In the following three centuries, the number fluctuated between 11 and 16 events per century. Documented tornado frequency increased significantly from the 19th century onwards, reaching peaks in 1931–1940 (44 tornadoes) and particularly in 2001–2010 (56 tornadoes); this rise, however, reflects the availability of relevant sources as well as increased social awareness and advances in communication technology. A total of 264 tornado days and 307 tornadoes were documented for the Czech Lands in 1119–2010. Although they are relatively homogeneously extended over the territory of the Czech Republic, tornadoes tend to occur more frequently at lower and medium altitudes. The highest frequency of tornadoes is recorded for the summer half-year (mainly from June to August), although they may develop between March and October. Probable tornadoes have also been recorded in the winter months. The strongest tornadoes in the Czech Lands may be classified as EF3, largely with significant damage to buildings and trees, but 13 related deaths have also been recorded. The paper presents not only a new chronology and climatology for Czech tornadoes but is also an important contribution to the study of tornadoes in Europe.”
Citation: Rudolf Brázdil, Kateřina Chromá, Petr Dobrovolný, Zbyněk Černoch, Atmospheric Research, http://dx.doi.org/10.1016/j.atmosres.2012.06.019.
Global warming trend has been particularly enhanced in semi-arid regions during cold season
Abstract: “This study examined surface air temperature trends over global land from 1901–2009. It is found that the warming trend was particularly enhanced, in the boreal cold season (November to March) over semi-arid regions (with precipitation of 200–600 mm yr−1) showing a temperature increase of 1.53 °C as compared to the global annual mean temperature increase of 1.13 °C over land. In mid-latitude semi-arid areas of Europe, Asia, and North America, temperatures in the cold season increased by 1.41, 2.42, and 1.5 °C, respectively. The semi-arid regions contribute 44.46% to global annual-mean land-surface temperature trend. The mid-latitude semi-arid regions in the Northern Hemisphere contribute by 27.0% of the total, with the mid-latitude semi-arid areas in Europe, Asia, and North America accounting for 6.29%, 13.81%, and 6.85%, respectively. Such enhanced semi-arid warming (ESAW) imply drier and warmer trend of these regions.”
Citation: Huang, J., Guan, X., and Ji, F.: Enhanced cold-season warming in semi-arid regions, Atmos. Chem. Phys., 12, 5391-5398, doi:10.5194/acp-12-5391-2012, 2012.
Climate change affects women worse than men
Abstract: “This paper proposes frameworks to analyze the gender dimensions of climate change-induced migration. The experiences, needs and priorities of climate migrants will vary by gender and these differences need to be accounted for if policies are to be inclusive. Among the vulnerable groups, women are likely to be disproportionately affected due to climate change because on average women tend to be poorer, less educated, have a lower health status and have limited direct access to or ownership of natural resources. Both the process (actual movement) and the outcomes (rural–rural or rural–urban migration, out-migration mainly of men) of climate change-induced migration are also likely to be highly gendered.”
Citation: Namrata Chindarkar, 2012 Environ. Res. Lett. 7 025601 doi:10.1088/1748-9326/7/2/025601.
In European Alps there won’t be much snow at low and medium elevations by 2100
Abstract: “Snow in a populated and economically diverse region such as the Alps plays an important role in both natural environmental systems, (e.g., hydrology and vegetation), and a range of socio-economic sectors (e.g., tourism or hydropower). Changes in snow amount and duration may impact upon these systems in various ways. The objective of this text is to assess whether the public perception that snow has been receding in recent decades in the European Alps is indeed upheld by observations of the behavior of the mountain snow-pack in the last few decades. This article will show that, depending on location—and in particular according to altitude—the quantity of snow and the length of the snow season have indeed changed over the past century. While a major driving factor for this is clearly to be found in recent warming trends, other processes also contribute to the reduction in snow, such as the influence of the North Atlantic Oscillation on the variability of the mountain snow-pack. This article ends with a short glimpse to the future, based on recent model studies that suggest that snow at low to medium elevations will indeed have all but disappeared by 2100.”
