Arguments
New research from last week 19/2012
Posted on 15 May 2012 by Ari Jokimäki
Wouldn't it be nice to see something like following headlines in popular news media:
"Growth change of oak and beech are related to climate time series and N deposition trends!"
"Atmospheric lifetime of methane only 9.1 ± 0.9 years!"
"WAIS Divide was colder than the last 1000-year average from 1300 to 1800 C.E.!"
"Concentrations of rBC in the ice cores displayed significant variability at annual to decadal time scales!"
I bet papers with these in their frontpage would be sold out in minutes.
Contrary to expectations, British butterflies don't utilise an increased range of habitat types with global warming
Abstract: "Climate warming threatens the survival of species at their warm, trailing-edge range boundaries, but also provides opportunities for the ecological release of populations at the cool, leading edges of their distributions. Thus, as the climate warms, leading-edge populations are expected to utilise an increased range of habitat types, leading to larger population sizes and range expansion. Here, we test the hypothesis that the habitat associations of British butterflies have expanded over three decades of climate warming. We characterise the habitat breadth of 27 southerly-distributed species from 77 monitoring transects between 1977 and 2007 by considering changes in densities of butterflies across 11 habitat types. Contrary to expectation, we find that 20 out of 27 (74%) butterfly species showed long term contractions in their habitat associations, despite some short-term expansions in habitat breadth in warmer-than-usual years. Thus, we conclude that climatic warming has ameliorated habitat contractions caused by other environmental drivers to some extent, but that habitat degradation continues to be a major driver of reductions in habitat breadth and population density of butterflies."
Citation: Tom H. Oliver, Chris D. Thomas, Jane K. Hill, Tom Brereton, David B. Roy, Global Change Biology, DOI: 10.1111/j.1365-2486.2012.02737.x.
Droughts have become more intense and last longer in Urmia Lake Basin, Iran
Observed climate variability and change in Urmia Lake Basin, Iran - Delju et al. (2012)
Abstract: "This paper analyzes climate variability and change in the Urmia Lake Basin, northwest of Iran. Annual average of the following data time series has been analyzed by statistical methods: dry bulb temperature, maximum and minimum temperature, precipitation, and number of rainy and snowy days. We have also used mean monthly temperature and precipitation data for analysis of drought spells for the period 1964–2005 to find out whether fluctuations in the lake level are attributable to natural drought. Our results indicate that mean precipitation has decreased by 9.2 % and the average maximum temperature has increased by 0.8°C over these four decades. The seasonal changes are particularly visible in winter and spring. Results of the Palmer Drought Severity Index show that on average, drought episodes have hit the Urmia Lake Basin every 5 years and most of them reached severe levels, but recent droughts have become more intense and last longer."
Citation: A. H. Delju, A. Ceylan, E. Piguet and M. Rebetez, Theoretical and Applied Climatology, 2012, DOI: 10.1007/s00704-012-0651-9.
Asian summer monsoon intensity has decreased with global warming
Abstract: "The trend of the Indian summer monsoon (ISM) intensity and its nature during the past 100 and 200 years still remain unclear. In this study we reconstructed the ISM intensity during the past 270 years from tree ring δ18O at Hongyuan, eastern edge of the Tibet Plateau. The monsoon failures inferred from δ18Otree ring correlate well with those recorded in ice cores, speleothem, and historical literature sources. 22.6, 59.0, and 110.9-years frequency components in the Hongyuan δ18Otree ring series, which may be the responses to solar activities, synchronize well with those recorded in other ISM indices. A notable feature of the reconstructed ISM intensity is the gradually decreasing trend from about 1860 to the present, which is inversely related to the increasing temperature trend contemporaneously. Such “decreasing ISM intensity–increasing temperature” tendency can also be supported by ice core records and meteorological records over a wide geographic extension. The decrease in sea surface temperature gradient between tropical and north Indian Ocean, and the decrease in land-sea thermal contrast between tropical Indian Ocean and “Indian sub-continent–western Himalaya” are possibly responsible for the observed decreasing ISM trend."
Citation: Hai Xu, Yetang Hong and Bin Hong, Climate Dynamics, 2012, DOI: 10.1007/s00382-012-1378-0.
