Countries are emitting more CO2 than they are reporting.
That's according to a new study, which says the gap is actually quite large – 5.5 billion tonnes of carbon dioxide per year,
equivalent to what the United States emits annually.
But the discrepancy is not because any country is doing anything wrong.
Scientists say the emissions gap is all about scientific modelling.
There are differences in approaches between methods used in national inventories that countries report under the 2015 Paris agreement on climate change…
and methods used by international independent models.
Giacamo Grassi, an author of the study and scientific officer at the Joint Research Center of the European Commission, explained that:
"If models and countries speak a different language, assessing country climate progress will be more difficult... To address the problem, we need to find a way to compare these estimates."
The emissions gap could mean some countries will have to adjust their emissions reductions.
For instance, the country models done by the U.S. and other nations show more carbon-absorbing managed forest land than the independent models indicate.
The study finds the national estimates, which allow more flexible definitions for those lands, show about 3 billion hectares more of managed forest land around the world than in the independent models.
The risk is that some countries could claim managed forests are absorbing large amounts of emissions…
and not do enough to cut emissions from cars, homes and factories.
Under the Paris Agreement, countries are working to limit the global temperature rise to 1.5 degrees Celsius above pre-industrial levels.
They’ll be reviewing their progress every five years via a process called "Global stocktake."
But authors of the study warn that the discrepancies in emissions figures could present a large issue, and say further work is required to develop country-specific adjustments.