Understanding Of Regional Climate Change Research Articles

Observed multi-decadal trends in subsurface temperature adjacent to the East Australian Current

Abstract. Sea surface temperature observations have shown that western boundary currents, such as the East Australian Current (EAC), are warming faster than the global average. However, we know little about coastal temperature trends inshore of these rapidly warming regions, particularly below the surface. In addition to this, warming rates are typically estimated linearly, making it difficult to know how these rates have changed over time. Here we use long-term in situ temperature observations through the water column at five coastal sites between approximately 27.3–42.6∘ S to estimate warming trends between the ocean surface and the bottom. Using an advanced trend detection method, we find accelerating warming trends at multiple depths in the EAC extension region at 34.1 and 42.6∘ S. We see accelerating trends at the surface and bottom at 34.1∘ S but similar trends in the top 20 m at 42.6∘ S. We compare several methods, estimate uncertainty, and place our results in the context of previously reported trends, highlighting that magnitudes are depth-dependent, vary across latitude, and are sensitive to the data time period chosen. The spatial and temporal variability in the long-term temperature trends highlight the important role of regional dynamics against a background of broad-scale ocean warming. Moreover, considering that recent studies of ocean warming typically focus on surface data only, our results show the necessity of subsurface data for the improved understanding of regional climate change impacts.

Preface

2022 International Conference on Sustainability and Technology in Climate Change: Adaptation Action (IC-STCC 2022)The 2022 International Conference on Sustainability and Technology in Climate Change: Adaptation Action (IC-STCC 2022) was organized by the E-Governance and Sustainability Institute (ESi). The IC-STCC 2022 is one of ESI annual events that aims to expand the promotion of research and publications related to the advancement of sustainability and technology in climate change studies. Sustainability and Technology in Climate Change: Adaptation Action is the main theme of ICSTCC 2022, with numerous sub-themes including sustainable development issues, climate change, biodiversity, artificial intelligence, technology, internet of things, social science, and social sustainability, politics, economy, gender, culture, and science, among others. This international conference was conducted in Yogyakarta, Indonesia. Due to Covid-19 pandemics and severe regulations in Indonesia, this meeting was held online (virtually). Furthermore, to prevent the spread of the pandemic, several daily activities that can create crowds or people to congregate have been limited by imposing stringent health procedures. As a result, the IC-STCC 2022 organizers are concerned about health, and we want to do our share to keep everyone safe by holding meetings virtually. However, the participants’ enthusiasm did not prevent them from contributing ideas based on the authors’ research. Even though organized through online and challenged by Covid-19, there are more than 120 people from six countries, including Indonesia, Thailand, Finland, Netherlands, Taiwan, and Malaysia, participated in this event, which featured 65 well-presented quality papers. The earth is vulnerable to climate change risks such as glacier retreat, rising temperatures, Climate change concerns include glacier retreat, rising temperatures, and more varied and extreme weather events. However, there are significant gaps in our understanding of regional climate change and how it will affect human and environmental systems, making it difficult to foresee, plan for, and adapt to the coming changes. The Internet of Things paradigm in this area can improve our understanding of regional climate by utilizing technology solutions, while also providing the dynamic climate elements based on integrated environmental sensing and communications that are required to support climate change impacts assessments in each of the related areas. Researchers can aid citizens, communities, and organizations in meeting the problem of digital sustainability. Climate change is one of the most important global issues confronting humanity today, with potentially disastrous long-term consequences for individuals, organizations, and nations. Combating climate change is a global effort, and a variety of actions and efforts, such as reducing greenhouse gas emissions and fulfilling carbon emission targets, energy efficiency projects, and renewable energy investments, have been widely implemented worldwide. Digital technology may play two critical roles in enhancing sustainability results and tackling concerns such as climate change. The first is that of an enabler, in which digital solutions can be deployed to remedy problems. The second is the technology itself, which piques people’s interest in conversations about the environment. The background of the theme taken in this conference is the Internet of Things for environmental sustainability and climate change. We, the committee, hope that the papers at this conference will contribute to the development and support of future research.List of Editorial Boards, Peer Reviewer, Committee are available in this pdf.

