scholarly journals Impact of future land cover changes on HNO<sub>3</sub> and O<sub>3</sub> surface dry deposition

2015 ◽  
Vol 15 (13) ◽  
pp. 18459-18485
Author(s):  
T. Verbeke ◽  
J. Lathière ◽  
S. Szopa ◽  
N. de Noblet-Ducoudré
Keyword(s):  
Climate Change ◽  
Land Cover ◽  
Land Cover Change ◽  
Dry Deposition ◽  
Chemical Properties ◽  
Land Cover Changes ◽  
Vegetation Distribution ◽  
The Future ◽  
Change Impact ◽  
The Impact

Abstract. Dry deposition is a key component of surface–atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries, and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between present-day (2006) and the future (2050) on dry deposition rates, with special interest for ozone (O3) and nitric acid vapor (HNO3), two compounds which are characterized by very different physico-chemical properties. The 3-D chemistry transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections RCPs 2.6, 4.5 and 8.5. The 2050 RCP 8.5 vegetation distribution leads to a rise up to 7 % (+0.02 cm s−1) in VdO3 and a decrease of −0.06 cm s−1 in VdHNO3 relative to the present day values in tropical Africa, and up to +18 and −15 % respectively in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land cover change in Eurasia, VdHNO3 increases by up to 20 % (annual-mean value) and reduces VdO3 by the same magnitude in this region. When analyzing the impact of dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual mean surface ozone concentration, for both for the RCP8.5 and RCP2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios, regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a significant increase of the surface O3 concentration reaching locally up to 5 ppb (+5 %) is calculated on average during the June–August period. This scenario induces also an increase of HNO3 deposited flux exceeding locally 10 % for monthly values. Comparing the impact of land-cover change to the impact of climate change, considering a 0.93 °C increase of global temperature, on dry deposition velocities, we estimate that the strongest increase over lands occurs in the North Hemisphere during winter especially in Eurasia, by +50 % (+0.07 cm s−1) for VdO3 and +100 % (+0.9 cm s−1) for VdHNO3. However, different regions are affected by both changes, with climate change impact on deposition characterized by a latitudinal gradient, while the land-cover change impact is much more heterogeneous depending on vegetation distribution modification described in the future RCP scenarios. The impact of long-term land-cover changes on dry deposition is shown to be non-negligible and should be therefore considered in biosphere-atmospheric chemistry interaction studies in order to have a fully consistent picture.

scholarly journals Impact of future land-cover changes on HNO<sub>3</sub> and O<sub>3</sub> surface dry deposition

2015 ◽  
Vol 15 (23) ◽  
pp. 13555-13568 ◽  
Author(s):  
T. Verbeke ◽  
J. Lathière ◽  
S. Szopa ◽  
N. de Noblet-Ducoudré
Keyword(s):  
Land Cover ◽  
Land Cover Change ◽  
Dry Deposition ◽  
Deposition Velocity ◽  
Land Cover Changes ◽  
Vegetation Distribution ◽  
Deposition Velocities ◽  
The Future ◽  
Rcp 8.5 ◽  
The Impact

Abstract. Dry deposition is a key component of surface–atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between the present day (2006) and the future (2050) on dry deposition velocities at the surface, with special interest for ozone (O3) and nitric acid (HNO3), two compounds which are characterized by very different physicochemical properties. The 3-D chemistry-transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections, RCPs 2.6, 4.5 and 8.5, and present-day (2007) meteorology. The 2050 RCP 8.5 vegetation distribution leads to a rise of up to 7 % (+0.02 cm s−1) in the surface deposition velocity calculated for ozone (Vd,O3) and a decrease of −0.06 cm s−1 in the surface deposition velocity calculated for nitric acid (Vd,HNO3) relative to the present-day values in tropical Africa and up to +18 and −15 %, respectively, in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land-cover change in Eurasia, Vd,HNO3 increases by up to 20 % (annual-mean value) and reduces Vd,O3 by the same magnitude in this region. When analyzing the impact of surface dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual-mean surface ozone concentration for both the RCP 8.5 and RCP 2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a significant increase of the surface O3 concentration reaching locally by up to 5 ppb (+5 %) is calculated on average during the June–August period. This scenario also induces an increase of HNO3 deposited flux exceeding locally 10 % for monthly values. Comparing the impact of land-cover change to the impact of climate change, considering a 0.93 °C increase of global temperature, on dry deposition velocities, we estimate that the strongest increase over lands occurs in the Northern Hemisphere during winter, especially in Eurasia, by +50 % (+0.07 cm s−1) for Vd,O3 and +100 % (+0.9 cm s−1) for Vd,HNO3. However, different regions are affected by both changes, with climate change impact on deposition characterized by a latitudinal gradient, while the land-cover change impact is much more heterogeneous depending on vegetation distribution modification described in the future RCP scenarios. The impact of long-term land-cover changes on dry deposition is shown to be significant and to differ strongly from one scenario to another. It should therefore be considered in biosphere–atmospheric chemistry interaction studies in order to have a fully consistent picture.

