Climate Blog and News Recap: 2011 02 26
A pair of solar-driven climate papers by Weber and Le Mouël …
Strong signature of the active Sun in 100 years of terrestrial insolation data
Article first published online: 21 MAY 2010
A solar pattern in the longest temperature series from three stations in Europe
Le Mouël, Jean-Louis; Kossobokov, Vladimir; Courtillot, Vincent
Journal of Atmospheric and Solar-Terrestrial Physics, Volume 72, Issue 1, p. 62-76.
has come under criticism by Feulner and Legras, respectively.
The Smithsonian solar constant data revisited: no evidence for cosmic-ray induced aerosol formation in terrestrial insolation data
Volumes and Issues Contents of Issue 1
Atmos. Chem. Phys. Discuss., 11, 2297-2316, 2011
A critical look at solar-climate relationships from long temperature series
B. Legras, O. Mestre, E. Bard, and P. Yiou
Clim. Past, 6, 745-758, 2010
Zeke tries to tease out natural -v- anthropogenic attribution in the AMO.
The Atlantic Multidecadal Oscillation and Modern Warming Hausfather @ The Blackboard
I’ve udpated the previous recap with some work by Stokes on Antarctic warming and Eschenbach on precipitation extremes.
Note: Science Direct is down for maintenance this morning – so some links may not work and some abstracts are missing. Updated
We studied the relationship between the dominant patterns of sea surface temperature (SST) variability in the North Pacific and the North Atlantic. The patterns are known as the Pacific Decadal Oscillation (PDO) and the Atlantic Multi-decadal Oscillation (AMO). In the analysis we used two different observational data sets for SST. Due to the high degree of serial correlation in the PDO and AMO time series, various tests were carried out to assess the significance of the correlations. The results demonstrated that the correlations are significant when the PDO leads the AMO by 1 year and when the AMO leads the PDO by 11–12 years. The possible physical processes involved are discussed, along with their potential implication for decadal prediction.
.. Here, we present the first long-term paleoenvironmental record from the northern Levant, presently much wetter than the southern Levant. Our record derives from the multi-proxy study of a sediment core (36 m long) retrieved from the small intra-mountainous, tectonic basin of Yammoûneh (Lebanon), which is mainly supplied by karstic springs…. ►This study focuses on environmental changes in Lebanon during the last 250 ka ►Interglacials are characterized by warm and relatively wet conditions ►Decrease in water availability during the coldest glacial periods ►Significant differences with lake records of southern Levant ►These differences suggest changes in the rainfall gradient or local factors influence
A 250 ka sedimentary record from a small karstic lake in the Northern Levant (Yammoûneh, Lebanon). Paleoclimatic implications (Palaeogeography, palaeoclimatology, palaeoecology)
The eastern tropical Pacific plays a key role in the tropical atmospheric circulation and in the global carbon cycle, and assessing the sensitivity of this region to global climate changes is a major challenge facing climatologists. Provided here is a synthesis of proxy records of the mean climate of the mid-Holocene (5-8 ka) along the south eastern Pacific margin and four regions of South America. These regions were selected for the strength and stability of ENSO teleconnections, and located outside the direct influence of the intertropical convergence zone or the southern westerlies in order to avoid the overprinting signal of their insolation-related variations and focus on the relationship between the eastern tropical Pacific and South America. This study is based on a review of published multiproxy data as well as new isotopic data from the Peruvian and Chilean coast. The available evidence indicates that sea surface temperatures were ˜1-4 C° cooler from the Galapagos to the southern Peruvian coast as a result of increased coastal upwelling forced by changes in longshore windfields. The mean La Niña-like conditions in the eastern South Pacific were associated to aridity in southern Brazil and along the whole South American Pacific coast from central Chile to the Galapagos, and to wetter conditions on the western central Andes. This regional synthesis provides a coherent picture of the South American mean climate that is very similar to the modern precipitation pattern observed during La Niña conditions, suggesting that atmospheric teleconnections linking the South Eastern Pacific to these continental areas were similar in the middle Holocene.
