Hydrological processes in the humid tropics differ from other regions in having greater energy inputs and faster rates of change. In this Review it is argued that understanding of the key hydrological interactions there remains limited, and a vision of future research designed to address these shortcomings is outlined.

Amphibian population declines far exceed those of other vertebrate groups, with 30% of all species listed as threatened by the International Union for Conservation of Nature. The causes of these declines are a matter of continued research, but probably include climate change, land-use change and spread of the pathogenic fungal disease chytridiomycosis. Here we assess the spatial distribution and interactions of these primary threats in relation to the global distribution of amphibian species.

This work aims to identify the geographic distribution of photovoltaic (PV) energy potential considering the effect of temperature on PV system performance. A simple framework is developed that uses the JIS C 8907 Japanese industrial standard to evaluate the effects of irradiation and temperature on PV potential. The global distributions of PV potential and yearly performance ratio are obtained by this framework. Generally, the performance ratio decreases with latitude because of temperature. However, regions with high altitude have higher performance ratios due to low temperature.

Big river basins are complex systems of people and nature. This article explores the resilience of nine case studies of big river basins. A system description and generic conceptual model suggests that resilience to changes in water quantity is critical. When water becomes limiting, the social-ecological system must adapt rapidly if key elements (for example, communities, biodiversity) are to be maintained. Water limitation imposes a water economy and alters political and institutional links between actors.

The Andes have daily (rather than seasonal) temperature extremes, unpre-
dictable weather from one year to the next, and a myriad of environmental niches scattered across the elevations. To survive in such an adverse environment, highland farming evolved to be robust, with complex

The role of the tropics in triggering, transmitting, and amplifyinginterhemispheric climate signals remains a key debate in paleoclimatology.Tropical glacier fluctuations provide important insight on regionalpaleoclimatic trends and forcings, but robust chronologies arescarce.