Climate Record Research Articles

A review of weather conditions monitoring system based on iot

Continually varying climate settings are controlled by weather adjusting schemes. These sensor units gather information that is utilized for climate recording, monitor surrounding setting, and work out varies in a certain spot. In fact, examination of changing climatic and surrounding settings in a certain zone, as well as the investigation of environment, benefit extraordinarily from this information. Likewise, various implementations, including horticulture, geography, mining, and climate expectation model turn of events, could profit from the gathered information and investigation. An Internet of Things (IOT)- based climate measurement framework includes making a live climate surveillance framework that might follow area heat, moisture, barometric pressure, and precipitation stage. In this study various kinds of climate measurement frameworks are checked on,and the contributions of researchers in this field will be reviewed by examining the latest scientific articles and studies in the field of climate controling systems. The technologies used will be identified and their advantages, disadvantages, determinants and problems facing their implementation will be studied to reach a comprehensive vision to know the best technologies that can be applied in a weather measurement system based on the Internet of Things (IOT).

Preservation of chemical and isotopic signatures within the Weißseespitze millennial old ice cap (Eastern Alps), despite the ongoing ice loss

Alpine ice core research has long focused on a few suitable drilling sites at high elevation in the Western European Alps, assuming that the counterparts at lower elevation in the eastern sector are unsuitable for paleoenvironmental studies, due to the presence of melting and temperate basal conditions. However, it has been demonstrated that even in the Eastern Alpine range, below 4,000 m a.s.l., cold ice frozen to bedrock can exist. In fact, millennial-old ice has been found at some locations, such as at the Weißseespitze (WSS) summit ice cap (Ӧtztal Alps, 3,499 m a.s.l.), where about 6 kyrs appear locked into 10 m of ice. In this work, we present a full profile of the stable water isotopes (δ18O, δ2H), major ions (Na+, K+, Mg2+, Ca2+, NH4+, Cl−, NO3−, SO42−), levoglucosan, and microcharcoal for two parallel ice cores drilled at the Weißseespitze cap. We find that, despite the ongoing ice loss, the chemical and isotopic signatures appear preserved, and may potentially offer an untapped climatic record. This is especially noteworthy considering that chemical signals of other archives at similar locations have been partially or full corrupted by meltwater (i.e., Silvretta glacier, Grand Combin glacier, Ortles glacier). In addition, the impurity concentration near the surface shows no signs of anthropogenic contamination at WSS, which constrains the age at the surface to fall within the pre-industrial age.

The Geochronology of Quaternary Climate Records: 2023 Benjamin Franklin Medal in Earth and Environmental Science presented to R. Lawrence Edwards, Ph.D.

The Geochronology of Quaternary Climate Records: 2023 Benjamin Franklin Medal in Earth and Environmental Science presented to R. Lawrence Edwards, Ph.D.

Satellite Lidar Measurements as a Critical New Global Ocean Climate Record

The year 2023 marked the tenth anniversary of the first published description of global ocean plankton stocks based on measurements from a satellite lidar. Diverse studies have since been conducted to further refine and validate the lidar retrievals and use them to discover new characteristics of plankton seasonal dynamics and marine animal migrations, as well as evaluate geophysical products from traditional passive ocean color sensors. Surprisingly, all of these developments have been achieved with lidar instruments not designed for ocean applications. Over this same decade, we have witnessed unprecedented changes in ocean ecosystems at unexpected rates and driven by a multitude of environmental stressors, with a dominant factor being climate warming. Understanding, predicting, and responding to these ecosystem changes requires a global ocean observing network linking satellite, in situ, and modeling approaches. Inspired by recent successes, we promote here the creation of a lidar global ocean climate record as a key element in this envisioned advanced observing system. Contributing to this record, we announce the development of a new satellite lidar mission with ocean-observing capabilities and then discuss additional technological advances that can be envisioned for subsequent missions. Finally, we discuss how a potential near-term gap in global ocean lidar data might, at least partially, be filled using on-orbit or soon-to-be-launched lidars designed for other disciplinary purposes, and we identify upcoming needs for in situ support systems and science community development.

