Regional Climate Dynamics Research Articles

Research on the influencing factors of the difference in warming rates between the east, west and central regions of North America during the 21st century

Temperature in North America (NA) is a significant focus of current climate change research. This study focuses on various climate variables and employs linear regression and correlation coefficient analysis to examine the factors influencing the differences in warming rates across the eastern, western, and central regions of NA in the 21st century, as well as the correlations between these factors and temperature. Results indicate that NA temperatures are rising with notable regional variations in warming rates. Under the influence of cloud cover, the impact of precipitation on warming rates is relatively minor, whereas radiation significantly affects warming rates. Additionally, sea level pressure influences wind patterns, thereby significantly impacting warming rates. This study highlights the complexity of regional climate dynamics in NA and provides deep insights into regional climate differences.

Impact of Climate and Vegetation Dynamics on the Ecosystem Services of Subtropical Forests—A Case Study of Baishanzu National Park Area, China

Forest ecosystems, as the primary component of terrestrial ecosystems, provide essential ecosystem services (ESs) critical for sustainable human development. However, changes in climate and vegetation can alter these forest ESs. Understanding the complex relationships between regional climate, vegetation, and ESs is key to ensuring the sustainable management of forest ESs. Therefore, this study, using Baishanzu National Park as a case example, analyzed the impacts of regional climate and vegetation dynamics (vegetation coverage, forest type, and forest structure) on forest ESs, specifically water yield (WY), soil conservation (SC), net primary productivity (NPP), and habitat quality (HQ). The results indicate that from 2000 to 2020, the forest Composite Index of Ecosystem Services (CIES) in Baishanzu National Park increased. Climate and vegetation dynamics have significant effects on forest ESs. Specifically, changes in WY and SC are primarily influenced by climate change, while changes in NPP and HQ are mainly affected by changes in forest type and structure. Complex trade-offs and synergies exist among different ESs, and the driving mechanisms of climate and vegetation changes on ES variations are also complex, involving both direct and indirect effects, with significant spatial heterogeneity. This study provides important references for the sustainable management and appropriate restoration of regional forest ESs.

Impact of meteorological parameters on black carbon mass concentrations over Silicon City “ Bengaluru, Southern part of India” – A Case Study

In the context of Bengaluru, the impact of black carbon (BC) aerosols on regional climate dynamics emerges as a crucial area of investigation. Due to the lack of high-resolution BC data, it was collected at 5 different locations in Bengaluru, Karnataka, from January 2019 to December 2019. The mean mass concentration of BC was 5.91 microg m-3, whereas the higher mass concentration of BC was 7.71 microg m-3 over the city railway station and the lower (3.69 microg m-3) was in Jayanagara. The contribution of BC in higher-traffic and industrial locations was approximately 41% higher than the residential locations, which indicates a large fraction of soot particles are from anthropogenic activities mainly from fossil fuel combustion. The seasonal concentrations of BC have also exhibited a large variability, with the highest sequence in magnitude during the winter season (9 microg m-3) followed by the summer (6.3 microg m-3), post-monsoon (5.8 microg m-3) and monsoon (3.4 microg m-3) seasons during the study period. The concentrations of BC during the monsoon season were very low as compared to the winter season due to the impact of the washout effect. The BC was negatively significantly correlated (-0.70) with rainfall indicating the washout effect, however, during the winter season, it was due to impact of boundary layer condition. Overall (annually) the mean concentrations of BC have increased by around 55% within five years over the urban region, which indicates the impact of man-made activities. The higher mass concentration of BC over Bangalore in the southern part of India, indicates serious implications for the regional climate that need to be investigated and mitigated. Finally, the study suggests that immediate action is required to mitigate the emission of BC into the urban environment in the southern part of India.

