168 research outputs found
Anomalous mid-twentieth century atmospheric circulation change over the South Atlantic compared to the last 6000 years
Determining the timing and impact of anthropogenic climate change in data-sparse regions is a considerable challenge. Arguably, nowhere is this more difficult than the Antarctic Peninsula and the subantarctic South Atlantic where observational records are relatively short but where high rates of warming have been experienced since records began. Here we interrogate recently developed monthly-resolved observational datasets from the Falkland Islands and South Georgia, and extend the records back using climate-sensitive peat growth over the past 6000 years. Investigating the subantarctic climate data with ERA-Interim and Twentieth Century Reanalysis, we find that a stepped increase in precipitation across the 1940s is related to a change in synoptic atmospheric circulation: a westward migration of quasi-permanent positive pressure anomalies in the South Atlantic has brought the subantarctic islands under the increased influence of meridional airflow associated with the Amundsen Sea Low. Analysis of three comprehensively multi-dated (using 14C and 137Cs) peat sequences across the two islands demonstrates unprecedented growth rates since the mid-twentieth century relative to the last 6000 years. Comparison to observational and reconstructed sea surface temperatures suggests this change is linked to a warming tropical Pacific Ocean. Our results imply 'modern' South Atlantic atmospheric circulation has not been under this configuration for millennia
Alcohol-induced retrograde facilitation renders witnesses of crime less suggestible to misinformation
RATIONALE: Research has shown that alcohol can have both detrimental and facilitating effects on memory: intoxication can lead to poor memory for information encoded after alcohol consumption (anterograde amnesia) and may improve memory for information encoded before consumption (retrograde facilitation). This study examined whether alcohol consumed after witnessing a crime can render individuals less vulnerable to misleading post-event information (misinformation). METHOD: Participants watched a simulated crime video. Thereafter, one third of participants expected and received alcohol (alcohol group), one third did not expect but received alcohol (reverse placebo), and one third did not expect nor receive alcohol (control). After alcohol consumption, participants were exposed to misinformation embedded in a written narrative about the crime. The following day, participants completed a cued-recall questionnaire about the event. RESULTS: Control participants were more likely to report misinformation compared to the alcohol and reverse placebo group. CONCLUSION: The findings suggest that we may oversimplify the effect alcohol has on suggestibility and that sometimes alcohol can have beneficial effects on eyewitness memory by protecting against misleading post-event information
The Reliability of Global and Hemispheric Surface Temperature Records
The purpose of this review article is to discuss the development and associated estimation of uncertainties in the global and hemispheric surface temperature records. The review begins by detailing the groups that produce surface temperature datasets. After discussing the reasons for similarities and differences between the various products, the main issues that must be addressed when deriving accurate estimates, particularly for hemispheric and global averages, are then considered. These issues are discussed in the order of their importance for temperature records at these spatial scales: biases in SST data, particularly before the 1940s; the exposure of land-based thermometers before the development of louvred screens in the late 19th century; and urbanization effects in some regions in recent decades. The homogeneity of land-based records is also discussed; however, at these large scales it is relatively unimportant. The article concludes by illustrating hemispheric and global temperature records from the four groups that produce series in near-real time
Enhanced warming over the global subtropical western boundary currents
Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Climate Change 2 (2012): 161-166, doi:10.1038/nclimate1353.Subtropical western boundary currents are warm, fast flowing currents that
form on the western side of ocean basins. They carry warm tropical water to the
mid-latitudes and vent large amounts of heat and moisture to the atmosphere
along their paths, affecting atmospheric jet streams and mid-latitude storms, as
well as ocean carbon uptake. The possibility that these highly energetic and
nonlinear currents might change under greenhouse gas forcing has raised
significant concerns, but detecting such changes is challenging owing to limited
observations. Here, using reconstructed sea surface temperature datasets and
newly developed century-long ocean and atmosphere reanalysis products, we
find that the post-1900 surface ocean warming rate over the path of these
currents is two to three times faster than the global mean surface ocean warming
rate. The accelerated warming is associated with a synchronous poleward shift
and/or intensification of global subtropical western boundary currents in
conjunction with a systematic change in winds over both hemispheres. This enhanced warming may reduce ocean's ability to absorb anthropogenic carbon
dioxide over these regions. However, uncertainties in detection and attribution of
these warming trends remain, pointing to a need for a long-term monitoring
network of the global western boundary currents and their extensions.This work is supported by China National Key Basic Research Project
(2007CB411800) and National Natural Science Foundation Projects (40788002,
40921004). WC is supported by the Australian Climate Change Science program and
the Southeast Australia Climate Initiative. HN is supported in part by the Japanese
Ministry of Education, Culture, Sports, Science and Technology through Grant-in-Aid
for Scientific Research on Innovative Areas #2205 and by the Japanese Ministry of
Environment through Global Environment Research Fund (S-5). MJM is supported by
NOAAâs Climate Program Office.2012-07-2
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Rescuing historical weather observations improves quantification of severe windstorm risks
Billions of historical climatological observations remain
unavailable to science as they exist only on paper, stored in numerous
archives around the world. The conversion of these data from paper to
digital could transform our understanding of historical climate variations,
including extreme weather events. Here we demonstrate how the rescue of such
paper observations has improved our understanding of a severe windstorm that
occurred in February 1903 and its significant impacts. By assimilating newly
rescued atmospheric pressure observations, the storm is now credibly
represented in an improved reanalysis of the event. In some locations this
storm produced stronger winds than any event during the modern period
(1950â2015) and it is in the top-4 storms for strongest winds anywhere over
land in England and Wales. As a result, estimates of risk from severe
storms, based on modern period data, may need to be revised. Examining the
atmospheric structure of the storm suggests that it is a classic
ShapiroâKeyser-type cyclone with âsting-jetâ precursors and associated
extreme winds at locations and times of known significant damage. Comparison
with both independent observations and qualitative information, such as
photographs and written accounts, provides additional evidence of the
credibility of the atmospheric reconstruction, including sub-daily
rainfall variations. Simulations of the storm surge resulting from this
storm show a large coastal surge of around 2.5âm, comparing favourably with
newly rescued tide gauge observations and adding to our confidence in the
reconstruction. Combining historical rescued weather observations with
modern reanalysis techniques has allowed us to plausibly reconstruct a
severe windstorm and associated storm surge from more than 100Â years ago,
establishing an invaluable end-to-end tool to improve assessments of risks
from extreme weather.</p
Do intoxicated witnesses produce poor facial composite images?
