WASHINGTON, Nov. 19, 2014 /PRNewswire-USNewswire/ -- In order to limit global temperature rise to 2 Degrees Celsius and head off the worst impacts of climate change, global carbon neutrality should be attained by mid-to-late century. This would also keep in check the maximum amount of carbon dioxide (CO2) that can be emitted into the atmosphere while staying within safe temperature limits beyond 2020, says a new report by the UN Environment Programme (UNEP).
Exceeding an estimated budget of just 1,000 gigatonnes of carbon dioxide (Gt CO2) would increase the risk of severe, pervasive, and in some cases irreversible climate change impacts.
Released days ahead of the UN Conference on Climate Change in Lima, Peru, UNEP's Emissions Gap Report 2014 is the fifth in a series that examines whether the pledges made by countries are on track to meet the internationally agreed under 2 Degrees Celsius target. It is produced by 38 leading scientists from 22 research groups across 14 countries.
Building on the findings of the Fifth Assessment Report by the International Panel on Climate Change (IPCC), UNEP's Emissions Gap Report shows the global emission guardrails that would give a likely chance of staying within the 2 Degrees Celsius limit, including a peaking of emissions within the next ten years, a halving of all greenhouse gas emissions by mid-century; and in the second half of the century, carbon neutrality followed by net zero total greenhouse gas emissions.
Achim Steiner, UN Under-Secretary-General and Executive Director of UNEP, said, "Countries are giving increasing attention to where they realistically need to be by 2025, 2030 and beyond in order to limit a global temperature rise to below 2 Degrees Celsius. This fifth Emissions Gap Report underlines that carbon neutrality--and eventually net zero or what some term climate neutrality--will be required so that what cumulative emissions are left are safely absorbed by the globe's natural infrastructure such as forests and soils," he added. "The Sustainable Development Goals underscore the many synergies between development and climate change mitigation goals. Linking development policies with climate mitigation will help countries build the energy-efficient, low-carbon infrastructures of the future and achieve transformational change that echoes the true meaning of sustainable development," he concluded.
To avoid exceeding the budget, global carbon neutrality should be reached between 2055 and 2070, meaning that annual anthropogenic CO2 emissions should hit net zero by then on the global scale. Net zero implies that some remaining CO2 emissions could be compensated by the same amount of carbon dioxide uptake, or 'negative' emissions, so long as the net input to the atmosphere due to human activity is zero, the report finds. Taking into account non-CO2 greenhouse gases, including methane, nitrous oxide and hydrofluorocarbons, total global greenhouse gas emissions need to shrink to net zero between 2080 and 2100.
SOURCE UN Environment Programme (UNEP)