Almost half of the animal species on the world's surface are currently undergoing declines in their population sizes, new research has found. The paper, published today, examines changes in population densities of more than 70,000 species of animals from across the world's surface over time, making it the most comprehensive research of its kind to date. The researchers from Queen's University Belfast said the findings are a "drastic alert" as global biodiversity loss caused by human industrialisation is significantly more alarming than previously thought. They found that 48% of species on Earth are currently undergoing declines in their population sizes, whereas less than 3pc of them are increasing in population size. The extent of species going extinct has traditionally been measured by the International Union for the Conservation of Nature's (IUCN) threat conservation categories, which found that 28pc of life on Earth is currently threatened with extinction.