Improved geographic opportunistic routing protocol for void hole elimination in underwater IoTs: Parameter tuning by TSA optimization

SummaryUnderwater IoT is incredibly helpful in monitoring a variety of jobs, from instrument monitoring to climate recording, from pollution management to natural catastrophe forecasting. Nevertheless, there exist various issues that have an impact on a network's efficiency such as the formation of void holes, excessive EC, and low PDR. As a result, the IGOR protocol is suggested in this study to increase PDR by reducing the percentage of void hole occurrence. The developed routing protocols' scalability is also examined. Here, the parameter optimization for the EC minimization and PDR maximization is performed by a meta‐heuristic optimization algorithm referred to as TSA. In order to verify that the suggested protocol is EC‐optimal by calculating the viable areas. In addition, suggested protocols are evaluated against contemporaries' benchmark routing protocols. The outcomes of the simulations clearly demonstrate that the suggested routing protocols obtained greater PDR than the current techniques. Additionally, there exists a reduction in the ratio of void hole incidence. Comparative research reveals that suggested routing protocols outperformed benchmark routing protocols by 80–81% in PDR. Further, the suggested routing procedures reduced the frequency of void holes by around 30%.

Vegetation, hydrology, and quantitative monsoon precipitation since the Last Glacial Maximum in Central China

The Yangtze River Basin is a crucial region in the monsoon region of China, and reconstructing its hydrological and precipitation evolution is important for developing a more robust understanding of the evolution of the East Asian Summer Monsoon. A pollen record from a strata profile (JZ2010) in the Jianghan Basin of Central China reveals variations in paleovegetation and paleoenvironmental and paleoclimatic conditions covering the last 24 cal kyr BP at ~90 years resolution. We perform a quantitative precipitation reconstruction (based on a weighted averaged partial least squares method). Results of the study show that the vegetation in the region experienced a succession from coniferous and broad-leaved mixed forest to evergreen and deciduous mixed forest and then to secondary coniferous forest. Over the past 24 kyr, the climate was relatively dry during the deglacial period, particularly during HS1 and the Younger Dryas cold event, interrupted by a warm and humid Bølling-Allerød. Precipitation in the early Holocene was at its maximum, peaking between 10.0 and 7.0 cal kyr BP followed by drier conditions between 6.5 and 4.5 cal kyr BP. Subsequent wetter conditions lasted until 3.8 cal kyr BP, after which precipitation gradually declined. Overall, the quantitative precipitation reconstruction is consistent with other proxy-based precipitation reconstructions in the Yangtze River region. However, the temporal pattern of variations in precipitation is distinct from that of the northern China monsoon region, where the precipitation peak occurred during the mid-Holocene. The study suggests that, prior to the Holocene, climate change was controlled by insolation dynamics and high latitude teleconnections, while during the Holocene it was primarily influenced by low latitude teleconnections, including the El Niño-Southern Oscillation, which controlled the dipolar rainfall pattern in the monsoon region of China. The high resolution record of changing climate in the East Asian monsoon region over a period spanning the LGM and Holocene provides a useful benchmark for modelling future precipitation change in southern and northern China against the background of global warming.

Flood Forecasting by Using Machine Learning: A Study Leveraging Historic Climatic Records of Bangladesh

Forecasting rainfall is crucial to the well-being of individuals and is significant everywhere in the world. It contributes to reducing the disastrous effects of floods on agriculture, human life, and socioeconomic systems. This study discusses the challenges of effectively forecasting rainfall and floods and the necessity of combining data with flood channel mathematical modelling to forecast floodwater levels and velocities. This research focuses on leveraging historical meteorological data to find trends using machine learning and deep learning approaches to estimate rainfall. The Bangladesh Meteorological Department provided the data for the study, which also uses eight machine learning algorithms. The performance of the machine learning models is examined using evaluation measures like the R2 score, root mean squared error and validation loss. According to this research’s findings, polynomial regression, random forest regression, and long short-term memory (LSTM) had the highest performance levels. Random forest and polynomial regression have an R2 value of 0.76, while LSTM has a loss value of 0.09, respectively.