Mid-Holocene mean climate in the south-eastern Pacific and its influence on South America (Quaternary international)
Research led by Dr Amelia Shevenell (UCL Geography), published in Nature (9 February), shows that the Antarctic Peninsula is one of the fastest-warming places on Earth, experiencing dramatic regional climate change in recent decades, especially during La Nina years.
Past Antarctic cooling may help studies of global warming (PHYSorg.com: Space & Earth)
The contribution of Greenland to global sea level change and the mapping of previously unknown basins and mountains beneath the Antarctic Ice Sheet are highlighted in a new film released by Cambridge University this morning.
Greenland’s glaciers double in speed (PHYSorg.com: Space & Earth)
The variability of stratospheric planetary waves and their possible connection with the 11-yr solar cycle forcing have been investigated using annual-mean temperatures for the period of 1958-2001 derived from two reanalysis data sets. The significant planetary waves (wavenumbers 1-3) can be identified in the northern mid-high latitudes (55-75°N) in the stratosphere using this data. Comparisons with satellite-retrieved products from the Microwave Sounding Unit (MSU) confirm the significant planetary wave variability seen in the reanalyses. A planetary wave amplitude index (PWAI) is defined to indicate the strength of the stratospheric planetary waves. The PWAI is derived from Fourier analysis of the temperature field for wavenumbers 1-3 and averaged over 55-75°N latitude and the 70-20 hPa layers. The results include two meaningful inter-annual oscillations (2-yr and 8-yr) and one decadal trend (16-yr) that was derived from wavelet analysis. The stratospheric temperature structure of the wave amplitudes appear associated with the Arctic Oscillation (AO) which explicitly changed with the PWAI. The temperature gradients between the polar and mid-high latitudes show opposite tendencies between the top-10 strong and weak wave regimes.
The variation of the planetary wave amplitude appears closely related to the solar forcing during the recent four solar cycles (20-23). The peak of the 2-yr oscillation occurs synchronously with solar minimum, and is consistent with the negative correlation between the PWAI and the observed solar UV irradiance. The UV changes between the maxima and minima of the 11-yr solar cycle impact the temperature structure in the middle-lower stratosphere in the mid-high latitudes and hence influence the planetary waves. During solar maximum, the dominant influence appears to be exerted through changes in static stability, leading to a reduction in planetary wave amplitude. During solar minimum, the dominant influence appears to be exerted through changes in the meridional temperature gradient and vertical wind shear, leading to an enhancement of planetary wave amplitude.
Possible solar forcing of interannual and decadal stratospheric planetary wave variability in the northern hemisphere: An observational study (Journal of atmospheric and solar – terrestrial physics)
This study presents an evaluation of a new biosphere-atmosphere Regional Climate Model. COSMO-CLM2 results from the coupling between the non-hydrostatic atmospheric model COSMO-CLM version 4.0 and the Community Land Model version 3.5 (CLM3.5). In this coupling, CLM3.5 replaces a simpler land surface parameterization (TERRA_ML) used in the standard COSMO-CLM. Compared to TERRA_ML, CLM3.5 comprises a more complete representation of land surface processes including hydrology, biogeophysics, biogeochemistry and vegetation dynamics. … Overall, these results highlight the importance of land surface processes in shaping the European climate and the benefit of using an advanced land surface model for regional climate simulations.
In this study, El Niño Southern Oscillation (ENSO)-induced interannual variability in the South China Sea (SCS) is documented using outputs from an eddy-resolving data-assimilating model. It is suggested that during an El Niño (La Niña) event, off-equatorial upwelling (downwelling) Rossby waves induced by Pacific equatorial wind anomalies impinge on the Philippine Islands and excite upwelling (downwelling) coastal Kelvin waves that propagate northward along the west coast of the Philippines after entering the SCS through the Mindoro Strait. The coastal Kelvin waves may then induce negative (positive) sea level anomalies in the southeastern SCS and larger (smaller) volume transport through the Mindoro and Luzon Straits during an El Niño (La Niña) event.