Sunshine hour decline in China since 1960's due to air pollution
The magnitude of the effect of air pollution on sunshine hours in China - Wang et al. (2012)
Abstract: "This study investigates the changes in sunshine hours in relation to API (Air Pollution Index) across China. Data were collected from a total of 38 cities over the period of 1960–2009. Sunshine hours in over 84% of the cities significantly (p < 0.05) decline with an average of 16.7% for the 1960s–2000s. This decline is mainly prevalent over Sichuan Basin (22.4%), North China Plain (18.8%), and Yangtze River Delta (18.2%). While the sunshine hour decline is largely in the 20th century (with the strongest drop in the 1980s and the least in the 1990s), it rebounds by 0.3% after 2000. For especially in winter seasons and the North China region, API is negatively related with sunshine hours. For days with API > 80, sunshine hours are on the average 0.7 h d−1 (8.4%) shorter than for days with API ≤ 80 under clear-sky condition for 2001–2005. In cities with average daily API ≤ 80 and >80 for the 2000s, sunshine hour decline for the 1960s–2000s is 0.8 h d−1 (13.4%) and 1.0 h d−1 (15.9%) respectively. Winter seasons with high API (90) exhibit the highest sunshine hour decline (21.5%). The study shows that spatiotemporal changes in sunshine hours in China could largely be explained in terms of API."
Citation: Wang, Y., Y. Yang, N. Zhao, C. Liu, and Q. Wang (2012), The magnitude of the effect of air pollution on sunshine hours in China, J. Geophys. Res., 117, D00V14, doi:10.1029/2011JD016753.
In 2007 there were lot of melt ponds on Arctic sea ice and in 2011 there were even more
Abstract: "Melt ponds contribute to the ice-albedo feedback as they reduce the surface albedo of sea ice, and hence accelerate the decay of Arctic sea ice. Here, we analyze the melt pond fraction, retrieved from the MODIS sensor for the years 2000–2011 to characterize the spatial and temporal evolution. A significant anomaly of the relative melt pond fraction at the beginning of the melt season in June 2007 is documented. This is followed by above-average values throughout the entire summer. In contrast, the increase of the relative melt pond fraction at the beginning of June 2011 is within average values, but from mid-June, relative melt pond fraction exhibits values up to two standard deviations above the mean values of 30 ± 1.2% which are even higher than in Summer 2007."
Citation: Rösel, A., and L. Kaleschke (2012), Exceptional melt pond occurrence in the years 2007 and 2011 on the Arctic sea ice revealed from MODIS satellite data, J. Geophys. Res., 117, C05018, doi:10.1029/2011JC007869.
Signal of human influence on climate has strengthened over the first decade of the 21st century
Abstract: "We carry out a detection and attribution analysis of observed near-surface temperatures to 2010 and demonstrate that the signal of human influence on climate has strengthened over the first decade of the 21st century. As a result, we show that global warming is set to continue, with the second decade of the 21st century predicted to be very likely warmer than the first. Estimates of future warming rates consistent with observations of past climate change are now better constrained than they were a decade ago. The highest rates of warming previously consistent with past warming now appear to be unlikely."
Citation: Peter A. Stott, Gareth S. Jones, Atmospheric Science Letters, DOI: 10.1002/asl.383.
Antactic ice core records of black carbon deposition since 1850
Changes in black carbon deposition to Antarctica from two high-resolution ice core records, 1850–2000 AD - Bisiaux et al. (2012) [FULL TEXT]
Abstract: "Refractory black carbon aerosols (rBC) emitted by biomass burning (fires) and fossil fuel combustion, affect global climate and atmospheric chemistry. In the Southern Hemisphere (SH), rBC is transported in the atmosphere from low- and mid-latitudes to Antarctica and deposited to the polar ice sheet preserving a history of emissions and atmospheric transport. Here, we present two high-resolution Antarctic rBC ice core records drilled from the West Antarctic Ice Sheet divide and Law Dome on the periphery of the East Antarctic ice sheet. Separated by ~3500 km, the records span calendar years 1850–2001 and reflect the rBC distribution over the Indian and Pacific ocean sectors of the Southern Ocean. Concentrations of rBC in the ice cores displayed significant variability at annual to decadal time scales, notably in ENSO-QBO and AAO frequency bands. The delay observed between rBC and ENSO variability suggested that ENSO does not directly affect rBC transport, but rather continental hydrology, subsequent fire regimes, and aerosol emissions. From 1850 to 1950, the two ice core records were uncorrelated but were highly correlated from 1950 to 2002 (cross-correlation coefficient at annual resolution: r = 0.54, p < 0.01) due to a common decrease in rBC variability. The decrease in ice-core rBC from the 1950s to late 1980s displays similarities with inventories of SH rBC grass fires and biofuel emissions, which show reduced emission estimates over that period."
Citation: Bisiaux, M. M., Edwards, R., McConnell, J. R., Curran, M. A. J., Van Ommen, T. D., Smith, A. M., Neumann, T. A., Pasteris, D. R., Penner, J. E., and Taylor, K.: Changes in black carbon deposition to Antarctica from two high-resolution ice core records, 1850–2000 AD, Atmos. Chem. Phys., 12, 4107-4115, doi:10.5194/acp-12-4107-2012, 2012.
