Abrupt Climate Research Articles

Nonlinear Response of Global Monsoon Precipitation to Atlantic Overturning Strength Variations During Marine Isotope Stage 3

AbstractMonsoon rainfall proxy records show clear millennial variations corresponding to abrupt climate events in Greenland ice cores during Marine Isotope Stage 3 (MIS3). The occurrence of these abrupt climate changes is associated with Atlantic Meridional Overturning Circulation (AMOC) strength variations which greatly impact the global oceanic energy transport. Hence, the AMOC most likely plays a key role in modulating the global monsoon rainfall at millennial time scale. No modeling work has hitherto investigated the global monsoon system response to AMOC changes under a MIS3 background climate. Using the coupled climate model CCSM3, we simulated MIS3 climate using full 38 ka before present boundary conditions and performed a set of freshwater hosing/extraction experiments. We show not only agreement between modeling results and proxies of monsoon rainfall within the global monsoon domain but also highlight a nonlinear relationship between AMOC strength and annual mean global monsoon precipitation related to oceanic heat transport constraints. During MIS3, a weakened AMOC induces a decrease in annual mean global monsoon rainfall dominated by the northern hemisphere, whereas southern hemisphere monsoon rainfall increases. Above about 16 Sverdrups a further strengthening of the AMOC has no significant impact on hemispheric and global monsoon domain annual mean rainfall. The seasonal monsoon rainfall shows the same nonlinear response like annual mean both hemispherically and globally.

Holocene wildfire on the Qinghai-Tibetan Plateau–witness of abrupt millennial timescale climate events

As the latest interglacial, the Holocene is an ideal period to determine wildfire activity during abrupt climate events, which can help elucidate the connection between wildfire occurrence (especially extreme wildfires) and climate change. In this study, we reconstruct a Holocene wildfire history using soot record from Qinghai Lake sediments in the northeast margin of the Tibetan Plateau. This record reflects climate change on a regional scale. Except for enhanced wildfire activity during the middle-late Holocene when climate became dry, the results also show rapid increasing periods of wildfire centered at ca. 1.6, 2.5, 4.1, 4.9, 6.3, 7.8, 9.6, 10.5 and 11.4 calibrated kiloyears before present (cal ka BP) that are strongly correlated with abrupt climate events. Drought climate in association with a weakened monsoon appear to be the major factor driving the increase of wildfires on sub-orbital and millennial timescales, likely modulated by solar radiation (activity). Potential human activities may promote wildfire occurrences and enhance soot emissions to some extent as well. The connection of wildfire with millennial timescale abrupt dry/cold climate events may differ from the broad expectation of increased fire occurrences in warmer periods and can provide new insights for fire prediction.

Sedimentary DNA reveals the link between microbial community dynamics and climate during the late last glaciation in the offshore region of the Zambezi River, Southwest Indian Ocean

Reconstructing the relationship between microbial communities and past abrupt climate change is of great importance for understanding current biodiversity patterns and predicting changes under future climate scenarios. However, little is currently known about how microbial communities respond to changes in key environmental stages due to a lack of research in this area. Here, we examine the variability in the communities of bacteria, archaea, and fungi from sediments deposited offshore region of the Zambezi River between 21.7 and 9.6 thousand years ago (ka) (covering the last glacial maximum, or LGM, and the early Holocene) using DNA metabarcoding approach via high-throughput sequencing. The results showed that (1) microbial assemblages differed across three key time intervals, with the last deglaciation having the most homogeneous prokaryotic assemblages, while for fungal communities in the LGM, and the early Holocene and LGM differing the most; (2) the warm early Holocene showed the highest diversity, whereas the lowest diversity was found in the LGM; and (3) the selected indicator species better reflected the climatic characteristics of different environmental stages. These results highlight the power of ancient sedimentary DNA to refine our understanding of microbial dynamics in marine sedimentary systems near large rivers, thus providing a basis for better modeling ecological processes in further research.

