Effects of human activities and climate change on the reduction of visibility in Beijing over the past 36 years

2018 ◽  
Vol 116 ◽  
pp. 92-100 ◽  
Author(s):  
Xuwu Chen ◽  
Xiaodong Li ◽  
Xingzhong Yuan ◽  
Guangming Zeng ◽  
Jie Liang ◽  
...  
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
The Past

The impact of climate change and human activities on the Aral Sea Basin over the past 50 years

2020 ◽  
Vol 245 ◽  
pp. 105125 ◽  
Author(s):  
Xuanxuan Wang ◽  
Yaning Chen ◽  
Zhi Li ◽  
Gonghuan Fang ◽  
Fei Wang ◽  
...  
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Aral Sea ◽  
Aral Sea Basin ◽  
Impact Of Climate Change ◽  
The Past ◽  
The Impact

scholarly journals Assessment of Anthropogenic Impact versus Climate Change on the Succession of the Diatom Community in Lugu Lake (Yunnan-Guizhou Plateau, China) Using the Sedimentary Record of Geochemical Elements

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 655 ◽  
Author(s):  
Yi Liu ◽  
Chuanhong Chen ◽  
Shao Yang
Keyword(s):  
Climate Change ◽  
Human Impact ◽  
Human Activities ◽  
Anthropogenic Sources ◽  
Diatom Community ◽  
The Third ◽  
The Past ◽  
Third Stage ◽  
Lugu Lake ◽  
Guizhou Plateau

The lake ecosystems on the Yunnan-Guizhou Plateau in China have degraded in recent decades under the effects of anthropogenic activities and climate change. The human impact on the oligotrophic Lugu Lake aquatic ecosystem was evaluated using the sediment records of metals, nitrogen isotopes (δ15N) and magnetic susceptibility over the past 200 years. Three periods were identified based on the trace metal and δ15N records. During the first stage (1816–1976 AD), the concentrations of metals, δ15N and magnetic susceptibility were low with small variations. The anthropogenic contributions to the inputs were also small, except for Ni, reflecting minor human activities in the watershed, and no significant change was observed in the sediment record of the diatom assemblage. During the second stage (1976–2001 AD), the concentrations of Zn and δ15N increased, as well as the anthropogenic contribution of Zn. However, no significant change was detected in the anthropogenic sources of the other metals. These results reflect the low-level use of chemical fertilizers. The major shift in the sediment diatom assemblage during this stage was mainly attributed to regional climate change. During the third stage (2001–2010 AD), the concentrations of the sedimentary metals (Ni, Cr, Mn, Cu, Hg and Al) increased rapidly, with the exception of As and Zn, and a similar increasing trend was observed in the changes by anthropogenic sources of Ni, Cr, Mn and Cu. RDA (Redundancy Analysis) and variance partitioning analysis showed that the human impact and climate proxies independently explained 31.59% and 4.26% of the change of diatom community, respectively, and the interaction between climate change and human impact accounted for 18.61% of the change of diatom community. Tourism-dominated human activities, which were reflected in the metals profiles, facilitated the dominance of eutrophic species and reduced that of oligotrophic species. The development of tourism was likely the main driving force for the succession of diatom assemblages in the third stage. In summary, the anthropogenic input of trace metals in Lugu Lake is still at a low level. However, the significant growth trend in metals over the past decade is significantly related to the change in the lake ecosystem. Therefore, the effects of human activities, especially tourism, on the watershed should be controlled for the protection of the oligotrophic Lugu Lake.

The Bakerian Lecture, 1991 The predictability of weather and climate

1991 ◽  
Vol 337 (1648) ◽  
pp. 521-572 ◽  
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Human Activities ◽  
Radiative Forcing ◽  
El Nino ◽  
Numerical Models ◽  
Milankovitch Cycles ◽  
The Past ◽  
Weather And Climate ◽  
Sst Anomalies