Most temperature proxies really are linear functions of annual mean temperature
A test for non-linearity in temperature proxy records - Støve et al. (2012)
Abstract: "Are temperature proxy records linear recorders of past temperature conditions? We apply a statistical test for linearity to 15 millennial-long proxy records with annual resolution that where shown to significantly respond to Northern Hemisphere annual mean temperature selected from a collection of 30 proxies. The test, based on generalized additive modeling, shows that most of the proxies can indeed be shown to be linear functions of annual mean temperature, but two proxy records do not appear to have a linear relationship with temperature -- this supports the assumption of linearity in most climate reconstruction work. The method tests for non-linearity in a proxy relative to the group of proxies it is being used together with. We test robustness of the results and find that the results are stable to choice of proxies. The linearity-testing method is quite general and could in the future be used for larger and more extensive sets of proxies."
Citation: Bård Støve, Fredrik Charpentier Ljungqvist, Peter Thejll, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-11-00632.1.
New technique for measuring past methane mixing ratios from ice cores
Continuous measurements of methane mixing ratios from ice cores - Stowasser et al. (2012) [FULL TEXT]
Abstract: "This work presents a new, field-deployable technique for continuous, high-resolution measurements of methane mixing ratios from ice cores. The technique is based on a continuous flow analysis system, where ice core samples cut along the long axis of an ice core are melted continuously. The past atmospheric air contained in the ice is separated from the melt water stream via a system for continuous gas extraction. The extracted gas is dehumidified and then analyzed by a Wavelength Scanned-Cavity Ring Down Spectrometer for methane mixing ratios. We assess the performance of the new measurement technique in terms of precision (±0.8 ppbv, 1σ), accuracy (±8 ppbv), temporal (ca. 100 s), and spatial resolution (ca. 5 cm). Using a firn air transport model, we compare the resolution of the measurement technique to the resolution of the atmospheric methane signal as preserved in ice cores in Greenland. We conclude that our measurement technique can resolve all climatically relevant variations as preserved in the ice down to an ice depth of at least 1980 m (66 000 yr before present) in the North Greenland Eemian Ice Drilling ice core. Furthermore, we describe the modifications, which are necessary to make a commercially available spectrometer suitable for continuous methane mixing ratio measurements from ice cores."
Citation: Stowasser, C., Buizert, C., Gkinis, V., Chappellaz, J., Schüpbach, S., Bigler, M., Faïn, X., Sperlich, P., Baumgartner, M., Schilt, A., and Blunier, T.: Continuous measurements of methane mixing ratios from ice cores, Atmos. Meas. Tech., 5, 999-1013, doi:10.5194/amt-5-999-2012, 2012.
Evidence for global Little Ice Age from West Antarctic borehole temperatures
Abstract: "The largest climate anomaly of the last 1000 years in the Northern Hemisphere was the Little Ice Age (LIA) from 1400–1850 C.E., but little is known about the signature of this event in the Southern Hemisphere, especially in Antarctica. We present temperature data from a 300 m borehole at the West Antarctic Ice Sheet (WAIS) Divide. Results show that WAIS Divide was colder than the last 1000-year average from 1300 to 1800 C.E. The temperature in the time period 1400–1800 C.E. was on average 0.52 ± 0.28°C colder than the last 100-year average. This amplitude is about half of that seen at Greenland Summit (GRIP). This result is consistent with the idea that the LIA was a global event, probably caused by a change in solar and volcanic forcing, and was not simply a seesaw-type redistribution of heat between the hemispheres as would be predicted by some ocean-circulation hypotheses. The difference in the magnitude of the LIA between Greenland and West Antarctica suggests that the feedbacks amplifying the radiative forcing may not operate in the same way in both regions."
Citation: Orsi, A. J., B. D. Cornuelle, and J. P. Severinghaus (2012), Little Ice Age cold interval in West Antarctica: Evidence from borehole temperature at the West Antarctic Ice Sheet (WAIS) Divide, Geophys. Res. Lett., 39, L09710, doi:10.1029/2012GL051260.