scholarly journals Quantitative analysis of the impacts of climate and land-cover changes on urban flood runoffs: a case of Dar es Salaam, Tanzania

2021 ◽  
Author(s):  
Philip Mzava ◽  
Patrick Valimba ◽  
Joel Nobert
Keyword(s):  
Climate Change ◽  
Land Cover ◽  
Land Cover Change ◽  
Dar Es Salaam ◽  
Land Cover Changes ◽  
Urban Flooding ◽  
Combined Effects ◽  
Peak Flows ◽  
The Past ◽  
The Future

Abstract Over the past half-century, the risk of urban flooding in Dar es Salaam has increased due to changes in land cover coupled with climatic changes. This paper aimed to quantify the impacts of climate and land-cover changes on the magnitudes and frequencies of flood runoffs in urban Dar es Salaam, Tanzania. A calibrated and validated SWAT rainfall-runoff model was used to generate flood hydrographs for the period 1969–2050 using historical rainfall data and projected rainfall based on the CORDEX-Africa regional climate model. Results showed that climate change has a greater impact on change in peak flows than land-cover change when the two are treated separately in theory. It was observed that, in the past, the probability of occurrence of urban flooding in the study area was likely to be increased up to 1.5-fold by climate change relative to land-cover change. In the future, this figure is estimated to decrease to 1.1-fold. The coupled effects of climate and land-cover changes cause a much bigger impact on change in peak flows than any separate scenario; this scenario represents the actual scenario on the ground. From the combined effects of climate and land-cover changes, the magnitudes of mean peak flows were determined to increase between 34.4 and 58.6% in the future relative to the past. However, the change in peak flows from combined effects of climate and land-cover changes will decrease by 36.3% in the future relative to the past; owing to the lesser variations in climate and land-cover changes in the future compared with those of the past.

scholarly journals The Impact of Land Use/Land Cover Change (LULCC) on Water Resources in a Tropical Catchment in Tanzania under Different Climate Change Scenarios

2019 ◽  
Vol 11 (24) ◽  
pp. 7083 ◽  
Author(s):  
Kristian Näschen ◽  
Bernd Diekkrüger ◽  
Mariele Evers ◽  
Britta Höllermann ◽  
Stefanie Steinbach ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Water Resources ◽  
Land Cover ◽  
Water Balance ◽  
Land Cover Change ◽  
Sub Saharan Africa ◽  
Climate Change Scenarios ◽  
Land Use Land Cover ◽  
The Impact

Many parts of sub-Saharan Africa (SSA) are prone to land use and land cover change (LULCC). In many cases, natural systems are converted into agricultural land to feed the growing population. However, despite climate change being a major focus nowadays, the impacts of these conversions on water resources, which are essential for agricultural production, is still often neglected, jeopardizing the sustainability of the socio-ecological system. This study investigates historic land use/land cover (LULC) patterns as well as potential future LULCC and its effect on water quantities in a complex tropical catchment in Tanzania. It then compares the results using two climate change scenarios. The Land Change Modeler (LCM) is used to analyze and to project LULC patterns until 2030 and the Soil and Water Assessment Tool (SWAT) is utilized to simulate the water balance under various LULC conditions. Results show decreasing low flows by 6–8% for the LULC scenarios, whereas high flows increase by up to 84% for the combined LULC and climate change scenarios. The effect of climate change is stronger compared to the effect of LULCC, but also contains higher uncertainties. The effects of LULCC are more distinct, although crop specific effects show diverging effects on water balance components. This study develops a methodology for quantifying the impact of land use and climate change and therefore contributes to the sustainable management of the investigated catchment, as it shows the impact of environmental change on hydrological extremes (low flow and floods) and determines hot spots, which are critical for environmental development.