Empirical record, geochronology and theoretical determinates of Mesozoic climate in the Junggar Basin, NW China, in relation to other basins in NE China

Abstract Mesozoic continental basins of northern China, including the Junggar Basin, provide some of the most spectacular and important fossil assemblages in the world, but their climatic and environmental contexts have been shrouded in uncertainty. Here we examine the main factors that determine those contexts: palaeolatitude; the effects of changing atmospheric gases on the radiative balance; and orbitally paced variations in insolation. Empirical evidence of these factors is accumulating rapidly and promises to upend many long-standing paradigms. We focus primarily on the Junggar Basin in Xinjiang, NW China, with the renowned Shishugou Biota, and the basins in Liaoning, Hebei and Inner Mongolia with their famous Jehol and Yanliao biotas. Accurate geochronology is necessary to disentangle these various factors, and we review the Late Triassic to Early Cretaceous U–Pb ages for these areas and supply a new laser ablation inductively coupled plasma mass spectrometry age for the otherwise un-dated Sangonghe Formation of Early Jurassic age. We review climate-sensitive facies patterns in North China and show that the climatic context changed synchronously in northwestern and northeastern China consistent with a previously proposed huge Late Jurassic–earliest Cretaceous true polar wander event, with all the major plates of East Asia docked with Siberia and moving together since at least the Triassic when the North China basins were at Arctic latitudes. We conclude that this true polar wander shift was responsible for the coal beds and ice-rafted debris being produced at high latitudes and the red beds and aeolian strata being deposited at low latitudes within the same basin. The climatic and taphonomic context in which the famous Shishugou, Yanliao and Jehol biotas were preserved was thus a function of true polar wander, as opposed to local tectonics or climate change.

The Importance of Isentropic Mixing in the Formation of the Martian Polar Layered Deposits

Layers of ice and dust at the poles of Mars reflect variations in orbital parameters and atmospheric processes throughout the planet's history and may provide a key to understanding Mars's climate record. Previous research has investigated transport changes into the polar regions and found a nonlinear response to obliquity that suggests that Mars may currently be experiencing a maximum in transport across the winter poles. The thickness and composition of layers within the polar layered deposits (PLDs) are likely influenced by changes in horizontal atmospheric mixing at the poles, which is an important component of the transport of aerosols and chemical tracers. No study has yet investigated horizontal mixing alone, which may be influenced by polar vortex morphology. We show that mixing in an idealized Martian global climate model varies significantly with obliquity and dust abundance by using a diagnostic called effective diffusivity, which has been used to study the stratospheric polar vortices on Earth and to understand their role as a mixing barrier but has not been applied to Mars's polar vortices. We find that mixing in the winter southern hemisphere doubles with either an octupling of dust loading or an increase in obliquity from 10° to 50°. We find a weaker response to changing dust loading or obliquity in the northern hemisphere. We demonstrate that horizontal mixing is an important component of transport into Mars’s polar regions, may contribute to the formation of the PLDs, and presents effective diffusivity as a useful method to understand mixing in the Martian atmosphere.

