Climate Since the Ice Began to Melt: Newly mapped climate changes of the past 18,000 years are being simulated in computer models, helping to point toward causes and to verify the models

Science ◽  
1984 ◽  
Vol 226 (4672) ◽  
pp. 326-327 ◽  
Author(s):  
R. A. KERR
2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Masayoshi Ishii ◽  
Nobuhito Mori

Abstract A large-ensemble climate simulation database, which is known as the database for policy decision-making for future climate changes (d4PDF), was designed for climate change risk assessments. Since the completion of the first set of climate simulations in 2015, the database has been growing continuously. It contains the results of ensemble simulations conducted over a total of thousands years respectively for past and future climates using high-resolution global (60 km horizontal mesh) and regional (20 km mesh) atmospheric models. Several sets of future climate simulations are available, in which global mean surface air temperatures are forced to be higher by 4 K, 2 K, and 1.5 K relative to preindustrial levels. Nonwarming past climate simulations are incorporated in d4PDF along with the past climate simulations. The total data volume is approximately 2 petabytes. The atmospheric models satisfactorily simulate the past climate in terms of climatology, natural variations, and extreme events such as heavy precipitation and tropical cyclones. In addition, data users can obtain statistically significant changes in mean states or weather and climate extremes of interest between the past and future climates via a simple arithmetic computation without any statistical assumptions. The database is helpful in understanding future changes in climate states and in attributing past climate events to global warming. Impact assessment studies for climate changes have concurrently been performed in various research areas such as natural hazard, hydrology, civil engineering, agriculture, health, and insurance. The database has now become essential for promoting climate and risk assessment studies and for devising climate adaptation policies. Moreover, it has helped in establishing an interdisciplinary research community on global warming across Japan.


2012 ◽  
Vol 56 (2) ◽  
pp. 321-329 ◽  
Author(s):  
QuanSheng Ge ◽  
JingYun Zheng ◽  
ZhiXin Hao ◽  
HaoLong Liu

2021 ◽  
Author(s):  
Kseniia Golubenko ◽  
Eugene Rozanov ◽  
Genady Kovaltsov ◽  
Ari-Pekka Leppänen ◽  
Ilya Usoskin

<p>We present the first results of modelling of the short-living cosmogenic isotope <sup>7</sup>Be production, deposition, and transport using the chemistry-climate model SOCOLv<sub>3.0</sub> aimed to study solar-terrestrial interactions and climate changes. We implemented an interactive deposition scheme,  based on gas tracers with and without nudging to the known meteorological fields. Production of <sup>7</sup>Be was modelled using the 3D time-dependent Cosmic Ray induced Atmospheric Cascade (CRAC) model. The simulations were compared with the real concentrations (activity) and depositions measurements of <sup>7</sup>Be in the air and water at Finnish stations. We have successfully reproduced and estimated the variability of the cosmogenic isotope <sup>7</sup>Be produced by the galactic cosmic rays (GCR) on time scales longer than about a month, for the period of 2002–2008. The agreement between the modelled and measured data is very good (within 12%) providing a solid validation for the ability of the SOCOL CCM to reliably model production, transport, and deposition of cosmogenic isotopes, which is needed for precise studies of cosmic-ray variability in the past. </p>


Radiocarbon ◽  
2005 ◽  
Vol 47 (3) ◽  
pp. 425-432 ◽  
Author(s):  
Naohiko Ohkouchi ◽  
Timothy I Eglinton ◽  
Konrad A Hughen ◽  
Ellen Roosen ◽  
Lloyd D Keigwin

As a result of the growing use of multiple geochemical proxies to reconstruct ocean and climate changes in the past, there is an increasing need to establish temporal relationships between proxies derived from the same marine sediment record and ideally from the same core sections. Coupled proxy records of surface ocean properties, such as those based on lipid biomarkers (e.g. alkenone-derived sea surface temperature) and planktonic foraminiferal carbonate (oxygen isotopes), are a key example. Here, we assess whether 2 different solvent extraction procedures used for isolation of molecular biomarkers influence the radiocarbon contents of planktonic foraminiferal carbonate recovered from the corresponding residues of Bermuda Rise and Cariaco Basin sediments. Although minor Δ14C differences were observed between solvent-extracted and unextracted samples, no substantial or systematic offsets were evident. Overall, these data suggest that, in a practical sense, foraminiferal shells from a solvent-extracted residue can be reliably used for 14C dating to determine the age of sediment deposition and to examine age relationships with other sedimentary constituents (e.g. alkenones).