Spatio-temporal variation in quartz luminescence sensitivity in the coastal area of China

Quartz luminescence signals have been proven to be an effective index for identifying sediment provenance. The provenance of quartz minerals on typical sandy coasts along the east coast of China serves as important evidence for estuarine and coastal aeolian geomorphological processes in coastal zones. However, the temporal and spatial differences in the sensitivity characteristics of quartz grains on the east coast of China remain controversial owing to a lack of systematic analyses of coastal sediments. In this study, we present the thermoluminescence (TL) and optical luminescence (OSL) sensitivity of quartz minerals from core FN1 in the coastal area of Fujian Province, and the relative OSL sensitivity of quartz minerals obtained from Hebei, Fujian, Hainan, and Taiwan provinces. Our results indicate that (1) the OSL sensitivity values of quartz grains in the FN1 core are closely correlated with the mean grain size, electrical conductivity, potential of hydrogen, and end-member, suggesting that the change in luminescence sensitivity may be closely related to climate changes; specifically, cold climatic events during this period can cause significant fluctuations in the sensitivity; further, the percentage contents of fast, medium, and slow components are also different; (2) spatially, there are clear differences between the %FAST value of quartz grains from different sandy coasts; in these coastal dune samples, the %FAST value of the quartz grains during the Last Glacial Maximum (LGM) was significantly different from that of the quartz grains during the interglacial; thus, %FAST can be used to distinguish between glacial and interglacial samples; specifically, the sensitivity of quartz from the glacial dune was higher than that from the interglacial dune, and the sensitivity dispersion of quartz from the glacial as smaller than that from the interglacial coastal dune sand; and (3) the change in the luminescence sensitivity of quartz grains was ultimately controlled by the provenance change. In different geological periods, transgression, regression, and abrupt climate change trigger changes in the supply range of sources, which indirectly affects the sensitivity characteristics of quartz minerals. The spatial difference in quartz sensitivity in the eastern coastal area of China is mainly affected by the characteristics of quartz crystals and types of bedrock, which require further systematic study.

Kinetic evaluation of Pachira aquatica Aubl biomass slow pyrolysis towards to biochar production

The abrupt climate change, caused by the anthropogenic activities in the environment, intensified the search for sustainable sources of energy aiming reduce the dependence on fossil fuels. In this study, a multivariate study design was applied within a batch reactor system to determine the influence of process variables and kinetic parameters of slow pyrolysis of Pachira aquatica Aubl fruit peel towards biochar generation. The statistical evaluation of Box Behnken planning model was applied and showed good adjustment to the model establishing the model that describes the significant effect of variables behavior. The maximum biochar yield (41.22%) was observed were temperature (T) = 406 °C, heating rate β = 2 °C min−1, and residence time t R = 60 min, under nitrogen atmosphere. It is also observed that temperature was the most substantial influence on the process, followed by heating rate and the remaining process variables did not exhibit significant individual effects. The empirical model obtained was applied into mass change equation aiming calculate the activation energy (Ea)=77.10 kJ mol−1 and frequency factor (A 0)= 6.28 × 1010 s−1. The low activation energy in maximum biochar yield region showed a great potential of Pachira aquatica Aubl fruit peel thermoconversion towards to biochar.

Coastal permafrost was massively eroded during the Bølling-Allerød warm period

The Bølling-Allerød interstadial (14,700–12,900 years before present), during the last deglaciation, was characterized by rapid warming and sea level rise. Yet, the response of the Arctic terrestrial cryosphere during this abrupt climate change remains thus far elusive. Here we present a multi-proxy analysis of a sediment record from the northern Svalbard continental margin, an area strongly influenced by sea ice export from the Arctic, to elucidate sea level - permafrost erosion connections. We show that permafrost-derived material rich in biospheric carbon became the dominant source of sediments at the onset of the Bølling-Allerød, despite the lack of direct connections with permafrost deposits. Our results suggest that the abrupt temperature and sea level rise triggered massive erosion of coastal ice-rich Yedoma permafrost, possibly from Siberian and Alaskan coasts, followed by long-range sea ice transport towards the Fram Strait and the Arctic Ocean gateway. Overall, we show how coastal permafrost is susceptible to large-scale remobilization in a scenario of rapid climate variability.