Polar oceans and sea ice in a changing climate

Polar oceans and sea ice cover 15% of the Earth’s ocean surface, and the environment is changing rapidly at both poles. Improving knowledge on the interactions between the atmospheric and oceanic realms in the polar regions, a Surface Ocean–Lower Atmosphere Study (SOLAS) project key focus, is essential to understanding the Earth system in the context of climate change. However, our ability to monitor the pace and magnitude of changes in the polar regions and evaluate their impacts for the rest of the globe is limited by both remoteness and sea-ice coverage. Sea ice not only supports biological activity and mediates gas and aerosol exchange but can also hinder some in-situ and remote sensing observations. While satellite remote sensing provides the baseline climate record for sea-ice properties and extent, these techniques cannot provide key variables within and below sea ice. Recent robotics, modeling, and in-situ measurement advances have opened new possibilities for understanding the ocean–sea ice–atmosphere system, but critical knowledge gaps remain. Seasonal and long-term observations are clearly lacking across all variables and phases. Observational and modeling efforts across the sea-ice, ocean, and atmospheric domains must be better linked to achieve a system-level understanding of polar ocean and sea-ice environments. As polar oceans are warming and sea ice is becoming thinner and more ephemeral than before, dramatic changes over a suite of physicochemical and biogeochemical processes are expected, if not already underway. These changes in sea-ice and ocean conditions will affect atmospheric processes by modifying the production of aerosols, aerosol precursors, reactive halogens and oxidants, and the exchange of greenhouse gases. Quantifying which processes will be enhanced or reduced by climate change calls for tailored monitoring programs for high-latitude ocean environments. Open questions in this coupled system will be best resolved by leveraging ongoing international and multidisciplinary programs, such as efforts led by SOLAS, to link research across the ocean–sea ice–atmosphere interface.

A ∼5000 year multiproxy record of summer climate in NE Greenland

The High Arctic plays a vital role in Earth's climate system, and its ecosystems are highly sensitive to global climate change. High Arctic lakes are valuable sentinels of climate change, as their sediments integrate long-term natural climatic fluctuations and anthropogenic influences. Here, we present a high-resolution ∼5000 year-reconstruction of NE Greenland climate variability from Aucella Lake (74°N, 20°E) based on physical, chemical, and biological properties of lake sediments. We use CT-scans, hyperspectral imaging, organic matter, XRD, and diatom analyses to show that changing air temperatures were controlled by a mix of regional climatic changes and local landscape feedbacks. The latest Mid-Holocene (∼5.0–3.8 cal. ka BP) was characterized by relatively warmer conditions, while the onset of the Late-Holocene was marked by abrupt temperature decreases that coincided with the beginning of glacial advances elsewhere (∼3.8–3.4 cal. ka BP). From ∼3.4–2.4 cal. ka BP, the sedimentary record indicated progressive warming, with temperature peaking during the Medieval Climate Anomaly, although temperature rises were punctuated by abrupt, short-lived cold periods. From ∼1.1–0.05 cal. ka BP, the influence of landscape factors over the system diminished. Sedimentary indicators suggested a transition towards a colder, more humid climate, coinciding with the beginning of the Little Ice Age, that was characterized by a marked decrease in air temperature that reached minimum values at the end of this period. The last 50 years at Aucella Lake were marked by abrupt temperature rises, consistent with recently observed anthropogenic global warming. Our results illustrate the importance of high-resolution multiproxy studies for accurately characterizing lake linkages to their environment and climate.

Extremely 13C-enriched dolomite records interval of strong methanogenesis following a sulfate decline in the Miocene Ries impact crater lake