Yet another analysis suggests that greenhouse gases and aerosols controlled temperature after 1950
A fractal climate response function can simulate global average temperature trends of the modern era and the past millennium - van Hateren (2012) [FULL TEXT]
Abstract: "A climate response function is introduced that consists of six exponential (low-pass) filters with weights depending as a power law on their e-folding times. The response of this two-parameter function to the combined forcings of solar irradiance, greenhouse gases, and SO2-related aerosols is fitted simultaneously to reconstructed temperatures of the past millennium, the response to solar cycles, the response to the 1991 Pinatubo volcanic eruption, and the modern 1850–2010 temperature trend. Assuming strong long-term modulation of solar irradiance, the quite adequate fit produces a climate response function with a millennium-scale response to doubled CO2 concentration of 2.0 ± 0.3 °C (mean ± standard error), of which about 50 % is realized with e-folding times of 0.5 and 2 years, about 30 % with e-folding times of 8 and 32 years, and about 20 % with e-folding times of 128 and 512 years. The transient climate response (response after 70 years of 1 % yearly rise of CO2 concentration) is 1.5 ± 0.2 °C. The temperature rise from 1820 to 1950 can be attributed for about 70 % to increased solar irradiance, while the temperature changes after 1950 are almost completely produced by the interplay of anthropogenic greenhouse gases and aerosols. The SO2-related forcing produces a small temperature drop in the years 1950–1970 and an inflection of the temperature curve around the year 2000. Fitting with a tenfold smaller modulation of solar irradiance produces a less adequate fit with millennium-scale and transient climate responses of 2.5 ± 0.4 and 1.9 ± 0.3 °C, respectively."
Citation: J. H. van Hateren, Climate Dynamics, 2012, DOI: 10.1007/s00382-012-1375-3.
New derivations for atmospheric lifetimes of some GHG's
Abstract: "Knowledge of the atmospheric chemistry of reactive greenhouse gases is needed to accurately quantify the relationship between human activities and climate, and to incorporate uncertainty in our projections of greenhouse gas abundances. We present a method for estimating the fraction of greenhouse gases attributable to human activities, both currently and for future scenarios. Key variables used to calculate the atmospheric chemistry and budgets of major non-CO2 greenhouse gases are codified along with their uncertainties, and then used to project budgets and abundances under the new climate-change scenarios. This new approach uses our knowledge of changing abundances and lifetimes to estimate current total anthropogenic emissions, independently and possibly more accurately than inventory-based scenarios. We derive a present-day atmospheric lifetime for methane (CH4) of 9.1 ± 0.9 y and anthropogenic emissions of 352 ± 45 Tg/y (64% of total emissions). For N2O, corresponding values are 131 ± 10 y and 6.5 ± 1.3 TgN/y (41% of total); and for HFC-134a, the lifetime is 14.2 ± 1.5 y."
Citation: Prather, M. J., C. D. Holmes, and J. Hsu (2012), Reactive greenhouse gas scenarios: Systematic exploration of uncertainties and the role of atmospheric chemistry, Geophys. Res. Lett., 39, L09803, doi:10.1029/2012GL051440.
Causes and differences of temperature response of tree species radial growth
Abstract: "Both increasing and decreasing 20th century growth trends have been reported in forests throughout Europe, but only for few species and areas suitable modelling techniques have been used to distinguish individual tree growth (operating on a local scale) from growth change due to exogenous factors (operating on a broad geographical scale). This study relates for the first time observed growth changes, in terms of basal area increment (BAI) of dominant trees of pedunculate oak, common beech and Scots pine, in north-west European temperate lowland forests (Flanders) to climate, atmospheric CO2 and tropospheric O3 concentrations, N deposition, site quality and forest structure for more than a century (the period 1901–2008), applying mixed models. Growth change during the 20th century is observed for oak (increasing growth) and beech (increasing growth until the 1960s, growth decline afterwards), but not for pine. It was possible to relate growth change of oak and beech to climate time series and N deposition trends. Adding time series for CO2 and O3 concentration did not significantly improve model results. For oak and beech a switch from positive to negative growth response with increasing nitrogen deposition throughout time is observed. Growth increase for oak is mainly determined by the interaction between growing season temperature and soil water recharge. It is reasonable to assume that the observed growth trend for oak will continue for as long as early season water availability is not compromised. The decreasing trend in summer relative air humidity observed since the 1960s in the study area can be a main cause of recent beech BAI decrease. A further growth decline of beech can be expected, independent of site quality."
Citation: Vincent Kint, Wim Aertsen, Matteo Campioli, Dries Vansteenkiste and Andy Delcloo, et al., Climatic Change, 2012, DOI: 10.1007/s10584-012-0465-x.
CLASSIC OF THE WEEK: Lord Kelvin (1864)
On the secular cooling of the earth - Lord Kelvin (1864) [FULL TEXT (partial)]
Abstract: No abstract. Quote from the beginning of the paper: "For eighteen years it has pressed on my mind, that essential principles of Thermo-dynamics have been overlooked by those geologists who uncompromisingly oppose all paroxysmal hypostheses, and maintain not only that we have examples now before us, on the earth, of all the different actions by which its crust has been modified in geological history, but that these actions have never, or have not on the whole, been more violent in the past time than they are at present."
Citation: Lord Kelvin (William Thomson), Transactions of the Royal Society of Edinburgh, Vol. XXIII, pp. 167169, 1864. Read April 28, 1862.
This is a cross-post from AGW Observer. When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. At least some of these are also retweeted in Skeptical Science 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.
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