Citation: Martin Beniston, Wiley Interdisciplinary Reviews: Climate Change, DOI: 10.1002/wcc.179.
High frequency climate signals from tree rings and low frequency climate signals from peatland mosses
Abstract: “Stable isotope ratios from tree rings and peatland mosses have become important proxies of past climate variations. We here compare recent stable carbon and oxygen isotope ratios in cellulose of tree rings from white spruce (Picea glauca), growing near the arctic tree line; and cellulose of Sphagnum fuscum stems, growing in a hummock of a subarctic peatland, in west-central Canada. Results show that carbon isotopes in S. fuscum correlate significantly with July temperatures over the past ~20 yr. The oxygen isotopes correlate with both summer temperature and precipitation. Analyses of the tree-ring isotopes revealed summer temperatures to be the main controlling factor for carbon isotope variations, whereas tree-ring oxygen isotope ratios are controlled by a combination of spring temperatures and precipitation totals. We also explore the potential of combining high-frequency (annual) climate signals derived from long tree-ring series with low-frequency (decadal to centennial) climate signals derived from the moss remains in peat deposits. This cross-archive comparison revealed no association between the oxygen isotopes, which likely results from the varying sensitivity of the archives to different seasons. For the carbon isotopes, common variance could be achieved through adjustments of the Sphagnum age model within dating error.”
Citation: Steffen Holzkämper, Päivi Kaislahti Tillman, Peter Kuhry, Jan Esper, Quaternary Research, http://dx.doi.org/10.1016/j.yqres.2012.05.014.
Sunshine hours have increased over Iran
Abstract: “For the purpose of assessing solar energy resources in different parts of Iran, this article provides a synopsis of the spatial and temporal variability of sunshine hours at 37 first-order synoptic stations during the period 1981–2007. Annual and seasonal variations of sunshine duration were determined for four distinct regions within the country. By averaging the time series of sunshine hours in each subregion and standardizing them, four regional representative time series were developed. The results indicate, over all regions, the annual pattern of sunshine duration exhibited large sinusoidal increases and decreases, with minima occurring in 1990 and 2003. The trends of sunshine duration indicated that the sign of the seasonal and annual trends for the vast majority stations has been positive. The maximum positive trend was found across the western parts of the country for all seasons. The spring was found to have a negative trend in sunshine hours at only 2 of the 37 stations. On the annual scale, the change rates in sunshine hours from western to eastern part of Iran have gradually declined over time. The highest positive annual trend was found at Sanandaj station on the west side of Zagross Mountain, with of rate 253 h per decade. Given the increasing trends observed at many stations in Iran over the last 25 years, and recognizing the natural high sunshine duration experienced across the region, a strong case can be made for the introduction of solar energy across the country.”
Citation: Fatemeh Rahimzadeh, Mojdeh Pedram, Michael C. Kruk, Meteorological Applications, DOI: 10.1002/met.1334.
Measuring fossil fuel emissions from tree rings in Los Angeles
Abstract: “Quantifying local fossil fuel CO2 emissions in urban areas is challenging due to the heterogeneity in emissions and in atmospheric mixing ratios of CO2. Measurements of the radiocarbon content of urban tree rings are an alternative to large networks of CO2 monitoring stations. In this study, we calculated 3-year averages of CO2 mixing ratios from fossil fuel combustion from 1980 to 2008 using tree rings sampled at six sites within the Los Angeles basin and adjacent mountains. We observed CO2 mixing ratios from fossil fuel combustion of up to 23 μmol·mol−1 in the inland basin and ∼5–10 μmol·mol−1 at coastal sites. Although we expected to see increasing trends of fossil fuel-derived CO2 over time, not all sites showed a significant increase. Analysis of correlations between fossil fuel-derived CO2 and socioeconomic variables revealed that fossil fuel-derived CO2 followed trends in census tract and/or city population or in vehicle statistics at most sites. We also calculated CO/CO2 combustion ratios from tree ring radiocarbon and nearby measurements of atmospheric CO mixing ratios. We observed widespread declines in the combustion ratio that support increases in the efficiency of the automobile fleet over the past few decades. This study demonstrates the utility of tree ring radiocarbon measurements for quantifying temporal and spatial patterns in fossil fuel-derived CO2 emissions in urban areas.”