In impact crater lakes, the lacustrine sedimentary records may not solely reflect climatic changes but also potential erosional effects from lithologically distinct impactite formations. The hydrochemical and biogeochemical processes during the deposition of the Nördlinger Ries impact crater lake, which fall in the range of the mid-Miocene Climate Transition, were studied by analysing microcrystalline authigenic carbonates in a drill core succession, using stable oxygen and carbon isotopes in conjunction with biomarkers. These investigations revealed an early sulfidic interval characterized by thiophenes, iso- and anteiso-C15:0 acids derived from sulfate reducing bacteria, and dolomites with low to intermediate δ13Ccarb values. The subsequent distinctive interval is characterized by extremely 13C-enriched dolomite (δ13Ccarb up to +20.93 ± 0.05‰ V-PDB), decline of iso- and anteiso-C15:0 acids and is rich in an Archaea-derived archaeol that is 13C-enriched (−14.7‰), indicating extensive methanogenesis in sulfate-depleted lake porewater during early diagenesis. The sulfate decline results from successive sulfate reduction when replenishment by sulfate-bearing inflow water is limited. The carbonates exhibit enriched 18O due to pronounced evaporation in a long-resided water body and enriched 13C by methanogenesis. A change in provenance of water derived from the sulfur-rich suevite (impact melt-bearing breccia) and crystalline source rocks to the sulfur-poor Bunte Breccia (continuous ejecta blanket) is required. Intermittently high Si/Al and Zr/Al at the high δ13C interval suggests sporadic short-term runoff increase, leading to fluctuating physiochemical lake conditions. A subsequent decline in both δ13Ccarb and archaeol indicates a decreasing lake level with intermittent subaerial exposure events, supported by bioturbation and mud cracks. The concomitant lake oxygenation is well supported by increasing Pr/Ph ratios and lipids derived from aerobic methanotrophs (13C-depleted 3-methyl-hopanoids). In the youngest unit, allochthonous lignites and biomarkers from lacustrine/soil sources appear, high total sulphur contents and thiophenes recur, and stable C and O isotope values decrease again. These observations suggest another major provenance change of the inflowing solutes, with increasing influx from weathered pyrite-bearing Jurassic claystones. These findings demonstrate that the climatic record expected from the stable carbon and oxygen isotopes of the Ries carbonates is strongly overprinted by hydrochemical and biogeochemical processes due to changing ion influx from substrate rocks, along the course of the successive ejecta erosion and catchment changes. Such an intrinsic control of lacustrine biogeochemical processes is also expected for other hydrologically closed impact crater lake basins, where catchment rocks with distinctively different lithologies are present.

Ground-based climate data show evidence of warming and intensification of the seasonal rainfall cycle during the 1960–2020 period in Yangambi, central Congo Basin

Meteorological stations are rare in central Africa, which leads to uncertainty in regional climatic trends. This is particularly problematic for the Congo Basin, where station coverage decreased significantly during the last few decades. Here, we present a digitized dataset of daily temperature and precipitation from the Yangambi biosphere reserve, covering the period 1960–2020 (61 years) and located in the heart of the Congo Basin. Our results confirm a long-term increase in temperature and temperature extremes since the 1960s, with strong upward trends since the early 1990s. Our results also indicate a drying trend for the dry season and intensification of the wet season since the early 2000s. Ongoing warming and increasing precipitation seasonality and intensity already have a significant impact on crop yields in Yangambi. This calls for urgent development of climate-smart and dynamic agriculture and agroforestry systems. We conclude that systematic digitization and climate recording in the Congo Basin will be critical to improve much-needed gridded benchmark datasets of climatic variables.

Peatland history under post-glacial climate changes in the southern Baikal region: Biogeochemical evidence from the Vydrino Bog (Tankhoi piedmont plain)

The paper presents new data and reviews previously obtained results on the late glacial to Holocene history of peatlands in the southern part of the Baikal region under conditions of regional climate changes. To better understand climate signals, we have combined vegetation and geochemical variation data in 4.6 m thick peat deposits in the Vydrino bog located on the Tankhoi piedmont plain south of Lake Baikal. The territory has been swamped since 13.1 cal ka BP when the peatland started developing as a fen upon a sedimentary substrate. The 13.1–9.5 cal kyr climate record included two events of warming separated by an excursion of dry cold climate. Warming continued till 9.0 cal ka BP and eutrophic peat formation occurred in favorable temperature and moisture conditions. Another warming episode between 9.0 and 8.4 cal ka BP ended up with the Holocene climate optimum while the bog became mesotrophic. About 7.3–6.5 cal ka BP, the temperature and moisture inputs were no longer optimal for fir and spruce forests in the Vydrino area, which led to dramatic changes in landscape and vegetation. The wet and warm climate gradually became drier and colder from 6.5 to 2.3 cal ka BP, with a brief warm excursion about 5.5–5.3 cal ka BP. The peat deposition was interrupted in a cold climate from ∼2.3 cal ka BP to ∼0.7 cal ka BP, and the bog became oligotrophic afterwards. The newly obtained data allowed us to compare the paleoclimatic indicators available for the south Baikal region to determine their compatibility and inconsistency. In addition, we provide a general view to the quality of the climate and environmental reconstructions in the Baikal region by comparison of the data on its peatland study.