A 40‐year climatology of summer heavy hourly rainfall over mountainous Shanxi in China

AbstractIn this study, a statistical analysis of the spatiotemporal characteristics of summer heavy hourly rainfall (HHR) events during 1979–2018 over mountainous Shanxi Province is performed in order to examine regional climate change over such a transition region between North China and Northwest China. Results show that the regional 40‐year annual mean summer rainfall is about 272 mm, about 37% of which is associated with HHR events. High‐frequency and high‐intensity HHR events tend to take place in eastern mountainous subregions, whereas most basin subregions experience HHR events with low frequency and low intensity, showing the important influences of local topography and its interaction with prevailing large‐scale flows. The important topographical influences are also reflected by the observations that most mountainous subregions exhibit a major late‐afternoon peak with a secondary early morning maximum, and that the associated diurnal variations are much greater in amplitude than those in basin subregions. It is found that the regional total annual summer rainfall has a decreasing trend during the first 20 years, mostly by non‐HHR contributions, but a rapid increasing trend during the recent 20 years, with dominant HHR contributions. Most subregions with the increasing trends of HHR frequency are those dominated by rapidly increasing surface temperatures. In particular, more frequent HHR events occur over major urbanization areas, that are in close proximity to complex topography, during the recent two decades. The decadal trends in HHR are found to be correlated to the distribution and intensity changes of the East Asian summer monsoon. The above results have important implications to the operational prediction of HHR events, and a better understanding of regional climate change over mountainous Shanxi Province.

The Holocene lake-evaporation history of the afro-alpine Lake Garba Guracha in the Bale Mountains, Ethiopia, based on δ18O records of sugar biomarker and diatoms

AbstractIn eastern Africa, there are few long, high-quality records of environmental change at high altitudes, inhibiting a broader understanding of regional climate change. We investigated a Holocene lacustrine sediment archive from Lake Garba Guracha, Bale Mountains, Ethiopia, (3,950 m asl), and reconstructed high-altitude lake evaporation history using δ18O records derived from the analysis of compound-specific sugar biomarkers and diatoms. The δ18Odiatom and δ18Ofuc records are clearly correlated and reveal similar ranges (7.9‰ and 7.1‰, respectively). The lowest δ18O values occurred between 10–7 cal ka BP and were followed by a continuous shift towards more positive δ18O values. Due to the aquatic origin of the sugar biomarker and similar trends of δ18Odiatom, we suggest that our lacustrine δ18Ofuc record reflects δ18Olake water. Therefore, without completely excluding the influence of the ‘amount-effect’ and the ‘source-effect’, we interpret our record to reflect primarily the precipitation-to-evaporation ratio (P/E). We conclude that precipitation increased at the beginning of the Holocene, leading to an overflowing lake between ca. 10 and ca. 8 cal ka BP, indicated by low δ18Olake water values, which are interpreted as reduced evaporative enrichment. This is followed by a continuous trend towards drier conditions, indicating at least a seasonally closed lake system.

June–July Temperature Reconstruction of Kashmir Valley from Tree Rings of Himalayan Pindrow Fir