Transferability and Explainability of Deep Learning Emulators for Regional Climate Model Projections: Perspectives for Future Applications

Abstract Regional climate models (RCMs) are essential tools for simulating and studying regional climate variability and change. However, their high computational cost limits the production of comprehensive ensembles of regional climate projections covering multiple scenarios and driving Global climate models (GCMs) across regions. RCM emulators based on deep learning models have recently been introduced as a cost-effective and promising alternative that requires only short RCM simulations to train the models. Therefore, evaluating their transferability to different periods, scenarios, and GCMs becomes a pivotal and complex task in which the inherent biases of both GCMs and RCMs play a significant role. Here, we focus on this problem by considering the two different emulation approaches introduced in the literature as perfect and imperfect, that we here refer to as perfect prognosis (PP) and model output statistics (MOS), respectively, following the well-established downscaling terminology. In addition to standard evaluation techniques, we expand the analysis with methods from the field of explainable artificial intelligence (XAI), to assess the physical consistency of the empirical links learnt by the models. We find that both approaches are able to emulate certain climatological properties of RCMs for different periods and scenarios (soft transferability), but the consistency of the emulation functions differs between approaches. Whereas PP learns robust and physically meaningful patterns, MOS results are GCM dependent and lack physical consistency in some cases. Both approaches face problems when transferring the emulation function to other GCMs (hard transferability), due to the existence of GCM-dependent biases. This limits their applicability to build RCM ensembles. We conclude by giving prospects for future applications. Significance Statement Regional climate model (RCM) emulators are a cost-effective emerging approach for generating comprehensive ensembles of regional climate projections. Promising results have been recently obtained using deep learning models. However, their potential to capture the regional climate dynamics and to emulate other periods, emission scenarios, or driving global climate models (GCMs) remains an open issue that affects their practical use. This study explores the potential of current emulation approaches incorporating new explainable artificial intelligence (XAI) evaluation techniques to assess the reliability and transferability of the emulators. Our findings show that the different global and regional model biases involved in the different approaches play a key role in transferability. Based on the results obtained, we provide some prospects for potential applications of these models in challenging problems.

Long-Term Changes in Deep Ocean Currents between Ulleung Island and Dok Island in the East Sea from 1996 to 2023

This study presents a comprehensive analysis of long-term deep ocean currents between Ulleung Island and Dok Island in the East Sea, based on data observed from the East Sea Current Measurement 1 (EC1) mooring station spanning from 1996 to 2023. The deep current at the Ulleung Interplain Gap, a trough situated between Ulleung Island and Dok Island, originates from the Japan Basin, a region where deep water formation occurs within the East Sea. The southward flow and velocity of this deep water are reflective of both regional and global climate dynamics. Understanding these dynamics is crucial for assessing environmental impact, both locally in Korea and globally. Significant trends and anomalies were identified in the zonal and meridional velocities within the 1,800 and 2,500-meter depth range. Data from 2012 to 2014 required corrections due to unit inconsistencies, which, after adjustment, revealed a deceleration of the southward bottom current, with speeds decreasing from 1.49 cm s<sup>-1</sup> in November 1996 to 1.14 cm s<sup>-1</sup> in April 2023. These changes may be linked to global climate variations and bottom water formation in the Japan Basin, influencing regional circulation patterns. The findings highlight the importance of sustained ocean monitoring and enhanced data management to ensure the accuracy and utility of long-term oceanographic datasets.

Interannual Glacial Mass Changes in High Mountain Asia and Connections to Climate Variability