Holocene sediment source analysis and paleoclimatic significance of core KZK01 from the eastern part of the Beibu Gulf

Identifying the sources of sediments is of great significance in reconstructing Holocene paleoclimate evolution in the Beibu Gulf and in understanding the characteristics of regional responses to changes in global climate. The Holocene paleoclimatic evolutionary history of the Beibu Gulf was investigated by chronological, geochemical, and mineralogical means using the sediments of Core KZK01 from the eastern part of the Beibu Gulf. The rare earth element (REE) distribution curves, (Gd/Yb)N and (La/Yb)N discriminant diagram, and (Gd/Lu)N and ∑LREE/∑HREE discriminant diagram indicated that the detrital materials in the eastern part of the Beibu Gulf primarily originated from Hainan Island and its proximal sources, with considerable contributions from Taiwan and Pearl River materials. Source analysis of clay minerals showed that Luzon Island was the main source of smectite, followed by Hainan Island. Rivers in Taiwan were the main sources of illite in the study area, followed by the Red River. The Red River was the main contributor of chlorite, followed by the Pearl River. Kaolinite mainly originated from Hainan Island and Guangxi. Coastal currents, surface currents, and warm currents were the main drivers of material transport. Paleoclimatic variations since the Holocene in the Beibu Gulf were divided into three stages: 12–9 cal kyr BP, 9–1.3 cal kyr BP, and 1.3 cal kyr BP to the present. During different stages of climatic evolution, drought was often accompanied by cold and humidity coexisted with warmth, and cold-dry-warm-humid alternation is characterized by significant phases. The illite crystallinity clearly recorded the extreme cold events, such as Bond Events (except Bond6) and the Younger Dryas, and the change trend was essentially consistent with the regional climate record, reflecting the control of global climate change on the process of land–sea interaction in the tropical region. Furthermore, it highlights the great potential of illite crystallinity as a proxy indicator for reconstructing the surface chemical weathering processes of the region.