Citation: Djuricin, S., X. Xu, and D. E. Pataki (2012), The radiocarbon composition of tree rings as a tracer of local fossil fuel emissions in the Los Angeles basin: 1980–2008, J. Geophys. Res., 117, D12302, doi:10.1029/2011JD017284.
Postglacial warming causes errors to borehole reconstructions of last millennium temperatures
Abstract: “The investigation of observed borehole temperatures has proved to be a valuable tool for the reconstruction of ground surface temperature histories. However, there are still many open questions concerning the significance and accuracy of the reconstructions from these data. In particular, the temperature signal of the warming after the Last Glacial Maximum is still present in borehole temperature profiles. It is shown here that this signal also influences the relatively shallow boreholes used in current paleoclimate inversions to estimate temperature changes in the last centuries by producing errors in the determination of the steady state geothermal gradient. However, the impact on estimates of past temperature changes is weaker. For deeper boreholes, the curvature of the long-term signal is significant. A correction based on simple assumptions about glacial–interglacial temperature changes shows promising results, improving the extraction of millennial scale signals. The same procedure may help when comparing observed borehole temperature profiles with the results from numerical climate models.”
Citation: Rath, V., González Rouco, J. F., and Goosse, H.: Impact of postglacial warming on borehole reconstructions of last millennium temperatures, Clim. Past, 8, 1059-1066, doi:10.5194/cp-8-1059-2012, 2012.
Glaciers of the conterminous United States have been receding for the past century
Abstract: “Glaciers of the conterminous United States have been receding for the past century. Since 1900 the recession has varied from a 24 % loss in area (Mt. Rainier, Washington) to a 66 % loss in the Lewis Range of Montana. The rates of retreat are generally similar with a rapid loss in the early decades of the 20th century, slowing in the 1950s–1970s, and a resumption of rapid retreat starting in the 1990s. Decadal estimates of changes in glacier area for a subset of 31 glaciers from 1900 to 2000 are used to test a snow water equivalent model that is subsequently employed to examine the effects of temperature and precipitation variability on annual glacier area changes for these glaciers. Model results indicate that both winter precipitation and winter temperature have been important climatic factors affecting the variability of glacier variability during the 20th Century. Most of the glaciers analyzed appear to be more sensitive to temperature variability than to precipitation variability. However, precipitation variability is important, especially for high elevation glaciers. Additionally, glaciers with areas greater than 1 km2 are highly sensitive to variability in temperature.”
Citation: Gregory J. McCabe and Andrew G. Fountain, Climatic Change, 2012, DOI: 10.1007/s10584-012-0502-9.
Daily maximum and minimum temperatures have been increasing in Austria
Abstract: “Instrumental time series are often affected by inhomogeneities which can mask or amplify climate change signals. Various procedures for the detection and adjustment of breaks exist for monthly and annual time series. Homogenization methods on a daily basis are scarce and often disregard uncertainties accompanying the break adjustment. We present a complete homogenization procedure for daily extreme temperature series based on the break detection method PRODIGE and SPLIDHOM for break correction. Both parts of the homogenization rely on the existence of highly correlated reference stations. After the statistical comparison with neighbouring stations, detected breaks are verified and further localized by metadata. Uncertainties of the break adjustments are estimated by altering reference stations and by applying a bootstrapping technique providing an objective indication about the reliability of the homogenization. The method was tested and applied to 71 time series of daily minimum (TN) and maximum temperatures (TX) in Austria covering the period 1948–2009. For some series homogenization was not possible due to large uncertainties in the adjustments or a lack of suitable reference series. In the remaining 57 TN and 54 TX series a total number of 139 breaks were detected. Seventy-five percent of those breaks are documented in the metadata archive, with most of them being caused by station relocations and instrumentation changes. In general, the mean over the temperature dependent adjustments of all stations show a temperature reduction. However, the majority of breaks have mean amplitudes of less than 0.5 °C. A comprehensive analysis was performed on the new homogenized daily dataset, showing a widespread warming trend in both TN and TX series. The warming trend is in general amplified due to the homogenization. However, significant changes in the trend are only observed at very few stations. In autumn, however, the trend is reversed in many temperature based ‘climate change detection indices’.”