We use data from the Gravity Recovery and Climate Experiment and its Follow-On mission (GRACE/GRACE-FO) from April 2002 to December 2022 to analyze interannual glacial mass changes in High Mountain Asia (HMA) and its subregions and their driving factors. Glacial mass changes in the HMA subregions show clear regional characteristics. Interannual glacial mass changes in the HMA region are closely related to interannual oscillations of precipitation and temperature, and are also correlated with El Niño–Southern Oscillation (ENSO). Glacial mass changes in the regions (R1–R6) are dominated by precipitation, and ENSO affects interannual glacial mass changes mainly by affecting precipitation. In region (R7) and region (R8), the glacial mass changes are mainly controlled by temperature. ENSO also affects the interannual glacial mass changes by affecting interannual changes in temperature. The interannual glacial mass changes in regions (R9–R11) are jointly dominated by temperature and precipitation, and also related to ENSO. Another interesting finding of this study is that glacial mass changes in the western part of HMA (R1–R6) show a clear 6–7-year oscillation, strongly correlated with a similar oscillation in precipitation, while in the eastern part (R9–R11), a 2–3-year oscillation was found in both glacial mass change and precipitation, as well as temperature. These results verify the response of interannual HMA glacial mass changes to climate processes, crucial for understanding regional climate dynamics and sustainable water resource management.

Holocene aeolian environmental dynamics in fixed and semi-fixed deserts over the arid Central Asia revealed by comprehensive sand-dune records

Fixed and semi-fixed deserts are widely distributed in arid Central Asia (ACA). Environmental changes in these deserts can affect the regional radiation balance, climate dynamics, and global climate through a series of feedback effects. This study analyzed luminescence dating from 37 sites, with a particular focus on dendritic dunes (a pattern of vegetated linear dunes) and the ancient dunes beneath them in the Gurbantunggut Desert and yielded the following insights. (1) Primary ridges of dendritic dunes originated approximately 1.0 ka, whereas secondary ridges predominantly formed at 8.5 ± 0.3 ka. The formation of the underlying ancient dunes commenced at least 11.0 ± 0.5 ka and ended between 8.5 ± 0.3 ka and 8.2 ± 0.4 ka. (2) During the Holocene, the Gurbantunggut Desert underwent two distinct environmental phases. From 11.7 ka to 8.1 ± 0.1 ka, the region was characterized by vigorous aeolian activity, marked by the prevalence of mobile dunes. Conversely, the period from 8.1 ± 0.1 ka to 0 ka exhibited substantial environmental amelioration, with limited aeolian activity and the intermittent partial development of vegetated linear dunes. (3) A comprehensive analysis of the principal factors affecting regional aeolian activity revealed that at 11.7 ka–8.1 ± 0.1 ka, moisture (precipitation) and near-surface wind intensity primarily governed aeolian activity in the Gurbantunggut Desert. At 8.1 ± 0.1 ka–0 ka, aeolian activity was mainly influenced by moisture (precipitation), near-surface wind intensity, and external sand supply. (4) Similar patterns of Holocene aeolian activity were observed in the fixed Bayanbulak, Karakum, and Kizil Kum Deserts within the ACA. On a suborbital scale, winter insolation served as the primary driving factor, along with the ice volume and atmospheric CO2 concentration. These factors collectively controlled regional winter temperatures, which determined moisture (precipitation) and near-surface wind intensity by affecting the winter westerlies and Siberian High, ultimately controlling regional aeolian activity.

Unraveling climate trends in the mediterranean: a hybrid machine learning and statistical approach

This study presents a comprehensive spatiotemporal analysis of sea surface temperatures (SST) and surface air temperatures (TAS) across 15 Mediterranean coastal stations, leveraging centennial-scale data to analyze regional climate dynamics. The modeling framework integrates three sequential phases: data preprocessing, statistical analysis, and advanced machine learning techniques, creating a robust analytical pipeline. The data preprocessing phase harmonizes diverse datasets, addresses missing values, and applies transformations to ensure analytical consistency. The statistical modeling employs the Pettitt test for change point detection and linear trend analysis to unveil underlying patterns. The machine learning phase utilizes K-means clustering for climate regime classification and implements tailored Convolutional Neural Networks (CNNs) for cluster-specific future climate anomaly projections. Results unveil a marked anthropogenic climate signal, with contemporary observations consistently surpassing historical baselines. Breakpoint analyses and linear trend assessments reveal heterogeneous climatic shifts, with pronounced warming in the northern Mediterranean. Notably, Nice and Ajaccio exhibit the highest SST increases (0.0119 and 0.0113 °C/decade, respectively), contrasting with more modest trends in Alexandria (0.0052 °C/decade) and Antalya (0.0047 °C/decade) in the eastern Mediterranean. The application of clustering and CNN projections provides granular insights into differential warming trajectories. By 2050, cooler northwestern Mediterranean zones are projected to experience dramatic SST anomalies of approximately 3 °C above the average, with corresponding TAS increases of 2.5 °C. In contrast, warmer eastern and southern regions display more subdued warming patterns, with projected SST and TAS increases of 1.5–2.5 °C by mid-century. This research’s importance is highlighted by its potential to inform tailored adaptation strategies and contribute to the theoretical understanding of climate dynamics, advancing climate modeling and analysis efforts.

