Arctic warming can influence tundra ecosystem function with consequences for climate feedbacks, wildlife and human communities. Yet ecological change across the Arctic tundra biome remains poorly quantified due to field measurement limitations and reliance on coarse-resolution satellite data. Here, we assess decadal changes in Arctic tundra greenness using time series from the 30 m resolution Landsat satellites. From 1985 to 2016 tundra greenness increased (greening) at 37.3% of sampling sites and decreased (browning) at 4.7% of sampling sites. Greening occurred most often at warm sampling sites with increased summer air temperature, soil temperature, and soil moisture, while browning occurred most often at cold sampling sites that cooled and dried. Tundra greenness was positively correlated with graminoid, shrub, and ecosystem productivity measured at field sites.

Poleward shifts in species distributions are expected and frequently observed with a warming climate. In Arctic ecosystems, the strong warming trends are associated with increasing greenness and shrubification. Vertebrate herbivores have the potential to limit greening and shrub advance and expansion on the tundra, posing the question of whether changes in herbivore communities could partly mediate the impacts of climate warming on Arctic tundra. Therefore, future changes in the herbivore community in the Arctic tundra will depend on whether the community tracks the changing climates directly (i.e. occurs in response to temperature) or indirectly, in response to vegetation changes (which can be modified by trophic interactions). In this study, we used biogeographic and remotely sensed data to quantify spatial variation in vertebrate herbivore communities across the boreal forest and Arctic tundra biomes. We then tested whether present-day herbivore community structure is determined primarily by temperature or vegetation.

Researchers at the University of East Anglia have proposed a new way of using quantum light to see quantum sound. A new paper published today reveals the quantum-mechanical interplay between vibrations and particles of light, known as photons, in molecules. It is hoped that the discovery may help scientists better understand the interactions between light and matter on molecular scales. And it potentially paves the way for addressing fundamental questions about the importance of quantum effects in applications ranging from new quantum technologies to biological systems. Dr Magnus Borgh from the School of Physics said: “There is a long-standing controversy in chemical physics about the nature of processes where energy from particles of light is transferred within molecules. Are they fundamentally quantum-mechanical or classical? Molecules are complex and messy systems, constantly vibrating. How do these vibrations affect any quantum-mechanical processes in the molecule?” These processes are typically investigated using techniques that rely on polarisation – the same property of light used in sunglasses to reduce reflections.

“Techniques from quantum optics, the field of physics that studies the quantum nature of light and its interactions with matter on the atomic scale, can offer a way to investigate genuine quantum effects directly in molecular systems.” Quantum behaviour can be revealed by studying correlations in the emitted light from a molecule placed in a laser field. Correlations answer the question how likely it is that two photons are emitted very close together and can be measured using standard techniques. Ben Humphries, PhD student in theoretical chemistry, at UEA said: “Our research shows that when a molecule exchanges phonons with its environment, this produces a recognisable signal in the photon correlations.” While photons are routinely created and measured in laboratories all over the world, individual quanta of vibrations, which are the corresponding particles of sound, phonons, cannot in general be similarly measured. The new findings provide a toolbox for investigating the world of quantum sound in molecules. Lead researcher Dr Garth Jones, from the School of Chemistry, said: “We have also computed correlations between photon and phonons. It would be very exciting if our paper could inspire the development of new experimental technique” he added.