ENSO-induced interannual variability in the southeastern South China Sea (Journal of oceanography)
The surface temperature changes for the last 4000 years in northern inland Iberia (an area particularly sensitive to climate change) are determined by a high resolution study of carbon stable isotope records of stalagmites from three caves (Kaite, Cueva del Cobre, and Cueva Mayor) separated several 10 s km away in N Spain. Despite the local conditions of each cave, the isotopic series show a good overall coherence, and resulted to be strongly sensitive to surface temperature changes. … Spectral analysis of the time series shows consistent climatic cycles of ~ 400, ~ 900 and ~ 1300 yr, comparable with those recognized in the North Atlantic marine record, the Greenland ice cores, and other terrestrial records for the middle – late Holocene, suggesting common climate forcing mechanisms related to changes in solar irradiance and North Atlantic circulation patterns.
Land surface temperature changes in Northern Iberia since 4000 yr BP, based on ?13C of speleothems (Global and planetary change)
To investigate the Holocene climate and treeline dynamics in the European Russian Arctic, we analysed sediment pollen, conifer stomata, and plant macrofossils from Lake Kharinei, a tundra lake near the treeline in the Pechora area. We present quantitative summer temperature reconstructions from Lake Kharinei and Lake Tumbulovaty, a previously studied lake in the same region, using a pollen–climate transfer function based on a new calibration set from northern European Russia. Our records suggest that the early-Holocene summer temperatures from 11,500 cal yr BP onwards were already slightly higher than at present, followed by a stable Holocene Thermal Maximum (HTM) at 8000–3500 cal yr BP when summer temperatures in the tundra were ca. 3°C above present-day values. A Picea forest surrounded Lake Kharinei during the HTM, reaching 150 km north of the present taiga limit. The HTM ended with a temperature drop at 3500–2500 cal yr BP associated with permafrost initiation in the region. Mixed spruce forest began to disappear around Lake Kharinei at ca. 3500 cal yr BP, with the last tree macrofossils recorded at ca. 2500 cal yr BP, suggesting that the present wide tundra zone in the Pechora region formed during the last ca. 3500 yr.
The Southern Oscillation (SO) is usually described as the atmospheric component of the dynamically coupled phenomenon the El Nino/Southern Oscillation. We contend, however, that dynamical coupling is not required to produce the SO. We use simulations with atmospheric general circulation models that have varying degrees of coupling to the ocean to show that the SO emerges as a dominant mode of variability if the atmosphere and ocean are coupled only through heat and moisture fluxes. We are calling this mode of variability the ‘Thermally Coupled Walker’ (TCW) mode. … Despite the oversimplification due to the lack of interactive ocean dynamics, the physical mechanisms leading to the TCW should be active in the actual climate system. Moreover, the robustness and realism of the spatial patterns of this mode suggest that the physics of the TCW can explain some of the primary features of observed interannual and decadal variability in the Pacific and the associated global teleconnections.
Rethinking the Ocean’s Role in the Southern Oscillation (Journal of Climate)
Many climatic parameters (ground and ocean surface temperatures, pressure, atmospheric precipitation, etc.) have temporal variations with characteristic periods from several to several tens of years or more. The unknown cause of these oscillations, together with the similarity of some of them to known solar cycles, has stimulated attempts to relate these two phenomena. The basic arguments against the existence of such a relationship are that variations in climatic parameters do not always occur synchronously with the corresponding 11- and 22-year solar cycles: the phase shift between climatic and solar variations is inconstant and changes with time from 0° to 180°. In addition, the energy of terrestrial manifestations of solar activity seems insufficient to stimulate the considered weather-climatic processes, at least within the limits of the linear approach. In the present work, it is shown that in some cases, these contradictions can be removed for variations with a period more than 11 years under the assumption that climatic variations are forced oscillations driven by an external force (for example, a force related to solar activity), that implies the existence of intrinsic (natural) climatic oscillations. The result serves as an additional argument in favor of the reality of a sun-climate connection and probably points to its probable nonlinear mechanism.
An algorithm for estimating global sea surface temperatures (SST) from data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite has been developed empirically. Four atmospheric correction models for MODIS observations are examined, and the effects of ancillary data for corrections are discussed. A nonlinear (NLSST) model using high-temporal-resolution climatological SSTs as the first guess shows high accuracy and availability. The addition of a temperature-proportional term to the NLSST model effectively improves the estimate.