Dual-isotope ratios of carbonaceous aerosols for seasonal observation and their assessment as source indicators

Carbonaceous aerosols exhibit seasonal variations due to a complex interplay of emission sources, meteorological conditions, and chemical processes. This study presents the first year-round dual‑carbon isotopic analysis of carbonaceous aerosols in Northeastern Europe (Lithuania). The emphasis was placed on the processes affecting carbonaceous submicron particle (PM1) concentrations and their isotopic composition (δ13CTC, fc) during different seasons. Aerosol particles were collected in the two distinct sites: at an urban background site (Vilnius) and a coastal site (Preila). The concentrations of total carbon (TC) and black carbon (BC) varied both spatially and temporally. The annual average concentrations were 4 μg/m3 for TC and 2.3 μg/m3 for BC at the urban background site. They were considerably lower at the coastal site with 2.9 μg/m3 for TC and 0.74 μg/m3 for BC. The peak concentrations of TC and BC that occur during the cold season indicate a significant impact from residential heating. The δ13C in aerosols exhibited a distinct seasonal cycle with depleted δ13CTC values during the warm season (April–October). Through the integration of isotopic composition, contemporary carbon (fc), and BC source apportionment, we achieved precise predictions of isotopic parameter changes, encompassing pollution sources and the influence of meteorological parameters. To better understand the respective contributions of local and regional sources, air mass trajectories, wind patterns (speed and direction), and the polar conditional probability function (CPF) were studied in parallel. The study indicates that the isotopic composition of PM1 at both sites is primarily controlled by emission sources (local and regional), while meteorological conditions (temperature and mixing layer height) have less influence. These variations have important implications for regional air quality, climate dynamics, and public health, which are persistently subject to continuous research and monitoring.

Logistic curve modelling of sea surface temperature and latent heat flux variability in the Tropical Indian Ocean

The Tropical Indian Ocean (TIO) is one of the most vulnerable regions to climate change due to its unique ocean-atmosphere interactions. The region is characterized by warm temperatures, high evaporation rates, and strong convection, making it particularly vulnerable to greenhouse gases. This susceptibility leads to an overall trend of warming across the Earth's surface and atmosphere, intensifying sea surface temperatures (SST) and increasing evaporation rates, consequently influencing Surface Latent Heat Flux (SLHF). The strong influence of both SST and SLHF on atmospheric circulation and precipitation patterns makes them critical factors in determining the region's climate, particularly in monsoon-dominated regions. Analysis reveals a consistent upward trend in both SST and SLHF in the central region of TIO. To model this, standard Logistic Curve Model (LCM) has been applied to these parameters averaged over the central region of the TIO. The model is run for a period of 20 years from 2001 to 2020, grouped into four lustrums. The LCM-derived SST and SLHF are in good consistent with observed datasets during the above periods with, correlation coefficients ranging from 0.92 to 0.96 for SST and 0.86–0.90 for SLHF. Extending the model spatially across the entire TIO region explains the ability to project fluctuations in SST and SLHF values across different seasons. These findings highlight the model's relevance for capturing short-term, long-term, and seasonal variability of the parameters, providing important insights into regional climate dynamics.