Palaeoecological and palaeoenvironmental responses to abrupt climate changes during the Late Glacial: The unique archive recorded at the Osinki site (NE Poland) and its regional importance

The reconstruction of environmental changes at the termination of the Last Glaciation range in NE Europe during the Late Glacial is hampered by the multiplicity of processes underway at that time and during the Holocene that dynamically modified the Young Glacial landscape. In lake sediments, these changes are recorded in a manner that is almost always incomplete or disturbed. For this reason, the succession that was successfully reconstructed in two profiles from the Osinki site in NE Poland is extremely valuable. Palynological, Cladocera and geochemical analyses, as well as fragmentary malacofauna and diatom analyses, made it possible to trace the changes in the environment that took place in two differently functioning parts of a single lake, in not interrupted periods from the Oldest Dryas to the Younger Dryas. Detailed research results show that despite the proximity of natural environment components, their developments in both cases were conducted in different ways, what they prove to the changes in pollen record, Cladocera, and geochemical composition of sediments. Climate changes affected the changes in the vegetation, the composition of malacofauna, Cladocera and diatoms. They also influenced the erosion processes within the catchment and the oxidation-reduction conditions. On the basis of the research results, changes in water trophy, from oligotrophic to eutrophic, were also observed. In this case, we also observe significant differences between the two analysed profiles. These changes first occurred in Allerød in the shallow part of the lake, and then in its deeper zone in Young Dryas.In addition, Late Weichselian profiles from the Poland–Belarus–Lithuania borderland area were analysed in detail, and the age of the bottom of sediments is usually estimated to the Allerød, and the Bølling. The results of analyses from Osinki and Osinki2 profiles (beginning of sedimentation in the Oldest Dryas) indicate that the reason for this discrepancy is to be found in, among other things, the methodological limitations of the palynological analysis for most of the sites. The above-standard amount of mineral sediment allows the age of the sediment to be established as being much older than if determined using only pollen analysis of organic sediments.

Record of palaeoclimate across theCretaceous–Palaeogeneboundary from palaeosols in the west‐central San Juan Basin, New Mexico, USA

AbstractThe mass extinction at the Cretaceous–Palaeogene boundary is widely attributed to sudden and severe climate changes forced by bolide impact and/or flood basalt volcanism. In terrestrial depositional settings, these changes may potentially be recorded by palaeosols. To test the ability of pedogenic features to record both long‐term climate and shorter‐term changes preceding and following the Cretaceous–Palaeogene extinction event, palaeosols in the Upper Cretaceous (Maastrichtian) Naashoibito Member of the Ojo Alamo Formation and the lower Palaeocene (Danian) Nacimiento Formation in the San Juan Basin of north‐western New Mexico, USA, were examined, including data from previous studies. The fine‐grained facies of the Naashoibito Member comprises grey to greenish‐grey and red‐banded mudstones displaying pedogenic features including colour mottling, root traces, cutans, ped fabrics, pedogenic slickensides and calcareous nodules. Aside from a high‐chroma horizon at the formation base, palaeosols in the lower Nacimiento Formation are broadly similar to those observed in the Naashoibito Member. Lateral and vertical variability of the pedogenic features between correlated sections suggest that soil hydrology varied spatially and temporally from very saturated to seasonally well‐drained, with temporal variations controlled by basin sedimentation rates. Abrupt and/or catastrophic climate events precisely at the Cretaceous–Palaeogene boundary are not recorded due to an unconformity at the top of the Naashoibito Member. However, the presence of kaolinite in the clay mineral assemblage of the Nacimiento Formation, particularly near the formation base, but not in the Naashoibito Member, indicates episodic warmth and short (104 years) intervals of more intense weathering conditions during the very early Danian as compared to the late Maastrichtian. Aside from short warm intervals, the overall palaeoclimate during deposition of both formations was warm and consistently subhumid to humid and seasonal, suggesting no substantial long‐term (105–106) climate change took place across the Cretaceous–Palaeogene boundary in the San Juan Basin.