The effect of alcohol intoxication on witness memory and performance has been the subject of research for some time, however, whether intoxication affects facial composite construction has not been investigated. Intoxication was predicted to adversely affect facial composite construction. Thirty-two participants were allocated to one of four beverage conditions consisting of factorial combinations of alcohol or placebo at face encoding, and later construction. Participants viewed a video of a target person and constructed a composite of this target the following day. The resulting images were presented as a full face composite, or a part face consisting of either internal or external facial features to a second sample of participants who provided likeness ratings as a measure of facial composite quality. Intoxication at face encoding had a detrimental impact on the quality of facial composites produced the following day, suggesting that alcohol impaired the encoding of the target faces. The common finding that external compared to internal features are more accurately represented was demonstrated, even following alcohol at encoding. This finding was moderated by alcohol and target face gender such that alcohol at face encoding resulted in reduced likeness of external features for male composite faces only. Moderate alcohol intoxication impairs the quality of facial composites, adding to existing literature demonstrating little effect of alcohol on line-up studies. The impact of intoxication on face perception mechanisms, and the apparent narrowing of processing to external face areas such as hair, is discussed in the context of alcohol myopia theory
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Decadal predictions of the cooling and freshening of the North Atlantic in the 1960s and the role of ocean circulation
In the 1960s North Atlantic sea surface temperatures (SST) cooled rapidly. The magnitude of the cooling was largest in the North Atlantic subpolar gyre (SPG), and was coincident with a rapid freshening of the SPG. Here we analyze hindcasts of the 1960s North Atlantic cooling made with the UK Met Officeâs decadal prediction system (DePreSys), which is initialised using observations. It is shown that DePreSys capturesâwith a lead time of several yearsâthe observed cooling and freshening of the North Atlantic SPG. DePreSys also captures changes in SST over the wider North Atlantic and surface climate impacts over the wider region, such as changes in atmospheric circulation in winter and sea ice extent. We show that initialisation of an anomalously weak Atlantic Meridional Overturning Circulation (AMOC), and hence weak northward heat transport, is crucial for DePreSys to predict the magnitude of the observed cooling. Such an anomalously weak AMOC is not captured when ocean observations are not assimilated (i.e. it is not a forced response in this model). The freshening of the SPG is also dominated by ocean salt transport changes in DePreSys; in particular, the simulation of advective freshwater anomalies analogous to the Great Salinity Anomaly were key. Therefore, DePreSys suggests that ocean dynamics played an important role in the cooling of the North Atlantic in the 1960s, and that this event was predictable
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Social connections predict brain structure in a multidimensional free-ranging primate society
Reproduction and survival in most primate species reflects management of both competitive and cooperative relationships. Here, we investigated the links between neuroanatomy and sociality in free-ranging rhesus macaques. In adults, the number of social partners predicted the volume of the midâsuperior temporal sulcus and ventral-dysgranular insula, implicated in social decision-making and empathy, respectively. We found no link between brain structure and other key social variables such as social status or indirect connectedness in adults, nor between maternal social networks or status and dependent infant brain structure. Our findings demonstrate that the size of specific brain structures varies with the number of direct affiliative social connections and suggest that this relationship may arise during development. These results reinforce proposed links between social network size, biological success, and the expansion of specific brain circuits
Pacific origin of the abrupt increase in Indian Ocean heat content during the warming hiatus
Global mean surface warming has stalled since the end of the twentieth century1, 2, but the net radiation imbalance at the top of the atmosphere continues to suggest an increasingly warming planet. This apparent contradiction has been reconciled by an anomalous heat flux into the ocean3, 4, 5, 6, 7, 8, induced by a shift towards a La Niña-like state with cold sea surface temperatures in the eastern tropical Pacific over the past decade or so. A significant portion of the heat missing from the atmosphere is therefore expected to be stored in the Pacific Ocean. However, in situ hydrographic records indicate that Pacific Ocean heat content has been decreasing9. Here, we analyse observations along with simulations from a global oceanâsea ice model to track the pathway of heat. We find that the enhanced heat uptake by the Pacific Ocean has been compensated by an increased heat transport from the Pacific Ocean to the Indian Ocean, carried by the Indonesian throughflow. As a result, Indian Ocean heat content has increased abruptly, which accounts for more than 70% of the global ocean heat gain in the upper 700 m during the past decade. We conclude that the Indian Ocean has become increasingly important in modulating global climate variability
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