Investigating the impact of tropical deforestation on Indian monsoon hydro-climate: a novel study using a regional climate model

This study uses a state-of-the-art regional climate model (RCM) to examine how tropical deforestation affects the meteorology of the Indian Summer Monsoon (ISM). Incorporating insights from existing research on deforestation by climate scientists, alongside evidence of environmental deterioration in semi-arid, hilly and tropical regions of Southeast Asia, this research seeks to elucidate the critical influence of anthropogenic reasons of climate change on the hydroclimate of ISM. Employing “tropical deforestation” design experiments with the ICTP-RegCMv4.4.5.10 RCM the study evaluates the effects on meteorological parameters including precipitation, circulation patterns and surface parameters. This experimental design entails substituting vegetation type in the land use map of RegCMv4.4.5.10 model, such as deciduous and evergreen trees in Southeast Asia with “short grass” to mimic tropical deforestation. Findings reveal that deforestation induces abnormal anti-cyclonic circulation over eastern India curtails moisture advection, diminishing latent heat flux and moisture transport, leads to a decrease in precipitation compared to control experiment scenario. Alterations in albedo and vegetation roughness length attributable to deforestation impact temperature, humidity, precipitation, consequently exacerbating drought and heatwave occurrences. Additionally, the study also explores deforestation-induced feedback on ISM precipitation variability. The study concludes that deforestation substantially alters land-surface characteristics, water and energy cycle, and atmospheric circulation, thereby influencing regional climate dynamics. These findings offer foundational insights into comprehending land-use and land-cover changes and their implications for climate change adaptation strategies.

Physical characteristics of convective and non-convective cirrus clouds from CALIPSO data over the South China Sea

Studying the characteristics and mechanisms of convective and non-convective cirrus clouds over the South China Sea is vital for their impact on regional climate dynamics, and enhancing predictive models for weather and climate forecasts. This study utilizes eight years of CALIPSO data (from March 2007 to February 2015) to investigate convective and non-convective cirrus clouds. Explicit new insights include the observation that convective cirrus cloud samples are three times more numerous than non-convective cirrus clouds. Convective cirrus clouds are associated with humid conditions and demonstrate higher ice water content (IWC) values ranging from 10−3 to 10−1 g m−3, whereas non-convective cirrus clouds tend to be drier, exhibiting IWC values ranging from 10−4 to 10−3 g m−3. Both cirrus cloud types exhibit a maximum cloud fraction at 10°N. Convective cirrus reach their peak cloud fraction at an altitude of 14 km, while non-convective cirrus typically occur at altitudes between 15 and 16 km. The seasonal variability of the convective cirrus cloud fraction primarily reflects bottom-up positive specific humidity anomalies originating from convective activity, whereas the non-convective cirrus cloud fraction is influenced by top-down negative temperature anomalies.

Hydrogen isotope records of long-chain alkanes from the monsoon boundary zone over the last 2400 years in North China