Perceptions, trends and adaptation to climate change in Yala wetland, Kenya

Purpose Tropical wetland ecosystems are threatened by climate change but also play a key role in its mitigation and adaptation through management of land use and other drivers. Local-level assessments are needed to support evidence-based wetland management in the face of climate change. This study aims to examine the local communities’ knowledge and perception of climate change in Yala wetland, Kenya, and compare them with observed data on climate trends. Such comparisons are useful to inform context-specific climate change adaptation actions. Design/methodology/approach The study used a mixed methods approach that combined analysis of climate data with perceptions from the local community. Gridded data on temperature and rainfall for the period from 1981 to 2018 were compared with data on climate change perceptions from semi-structured questionnaires with 286 key informants and community members. Findings Majority of the respondents had observed changes in climate parameters – severe drought (88.5%), increased frequency of floods (86.0%) and irregular onset and termination of rains (90.9%) in the past 20 years. The perceptions corresponded with climate trends that showed a significant increasing trend in the short rains and the average maximum temperature, high incidence of very wet years and variability in onset and termination of rainfall between 1981 and 2018. Gender, age and education had little influence on knowledge and awareness of climate change, except for frequency of floods and self-reported understanding of climate change. The community perceived the wetland to be important for climate change adaptation, particularly the provision of resources such as grazing grounds during drought. Research limitations/implications The study faced challenges of low sample size, use of gridded climate data and reproducibility in other contexts. The results of this study apply to local communities in a tropical wetland in Western Kenya, which has a bi-modal pattern of rainfall. The sample of the study was regional and may therefore not be representative of the whole of Kenya, which has diverse socioeconomic and ecological contexts. Potential problems have been identified with the use of gridded data (for example, regional biases in models), although their usefulness in data scarce contexts is well established. Moreover, the sample size has been found to be a less important factor in research of highly complex socio-ecological systems where there is an attempt to bridge natural and social sciences. Practical implications This study addresses the paucity of studies on climate change trends in papyrus wetlands of sub-Saharan Africa and the role of local knowledge and perceptions in influencing the management of such wetlands. Perceptions largely influence local stakeholders’ decisions, and a study that compares perceptions vs “reality” provides evidence for engagement with the stakeholders in managing these highly vulnerable ecosystems. The study showed that the local community’s perceptions corresponded with the climate record and that adaptation measures are already ongoing in the area. Originality/value This study presents a case for the understanding of community perceptions and knowledge of climate change in a tropical wetland under threat from climate change and land use change, to inform management under a changing climate.

An age scale for new climate records from Sherman Island, West Antarctica

Abstract. Few ice cores from the Amundsen Sea and Bellingshausen Sea sectors of the West Antarctic Ice Sheet (WAIS) extend back in time further than a few hundred years. The WAIS is believed to be susceptible to collapse as a result of anthropogenic climate change and may have at least partially collapsed during the Last Interglacial (LIG) period. Understanding the stability of the WAIS during warm periods such as the LIG and Holocene is important. As part of the WACSWAIN (WArm Climate Stability of the West Antarctic ice sheet in the last INterglacial) project, the British Antarctic Survey's (BAS) Rapid Access Isotope Drill (RAID) was deployed in 2020 on Sherman Island in the Abbot Ice Shelf, West Antarctica. We drilled a 323 m deep borehole, with discrete samples of ice chippings collected that cover the entire depth range of the drilled ice. The samples were analysed for stable water isotope composition and major ion content at BAS from 2020–2022. Using annual layer counting of chemical records, volcanic horizon identification and ice modelling, an age scale for the record of 1724 discrete samples is presented. The Sherman Island ice record extends back to greater than 1240 years, providing the oldest, continuous ice-derived palaeoclimate records in the coastal Amundsen and Bellingshausen Sea sectors to date. We demonstrate the potential for recovery of a complete Holocene climate record from Sherman Island in the future and confidence in the ability of RAID samples to contain sufficiently resolved records for meaningful climatic interpretation.

How will future climates in the Pakistani Punjab rice-wheat system affect the optimal agronomic settings, and can adaptation offset losses?

