Hydrodynamic evaluation of long term impacts of climate change and coastal effluents in the Arabian Gulf

Is the development of desalination compatible with sustainable development of the Arabian Gulf?

The development of desalination has been essential to the rapid economic development of the countries bordering the Arabian Gulf. The current production capacity of sea water desalination plants drawing water from Gulf is over 20 million m³ day^-1, which may rise to 80 million m³ day^-1 by 2050. Whilst supporting aspects of sustainable development related to water and sanitation, desalination impacts the marine environment through impingement and entrainment of organisms in intakes, and through thermal, brine and chemical discharges. This may compromise other objectives for sustainable development related to sustainable use of the oceans. Under business as usual scenarios, by 2050, the impact of individual desalination plants will combine causing a regional scale impact. Without mitigating actions to avoid the business as usual scenario, by 2050, desalination in combination with climate change, will elevate coastal water temperatures across more than 50% of the Gulf by at least 3 °C, and a volume of water equivalent to more than a third of the total volume of water between 0 and 10 m deep will pass through desalination plants each year. This will adversely impact the coastal ecosystem of the Gulf, with impacts on biodiversity, fisheries and coastal communities and may cause potential loss of species and habitats from the Gulf. Given the significant implications of these preliminary findings, and in light of the precautionary approach to management, it is recommended that mitigating options addressing behavioural, regulatory and technological change are rapidly evaluated and implemented to avoid the development of desalination in the region along a business as usual pathway, and multidisciplinary research studies should be conducted to reduce uncertainty in predictions of future impacts.

Analysis and prediction of vegetation dynamics under the background of climate change in Xinjiang, China

Background

Vegetation dynamics is defined as a significant indictor in regulating terrestrial carbon balance and climate change, and this issue is important for the evaluation of climate change. Though much work has been done concerning the correlations among vegetation dynamics, precipitation and temperature, the related questions about relationships between vegetation dynamics and other climatic factors (e.g., specific humidity, net radiation, soil moisture) have not been thoroughly considered. Understanding these questions is of primary importance in developing policies to address climate change.

Methods

In this study, the least squares regression analysis method was used to simulate the trend of vegetation dynamics based on the normalized difference vegetation index (NDVI) from 1981 to 2018. A partial correlation analysis method was used to explore the relationship between vegetation dynamics and climate change; and further,the revised greyscale model was applied to predict the future growth trend of natural vegetation.

Results

The Mann-Kendall test results showed that th e air temperature rose sharply in 1997 and had been in a state of high fluctuations since then. Strong changes in hydrothermal conditions had major impact on vegetation dynamics in the area. Specifically, the NDVI value of natural vegetation showed an increasing trend from 1981 to 2018, and the same changes occurred in the precipitation. From 1981 to 1997, the values of natural vegetation increased at a rate of 0.0016 per year. From 1999 to 2009, the NDVI value decreased by an average rate of 0.0025 per year. From 2010 to 2018, the values began an increasing trend and reached a peak in 2017, with an average annual rate of 0.0033. The high vegetation dynamics areas were mainly concentrated in the north and south slopes of the Tianshan Mountains, the Ili River Valley and the Altay area. The greyscale prediction results showed that the annual average NDVI values of natural vegetation may present a fluctuating increasing trend. The NDVI value in 2030 is 0.0196 higher than that in 2018, with an increase of 6.18%.

Conclusions

Our results indicate that: (i) the variations of climatic factors have caused a huge change in the hydrothermal conditions in Xinjiang; (ii) the vegetation dynamics in Xinjiang showed obvious volatility, and then in the end stage of the study were higher than the initial stage the vegetation dynamics in Xinjiang showed a staged increasing trend; (iii) the vegetation dynamics were affected by many factors,of which precipitation was the main reason; (iv) in the next decade, the vegetation dynamics in Xinjiang will show an increasing trend.

Climate change impacts on marine biodiversity, fisheries and society in the Arabian Gulf

Climate change–reflected in significant environmental changes such as warming, sea level rise, shifts in salinity, oxygen and other ocean conditions–is expected to impact marine organisms and associated fisheries. This study provides an assessment of the potential impacts on, and the vulnerability of, marine biodiversity and fisheries catches in the Arabian Gulf under climate change. To this end, using three separate niche modelling approaches under a ‘business-as-usual’ climate change scenario, we projected the future habitat suitability of the Arabian Gulf (also known as the Persian Gulf) for 55 expert-identified priority species, including charismatic and non-fish species. Second, we conducted a vulnerability assessment of national economies to climate change impacts on fisheries. The modelling outputs suggested a high rate of local extinction (up to 35% of initial species richness) by 2090 relative to 2010. Spatially, projected local extinctions are highest in the southwestern part of the Gulf, off the coast of Saudi Arabia, Qatar and the United Arab Emirates (UAE). While the projected patterns provided useful indicators of potential climate change impacts on the region’s diversity, the magnitude of changes in habitat suitability are more uncertain. Fisheries-specific results suggested reduced future catch potential for several countries on the western side of the Gulf, with projections differing only slightly among models. Qatar and the UAE were particularly affected, with more than a 26% drop in future fish catch potential. Integrating changes in catch potential with socio-economic indicators suggested the fisheries of Bahrain and Iran may be most vulnerable to climate change. We discuss limitations of the indicators and the methods used, as well as the implications of our overall findings for conservation and fisheries management policies in the region.

Dynamic hydrographic variations in northwestern Arabian Gulf over the past three decades: Temporal shifts and trends derived from long-term monitoring data

Hydrographic variables were monitored in northwestern Arabian Gulf over the past three decades and the time-series data were statistically analyzed. The results show that while salinity has undergone several shifts, seawater temperature exhibited a steady increasing trend since the 1980s. The observed salinity shows strong correlation with Shatt Al-Arab River discharge indicating primary contribution of freshwater to salinity among other factors (evaporation and desalination effluent). Recent data show that salinity is at its highest level in the last 30years with less pronounced seasonal variability in response to severe decline in the freshwater runoff into the northwestern Arabian Gulf. The changes in hydrographic conditions may have significant implications on hydrodynamics, water quality, and ecosystems in the Gulf. Thus, cooperation among the concerned countries - both coastal and riparian nations - would be essential for prevention of further major changes in the Gulf.