The Carbon Budget is almost used up

 

The following is from the press release from Imperial College London and the Study cited below:

Lamboll, R.D., Nicholls, Z.R.J., Smith, C.J. et al. Assessing the size and uncertainty of remaining carbon budgets. Nat. Clim. Chang. 13, 1360–1367 (2023). https://doi.org/10.1038/s41558-023-01848-5

Researchers at Imperial College London recently published a study in Nature Climate Change, that is the most up-to-date and comprehensive analysis of the global carbon budget. The carbon budget is an estimate of the amount of carbon dioxide emissions that can be emitted while keeping global warming below certain temperature limits.

In 2015 196 countries adopted  the Paris Climate Accord that was intended to put the nations on a course to reduce carbon dioxide emissions from the combustion of fossil fuels. The agreement was signed on Earth Day 2016 at the United Nations. The signing was a very hopeful moment. The Paris Agreement aims to limit global temperature increase to well below 2°C above preindustrial levels and pursue efforts to limit it to 1.5°C. The remaining carbon budget is one commonly used way to assess global progress against these targets.

The researchers state that previous found that global temperature rise is not strongly dependent on when carbon emissions occur, only on what the emissions cumulative sum is. However, the remaining carbon budget is strongly dependent on both how much and when different types of non-CO2 greenhouse gas emissions occur.  Using two models to account for this, the Imperial College London study estimates that for a 50% chance of limiting warming to 1.5°C, there are less than 250 gigatonnes of carbon dioxide left in the global carbon budget.

from the GCP

The researchers warn that if carbon dioxide emissions remain at 2022 levels of about 40 gigatonnes per year, the carbon budget will be exhausted by 2029, committing the world to warming of 1.5°C above preindustrial levels. To remain within 2°C above preindustrial temperatures humans need to emit less than 500 gigatons of additional carbon dioxide. At the current rate of emissions that is 12 years. There is still room for action in the 2°C above preindustrial level remaining carbon budget for global action.

Earlier studies had found that if carbon dioxide emissions continue at current levels, the remaining carbon budget to keep the global temperature within  2°C of preindustrial levels would be exhausted by 2046. The new study tells us that date is now 2036.

The finding means the budget is less than previously calculated and has approximately halved since 2020 due to the continued increase of global greenhouse gas emissions, caused primarily from the burning of fossil fuels as well as an improved estimate of the cooling effect of aerosols lost due to measures to improve air quality and reduce emissions.

The planet is faced with a huge challenge. Even if every nation met their current  pledge to reduce carbon dioxide emissions made in the Paris Climate Accord and its updates, the reductions promised are not enough to even maintain global temperatures within 2 °C above pre-industrial levels; and the nations are not meeting those pledges. Neither China nor India representing about a 40% of world carbon dioxide  emissions have committed to any reductions. Instead, they are projecting when their greenhouse gas emissions will peak and that is in more than a decade.