Global carbon emissions much higher than reported, EU researchers find

This unaccounted-for quantity of CO2, which is approximately equal to annual US emissions, may be significant enough to derail decarbonisation efforts. Under the terms of the Paris Agreement, governments are attempting to limit carbon emissions to keep the global temperate rise within 2°C of pre-industrial levels.

Inconsistencies were found between the CO2 estimates in the national inventories that countries submit (an obligation under the Paris Agreement) and estimates from international models. While some countries monitor their greenhouse gas emissions using methodologies agreed by the Intergovernmental Panel on Climate Change, some use alternative models. The divergence in methodology led to different estimates of CO2 absorption.

“If models and countries speak a different language, assessing country climate progress will be more difficult,” said Giacomo Grassi, an author of the study from the Joint Research Center of the European Commission. “To address the problem, we need to find a way to compare these estimates.”

The team proposes calibrating how emissions are measured such that national estimates can be compared. The differences can mostly be accounted for by variation in how carbon absorption of forests is calculated. The model used by the US, for example, account for more carbon-absorbing managed forest land than the independent models do.

“Since there is no perfect way to estimate the anthropogenic CO2 sink, what counts most is the transparency and comparability of these estimates, across countries and with global models,” the scientists said.

The discrepancy could force some countries to take a firmer stance on carbon reduction to meet targets for net-zero carbon emissions by 2050.

A group of MPs recently warned that the 2°C goal as laid out in the Paris Agreement will not be kept without significant action being agreed upon at the upcoming COP26 summit in Glasgow. In December 2018, a Climat Action Tracker report stated that even if all countries meet their goals (aligned with the Paris Agreement), the world will still warm by 3°C.