How severe can climate change become in a warming world? Worse than anything we’ve seen in written history, according to results of a study appearing this week in the journal Science
How Severe Can Climate Change Become? (Geology News)
National Assessment of Shoreline Change: Historical Shoreline Change along the New England and Mid-Atlantic Coasts is a new open file report (2010-1118) by the United States Geological Survey. It contains an interesting set of graphs illustrating sea level change, based upon tidal gauges, for several locations on the Atlantic Ocean coast (shown below) The variable rates of sea level rise are attributed to a combination of “residual post-glacial isostatic rebound, hydrostatic loading, differential increases in tidal range, and neotectonics.”
Sea Level Rise on the Atlantic Coast (Geology News)
Assemblages of acritarchs, prasinophytes, and miospores were recovered from the uppermost Iquiri and lower portion of the Itacua formations in southeast Bolivia. Analysis of the diverse and somewhat abundant well-preserved palynomorph assemblage indicates a Late Devonian (late Famennian) age for both formations, and further subdivision in ascending stratigraphic order into the ?VCo, LL, LE, and LN miospore biozones of Western Europe. The presence of age-diagnostic miospore taxa from South America and North America indicates contemporaneous glaciation events between these two regions. The results from close sampling of the diamictite facies of the Itacua Formation at the Bermejo West section, Bolivia, correlate the latest Famennian spore inceptions used to define the Euramerica miospore biozone sequence (LL, LE, and LN zones). The Itacua Formation diamictite sequence examined is relatively thin compared to other diamictite sequences in Bolivia. Furthermore, the miospore biozones represent an estimated duration of three million years, whereas orbitally-forced glacial-interglacial events (e.g., Ruddiman, 2001) are of the Milankovitch frequency range of between 20,000 to 400,000 years. Therefore, it seems most likely that a number of glacial/interglacial events are represented, rather than a single glacial episode
Was the latest Devonian glaciation a multiple event? New palynological evidence from Bolivia (Palaeogeography, palaeoclimatology, palaeoecology)
ime series of profiles of potential temperature, salinity, dissolved oxygen and planetary potential vorticity at intermediate depths in the Labrador Sea, the Irminger Sea, and the Iceland Basin have been constructed by combining the hydrographic sections crossing the sub-arctic gyre of the North Atlantic Ocean from the coast of Labrador to Europe, occupied nearly annually since 1990, and historic hydrographic data from the preceding years since 1950. The temperature data of the last 60 year mainly reflect a multi-decadal variability, with a characteristic time scale of about 50 years. With the use of a highly simplified heat budget model it was shown that this long-term temperature variability in the Labrador Sea mainly reflects the long-term variation of the net heat flux to the atmosphere. However, the analysis of the data on dissolved oxygen and planetary potential vorticity show that convective ventilation events, during which successive classes of Labrador Sea Water (LSW) are formed, occur on decadal or shorter time scales. …
Decadal and multi-decadal variability of Labrador Sea Water in the north-western North Atlantic Ocean derived from tracer distributions: heat budget, ventilation, and advection (Deep-sea research. Part I, Oceanographic research papers)
High-resolution analysis of stable carbon and oxygen isotopic composition (δ13C and δ18O) of tree-ring α-cellulose has been increasingly in demand for the study of climate seasonality, droughts, and tropical cyclone (hurricane) activity. The peeling-grinding method commonly used for tree-ring α-cellulose preparation is both time-consuming and labor-intensive, and often results in cross-tracheid sampling that masks high-frequency intra-annual climate signals and short-term climate events. Here, we present a new method by extracting tree-ring α-cellulose directly from wholewood spline that omits the peeling-grinding step, and allows for micro-scale δ13C and δ18O analysis that facilitates high-resolution seasonal climate study. This ultrasound-assisted non-destructive extraction method has significantly increased the output of tree-ring α-cellulose preparation while retaining the wood cell fabric…. An algorithm is developed for establishing regional patterns of tree-ring seasonal δ13C and δ18O for the study of the mean state of climate seasonality and its anomalies.
