891. Remaining Carbon Budget to Stop Global Warming

The concept of carbon budget represents the maximum allowable cumulative CO2 emissions to keep global warming within a predefined temperature increase threshold and associated probability. This calculation also takes into account the effects of other human-induced climate change variables.

To meet the Paris Agreement's ambitious goal of limiting global warming to 1.5°C, the imperative is clear: CO2 emissions must be reduced to net zero, effectively stopping the addition of CO2 to the atmosphere.

A paper published in Nature Climate Change on October 30, 2011 underscores the precarious state of our Remaining Carbon Budget (RCB), the amount of CO2 emissions that can still be released without exceeding the 1.5°C target. It highlights the inherent uncertainties in calculating this RCB.

The study highlights that the RCB to limit warming to 1.5°C with a 50% probability is about 250 gigatons of CO2 (GtCO2) as of January 2023, which represents just six years of emissions at current CO2 emission rates, in stark contrast to an earlier estimate of 1,200 GtCO2.

The main source of uncertainty in the carbon budget estimates comes from non-CO2 greenhouse gas emissions, which are strongly influenced by both geophysical and socioeconomic variables, as described in the report.

Significantly, the food system is responsible for a significant proportion of non-CO2 greenhouse gas emissions, including methane (CH4) and nitrous oxide (N2O). As a result, there is an urgent need for food industry stakeholders to adopt innovative practices and behavioral changes that can mitigate greenhouse gas emissions while minimizing their environmental footprint and ensuring access to nutritious food for the world's population.
 

Reference
Lamboll, R.D., Nicholls, Z.R.J., Smith, C.J. et al. Assessing the size and uncertainty of remaining carbon budgets. Nat. Clim. Chang. (2023). https://doi.org/10.1038/s41558-023-01848-5

Contributor: Miyuki Iiyama, Information Program)