Carbon budget
Introduction
An emissions budget may also be associated with targets for other related climate variables, such as radiative forcing.
Global emissions budgets are calculated based on historical cumulative emissions from fossil fuel combustion, industrial processes, and land use changes, but vary depending on the global temperature target chosen, the probability of remaining below that target, and the emission of other greenhouse gases (GHGs).[5][6] Global emissions budgets can be divided into national emissions budgets so that countries can set specific climate change mitigation targets. Emissions budgets are relevant to climate change mitigation because they indicate a finite amount of carbon dioxide that can be emitted over time, before generating dangerous levels of global warming. The change in global temperature is independent of the geographic location of these emissions and is largely independent of the timing of these emissions.[7][8].
According to the IPCC's 2018 Special Report on 1.5°C Global Warming, the Mercator Research Institute on Global Commons and Climate Change estimates that the CO budget associated with 1.5°C of warming will be exhausted by 2028 if emissions remain at the current level of the late 2010s.[9] Beyond a 1.5°C temperature increase, the risk increases. of lasting and irreversible consequences of climate change.[10].
An emissions budget should be distinguished from an emissions target"), as an emissions target may be set at an international or national level according to targets other than a specific global temperature. This includes targets created for their political feasibility, rather than targets based on scientific evidence.[11].
Estimates
The finding of a nearly linear relationship between global temperature rise and cumulative carbon dioxide emissions[8] has encouraged the estimation of global emissions budgets to stay below dangerous levels of warming. From the pre-industrial period to 2011, approximately 1,890 GtCO of CO 2 (GtCO) have already been emitted globally, and 2,050 GtCO until 2015.[12].
Scientific estimates of the remaining global emissions budgets/quotas differ widely due to the variety of methodological approaches and threshold considerations.[12] Most estimates still underestimate the amplification of climate change feedbacks.[13][14][15][16].
Some common carbon budget estimates are those associated with 1.5°C[17][18][19] and 2°C global warming.[2][5][20] These estimates depend largely on the likelihood or probability of achieving a temperature target. The values for the depleted budget in the table below have been derived from a scenario in which CO emissions remain at the current level of 42 Gt per year.