Distributions of Earth's species are changing at accelerating rates, increasingly driven by human-mediated climate change. Such changes are already altering the composition of ecological communities, but beyond conservation of natural systems, how and why does this matter? We review evidence that climate-driven species redistribution at regional to global scales affects ecosystem functioning, human well-being, and the dynamics of climate change itself. Production of natural resources required for food security, patterns of disease transmission, and processes of carbon sequestration are all altered by changes in species distribution. Consideration of these effects of biodiversity redistribution is critical yet lacking in most mitigation and adaptation strategies, including the United Nation's Sustainable Development Goals.

Antarctic terrestrial biodiversity almost exclusively occurs in ice-free areas that cover less than 1% of the continent. Climate change will alter the extent and configuration of ice-free areas, yet the distribution and severity of these effects remain unclear. Here we quantify the impact of 21 st century climate change on ice-free areas under two IPCC climate forcing scenarios using temperature-index melt modelling. Under the strongest forcing scenario, icefree areas could expand by over 17,000 km 2 by the end of the century, close to a 25% increase. Most of this expansion will occur in the Antarctic Peninsula, where a threefold increase in ice-free area could drastically change the availability and connectivity of biodiversity habitat. Isolated ice-free areas will coalesce, and while the impacts on biodiversity are uncertain, we hypothesise that they could eventually lead to increasing regional scale biotic homogenisation, the extinction of less competitive species and the spread of invasive species.

Plants collected from diverse sites on subantarctic Macquarie Island varied by up to 30‰ in their leaf δN values. N natural abundance of plants, soils, animal excrement and atmospheric ammonia suggest that the majority of nitrogen utilised by plants growing in the vicinity of animal colonies or burrows is animal-derived. Plants growing near scavengers and animal higher in the food chain had highly enriched δN values (mean = 12.9‰), reflecting the highly enriched signature of these animals' excrement, while plants growing near nesting penguins and albatross, which have an intermediate food chain position, had less enriched δN values (>6‰). Vegetation in areas affected by rabbits had lower δN values (mean = 1.2‰), while the highly depleted δN values (below -5‰) of plants at upland plateau sites inland of penguin colonies, suggested that a portion of their nitrogen is derived from ammonia (mean N =-10‰) lost during the degradation of penguin guano. Vegetation in a remote area had δN values near -2‰. These results contrast with arctic and subarctic studies that attribute large variations in plant N values to nitrogen partitioning in nitrogen-limited environments. Here, plantN reflects the N of the likely nitrogen sources utilised by plants.

Global comparisons show that Antarctica's terrestrial biodiversity is poorly protected. Existing protected areas are inadequate, unrepresentative, and threatened by increasing human activity.