However, even the revised budget of 1.5oC should not be the end of the debate, given a series of significant uncertainties. These include: co2 budgets are a simplified way to measure the additional emissions that can be released into the atmosphere if the world is to limit global warming to a level of 1.5 degrees Celsius. They are based on the fact that the amount of warming that will occur can be reconciled by all CO2 emissions. Table II shows a comparison of each country`s unconditional contributions to the reduction compared to the same reference year (2010) and the per capita emissions of those countries in 2010. Demographic data comes from the undesa population division (undesa, 2015). Per capita emissions are a good benchmark for assessing countries` efforts to combat climate change. In 2010, global per capita greenhouse gas emissions were 6.2 tCO2eq. The red line between China and Mexico separates countries that are above the global average from those below. Global carbon dioxide emissions by jurisdiction.
  The figure below shows different estimates of the authorized carbon budget to keep temperatures well below 1.5 degrees Celsius, with a 66% probability of keeping temperatures below 1.5 degrees Celsius (and an equivalent probability of 33% exceeding the target). These probabilities reflect significant uncertainty in climate sensitivity to CO2 emissions. The coloured bars correspond to the coal budget of several studies listed on the left, while current cumulative emissions already exceed the carbon budget « significantly less » at 1.5 C. IPCC carbon budgets and ieA/IRENA policy scenarios also present different assumptions about their final objectives and the extent to which the temperature target can be temporarily exceeded. While a « real » carbon budget is a total amount of emissions that can be released and must ultimately achieve net zero emissions, the scenarios can only cover part of the period up to that stage. With a single click, the top left corner will take you to the 2-degree target scenario and the top right corner to the 1.5-degree target. In both cases, the watch shows the remaining carbon budget and the remaining time. Climate models that contain a carbon cycle – so-called « Earth System Models » (SMEs) – can be used to estimate the emissions that would be needed to produce the atmospheric CO2 concentrations used to make climate models. Global emission budgets are calculated on the basis of cumulative historical emissions from fossil fuel combustion, industrial processes and land use changes, but vary depending on the overall temperature target chosen, the likelihood of staying below that target, and emissions of other greenhouse gases (GHGs).   Global emission budgets can continue to be subdivided into national emission budgets, so that countries can set specific climate change targets.