Abstract. Despite recent research identifying a clear anthropogenic impact on glacier recession, the effect of recent climate change on glacier-related hazards is at present unclear. Here we present the first global spatio-temporal assessment of glacial lake outburst floods (GLOFs) focusing explicitly on lake drainage following moraine dam failure. These floods occur as mountain glaciers recede and downwaste. GLOFs can have an enormous impact on downstream communities and infrastructure. Our assessment of GLOFs associated with the rapid drainage of moraine-dammed lakes provides insights into the historical trends of GLOFs and their distributions under current and future global climate change. We observe a clear global increase in GLOF frequency and their regularity around 1930, which likely represents a lagged response to post-Little Ice Age warming. Notably, we also show that GLOF frequency and regularity – rather unexpectedly – have declined in recent decades even during a time of rapid glacier recession. Although previous studies have suggested that GLOFs will increase in response to climate warming and glacier recession, our global results demonstrate that this has not yet clearly happened. From an assessment of the timing of climate forcing, lag times in glacier recession, lake formation and moraine-dam failure, we predict increased GLOF frequencies during the next decades and into the 22nd century.
There appears to be no single axis of causality between life and its landscape, but rather, each exerts a simultaneous infl uence on the other over a wide range of temporal and spatial scales. These infl uences occur through feedbacks of differing strength and importance with co-evolution representing the tightest coupling between biological and geomorphological systems. The ongoing failure to incorporate these dynamic bio-physical interactions with human activity in landscape studies limits our ability to predict the response of landscapes to human disturbance and climate change. This limitation is a direct result of the poor communication between the ecological and geomorphological communities and consequent paucity of interdisciplinary research. Recognition of this failure led to the organization of the Meeting of Young Researchers in Earth Science (MYRES) III, titled 'Dynamic Interactions of Life and its Landscape'. This paper synthesizes and expands upon key issues and fi ndings from that meeting, to help chart a course for future collaboration among Earth surface scientists and ecologists: it represents the consensus view of a competitively selected group of 77 early-career researchers. Two broad themes that serve to focus and motivate future research are identifi ed: (1) co-evolution of landforms and biological communities; and (2) humans as modifi ers of the landscape (through direct and indirect actions). Also outlined are the state of the art in analytical, experimental and modelling techniques in ecological and geomorphological research, and novel new research avenues that combine these techniques are suggested. It is hoped that this paper will serve as an interdisciplinary reference for geomorphologists and ecologists looking to learn more about the other fi eld.
Understanding how landscapes respond to climate dynamics in terms of macroscale (average topographic features) and microscale (landform reorganization) is of interest both for deciphering past climates from today's landscapes and for predicting future landscapes in view of recent climatic trends. Although several studies have addressed macro-scale response, only a few have focused on quantifying smaller-scale basin reorganization. To that goal, a series of controlled laboratory experiments were conducted where a self-organized complete drainage network emerged under constant precipitation and uplift dynamics. Once steady state was achieved, the landscape was subjected to a fivefold increase in precipitation (transient state). Throughout the evolution, high-resolution spatiotemporal topographic data in the form of digital elevation models were collected. The steady state landscape was shown to possess three distinct geomorphic regimes (unchannelized hillslopes, debris-dominated channels, and fluvially dominated channels). During transient state, landscape reorganization was observed to be driven by hillslopes via accelerated erosion, ridge lowering, channel widening, and reduction of basin relief as opposed to channel base-level reduction. Quantitative metrics on which these conclusions were based included slope-area curve, correlation analysis of spatial and temporal elevation increments, and wavelet spectral analysis of the evolving landscapes. Our results highlight that landscape reorganization in response to increased precipitation seems to follow ''an arrow of scale'': major elevation change initiates at the hillslope scale driving erosional regime change at intermediate scales and further cascading to geomorphic changes at the channel scale as time evolves.
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