There is large public and political interest in the predictability of weather and climate, in particular in the influence of human activities on the likely climate change during the next century. Numerical models are the main tools which enable the nonlinear processes involved in the dynamics and physics of the atmosphere and other components of the climate system to be integrated in an effective way. The performance of such models used for weather forecasting has continued to improve as more accurate data with better coverage has become available, as improved descriptions of the physics and dynamics have been incorporated and as computing capacity and speed have increased. Studies of the predictability with models suggest that with further improvements in data and models deterministic forecasting of detailed weather may ultimately have useful skill up to 2-3 weeks ahead. Beyond the limit of deterministic forecasting, some skill remains for the forecasting of general weather patterns which can be pursued by studying ensembles of model forecasts from slightly varying initial conditions. The largest difficulty with further improvements of numerical models lies in their inadequate treatment of the motions too small to be explicitly resolved. Interactions between the atmosphere and the ocean are responsible for substantial variations on seasonal, interannual and longer timescales. Forecasts are being provided of seasonal precipitation in the Sahel region of Africa based on a knowledge of global sea surface tem perature (SST) anomalies together with the assumption that such anomalies tend to persist from one season to the next. Attempts to forecast SST anomalies have centred on tropical regions in particular on the El Nino. Simple models show some skill in forecasting El Nino events 3-9 months in advance. Studies with more elaborate models which as yet only show partial success in simulating these events demonstrate the complex nature of the interactions involved. Turning to the likely changes in climate next century: if no changes occur in the atmosphere other than the increase in C0 2 and other greenhouse gases due to human activities, the increase in radiative forcing due to a doubling of atmospheric C0 2 concentration would lead to an increase of about 1.2 °C in global average temperature. Water vapour and ice-albedo feedbacks raise this to a figure of about 2.5 °C (with an uncertainty range of 1.5—4.5 °C) as estimated by the Intergovernmental Panel for Climate Change. Such a change would dominate over forcing likely to arise from other factors, and this estim ated rate of change next century is probably greater than any which has occurred on earth during the past 10000 years. The main uncertainties in climate change predictions arise from the inadequacies of the models in their descriptions of cloud-radiation and ocean circulation feedbacks. Until there is more confidence in the treatment of these feedbacks there are bound to be large uncertainties associated with any predictions of regional climate change. To reduce the uncertainties there need to be improvements in computer power, in model formulation and in our understanding of climate processes together with a large programme of observations of climate parameters to provide early detection of climate change and to provide validation of climate models and to provide data for initialization of model integrations. An important question is whether changes in climate due to changes in radiative forcing are predictable. It is pointed out that the response to climate over the past half million years to changes in forcing due to the variations in the Earth ’s orbit (Milankovitch cycles) is a regular one; some 60% of variations in the global temperature as established from the palaeontological record occur near frequencies of the Milankovitch cycles. We can, therefore, expect the changes in climate due to increasing greenhouse gases to be a largely predictable response. Large, but probably predictable, changes in the circulation of the deep ocean have modified climate change during past epochs and could have significant influence on future climate change.

scholarly journals Quantifying Contributions of Climate Change and Local Human Activities to Runoff Decline in the Second Songhua River Basin

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2659
Author(s):  
Bao Shanshan ◽  
Yang Wei ◽  
Wang Xiaojun ◽  
Li Hongyan
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Human Activities ◽  
Annual Runoff ◽  
Songhua River ◽  
Songhua River Basin ◽  
The Past ◽  
Runoff Change ◽  
Significant Downward Trend ◽  
The Second Songhua River

In the past several decades, climate change and human activities have influenced hydrological processes, and potentially caused more frequent and extensive flood and drought risks. Therefore, identification and quantification of the driving factors of runoff variation have become a hot research area. This paper used the trend analysis method to show that runoff had a significant downward trend during the past 60 years in the Second Songhua River Basin (SSRB) of Northeast China. The upper, middle, and lower streams of five hydrological stations were selected to analyze the breakpoint of the annual runoff in the past 60 years, and the breakpoints were used to divide the entire study period into two sub-periods (1956–1974 and 1975–2015). Using the water–energy coupling balance method based on Choudhury–Yang equation, the climatic and catchment landscape elasticity coefficient of the annual runoff change was estimated, and attribution analysis of the runoff change was carried out for the Fengman Reservoir and Fuyu stations in SSRB. The change in potential evapotranspiration has a weak effect on the runoff, and change in precipitation and catchment landscape were the leading factors affecting runoff. Impacts of climate change and land cover change were accountable for the runoff decrease by 80% and 11% (Fengman), 17% and 206% (Fuyu) on average, respectively; runoff was more sensitive to climate change in Fengman, and was more sensitive to catchment landscape change in Fuyu. In Fengman, the population was small, owing to the comparatively inhospitable natural conditions, and so human activities were low. However, in Fuyu, human activities were more intensive, and so had more impact on runoff for the Lower Second Songhua River compared to the Upper Second Songhua River.

9. The future of our oceans

2020 ◽  
pp. 167-174
Author(s):  
Philip V. Mladenov
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Marine Ecosystems ◽  
The State ◽  
The Past ◽  
The Future ◽  
Impacts Of Climate Change

Current marine ecosystems have profoundly changed since the pre-industrial era and the pace of change has accelerated greatly over the past four decades. What will be the state of our oceans in 2050? Are we capable of plotting a new course and reversing many of the most severe impacts we have had on the oceans so far? ‘The future of our oceans’ explains that recent studies have shown that no ocean wilderness remains anywhere on the planet since the impacts of climate change and human activities are so widespread and unmanageable. The challenge now is to find ways to stabilize and prevent the further degradation of marine ecosystems and embark on a path of ocean restoration.

