UN Raises Global Greenhouse Gas Emissions ‘Point Of No Return’ Ceiling. The U.N.’s environmental authority has quietly raised its assessment of the level at which global greenhouse gas emissions must peak to avoid dangerous climate change.
In annual emissions reports since 2010, the United Nations Environment Program has said emissions must not exceed 44 billion tons in 2020 for the world to limit global warming to 2 degrees C (3.6 degrees F).
But in this year’s report, a summary of which was released Friday, UNEP says 52 billion tons in 2020 is consistent with the 2-degree target. UN Raises Global Greenhouse Gas Emissions ‘Point Of No Return’ Ceiling
The new analysis assumes that emissions cuts will drop faster after 2030 than was assumed in previous reports.
Explaining the change, UNEP chief scientist Jacqueline McGlade said earlier assessments were based on emissions scenarios that are “no longer realistic.”Human activities since the beginning of the Industrial Revolution (around 1750) have produced a 45% increase in the atmospheric concentration of carbon dioxide, from 280 ppm in 1750 to 415 ppm in 2019.
The last time the atmospheric concentration of carbon dioxide was this high was over 3 million years ago. This increase has occurred despite the uptake of more than half of the emissions by various natural “sinks” involved in the carbon cycle.The vast majority of anthropogenic carbon dioxide emissions come from combustion of fossil fuels, principally coal, petroleum (including oil) and natural gas,