The East Asian Summer Monsoon (EASM) plays a key role in the climate dynamics of East Asia, affecting the livelihood of millions of people by contributing to agriculture and water resources. The monsoon boundary zone (MBZ) is particularly sensitive to shifts in climate patterns. However, the complexity of water vapor sources in the region makes it difficult to understand precipitation processes. To address this issue, the records of lipid biomarker abundances and leaf wax stable hydrogen isotope composition of C31–alkanes (δDwax-C31) from a 238 cm sediment core extracted in Lake Dali, located at the northern edge of the EASM, were sampled and examined by 2 cm per sample. Based on analyses of the biogenic molecular indicators(biomarkers), precipitation isotopes, and other indicators of the evolution of the climate environment, we have reconstructed precipitation change history over the past 2400 years. The results show the decrease in alkanes concentrations, along with high A.I. values in Lake Dali sediments indicate an arid trend over the past 2400 years, which have led to a decrease in basin productivity and the development of grasslands. The low temperatures greatly limit the growth of C4 vegetation in this cold region, so the long-chain alkanes in the lake sediments is mainly derived from the leaf wax lipids of C3 vegetation in the grassland. The increase of Paq and the reduction of ACL indicate that the decrease of grass vegetation inputs in the basin and the outbreak of aquatic vegetation. Notably, aquatic vegetation outbreaks may be due to reduced precipitation leading to shrinking lakes and increased nutrients in the lakes. By comparing with the biogenic indicators of Lake Dali and other regional records, the δDwax-C31 value can be used as a proxy for the regional precipitation, with a gradual decrease from about −240 ‰ to about −190 ‰, which indicates a general decreasing trend in the precipitation in the last 2400 years. Specifically, in exception of some significant fluctuations on the centennial to millennial scale, δDwax-C31 value decrease by about 40 ‰ between 1800 and 1600 cal.a BP over a period of only 200 years. As we know, the diminishing solar radiation might lead to a weaker EASM and a reduction in precipitation. Thus, the decrease in regional temperature became the main reason for the anomalous negative precipitation isotope phenomenon due to the lower precipitation from 1800 to 1600 cal.a BP in the monsoon boundary zone (MBZ, this represents only the northern boundary). This study contributes to our understanding of δDwax-C31 within the MBZ and its significance as an indicator of rainfall processes. By analyzing this molecular proxy, the researchers gain insights into the past precipitation patterns and their implications for regional climate. Importantly, the study demonstrates the value of combining biogenic molecular indicators with geochemical indicators, as it leads to improved accuracy in reconstructing regional climate conditions. The findings shed light on long-term climate trends and provide a more comprehensive understanding of the historical impacts of climate change on the EASM region. Moreover, the study's contribution to interpreting the paleoclimate record is crucial for validating climate models used to project future climate scenarios. Overall, this research enhances our knowledge of regional climate dynamics and their implications, offering valuable insights for both historical analysis and future climate projections.

Paleoenvironmental changes in the coastal zone of the northwest South China Sea during the last 13 kyr

Marine sediments in coastal zones serve as valuable archives for understanding the history of silicate chemical weathering and summer monsoon rainfall in source areas, providing insights into terrigenous climate and environmental evolution. In this study, we investigated the grain size, clay minerals, and geochemistry of sediments retrieved from core KZK01 in the coastal zone of the northwest South China Sea during the past 13 thousand years before present (kyr BP). Our findings demonstrated that the illite crystallinity index served as a reliable proxy for assessing the intensity of chemical weathering in the source area. Moreover, it distinctly recorded significant climatic events such as the Younger Dryas and Bond events during the Holocene. The dominant driver of the regional East Asian summer monsoon was identified as summer solar radiation in the Northern Hemisphere at low latitudes. Cold climate events exhibited global consistency, potentially influenced by the presence of ice sheets at high latitudes. Lastly, our records revealed a distinct transition at 9.0 kyr, highlighting significant impacts of the Qiongzhou Strait and sea level rise on regional climate dynamics.

Buried channels under the northern Bohai Sea: Evidence for a great Bohai Paleolake during the late MIS3