Human impacts, climate change, and aquatic ecosystem response during the past 2000 yr at Lake Wandakara, Uganda

2009 ◽  
Vol 72 (3) ◽  
pp. 315-324 ◽  
Author(s):  
James M. Russell ◽  
S.J. McCoy ◽  
D. Verschuren ◽  
I. Bessems ◽  
Y. Huang
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Human Impacts ◽  
Organic Geochemistry ◽  
Abundance Ratio ◽  
Terrestrial Vegetation ◽  
The Past ◽  
Leaf Waxes ◽  
Hydrogen Isotope Ratios ◽  
Abrupt Shifts

AbstractAnalyses of carbon and hydrogen isotope ratios of terrestrial leaf waxes and the carbon and nitrogen abundance, ratio, and isotopic composition of bulk sediments from Lake Wandakara, a crater lake in western Uganda, East Africa, document human and climatic controls on the aquatic system and on the surrounding terrestrial vegetation during the past two millennia. Our data indicate that Wandakara was a relatively stable, productive lake surrounded by C3 vegetation from AD 70 to 1000. Abrupt changes in the δ13C of terrestrial leaf waxes indicate a series of abrupt shifts in the relative abundance of C3 and C4 vegetation caused by a combination of climate change and human activities around Wandakara beginning at AD 1000. Abrupt shifts in bulk sediment organic geochemistry, particularly C/N ratios and δ15N, indicate that human activities at this time caused permanent changes in the limnology of Lake Wandakara, including eutrophication. Our results suggest that the biogeochemistry of Lake Wandakara was more sensitive to shifting human impacts than to climate variations during the past millennium, highlighting the importance of understanding the intensity of pre-colonial human impacts on Africa's aquatic ecosystems.

scholarly journals A 100-year record of climate change and human activities inferred from the geochemical composition of sediments in Chaiwopu Lake, arid northwest China

2016 ◽  
Author(s):  
Wen Liu ◽  
Jinglu Wu ◽  
Xiangliang Pan
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Chemical Weathering ◽  
Northwest China ◽  
Past Century ◽  
Surface Erosion ◽  
Geochemical Composition ◽  
The Past ◽  
Element Concentrations ◽  
Arid Northwest China

An 81-cm sediment core from Chaiwopu Lake in arid northwest China was analyzed for <sup>137</sup>Cs activity and concentrations of major and trace elements. We used these data to discriminate between the influence of climate change and human activities on the geochemical change of the lake sediments over the past century. Elements Al, K, Ba, Ti, V, Fe, Ni, Mn, Li, and Be were mainly from detrital. Ca, Sr, and Mg concentrations were controlled by chemical weathering processes. Na came mainly from salt precipitation caused by a decline in water level. Enrichment factors for Pb and P in recent deposits are large, indicating they were influenced by human activies. Geochemical conditions during the past century can be divided into three stages: i) From ca. 1900 to the1950s element concentrations varied widely and frequently. In general, concentrations of typical mobile elements Ca, Sr, and Mg stay relatively high whereas values for other elements remained relatively low. This was interpreted to reflect variable climate under conditions of weak surface erosion intensity. ii) From the 1950s to the early 2000s, element concentrations display less variability. The Al, K, Ba, Ti, P, Cr, V, Fe, Ni, Mn, Co, Cu, Li, Zn, Be, Pb, and Na contents were generally higher, whereas contents of Ca, Sr, and Mg were on average lower. This indicates that the regional environment was conducive to surface erosion. Enrichment of trace metals and major elements in the sediment reflects enhanced human activities. iii) In the last decade, Pb and P exhibited a great increase, possibly associated with the input from fossil fuel combustion, sewage discharge and non-point-source pollution in the watershed. The lake volume decreased substantially because of groundwater extraction for municipal water, which resulted in a marked increase in salinity and enhanced Na precipitation.

Influences of climate change and human activities on Tarim River runoffs in China over the past half century

2011 ◽  
Vol 67 (1) ◽  
pp. 231-241 ◽  
Author(s):  
Haiying Zhou ◽  
Xiaolei Zhang ◽  
Hailiang Xu ◽  
Hongbo Ling ◽  
Pujia Yu
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Tarim River ◽  
Half Century ◽  
The Past ◽  
Past Half Century ◽  
Past Half
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