Carbon budget

A carbon budget is a concept used in climate policy to help set emissions reduction targets in a fair and effective way.

Emissions budgets indicate a finite amount of carbon dioxide that can be emitted over time, before resulting in dangerous levels of global warming.

[12] There are many differences between nations, such as population size, level of industrialisation, historic emissions, and mitigation capabilities.

It identifies three major issues for improving reliable accuracy of monitoring, shows that China and India surpassed 2019 levels (by 5.7% and 3.2%) while the EU and the US stayed beneath 2019 levels (by 5.3% and 4.5%), quantifies various changes and trends, for the first time provides models' estimates that are linked to the official country GHG inventories reporting, and suggests that the remaining carbon budget at 1.

Jan 2022 for a 50% likelihood to limit global warming to 1.5 °C (albeit a temporary exceedence is to be expected) is 120 GtC (420 GtCO2) – or 11 years of 2021 emissions levels.

[19] In October 2023 a group of researchers updated the carbon budget including the CO2 emitted at 2020-2022 and new findings about the role of reduced presence of polluting particles in the atmosphere.

[21] They found we can emit 250 GtCO2 or 6 years of emissions at current level starting from January 2023, for having a 50% chance to stay below 1.5 degrees.

[9] Scientific estimations of the remaining global emissions budgets/quotas differ due to varied methodological approaches, and considerations of thresholds.

[24] Estimations might not include all amplifying climate change feedbacks,[25][26][27][28] although the most authoritative carbon budget assessments as summarised by the IPCC do account explicitly for these.

[9] Carbon budget estimates depend on the likelihood or probability of avoiding a temperature limit, and the assumed warming that is projected to be caused by non-CO2 emissions.

Scientists estimated that remaining carbon budgets can be 220 Gt CO2 higher or lower depending on how successful non-CO2 emissions are reduced.

In light of the many differences between nations, including but not limited to population, level of industrialisation, national emissions histories, and mitigation capabilities, scientists have made attempts to allocate global carbon budgets among countries using methods that follow various principles of equity.

This principle stipulates individuals should have equal rights, and therefore emissions budgets should be distributed proportionally according to state populations.

[32][33][34][40] This principle may be favoured by nations with larger or rapidly growing populations,[39] but raises the question whether individuals can have a right to pollute.

Cleanly generated electricity can usually replace fossil fuels for powering transportation, heating buildings, and running industrial processes.

Methane is a short lived greenhouse gas that is produced by decaying organic matter and livestock, as well as fossil fuel extraction.

Carbon budget and emission reduction scenarios needed to reach the two-degree target agreed to in the Paris Agreement (without net negative emissions , based on peak emissions) [ 1 ] [ obsolete source ]
Estimating the remaining carbon budget at the global level depends on climate science and value judgments or choices. To translate a global budget to the national level, further value judgments and choices have to be made. [ 12 ]