The Himalaya is one of the major mountain ecosystems that is most likely to be impacted by climate change. The main drawback in understanding climate change in the remote Himalayan ecosystems is the lack of long-term instrumental climate records. Reconstructing past climates from tree-rings offers a useful proxy for adding data to the instrumental climate records. In this study, climatically sensitive tree-rings of Himalayan fir (Abies pindrow) were used for reconstruction of mean June–July temperatures of Kashmir valley. Total ring-width chronology was built from 60 tree-ring cores growing near the higher altitudinal limits of the species. The radial growth showed a strong positive response to growing season temperature. The strong response of site chronology to mean June–July temperatures was used for reconstruction purposes. Mean June–July temperatures of Kashmir valley were reconstructed since 1773 from residual site chronology. Though the reconstruction did not show any strong long-term trend, on a centennial-scale, 20th-century summers were the warmest with a mean annual summer temperature of 22.99 °C. Seven of the warmest years and five of the warmest decades were seen in the 20th century. The reconstruction for 1773–2012 showed 23 extreme hot summers above the hot threshold of a 23.47 °C mean temperature and 19 extreme cold years below the cold threshold of a 22.46 °C mean summer temperature. The cold years in the reconstruction did not coincide with known volcanic eruptions. This reconstruction will help in providing a better understanding of regional climate change.

Long‐term variability and trends in meteorological droughts in Western Europe (1851–2018)

AbstractWe analysed long‐term variability and trends in meteorological droughts across Western Europe using the Standardized Precipitation Index (SPI). Precipitation data from 199 stations spanning the period 1851–2018 were employed, following homogenisation, to derive SPI‐3 and SPI‐12 series for each station, together with indices on drought duration and severity. Results reveal a general absence of statistically significant long‐term trends in the study domain, with the exception of significant trends at some stations, generally covering short periods. The largest decreasing trends in SPI‐3 (i.e., increasing drought conditions) were found for summer in the British and Irish Isles. In general, drought episodes experienced in the last two or three decades have precedents during the last 170·years, emphasizing the importance of long records for assessing change. The main characteristic of drought variability in Western Europe is its strong spatial diversity, with regions exhibiting a homogeneous temporal evolution. Notably, the temporal variability of drought in Western Europe is more dominant than long‐term trends. This suggests that long‐term drought trends cannot be confirmed in Western Europe using precipitation records alone. This study provides a long‐term regional assessment of drought variability in Western Europe, which can contribute to better understanding of regional climate change during the past two centuries.

Climatic change in southern Kazakhstan since 1850 C.E. inferred from tree rings.

Although global warming is an indisputable fact, there is still uncertainty about how climate change will occur at regional levels. Kazakhstan is the largest landlocked country in the world. To best manage this country's limited water resources, socio-economic development and environmental protection, a solid understanding of regional climate change impacts is needed. In this study, tree-ring width and δ13C chronologies were established based on 99 tree-ring samples of Schrenk spruce (Picea schrenkiana Fisch. et Mey.) collected in Almaty, Kazakhstan. Climate response analysis between the tree-ring chronologies and climate data indicates that summer mean temperature is the strongest climate signal recorded by tree-ring δ13C. We reconstructed temperature change in southern Kazakhstan since 1850 C.E. using the tree-ring δ13Ccorr chronology. The results show that the temperatures in southern Kazakhstan have risen at a rate of about 0.27°C per decade over the past 166years. However, the rate has increased by as much as 0.44°C per decade over the past 30years. Analyses of temperature and precipitation data show that the climate has alternated between warm-dry and cold-humid periods over the past 166years. The extreme droughts of 1879, 1917 and 1945 were caused by the combination of continuously high temperatures and reduced precipitation.

Snow depth reconstruction over last century: Trend and distribution in the Tianshan Mountains, China