Scientists are unravelling the environmental changes that took place around the Arctic during an exceptional episode of ancient global warming. Newly published results from a high-resolution study of sediments collected on Spitsbergen represent a significant contribution to this endeavour. The study was led by Dr Ian Harding and Prof John Marshall of the University of Southampton’s School of Ocean and Earth Science (SOES), based at the National Oceanography Centre, Southampton.
Arctic environment during an ancient bout of natural global warming (PHYSorg.com: Space & Earth)
Long climate records are scarce on the Tibetan Plateau for understanding the climate variability on long-term context. Here we presented an early summer (May–June) temperature reconstruction since ad 1440 for Qamdo area using tree rings of Sabina tibetica. The reconstruction accounted for 64% of the variance in the instrumental record. It showed warm periods during … Cool early summer occurred during … Comparison with other proxy or meteorological records suggested that there is obvious spatial variability in the May–June temperature variations along the eastern margin of the Tibetan Plateau.
Early summer temperature reconstruction in the eastern Tibetan plateau since ad 1440 using tree-ring width of Sabina tibetica (Theoretical and Applied Climatology)
The Medieval Warm Period is an interval of purportedly warm climate during the early part of the past millennium. The duration, areal extent, and even existence of the Medieval Warm Period have been debated; in some areas the climate of this interval appears to have been affected more by changes in precipitation than in temperature. Here, we provide new evidence showing that several glaciers in western North America advanced during Medieval time and that some glaciers achieved extents similar to those at the peak of the Little Ice Age, many hundred years later. The advances cannot be reconciled with a climate similar to that of the twentieth century, which has been argued to be an analog, and likely were the result of increased winter precipitation due to prolonged La Niña-like conditions that, in turn, may be linked to elevated solar activity. Changes in solar output may initiate a response in the tropical Pacific that directly impacts the El Niño/Southern Oscillation and associated North Pacific teleconnections.
Extensive glaciers in northwest North America during Medieval time (Climatic Change)
Long-term high-resolution climate proxies are essential for understanding climate variability on the Tibetan Plateau (TP), where few long-term climate records are available. In this paper, we describe a summer (August) temperature reconstruction over the period 1385-2002 based on a tree-ring width chronology of Balfour spruce (Picea likiangensis var. balfouriana) on the southeastern TP created using the Regional Curve Standardization method. The reconstruction explains 44.7% of the variance in the instrumental temperature records during the calibration period (1962-2002), and captures temperature variability over a broad region of the TP. Warmer than average Augusts were found during the periods 1446-1494, 1509-1522, 1553-1567, 1797-1812, 1845-1905 and 1918-2002. Cooler than average Augusts occurred from 1385-1416, 1426-1445, 1495-1508, 1523-1552, 1568-1686, 1695-1718, 1725-1796, 1813-1844 and 1906-1917. A warming trend in the 20th century was unprecedented during the past six centuries. The reconstruction closely matched other tree-ring summer temperature reconstructions from neighboring regions, as well as patterns from ice-core δO18 data, and fluctuated in synchrony with Northern Hemisphere temperature reconstructions.
August temperature variability in the southeastern Tibetan Plateau since AD 1385 inferred from tree rings (Palaeogeography, palaeoclimatology, palaeoecology)
This study examines systematic biases in sea surface temperature (SST) under the stratus cloud deck in the southeast Pacific and upper ocean processes relevant to the SST biases in 19 coupled general circulation models (CGCMs) participating in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). The twenty years of simulations from each model are analyzed. Pronounced warm SST biases in a large portion of the southeast Pacific stratus region are found in all models. Processes that could contribute to the SST biases are examined in detail based on the computation of major terms in the upper ocean heat budget. Negative biases in net surface heat fluxes are evident in most of the models, suggesting that the cause of the warm SST biases in models is not explained by errors in net surface heat fluxes. Biases in heat transport by Ekman currents largely contribute to the warm SST biases both near the coast and the open ocean. In the coastal area, southwestward Ekman currents and upwelling in most models are much weaker than observed due to weaker alongshore winds, resulting in insufficient advection of cold water from the coast. In the open ocean, warm advection due to Ekman currents is overestimated in models because of the larger meridional temperature gradient, the smaller zonal temperature gradient and overly weaker Ekman currents.