The Himalaya is a wedge-shaped, continent-continent collision orogen that has been active for the past ~55 Ma.

Climate-tectonics interaction imparts a temporal cyclicity to the Himalayan wedge, with periods when erosion dominates and others when tectonics does. Dominance of climate-induced erosion is expressed as secular and focused erosion in the wedge, leading to a reduction in topography throughout the wedge or in certain regions within the wedge, respectively. Both drive out-of-sequence deformation within the Himalayan wedge to compensate for mass balance. Dominance of tectonics results in topographic growth and the lengthening of the Himalayan wedge into its foreland through in-sequence deformation within the wedge. This cyclicity has continued into the Quaternary, as evident from both in-sequence and out-of-sequence neotectonic deformation signatures in the Himalayan Quaternary section. Climate-neotectonics interaction in the Quaternary is also coupled with Himalayan natural hazards. In-sequence deformation results in the deformation of the Quaternary section in the frontal part of the wedge during great earthquakes. Out-of-sequence deformation deforms the Quaternary section potentially anywhere within the wedge. Out-of-sequence deformation also causes major earthquakes and associated uplift that can steepen topographic slopes and induce landslides. These processes have allowed the delineation of an earthquake "nursery" in the central part of the Himalayan wedge that is currently overlain by overfilled glacial lakes caused by climate change-induced glacial melting. A major-to-great earthquake can trigger landslides and Glacial Lake Outburst Floods (GLOFs) simultaneously, thereby painting a grim worst-case natural hazard scenario in the Himalayan orogen. This talk will present a synoptic view of how the climate-tectonics interaction in the Quaternary fits within our overall understanding of the evolution of the Himalayan orogen and the resulting natural hazards.