Buried channels are widespread on continental shelves and potentially record Quaternary glacial–interglacial environmental changes. The Bohai Sea, an epicontinental basin, is extraordinarily sensitive to such environmental changes, but the evolution of buried channels there remains poorly understood. Here, combined seismic and sedimentological data were used to investigate the evolution of buried channels in western Liaodong Bay, northern Bohai Sea. We identified over six sets of channels, up to 15 m thick and up to 4 km wide, at different horizons within a terrestrial bed formed during the late Marine Oxygen Isotope Stage (MIS) 3 between 35 and 30 kyr BP. Most of these channels are interpreted as incised valley systems of fluvial origin, with complex combinations of fill facies. They were truncated on their tops by transgressive ravinements, which formed during base-level rise. Our findings suggest that these incised valley systems formed and evolved over multiple cycles of incision/filling controlled by the alternation of subaerially exposed and drowned environments during the late MIS3, and the contemporaneous shoreline advanced and retreated repeatedly within our study area. Given that sea level during this period was ∼10–45 m lower than the buried channels in our study area, the evolution of the multiple channels appears to be dominated by lake level fluctuations rather than global eustasy. We hypothesize that during late MIS3, the Bohai Basin transformed into a great paleolake (>39000 km2) as a result of falling sea levels, separating it from the Pacific Ocean, which is also supported by the microfossils in a core collected from the more basinward location. Our stratigraphic evidence also suggests that lake level fluctuations were intensive and of different amplitudes (∼5 to >15 m), which is consistent with climate proxy records. These fluctuations in the paleolake level were presumably a response to and therefore could provide implications for reconstructing regional climate dynamics.

A comparison of pre-millennium eruption (946 CE) and modern temperatures from tree rings in Changbai Mountain, Northeast Asia

Abstract. High-resolution temperature reconstructions in the previous millennium are limited in Northeast Asia, but they are important for assessing regional climate dynamics. Here, we present, for the first time, a 202-year reliable reconstruction of April temperature changes before the millennium volcanic eruption in 946 CE using tree rings of carbonized logs buried in the tephra in Changbai Mountain, Northeast Asia. The reconstructed temperature changes were consistent with previous reconstructions in China and the Northern Hemisphere. The influences of large-scale oscillations (e.g. El Niño–Southern Oscillation, ENSO) on temperature variability were not significantly different between the periods of 745–946 CE preceding the eruption and 1883–2012. However, compared to the palaeotemperature of the previous millennium, the temperature changes were more complex with stronger temperature fluctuations, more frequent temperature abruption, and a weaker periodicity of temperature variance during the last 130 years. These recent changes correspond to long-term anthropogenic influences on regional climate.

Do farmers' risk perception, adaptation strategies, and their determinants benefit towards climate change? Implications for agriculture sector of Punjab, Pakistan.

Due to global and regional climatic dynamics for a couple of decades, agricultural productivity, rural livelihood, and food security have been badly affected in Pakistan. This study was conducted in Punjab, Pakistan, to explore the farmers' understanding of the impacts of climate change, adaptation strategies, determinants, and benefits on agriculture using data from 1080 respondents. Perceived risks by the farmers in the rice-wheat cropping system and the cotton-wheat cropping system were weed infestation, seed rate augmented, low-quality seeds, infestation of crop diseases and pests, change of cropping pattern, increase of input use, decrease of cropping intensity and productivity, decreasing soil fertility, increasing irrigation frequency, and increase of harvesting time. To alleviate the adverse influences of climate change, the adaptation strategies used by farmers were management of crop and variety, soil and irrigation water, diversification of agriculture production systems and livelihood sources, management of fertilizer and farm operations time, spatial adaptation, access to risk reduction measures and financial assets, adoption of new technologies, institutional support, and indigenous knowledge. Moreover, the results of Binary Logistic Regression indicate that adaptation strategies are affected by different factors like age, education, household family size, off-farm income, remittances, credit access, information on climatic and natural hazards, information on weather forecasting, land acreage, the experience of growing crops and rearing of livestock, tenancy status, tube well ownership, livestock inventory, access to market information, agricultural extension services, and distance from agricultural input/output market. There is a significant difference between adapters and nonadapters. The risk management system may be created to protect crops against failures caused by extreme weather events. There is a need to develop crop varieties that are both high yielding and resistant to climate change. Moreover, cropping patterns should be revised to combat the effects of climate change. To enhance farmers' standard of living, it is necessary to provide adequate extension services and a more significant number of investment facilities. These measures will assist farmers in maintaining their standard of living and food security over the long term to adapt to the effects of climate change based on various cropping zones.

