Human activity puts Earth’s systems at risk

Four of the nine systems that regulate the interaction between land, ocean, atmosphere, ice-sheets and life on Earth are at risk from destabilisation due to human activity, according to an international team including UCL scientists. The research shows the limits set for climate change, loss of biosphere integrity, land-system change and altered phosphorus and nitrogen cycles have been exceeded. Two of these - climate change and biosphere integrity - are 'core boundaries' as they influence other processes on Earth and managing these is a priority for maintaining a safe environment for society, say the scientists. Lead author, Professor Will Steffen at Stockholm Resilience Centre, Stockholm University and the Australian National University, Canberra, said: "Transgressing a boundary increases the risk that human activities could inadvertently drive the Earth System into a much less hospitable state, damaging efforts to reduce poverty and leading to a deterioration of human wellbeing in many parts of the world, including wealthy countries. In this new analysis we have improved our quantification of where these risks lie." The boundary for climate change uses carbon dioxide levels which should not cross 350 parts per million (ppm) in the atmosphere according to the team but levels are currently at 399ppm (December 2014) and growing by 3ppm per year. The limit of 350ppm is consistent with a stabilisation of global temperatures at about 1.5 degrees Celsius above pre-industrial levels, which is lower than the internationally agreed limit of 2 degrees, suggesting warming above 1.5 degrees is a risk for humanity.