Impact of climate change on freshwater ecosystems: a global-scale analysis of ecologically relevant river flow alterations

Abstract

Abstract. River flow regimes, including long-term average flows, seasonality, low flows, high flows and other types of flow variability, play an important role for freshwater ecosystems. Thus, climate change affects freshwater ecosystems not only by increased temperatures but also by altered river flow regimes. However, with one exception, transferable quantitative relations between flow alterations and ecological responses have not yet been derived. While discharge decreases are generally considered to be detrimental for ecosystems, the effect of future discharge increases is unclear. As a first step towards a global-scale analysis of climate change impacts on freshwater ecosystems, we quantified the impact of climate change on five ecologically relevant river flow indicators, using the global water model WaterGAP 2.1g to simulate monthly time series of river discharge with a spatial resolution of 0.5 degrees. Four climate change scenarios based on two global climate models and two greenhouse gas emissions scenarios were evaluated.We compared the impact of climate change by the 2050s to the impact of water withdrawals and dams on natural flow regimes that had occurred by 2002. Climate change was computed to alter seasonal flow regimes significantly (i.e. by more than 10%) on 90% of the global land area (excluding Greenland and Antarctica), as compared to only one quarter of the land area that had suffered from significant seasonal flow regime alterations due to dams and water withdrawals. Due to climate change, the timing of the maximum mean monthly river discharge will be shifted by at least one month on one third on the global land area, more often towards earlier months (mainly due to earlier snowmelt). Dams and Correspondence to: P. Döll

Possible impacts of climate change on wetlands and its biota in the Brazilian Amazon

“…These conditions associated with increased evapotranspiration, might reduce the extent of flooded areas or convert them into drylands (Burkett and Kusler, 2000). The absence of an adequate period of flooding, in magnitude, duration and time, might cause a decline of many species which depend on flooding to complete their life cycle, and, in addition, might promote the establishment of invasive species (Poff, 2002;Döll and Zhang, 2010).…”

Changing patterns of extreme water levels in urbanizing plain river network region of Taihu Basin, China: characteristics and causes

“…maximum and minimum water levels) are of increasing global attention because of the increased risk of floods and droughts on local or regional scales, as well as an increasing or decreasing water resources at the continental scale that have been observed Doell and Zhang, 2010;Assani et al, 2014). Meanwhile, water levels also have an important impact on the critical functions of river basins, such as ecosystem stability, water environment and engineering construction (Wen et al, 2011;Reid et al, 2013).…”

Impacts of climate change under CMIP5 RCP scenarios on the streamflow in the Dinder River and ecosystem habitats in Dinder National Park, Sudan

“…Consequently, under the smallest climatic change scenarios, 18 % of species were found to be committed to extinction, while the largest change scenario projected as many as 35 % of species to be at risk (Thomas et al, 2004). Many studies investigated the impact of the streamflow change on the freshwater ecosystems, which will probably have strong effects on the system components and abiotic characteristics (Poff and Ward, 1989;Poff and Zimmerman, 2010;Döll and Zhang, 2010;Mantyka-pringle et al, 2012). Erwin (2009) concluded that the wetlands will strongly be influenced due to climate alteration and, to overcome all these impacts, assessment of the affect should first be conducted.…”