Impact of human intervention and climate change on the land cover change in the glacial affected area of the Tianshan Mountains

2020 ◽  
Author(s):  
Hong Wei ◽  
Liyang Xiong ◽  
Guoan Tang ◽  
Josef Strobl ◽  
Kaikai Xue
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Cover ◽  
Snow Cover ◽  
Land Cover Change ◽  
Human Activities ◽  
Tianshan Mountains ◽  
Human Intervention ◽  
Large Spatial Scale ◽  
The Impact

&lt;p&gt;&lt;strong&gt;Abstract&lt;/strong&gt;: Land use/land cover change (LULC) in glacial affected areas are driven by climate change and human activities. Monitoring and simulation of the spatial and temporal land cover changes in this special region provide scientific basis in understanding the natural environment, helping to reveal the impact of climate change and human activities on LULC. In this study, the Tianshan Mountains (TSM), located in the hinterland of Eurasia, were selected as the study area to investigate the LULC of the glacial affected areas. The relationship between LULC, human intervention and climate change on a large spatial scale were also analyzed. The LULC of the TSM in China for the past 35 years were analyzed using a dynamical change model, a landscape pattern index, a centroid transfer model, and geoinformation TUPU based on the land use data of 1980, 1990, 2000, and 2015. Results show that the areas of cultivated and built-up lands immensely increased by 45.87% and 187%, respectively. Correspondingly, the areas of bare land and ice and snow cover decreased by 27% and 38%, respectively. The land use change in the TSM was characterized by different stages, and high conversion rate and intensity were obtained from 2000 to 2015. The landscape change was mainly reflected in terms of the significant increase in the number of patches and the simplification and regularization of patch shapes. The spatial connectivity of different land use types increased. The temperature and precipitation in the region show an increasing trend, and the melting rate of ice and snow cover significantly accelerated. This study can help to achieve a dynamic LULC model to investigate the interacting influences of climate change and human activities in glacial affected areas.&lt;/p&gt;

scholarly journals Modelled land use and land cover change emissions – a spatio-temporal comparison of different approaches

2021 ◽  
Vol 12 (2) ◽  
pp. 635-670
Author(s):  
Wolfgang A. Obermeier ◽  
Julia E. M. S. Nabel ◽  
Tammas Loughran ◽  
Kerstin Hartung ◽  
Ana Bastos ◽  
...  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Land Cover Change ◽  
Environmental Conditions ◽  
Agricultural Land ◽  
Environmental Changes ◽  
Land Cover Changes ◽  
Environmental Forcing ◽  
The Impact ◽  
Global Carbon