Iberian Margin surface ocean cooling led freshening during Marine Isotope Stage 6 abrupt cooling events

The high-resolution paleoclimate records on the Iberian Margin provide an excellent archive to study the mechanism of abrupt climate events. Previous studies on the Iberian Margin proposed that the surface cooling reconstructed by the alkenone-unsaturation index coincided with surface water freshening inferred from an elevated percentage of tetra-unsaturated alkenones, C37:4%. However, recent data indicate that marine alkenone producers, coccolithophores, do not produce more C37:4 in culture as salinity decreases. Hence, the causes for high C37:4 are still unclear. Here we provide detailed alkenone measurements to trace the producers of alkenones in combination with foraminiferal Mg/Ca and oxygen isotope ratios to trace salinity variations. The results indicate that all alkenones were produced by coccolithophores and the high C37:4% reflects decrease in SST instead of freshening. Furthermore, during the millennial climate changes, a surface freshening did not always trigger a cooling, but sometimes happened in the middle of multiple-stage cooling events and likely amplified the temperature decrease.

Settlement Discontinuities in Southwestern Arabia during the Middle and Late Holocene: The Bayḥān (Yemen) Region

ABSTRACT Recent research has produced an increasingly nuanced but still incomplete understanding of Neolithic through Iron Age communities in southwestern Arabia. Present evidence indicates that foraging communities in the lowland interior of Yemen adopted animal herding during the 6th millennium b.c. and irrigation farming during the 3rd millennium b.c. or possibly earlier. Survey in the Wādī Bayḥān area has identified multiple settlement discontinuities. Prehistoric structures in Wādī Ṣurbān reflect episodic occupation, probably by Bronze Age pastoralists. Geomorphological evidence for Bronze Age irrigation systems appears in large valleys; these systems continued into the Iron Age and developed in small valleys. Geomorphological and archaeological evidence suggests an occupation hiatus around 700 b.c. in some larger valleys such as Wādī Ḍurā’. Settlement discontinuities seem to have responded to abrupt climate fluctuations and to regional political history.

Global reorganization of atmospheric circulation during Dansgaard–Oeschger cycles

Ice core records from Greenland provide evidence for multiple abrupt cold-warm-cold events recurring at millennial time scales during the last glacial interval. Although climate variations resembling Dansgaard-Oeschger (DO) oscillations have been identified in climate archives across the globe, our understanding of the climate and ecosystem impacts of the Greenland warming events in lower latitudes remains incomplete. Here, we investigate the influence of DO-cold-to-warm transitions on the global atmospheric circulation pattern. We comprehensively analyze δ18O changes during DO transitions in a globally distributed dataset of speleothems and set those in context with simulations of a comprehensive high-resolution climate model featuring internal millennial-scale variations of similar magnitude. Across the globe, speleothem δ18O signals and model results indicate consistent large-scale changes in precipitation amount, moisture source, or seasonality of precipitation associated with the DO transitions, in agreement with northward shifts of the Hadley circulation. Furthermore, we identify a decreasing trend in the amplitude of DO transitions with increasing distances from the North Atlantic region. This provides quantitative observational evidence for previous suggestions of the North Atlantic region being the focal point for these archetypes of past abrupt climate changes.

Exploring genotypic variability and interrelationships among growth, yield, and quality characteristics in diverse tomato genotypes

Tomato is the most consumed vegetable crop worldwide, with excellent beneficial health properties and high content of vitamins, minerals, carotenoids, total antioxidants, and phenolic compounds. Hence, improving its genotypes is crucial to sustain its production and ensure food security, principally under the fast-growing worldwide population and abrupt global climate change. The present study aimed to explore the genotypic variability associated with specific characteristics in twenty-five diverse tomato genotypes. In addition, the relationships between growth, yield, and quality traits using both univariate (correlation coefficient, path analysis) and multivariate (principal component, principal coordinates, canonical variate) analysis methods were explored. The results indicated that the evaluated genotypes possessed highly significant variation. This is appropriate for future hybridization through tomato breeding programs. All evaluated genotypes demonstrated considerable potential to develop strong hybrid vigour for growth, yield, and quality characteristics. In particular, the genotypes LS009, LS011, and LS014 could be considered promising, high-yielding, and resistant to yellow leaf curl virus infestation (YLCV) disease parents for future breeding schemes. The number of fruits per plant, fruit diameter, and fruit weight proved strong positive relationships with fruit yield. Accordingly, these characteristics demonstrate their importance in improving fruit yield and could be exploited as indirect criteria for selecting high-yielding tomato genotypes through breeding programs.

