Comprehensive 2013 United Nations Environment Programme (UNEP) report examining the risk and extent of a future greenhouse gas 'emissions gap'.
This synthesis report concerns the global attempt to reduce greenhouse gas emissions, and seeks to identify the risk and possible extent of an emissions gap come 2020. The term ‘emissions gap’ refers to the difference between projected greenhouse gas emission levels in 2020, and the level considered as a maximum limit for a least-cost scenario that avoids a greater than 2C warming to remain possible. A key component of the study therefore focuses on the various pledges and commitments made by nations around the world, as well as their progress, or otherwise, toward fulfilling these goals.
The study confirms the view of previous UNEP studies examining potential emission gaps, underscoring the point that current pledges and commitments, even if entirely fulfilled, will fall short of the target whereby least-cost strategies remain viable. Indeed, emission levels are still rising globally, and at present are considerably higher than where they need to be in 2020. If this imbalance is not addressed, the world will have to rely on more costly, difficult, and riskier means of meeting emissions targets that would conceivably avoid a greater than 2C rise in temperatures beyond 2020.
With current trends and commitments taken as they are, the study estimates that total emissions in 2020 will likely be around 52-56 gigatonnes of carbon dioxide equivalent (GtCO2e), placing it far above the estimated 44 GtCO2e limit required for the 2C target. This means that even if all present pledges are fulfilled, there will remain an 8-12 GtCO2e emissions gap by 2020 which, if not closed, will severely increase the necessary rate of greenhouse gas reduction in the decades beyond if we are to avoid a greater than 2C rise in global temperatures.
The authors find that the technical potential for closing this gap by 2020 exists; assuming no barriers, it is estimated that a reduction of between 14-20 GtCO2e by 2020 is possible, but that time is quickly running out. Risk associated with missing this target include further lock-in of carbon-intensive infrastructure, greater costs of mitigation and risks of economic disruption, and a host of climate-related risks associated with increased climate change impacts. International cooperation, clearly defined visions and mandates, and greater funding and incentives of institutions and stakeholders are all required.