Mid-Holocene intensification of Southern Hemisphere westerly winds and implications for regional climate dynamics

Mid-Holocene intensification of Southern Hemisphere westerly winds and implications for regional climate dynamics

Very high Middle Miocene surface productivity on the U.S. mid-Atlantic shelf amid glacioeustatic sea level variability

The Miocene Climatic Optimum (MCO) provides important insights into how the climate system operates under elevated temperatures and atmospheric CO2 levels. Few western North Atlantic paleotemperature or paleoecological records exist from the MCO, despite their importance for understanding both regional and global climate dynamics. Here we present quantitative MCO paleoecological data from the western North Atlantic, specifically from the Baltimore Gas & Electric (BG&E) marine sediment core from southern Maryland, USA. We examine alkenones and planktic foraminifera and document the first sea surface temperature (SST) and productivity estimates for the MCO and the Middle Miocene Climate Transition (MMCT) from the continental shelf. Increased levels of planktic foraminifer species diversity and surface productivity accompany high sea level intervals of the MCO, indicating coastal upwelling. Cooling episodes correlate to unconformities in the BG&E core that reflect sea level lowstands; these and sedimentary cycles tie the record to eccentricity-paced Antarctic ice sheet growth and decay. This dynamic record not only captures the variability in SST, sea level and coastal productivity during the warm MCO and the transition to cooler global temperatures during the MMCT, but it also demonstrates the variability in local conditions within and between intervals of high sea level.

Amplified and suppressed regional imprints of global warming events on the southeastern Tibetan Plateau during MIS 3–2

Large amplitude, rapid climate oscillations, the so-called Dansgaard-Oeschger (D-O) events, are characteristic of the last glacial period. However, lithological evidence of D-O warming events is rare, mainly due to their brevity. Although the Tibetan Plateau (TP) is regarded as especially sensitive to climate change owing to its fragile cryosphere and ecological systems, little is known about the variability of the Indian summer monsoon (ISM) over the TP on millennial to centennial timescales. Here, we use a well-dated loess-paleosol sequence (LPS) in the Niyang River valley on the southeastern TP (SE TP), China, to determine the patterns and timing of millennial-to centennial-scale variations in paleomonsoon strength and to identify their causes. This stratigraphic sequence developed between 39.2 and 21.8 cal kyr BP, covering the late marine isotope stage (MIS) 3/2 transition. Ten paleosol units were identified within the sequence, based on field observations, high-resolution measurements of color, grain size and magnetic properties, as well as mineralogical and geochemical evidence. These paleosol units provide unambiguous evidence of D-O-like abrupt warming events and repeated climatic instability, associated with large-amplitude, abrupt changes of the ISM system over the SE TP. The amplitudes, duration, and frequency of these abrupt ISM strengthening events over the SE TP present unique features, including irregular spacing and varying amplitudes. In general, the amplitude of ISM oscillations was larger during MIS 2 than in the late MIS 3 period. Four well-developed paleosol units suggest that ISM intensity at ∼38.7, 28.3, 25.9 and 23.5 cal kyr BP was notably higher compared to the climate of the Holocene, including the present-day. However, two substantial abrupt warming events of global scale are not recorded within the LZ2 LPS. We suggest that this was because of the amplification and suppression of global warming events over the SE TP, caused by the interplay of global and regional climatic dynamics. Warming amplification occurred during intervals with less snow and glacier ice cover, whereas warming suppression was the result of unusually large snow and glacier ice cover on the TP. We suggest that anomalous fluctuations of the India-Burma Trough of the westerlies to the south of the TP during winter may have played a crucial role in determining the snowfall, snow cover, glacier accumulation, and the transition from warming amplification to warming suppression. Therefore, the anomalous ISM oscillations in the SE TP were the result of the coupling of global and local processes.