Dichotomy between freshwater and heat flux effects on oceanic conveyor belt stability and global climate

The Atlantic meridional overturning circulation is an important global-scale oceanic circulation, and its changes may be responsible for past abrupt climate change events. By using two versions of a coupled climate model, here we show that the stability of this circulation depends not only on the background climate, but also on the type of primary external forcing: freshwater vs. greenhouse gases. When freshwater forcing is dominant, hysteresis of this circulation (an abrupt collapse/reactivation) becomes possible only under simulated glacial conditions with closed Bering Strait. Under present day and future conditions, both freshwater and greenhouse gas forcings could collapse this circulation, but only greenhouse gas forcing produced a bi-stable equilibrium state comparable to abrupt climate change. Our results demonstrate that the Bering Strait status (open vs. closed) may facilitate or prohibit the existence of this circulation’s hysteresis, irrespective of the background climate conditions, but is directly related to the primary forcing.

Coral Paleoclimate Perspectives Support the Role of Low‐Latitude Forcing on the 4.2 ka BP Event

AbstractThe 4.2 ka BP Event is an abrupt climate change that might have contributed to the collapse of ancient civilizations and marks the transition between the mid‐ and late‐Holocene. Despite considerable research on this event, our understanding remains primarily based on terrestrial paleoclimate reconstructions, leaving a significant gap in understanding the role of the ocean in this event. Here, we present paired sea surface temperature (SST) and seawater δ18O reconstructions based on four fossil corals from the South China Sea. Our results demonstrate that the climate during the event was cooler, and there were meridional dry‐wet patterns in East Asia, indicating a weakened summer monsoon. Furthermore, our examination of additional coral records from the Pacific and Indian Oceans suggests that low‐latitude forcing (i.e., SST anomalies in the tropical Pacific) plays a crucial role in driving hydrology shifts in East Asia over the 4.2 ka BP interval.

Instability of Atlantic Meridional Overturning Circulation: Observations, Modelling and Relevance to Present and Future

The Atlantic Meridional Overturning Circulation (AMOC) has changed dramatically during the glacial–interglacial cycle. One leading hypothesis for these abrupt changes is thermohaline instability. Here, I review recent progress towards understanding thermohaline instability in both observations and modelling. Proxy records available seem to favor thermohaline instability as the cause of the abrupt climate changes during the glacial–deglacial period because the deep North Atlantic water mass and AMOC seemed to have changed before the North Atlantic climate. However, most fully Coupled General Circulation Models (CGCMs) so far seem to exhibit monostable AMOC, because (1) these models have failed to simulate abrupt AMOC changes unless they are forced by an abrupt change of external forcing and, (2) these models have shown opposite freshwater convergence from the current observations. This potential model bias in the AMOC stability leaves the model projection of the future AMOC change uncertain.

The spatiotemporal extent of the Green Sahara during the last glacial period

The Sahara Desert, one of today's most inhospitable environments, has known periods of enhanced precipitation that supported pre-historic humans. However, the Green Sahara timing and moisture sources are not well known due to limited paleoclimate information. Here, we present a multi-proxy (δ18O, δ13C, Δ17O, and trace elements) speleothem-based climate record from Northwest (NW) Africa. Our data document two Green Sahara periods during Marine Isotope Stage (MIS) 5a and the Early to Mid-Holocene. Consistency with paleoclimate records across North Africa highlights the east-west geographical extent of the Green Sahara, whereas millennial-scale North Atlantic cooling (Heinrich) events consistently resulted in drier conditions. We demonstrate that an increase in westerly-originating winter precipitation during MIS5a resulted in favorable environmental conditions. The comparison of paleoclimate data with local archaeological sequences highlights the abrupt climate deterioration and the decline in human density in NW Africa during the MIS5-4 transition, which suggests climate-forced dispersals of populations, with possible implications for pathways into Eurasia.

