Spatial co-localisation of extreme weather events: a clear and present danger.

Extreme weather events have become a dominant feature of the narrative surrounding changes in global climate with large impacts on ecosystem stability, functioning and resilience; however, understanding of their risk of co-occurrence at the regional scale is lacking. Based on the UK Met Office's long-term temperature and rainfall records, we present the first evidence demonstrating significant increases in the magnitude, direction of change and spatial co-localisation of extreme weather events since 1961. Combining this new understanding with land-use data sets allowed us to assess the likely consequences on future agricultural production and conservation priority areas. All land-uses are impacted by the increasing risk of at least one extreme event and conservation areas were identified as the hotspots of risk for the co-occurrence of multiple event types. Our findings provide a basis to regionally guide land-use optimisation, land management practices and regulatory actions preserving ecosystem services against multiple climate threats.

High-resolution seismic event detection using local similarity for Large-N arrays.

We develop a novel method for seismic event detection that can be applied to large-N arrays. The method is based on a new detection function named local similarity, which quantifies the signal consistency between the examined station and its nearest neighbors. Using the 5200-station Long Beach nodal array, we demonstrate that stacked local similarity functions can be used to detect seismic events with amplitudes near or below noise levels. We apply the method to one-week continuous data around the 03/11/2011 Mw 9.1 Tohoku-Oki earthquake, to detect local and distant events. In the 5-10 Hz range, we detect various events of natural and anthropogenic origins, but without a clear increase in local seismicity during and following the surface waves of the Tohoku-Oki mainshock. In the 1-Hz low-pass-filtered range, we detect numerous events, likely representing aftershocks from the Tohoku-Oki mainshock region. This high-resolution detection technique can be applied to both ultra-dense and regular array recordings for monitoring ultra-weak micro-seismicity and detecting unusual seismic events in noisy environments.