2014 ◽  
Vol 25 (2) ◽  
pp. 172 ◽  
Author(s):  
Mike Smith

This paper examines how the past of desert landscapes has been interpreted since European explorers and scientists first encountered them. It charts the research that created the conceptual space within which archaeologists and Quaternarists now work. Studies from the 1840s–1960s created the notion of a ‘Great Australian Arid Period'. The 1960s studies of Lake Mungo and the Willandra Lakes by Jim Bowler revealed the cyclical nature of palaeolakes, that changed with climate changes in the Pleistocene, and the complexity of desert pasts. SLEADS and other researchers in the 1980s used thermoluminescence techniques that showed further complexities in desert lands beyond the Willandra particularly through new studies in the Strzelecki and Simpson Dunefields, Lake Eyre, Lake Woods and Lake Gregory. Australian deserts are varied and have very different histories. Far from ‘timeless lands', they have carried detailed information about long-term climate changes on continental scales.


2021 ◽  
Author(s):  
Yulong Zhu ◽  
Tatsuya Ishikawa ◽  
Tomohito J. Yamada ◽  
Srikrishnan Siva Subramanian

Abstract This paper proposes an effective approach for evaluating the influences of climate change on slope stability in seasonally cold regions. Firstly, to semi-quantitatively assess the effects of climate changes on the uncertainty of climate factors, this study analyzes the trend of the two main climate factors (precipitation and air temperature) by the regression analysis using the meteorological monitoring data of the past 120 years in different scales (e.g., world, country (Japan), and city (Sapporo)), and the meteorological simulation data obtained by downscaling the outputs of three different regional atmospheric models (RAMs) with lateral boundary conditions from three different general circulation models (GCMs). Next, to discuss the effects of different climate factors (air temperature, precipitation, etc.) and to determine the key climate factors on the slope instability, an assessment approach for evaluating the effects of climate changes on slope instability is proposed through the water content simulation and slope stability analysis using a 2-dimensional (2D) finite element method (FEM) homogeneous conceptual slope model with considering freeze-thaw action. Finally, to check the effectiveness of the above assessment approach, assessment of instability of an actual highway embankment slope with the local layer geometry is done by applying the past and predicted future climate data. The results indicate that affected by global warming, the air temperature rise in some cold cities is more serious. The predicted future weather will affect the shape of the normal density curve (NDC) of the distribution of slope failures in one year. The climate changes (especially the increase in precipitation) in the future will increase the infiltration during the Spring season. It will lengthen the time that the highway slope is in an unstable state due to high volumetric water content, thereby enhancing the instability of the slopes and threatening more slopes in the future.


Author(s):  
Maxwell Deutscher

Memory is central to every way in which we deal with things. One might subsume memory under the category of intellect, since it is our capacity to retain what we sense, enjoy and suffer, and thus to become knowing in our perception and other activities. As intelligent retention, memory cannot be distinguished from our acquisition of skills, habits and customs – our capabilities both for prudence and for deliberate risk. As retention, memory is a vital condition of the formation of language. Amnesia illustrates dramatically the difference between memory as retention of language and skills, and memory as the power to recollect and to recognize specific events and situations. In amnesia we lose, not our general power of retention, but rather our recall of facts – the prior events of our life, and our power to recognize people and places. Amnesiacs recognize kinds of things. They may know it is a wristwatch they are wearing, while unable to recognize it as their own. This recall of events and facts that enables us to recognize things as our own, is more than just the ability to give correctly an account of them. One might accurately describe some part of one’s past inadvertently, or after hypnosis, or by relying on incidental information. Thus, present research on memory both as retention and as recall of specific episodes, attempts to describe the connection which persists between experience and recall. Neurological or computer models of such a connection owe something to traditional notions of a memory trace, but emphasize also the re-tracing of original memories by later experience and episodes of recall. Historically, recollection has often been thought of as a mode of perceiving the past. Such an idea lends an exaggerated status to the role of imagery, which is but one member of a family of recollective activities that includes reliving, remembering, reminiscing and mulling over what has happened. It may be not in having imagery but in miming someone’s behaviour that one relives an event. Also, like imagery, what we feel about the past may seem integral to recollection. A sense of being brought close to the past arises particularly when events that involve our feelings are concerned. Yet we may also recollect an event, vividly and accurately, while feeling clinically detached from it, devoid of imagery. How a past event or situation remains connected with subsequent recollection has become a principal theoretical question about memory. It is argued that it is because of what we did or experienced that we recollect it. Otherwise, we are only imagining it or relying upon ancillary information. Neurological or computer models of such a connection owe something to traditional notions of a memory trace, but emphasize also the re-tracing of original memories by later experience and episodes of recall. Some argue that our very idea of memory is that of the retention of a structural analogue of what we do recall of them. Such an idea is not of some perfect harmony between what we remember and our recollection of it. Rather, it is suggested, only to the extent that we retain a structural analogue of some aspect of an event or situation do we remember, rather than imagine or infer it.


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