Abstract. Quantifying the net carbon flux from land use and land cover changes (fLULCC) is critical for understanding the global carbon cycle and, hence, to support climate change mitigation. However, large-scale fLULCC is not directly measurable and has to be inferred from models instead, such as semi-empirical bookkeeping models and process-based dynamic global vegetation models (DGVMs). By definition, fLULCC estimates are not directly comparable between these two different model types. As an important example, DGVM-based fLULCC in the annual global carbon budgets is estimated under transient environmental forcing and includes the so-called loss of additional sink capacity (LASC). The LASC results from the impact of environmental changes on land carbon storage potential of managed land compared to potential vegetation and accumulates over time, which is not captured in bookkeeping models. The fLULCC from transient DGVM simulations, thus, strongly depends on the timing of land use and land cover changes mainly because LASC accumulation is cut off at the end of the simulated period. To estimate the LASC, the fLULCC from pre-industrial DGVM simulations, which is independent of changing environmental conditions, can be used. Additionally, DGVMs using constant present-day environmental forcing enable an approximation of bookkeeping estimates. Here, we analyse these three DGVM-derived fLULCC estimations (under transient, pre-industrial, and present-day forcing) for 12 models within 18 regions and quantify their differences as well as climate- and CO2-induced components and compare them to bookkeeping estimates. Averaged across the models, we find a global fLULCC (under transient conditions) of 2.0±0.6 PgC yr−1 for 2009–2018, of which ∼40 % are attributable to the LASC (0.8±0.3 PgC yr−1). From 1850 onward, the fLULCC accumulated to 189±56 PgC with 40±15 PgC from the LASC. Around 1960, the accumulating nature of the LASC causes global transient fLULCC estimates to exceed estimates under present-day conditions, despite generally increased carbon stocks in the latter. Regional hotspots of high cumulative and annual LASC values are found in the USA, China, Brazil, equatorial Africa, and Southeast Asia, mainly due to deforestation for cropland. Distinct negative LASC estimates in Europe (early reforestation) and from 2000 onward in the Ukraine (recultivation of post-Soviet abandoned agricultural land), indicate that fLULCC estimates in these regions are lower in transient DGVM compared to bookkeeping approaches. Our study unravels the strong dependence of fLULCC estimates on the time a certain land use and land cover change event happened to occur and on the chosen time period for the forcing of environmental conditions in the underlying simulations. We argue for an approach that provides an accounting of the fLULCC that is more robust against these choices, for example by estimating a mean DGVM ensemble fLULCC and LASC for a defined reference period and homogeneous environmental changes (CO2 only).

Identifying and quantifying the impact of non-climatic effects on the water cycle in a semi-arid environment 

2021 ◽  
Author(s):  
Julie Collignan ◽  
Jan Polcher ◽  
Pere Quintana Seguí
Keyword(s):  
Climate Change ◽  
Land Cover ◽  
Water Balance ◽  
Human Activities ◽  
River Discharge ◽  
Water Cycle ◽  
Land Cover Changes ◽  
Anthropogenic Changes ◽  
The Impact ◽  
Semi Arid

&lt;p&gt;In a context of climate change, the stakes surrounding water availability and use are getting higher,&amp;#160;especially in semi-arid climates. Human activities such as irrigation and land cover changes impact the water cycle, raising questions around the effects it could have on regional atmospheric circulation and how to separate the impact of climate change from the impact of anthropogenic activities to better understand their role in the historical records. The ORCHIDEE Land Surface Model from Institut Pierre Simon Laplace (IPSL) simulates global carbon cycle and aims at quantifying terrestrial water and energy balance. It is being developed at regional scale but does not include satisfying hypothesis to account for human activities such as irrigation at such scale so far.&lt;/p&gt;&lt;p&gt;We &lt;span&gt;propose&lt;/span&gt; a methodology to semi-empirically separate the effect of climate from the impact of the changing catchment characteristics on river discharge. &lt;span&gt;It is based on&lt;/span&gt; the Budyko framework and &lt;span&gt;allows to characterise the&lt;/span&gt; annual river discharge of over 363 river monitoring stations in Spain. The Budyko parameter is estimated for each basin and &lt;span&gt;represents&lt;/span&gt; its hydrological characteristics. Precipitations and potential evapotranspiration are derived from the forcing dataset GSWP3 (Global Soil Wetness Project Phase 3) &amp;#8211; from 1901 to 2010 &amp;#8211;. Two methods are used to estimate evapotranspiration : the first uses evapotranspiration from the ORCHIDEE LSM outputs while the second deduced evapotranspiration from river discharge observations and the water balance equation.&amp;#160;The first method only accounts for the effects of atmospheric forcing while the other combines, through the observations, &lt;span&gt;climatic and non-climatic processes&lt;/span&gt; over the watersheds.&amp;#160;We then study the evolution over the &lt;span&gt;Budyko&lt;/span&gt; parameter fitted with these two &lt;span&gt;estimates of evaporation&lt;/span&gt;. Studying the watershed parameter allows us to free ourselves from some of the climate interannual variability compared to directly looking at changes in the river discharge and better separate anthropogenic changes from the effect of climatic forcing.&lt;/p&gt;&lt;p&gt;Our results show that for most basins tested over Spain, there is an increasing trend in the &lt;span&gt;Budyko parameter representing increasing evaporation efficiency&lt;/span&gt; of the watershed which &lt;span&gt;can not be&lt;/span&gt; explained by the climate forcing. This trend is consistent with changes in irrigation equipment and land cover changes over the studied period. However changes of the basin characteristics can not be fully quantified by this variables. Other factors as glaciers melting which derails the water balance over our time of study.&lt;/p&gt;&lt;p&gt;The methodology needs to be extended to other areas such as Northern Europe to see if the differences in response of the catchments to anthropogenic changes quantified by our methodology corresponds to known contrasts. Balance between climatic and anthropogenic changes of basin characteristics are different in semi-arid climate than in northern more humid regions.&lt;/p&gt;

