Revisiting global hydrological cycle: Is it intensifying?

Abstract

Abstract. As a result of technological advances in monitoring atmosphere, hydrosphere, cryosphere and biosphere, as well as in data management and processing, several data bases 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 sea appears to be lower than the standard figures of literature, but with greater variability on climatic time scales, which is in accordance with Hurst-Kolmogorov stochastic dynamics. The most obvious anthropogenic signal in the hydrological cycle appears to be the overexploitation of groundwater, which has a visible effect on sea level rise. Melting of glaciers has an equal effect, but in this case it in not known which part is anthropogenic, as studies on polar regions attribute mass loss mostly to ice dynamics.

On the inter‐ and intra‐annual variability of ecosystem evapotranspiration and water use efficiency of an oak savanna and annual grassland subjected to booms and busts in rainfall

“…Nor did we did we find a temporal trend in inter‐annual evapotranspiration over the 1980–2000 time period using the biophysical Canveg model for a deciduous forest in Tennessee (Baldocchi & Wilson, 2001). Our results are also consistent with a recent analysis that revisited whether the global hydrological cycle is intensifying; it did not detect a secular trend in evapotranspiration (Koutsoyiannis, 2020).…”

“…What does the hydrological literature tell us about what has happened so far? The answer to this question is mixed because many of the assessments of terrestrial evaporation are inferred by models or by differences in the water budget (Koutsoyiannis, 2020).…”

“…What does the hydrological literature tell us about what has happened so far? The answer to this question is mixed because many of the assessments of terrestrial evaporation are inferred by models or by differences in the water budget (Koutsoyiannis, 2020). For example, one set of studies report that runoff from the continents is increasing and it may be evidence that plant transpiration may be decreasing as elevated CO 2 causes partial stomatal closure (Betts et al., 2007; Gedney et al., 2006; Knauer et al., 2017).…”

“…For example, one set of studies report that runoff from the continents is increasing and it may be evidence that plant transpiration may be decreasing as elevated CO 2 causes partial stomatal closure (Betts et al., 2007; Gedney et al., 2006; Knauer et al., 2017). In contrast, another set of papers infer that a small, increasing trend in global land evaporation is occurring, at a rate of about 1 mm/year 2 (Huntington, 2006; Ueyama et al., 2020), or no discernible trend in evaporation over land has been detected (Koutsoyiannis, 2020).…”

Does the Hook Structure Constrain Future Flood Intensification Under Anthropogenic Climate Warming?

“…Although an exact value for precipitation‐temperature scaling has not yet been established, there is a general agreement that global precipitation extremes should increase in response to a warming climate (Papalexiou & Montanari, 2019). More recently, Koutsoyiannis (2020) found that global mean and extreme precipitation both show large fluctuations, with deintensification prevailing in the 21st century. Understanding these precipitation changes will not only contribute to improving the design of early warning procedures, but also provide a scientific basis for implementing major climate adaptation and mitigation strategies (Drobinski et al., 2016).…”