Citation: Johanna Nemec, Christine Gruber, Barbara Chimani, Ingeborg Auer, International Journal of Climatology, DOI: 10.1002/joc.3532.
There are always winners and such seems to be case also for ocean acidification
Abstract: “Increased seawater pCO2, and in turn ‘ocean acidification’ (OA), is predicted to profoundly impact marine ecosystem diversity and function this century. Much research has already focussed on calcifying reef-forming corals (Class: Anthozoa) that appear particularly susceptible to OA via reduced net calcification. However, here we show that OA-like conditions can simultaneously enhance the ecological success of non-calcifying anthozoans, which play key ecological and biogeochemical roles in present day benthic ecosystems but also represent a model organism should calcifying anthozoans exist as less calcified (soft-bodied) forms in future oceans. Increased growth (abundance and size) of the sea anemone (Anemonia viridis) population was observed along a natural CO2 gradient at Vulcano, Italy. Both gross photosynthesis (PG) and respiration (R) increased with pCO2 indicating that the increased growth was, at least in part, fuelled by bottom up (CO2 stimulation) of metabolism. The increase of PG outweighed that of R and the genetic identity of the symbiotic microalgae (Symbiodinium spp.) remained unchanged (type A19) suggesting proximity to the vent site relieved CO2 limitation of the anemones’ symbiotic microalgal population. Our observations of enhanced productivity with pCO2, which are consistent with previous reports for some calcifying corals, convey an increase in fitness that may enable non-calcifying anthozoans to thrive in future environments, i.e. higher seawater pCO2. Understanding how CO2-enhanced productivity of non- (and less-) calcifying anthozoans applies more widely to tropical ecosystems is a priority where such organisms can dominate benthic ecosystems, in particular following localised anthropogenic stress.”
Citation: David J. Suggett, Jason M. Hall-Spencer, Riccardo Rodolfo-Metalpa, Toby G. Boatman, Ross Payton, D. Tye Pettay, Vivienne R. Johnson, Mark E. Warner, Tracy Lawson, Global Change Biology, DOI: 10.1111/j.1365-2486.2012.02767.x.
CLASSIC OF THE WEEK: Zdunkowski & Stowe (1968)
Abstract: “The influence of carbon dioxide upon the radiative heat budget of the lower few meters of the atmosphere is investigated. For this purpose, Elsasser’s (1960) radiative flux tables for the 15 micron carbon dioxide absorption band have been modified as described by Zdunkowski et al. (1966) and extended to very low optical pathlengths. In order to deal with the water vapor overlap effect in the carbon dioxide band, a series of so-called overlap tables have been constructed for different temperatures. These tables have been applied to obtain radiative flux divergence values for selected air masses which represent arctic, temperate, and tropical conditions. Moreover, for comparison purposes, the water vapor flux divergence, representing the total water vapor spectrum, has been determined for some cases, also. The latter task was accomplished by application of the emissivity method, which was also applied, as an independent check, to obtain carbon dioxide flux divergence. It was found in general that the influence of carbon dioxide upon the air layer near the ground should not be neglected.”
Citation: Wilford G. Zdunkowski, Larry L. Stowe Jr., Tellus, Volume 20, Issue 2, pages 293–299, May 1968, DOI: 10.1111/j.2153-3490.1968.tb00370.x.
When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. Here’s the archive for the research papers of previous weeks. If this sort of thing interests you, be sure to check out A Few Things Illconsidered. They also have a weekly posting containing lots of links to new research and other climate related news.