Pakistan is one of the most vulnerable countries in the world to future climatic changes, already with significant water and food sustainability issues. Rice and wheat production in the Pakistani Punjab is central to national food security and hence of particular concern. We sought to understand what optimal rice-wheat (RW) farmer agronomic practices (those which maximise RW system gross margins (GM) and irrigated water productivity (WPi)) look like under each of 6 projected future climate change scenarios for mid-century (2050). We also examined the impact on 2050 RW production if current farmer practices remained unchanged, to gauge the potential benefits of the optimal adaptations. Cropping systems simulation with a validated model (APSIM) enabled analysis of a broad range of current management practice modifications (6 agronomic management settings parameters, including crop sowing dates, varieties, fertiliser rates, and deficit irrigation strategies) in a large Monte-Carlo Matrix (96,768 elements) for the highest-yielding district in the Punjab, Gujranwala. We evaluated annual crop production, GM, WPi, nitrate leaching, and total system evapotranspiration (ET) for all combinations on an annual basis over a 31-year simulation period for each future climate scenario (as well as the historical record) seeking optimal parameter combinations within each. If current farmer practices were to remain unchanged into the future, we found reductions in farmer GM’s by 35–50% by 2050, with WPi decreasing even further (40–60%). Adaptation of current RW management practices is therefore essential. By adopting optimal practices now (derived using the historical climate record) we found that farmers also place themselves well for future climates and our study suggests they can maintain or maybe even increase current GM’s by 5–30% (depending on climate scenario) through smart adaptation. The best agronomic practices in 2050 look almost indistinguishable from the best agronomic practices now, regardless of future climate scenario chosen. However, compared with a hypothetical farmer operating under optimal practices now, our study suggests that a farmer in 2050 will earn considerably less, with gross margins under optimal practices falling by 25–40%, depending on which future climate scenario is considered. Declines are largely due to falling rice yields under future conditions (20–50% across examined climate scenarios), with wheat yields likely to be maintained or even slightly increased. Our study also indicated an increase in ET (10–15%) across all RW practices (regardless of future climate scenario and despite projections for generally reduced rainfall, runoff and drainage), compared with historical conditions. Our study suggests a rice varietal improvement need for heat tolerance, but that current wheat varieties are suitable to 2050.

A ca. 39,000-year record of vegetation and climate change from the margin of the Namib Sand Sea

AbstractThis paper presents the first continuous multi-proxy record of climate and vegetation change from the central Namib Desert extending over much of the last ca. 39,000 years. Derived from rock hyrax middens, evidence from stable carbon and nitrogen isotopes, pollen, and microcharcoal reveals significant differences between glacial-age and Holocene climates and vegetation types. Although still arid to semi-arid, conditions during Marine Oxygen Isotope Stages (MIS) 2–3 were significantly more humid than in the Late Holocene. Considerable associated vegetation change is apparent, with cooler temperatures and higher/more-regular rainfall promoting the westward expansion of relatively mesic shrubby karroid vegetation during MIS 2–3. With the last glacial–interglacial transition, increasing temperatures and less/less-regular rainfall resulted in marked vegetation changes and the establishment of current xeric grasslands. The inter-plant spacing of the karroid vegetation promoted by wetter conditions does not carry fire effectively, and the microcharcoal record indicates that more extensive fires may develop only with the development of grassier vegetation under drier conditions. As with other terrestrial records from the Namib Desert and environs, no Cape flora elements were found to support previously hypothesised expansion of the Fynbos Biome during the last glacial period.

Reconstructing river flows remotely on Earth, Titan, and Mars

Alluvial rivers are conveyor belts of fluid and sediment that provide a record of upstream climate and erosion on Earth, Titan, and Mars. However, many of Earth's rivers remain unsurveyed, Titan's rivers are not well resolved by current spacecraft data, and Mars' rivers are no longer active, hindering reconstructions of planetary surface conditions. To overcome these problems, we use dimensionless hydraulic geometry relations-scaling laws that relate river channel dimensions to flow and sediment transport rates-to calculate in-channel conditions using only remote sensing measurements of channel width and slope. On Earth, this offers a way to predict flow and sediment flux in rivers that lack field measurements and shows that the distinct dynamics of bedload-dominated, suspended load-dominated, and bedrock rivers give rise to distinct channel characteristics. On Mars, this approach not only predicts grain sizes at Gale Crater and Jezero Crater that overlap with those measured by the Curiosity and Perseverance rovers, it enables reconstructions of past flow conditions that are consistent with proposed long-lived hydrologic activity at both craters. On Titan, our predicted sediment fluxes to the coast of Ontario Lacus could build the lake's river delta in as little as ~1,000 y, and our scaling relationships suggest that Titan's rivers may be wider, slope more gently, and transport sediment at lower flows than rivers on Earth or Mars. Our approach provides a template for predicting channel properties remotely for alluvial rivers across Earth, along with interpreting spacecraft observations of rivers on Titan and Mars.