Freshwater consumption and the global hydrological cycle

Over the past 9 years, the Global Energy and Water Cycle Experiment (GEWEX), under the auspices of the World Climate Research Programme (WCRP), has coordinated the activities of the Continental Scale Experiments (CSEs) and other related research through the GEWEX Hydrometeorology Panel (GHP). The GHP contributes to the WCRP'S objective of “developing the fundamental scientific understanding of the physical climate system and climate processes [that is] needed to determine to what extent climate can be predicted and the extent of man's influence on climate.” It also contributes to more specific GEWEX objectives, such as determining the hydrological cycle and energy fluxes, modeling the global hydrological cycle and its impacts, developing a capability to predict variations in global and regional hydrological processes, and fostering the development of observing techniques, data management and assimilation systems. GHP activities include diagnosis, simulation, and experimental prediction of regional water balances and process and modeling studies aimed at understanding and predicting the variability of the global water cycle, with an emphasis on regional coupled land–atmosphere processes. GHP efforts are central to providing a scientific basis for assessing critical science issues, such as the consequences of climate change for the intensification of the global hydrological cycle and its potential impacts on regional water resources. This article provides an overview of the role and evolution of the GHP and describes scientific issues that the GHP is seeking to address in collaboration with the international science community.

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Global-scale surface salinity change since the 1870s.Implications for the global hydrological cycle

10.5194/egusphere-egu21-10037 ◽

2021 ◽

Author(s):

W John Gould ◽

Stuart Cunningham

Keyword(s):

Hydrological Cycle ◽

Surface Air Temperature ◽

Global Scale ◽

Rate Of Change ◽

Sea Surface ◽

Salinity Change ◽

Surface Salinity ◽

Global Hydrological Cycle ◽

Global Surface ◽

Scale Surface

Based on the first ever combined analysis of observations from the round-the-world voyages of HMS Challenger and SMS Gazelle in the 1870s, early in the industrial era, this paper shows that the amplification of the global surface salinity signal (saline areas becoming saltier and fresh areas fresher) has increased by 63&#177;5% since the 1950s compared to the period 1870s to 1950s. Other analyses of regional salinity change between the mid-20th century and present day have linked this amplification to anthropogenically-driven strengthening of the global hydrological cycle in line with increasing global temperatures. Our results show that the rate of change has indeed accelerated but more closely in line with changes in sea surface temperature than with surface air temperature over almost 150 years. This is the first global-scale analysis of salinities from these two expeditions in the 1870s and the first observational evidence of changes in the global hydrological cycle since the late 19th century.

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Revisiting the global hydrological cycle: is it intensifying?

Hydrology and Earth System Sciences ◽

10.5194/hess-24-3899-2020 ◽

2020 ◽

Vol 24 (8) ◽

pp. 3899-3932 ◽

Cited By ~ 10

Author(s):

Demetris Koutsoyiannis

Keyword(s):

Stochastic Dynamics ◽

Hydrological Cycle ◽

The Other ◽

Polar Regions ◽

Ice Dynamics ◽

Technological Advances ◽

Visible Effect ◽

Global Hydrological Cycle ◽

The One ◽

Over Exploitation

Abstract. As a result of technological advances in monitoring atmosphere, hydrosphere, cryosphere and biosphere, as well as in data management and processing, several databases have become freely available. These can be exploited in revisiting the global hydrological cycle with the aim, on the one hand, to better quantify it and, on the other hand, to test the established climatological hypotheses according to which the hydrological cycle should be intensifying because of global warming. By processing the information from gridded ground observations, satellite data and reanalyses, it turns out that the established hypotheses are not confirmed. Instead of monotonic trends, there appear fluctuations from intensification to deintensification, and vice versa, with deintensification prevailing in the 21st century. The water balance on land and in the sea appears to be lower than the standard figures of literature, but with greater variability on climatic timescales, which is in accordance with Hurst–Kolmogorov stochastic dynamics. The most obvious anthropogenic signal in the hydrological cycle appears to be the over-exploitation of groundwater, which has a visible effect on the rise in sea level. Melting of glaciers has an equal effect, but in this case it is not known which part is anthropogenic, as studies on polar regions attribute mass loss mostly to ice dynamics.

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