Lake Bonneville and the Wasatch Fault – new theories and new paradigms yield insights into present-day hazards in other regions of the world

Three new theories challenge the assumptions underlying 150 years of research regarding Lake Bonneville and extend and redefine the history of this late-Pleistocene/early-Holocene lake. These new theories have relevance to current-day hazards in many areas of the globe and are important to our understanding of the climate of the western United States. The lake’s level history and shorelines have presented a confusing array of conflicting data, which has universally and incorrectly been attributed to abrupt and temporary climate oscillations. The Earthquake-induced Surging Theory explains misunderstood lake features, extends the lake level data back to 40kya, and explains the Bonneville Flood, confirming a 17.4kya (cal) date for that event. The Isostatic Rebound Pop Seiche Theory explains the “Intermediate Shorelines” first identified by G.K. Gilbert with a shocking twist regarding timing. This theory teaches us something of importance regarding glacial lakes forming today. The Bear River Exclusion Theory explains the anomalously rapid fall from the Provo Level and resolves the early/late Provo Level controversy. This last theory is going to be important for addressing the future of the Great Salt Lake.

IoT Based System for Accident Detection, Monitoring and Landslide Detection Using GSM in Hilly Areas

This paper described the detailed study for the detection and monitoring of accidents in hilly areas. In the past few decades, road accidents are a major cause of death in suburban hilly areas. These accidents not only affect the life of the destitute but also affect the lives of others. Over the last few decades, hilly areas are now ideal locations for holidays, hence an adequate number of travellers are moving towards hill stations for enjoying free time. This movement also invites accidents to occur due to bad driving skills, blind turns, overspeeding, etc. Also, during the peak time of holidays, abrupt climate change occurs and leads to heavy rainfalls, which are the major cause of landslides. As a result, the loss of life of travellers and blocked roads affecting transportation of necessary goods occur in hilly areas which affect the development and living of other people. Internet of Things (IoT) system may be a better solution to detect monitor and prevent these accidents and landslides. IoT system consists of sensors, actuators, a powerful micro-controller, and a network interface. This system detects and monitors accidents and landslides and informs the command centre about the location. Implementation of the IoT system helps us to lower the accident rate and easily locate the affected areas of landslides using global service for mobile (GSM) or Wireless Fidelity (Wi-Fi) connectivity. It is always a challenging task for a rescue team to locate the exact area of an accident and carry out life-saving operations.

Post-Combustion Capture of Carbon Dioxide by Natural and Synthetic Organic Polymers

The elevation of carbon dioxide (CO2) levels in the atmosphere is responsible for global warming which in turn causes abrupt climate change and consequently poses a threat to living organisms in the coming years. To reduce CO2 content in the atmosphere CO2 capture and separation is highly necessary. Among various methods of CO2 capture post-combustion capture is very much useful because of its operational simplicity and applicability in many industries and power sectors, such as coal-fired power plants. Polymers with high surface area, high volume and narrow pores are ideal solid sorbents for adsorption-driven post-combustion CO2 capture. Natural polymers, such as polysaccharides are cheap, abundant, and can be modified by various methods to produce porous materials and thus can be effectively utilized for CO2 capture while the surface area and the pore size of synthetic porous organic polymers can be tuned precisely for high CO2 capturing capacity. A significant amount of research activities has already been established in this field, especially in the last ten years and are still in progress. In this review, we have introduced the latest developments to the readers about synthetic techniques, post-synthetic modifications and CO2 capture capacities of various biopolymer-based materials and synthetic porous organic polymers (POPs) published in the last five years (2018–2022). This review will be beneficial to the researchers to design smart polymer-based materials to overcome the existing challenges in carbon capture and storage/sequestration.

Cosplay, Academia, and Me—Some Thoughts, and a Note on the Future

Cosplay, Academia, and Me—Some Thoughts, and a Note on the Future