scholarly journals Modeling the Effects of Anthropogenic Land Cover Changes to the Main Hydrometeorological Factors in a Regional Watershed, Central Greece

Climate ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 129 ◽  
Author(s):  
Angeliki Mentzafou ◽  
George Varlas ◽  
Elias Dimitriou ◽  
Anastasios Papadopoulos ◽  
Ioannis Pytharoulis ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Cover ◽  
Case Studies ◽  
Air Temperature ◽  
River Discharge ◽  
Agricultural Land ◽  
Actual Evapotranspiration ◽  
Land Cover Changes ◽  
Central Greece ◽  
The Impact

In this study, the physically-based hydrological model MIKE SHE was employed to investigate the effects of anthropogenic land cover changes to the hydrological cycle components of a regional watershed in Central Greece. Three case studies based on the land cover of the years 1960, 1990, and 2018 were examined. Copernicus Climate Change Service E-OBS gridded meteorological data for 45 hydrological years were used as forcing for the model. Evaluation against observational data yielded sufficient quality for daily air temperature and precipitation. Simulation results demonstrated that the climatic variabilities primarily in precipitation and secondarily in air temperature affected basin-averaged annual actual evapotranspiration and average annual river discharge. Nevertheless, land cover effects can locally outflank the impact of climatic variability as indicated by the low interannual variabilities of differences in annual actual evapotranspiration among case studies. The transition from forest to pastures or agricultural land reduced annual actual evapotranspiration and increased average annual river discharge while intensifying the vulnerability to hydrometeorological-related hazards such as droughts or floods. Hence, the quantitative assessment of land cover effects presented in this study can contribute to the design and implementation of successful land cover and climate change mitigation and adaptation policies.

scholarly journals Regional Impacts of Climate and Land Cover on Ecosystem Water Retention Services in the Upper Yangtze River Basin

2019 ◽  
Vol 11 (19) ◽  
pp. 5300
Author(s):  
Pei Xu ◽  
Yingman Guo ◽  
Bin Fu
Keyword(s):  
Climate Change ◽  
Land Cover ◽  
Land Cover Change ◽  
River Basin ◽  
Yangtze River ◽  
Water Retention ◽  
Yangtze River Basin ◽  
Upper Yangtze River ◽  
The Impact ◽  
The Upper Yangtze River

Water retention is an important factor in ecosystem services, owing to its relationships with climate and land-cover change; however, quantifying the independent and combined impacts of these variables remains a challenge. We use scenario analysis and the InVEST model to assess individual or combined impacts of climate and land cover on water retention in the Upper Yangtze River Basin. Water retention decreased from 1986 to 2015 at a rate of 2.97 mm/10a in response to increasing precipitation (3.94 mm/10a) and potential evapotranspiration (16.47 mm/10a). The rate of water retention change showed regional variability (from 68 to −18 mm/a), with some eastern regions experiencing an increase and most other regions experiencing a decrease. Farmland showed the highest decrease (10,772 km2), with land mainly converted into forest (58.17%) and shrub land (21.13%) from 2000 to 2015. The impact of climate change (−12.02 mm) on water retention generally was greater than the impact of land cover change (−4.14 mm), at the basin scale. Among 22 climate zones, 77.27% primarily were impacted by climate change; 22.73% primarily were impacted by land cover change. Our results demonstrate that both individualistic and integrated approaches toward climate and vegetation management is necessary to mitigate the impacts of climate change on water resources.

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