Abstract Clarifying the long-term variations in snow depth is important for hydrological, meteorological and ecological implications. However, the short period of snow depth records in the mountains has made the assessment of regional long-term variation of snow depth difficult. Based on reanalysis datasets from 1901 to 2014 as well as observational data from 1961 to 2014, this study applied the artificial neural networks (ANN) method to reconstruct the historical snow depths in the Tianshan Mountains of China from 1901 to 1960. The variations in monthly snow depth were analyzed during the periods of 1901–1960, 1961–2014, and 1901–2014 as historical, observed, and overall periods, respectively. The results indicated that the reconstructed snow depths captured the long-term variation and spatial distribution in the study area. For temporal scale, increases in snow depth were detected in the southern and eastern Tianshan Mountains during all three periods. The trends in snow depth indicated an increase in the western, northern and overall Tianshan Mountains during the periods of 1901–1960 and 1961–2014, but showed a decrease during the overall period of 1901–2014. The difference in variation of snow depth trends in different temporal scales indicates that the time scale of snow depth increase is decadal rather than centennial. For spatial scale, higher values of snow depth occurred in the western and northern Tianshan Mountains, while lower ones appeared in the southern and eastern Tianshan Mountains. In addition, the increasing trend in the reconstructed snow depth was more profound with increased elevation in the Tianshan Mountains during 1901–1960, with the smallest increasing rate at the elevation of 1000 m–1500 m. Although some uncertainties exist within the reconstruction, this work proposed a method for developing historical snow depth for observation-limited areas, which provided additional data for hydrological and ecological simulation. The results also allow us to achieve a better understanding of regional climate change.

Eddy covariance measurements of water vapor and energy flux over a lake in the Badain Jaran Desert, China

Exploring the surface energy exchange between atmosphere and water bodies is essential to gain a quantitative understanding of regional climate change, especially for the lakes in the desert. In this study, measurements of energy flux and water vapor were performed over a lake in the Badain Jaran Desert, China from March 2012 to March 2013. The studied lake had about a 2-month frozen period (December and January) and a 10-month open-water period (February–November). Latent heat flux (LE) and sensible heat flux (Hs) acquired using the eddy covariance technique were argued by measurements of longwave and shortwave radiation. Both fluxes of longwave and shortwave radiation showed seasonal dynamics and daily fluctuations during the study period. The reflected solar radiation was much higher in winter than in other seasons. LE exhibited diurnal and seasonal variations. On a daily scale, LE was low in the morning and peaked in the afternoon. From spring (April) to winter (January), the diurnal amplitude of LE decreased slowly. LE was the dominant heat flux throughout the year and consumed most of the energy from the lake. Generally speaking, LE was mostly affected by changes in the ambient wind speed, while Hs was primarily affected by the product of water-air temperature difference and wind speed. The diurnal LE and Hs were negatively correlated in the open-water period. The variations in Hs and LE over the lake were differed from those on the nearby land surface. The mean evaporation rate on the lake was about 4.0 mm/d over the entire year, and the cumulative annual evaporation rate was 1445 mm/a. The cumulative annual evaporation was 10 times larger than the cumulative annual precipitation. Furthermore, the average evaporation rates over the frozen period and open-water period were approximately 0.6 and 5.0 mm/d, respectively. These results can be used to analyze the water balance and quantify the source of lake water in the Badain Jaran Desert.

Late-Holocene vegetation dynamics in response to a changing climate and anthropogenic influences – Insights from stratigraphic records and subfossil trees from southeast Lithuania

To increase our understanding of long-term climate dynamics and its effects on different ecosystems, palaeoclimatic and long-term botanical reconstructions need to be improved, in particular in underutilized geographical regions. In this study, vegetation, (hydro)climate, and land-use changes were documented at two southeast Lithuanian peatland complexes – Čepkeliai and Rieznyčia – for the Late-Holocene period. The documentation was based on a combination of pollen, plant macrofossils, peat stratigraphic records, and subfossil trees. Our results cover the last two millennia and reveal the existence of moist conditions in Southern Lithuania between 300 and 500 CE and from 950 to 1850 CE. Conversely, changes towards warmer and/or dryer conditions have been recorded in 100, 600, and 750 CE, and since the 1850s. Significant differences with other Baltic proxies prevent deriving a complete and precise long-term reconstruction of past hydroclimatic variability at the regional scale. Yet, our results provide an important cornerstone for an improved understanding of regional climate change, i.e. in a region for which only (i) few detailed palaeobotanical studies exist and which has, in addition, been considered as (ii) an ecologically sensitive region at the interface between the temperate and boreal bioclimatic zones.

Towards predictive understanding of regional climate change

This Review considers recent advances in our understanding of regional climate change, critically discusses outstanding issues, and recommends targets for future research. Regional information on climate change is urgently needed but often deemed unreliable. To achieve credible regional climate projections, it is essential to understand underlying physical processes, reduce model biases and evaluate their impact on projections, and adequately account for internal variability. In the tropics, where atmospheric internal variability is small compared with the forced change, advancing our understanding of the coupling between long-term changes in upper-ocean temperature and the atmospheric circulation will help most to narrow the uncertainty. In the extratropics, relatively large internal variability introduces substantial uncertainty, while exacerbating risks associated with extreme events. Large ensemble simulations are essential to estimate the probabilistic distribution of climate change on regional scales. Regional models inherit atmospheric circulation uncertainty from global models and do not automatically solve the problem of regional climate change. We conclude that the current priority is to understand and reduce uncertainties on scales greater than 100 km to aid assessments at finer scales.

An automated scheme for glacial lake dynamics mapping using Landsat imagery and digital elevation models: a case study in the Himalayas

Glacial lakes in alpine regions are sensitive to climate change. Mapping and monitoring these lakes would improve our understanding of regional climate change and glacier-related hazards. However, glacial lake mapping over large areas using remote sensing remains a challenge because of various disturbing factors in glacial and periglacial environments. This article presents an automated mapping algorithm based on hierarchical image segmentation and terrain analysis to delineate glacial lake extents. In this algorithm, each glacial lake is delineated with a local segmentation value, and the topographic features derived from digital elevation models (DEMs) are also used to separate mountain shadows from glacial lakes. About 100 scenes of Landsat Thematic Mapper/Enhanced Thematic Mapper Plus (TM/ETM+) images from circa 1990, circa 2000 and 2009 were used to map the glacial lakes and their changes over the entire Himalayas. The results show that the algorithm can map the glacial lakes effectively and efficiently. Mountain shadows or melting glaciers can be differentiated from glacial lakes automatically, and those lakes with mountain shadows can also be identified. Area changes of more than 1000 glacial lakes show that the glacial lakes in the Himalayas have experienced mixed directions of change, while the overall lake areas are expanding at an accelerated rate in the past two decades, indicating great changes to the glacial lakes in the Himalayas.

Indigenous Australians’ knowledge of weather and climate

Although the last 200 years of colonisation has brought radical changes in economic and governance structures for thousands of Aboriginal and Torres Strait Islanders living in remote areas of northern Australia, many of these Indigenous people still rely upon, and live closely connected to, their natural environment. Over millennia, living ‘on country’, many of these communities have developed a sophisticated appreciation of their local ecosystems and the climatic patterns associated with the changes in them. Some of this knowledge is recorded in their oral history passed down through generations, documented in seasonal weather calendars in local languages and, to a limited degree, transcribed and translated into English. This knowledge is still highly valued by these communities today, as it is used to direct hunting, fishing and planting as well as to inform many seasonally dependant cultural events. In recent years, local observations have been recognised by non-Indigenous scientists as a vital source of environmental data where few historic records exist. Similar to the way that phenological observations in the UK and US provide baseline information on past climates, this paper suggests that Indigenous observations of seasonal change have the potential to fill gaps in climate data for tropical northern Australia, and could also serve to inform culturally appropriate adaptation strategies. One method of recording recent direct and indirect climate and weather observations for the Torres Strait Islands is documented in this paper to demonstrate the currency of local observations of climate and its variability. The paper concludes that a comprehensive, participatory programme to record Aboriginal and Torres Strait Islander knowledge of past climate patterns, and recent observations of change, would be timely and valuable for the communities themselves, as well as contributing to a greater understanding of regional climate change that would be useful for the wider Australian population.