The U.K.'s carbon emissions fell for the sixth consecutive year in 2018, hitting some of the lowest levels seen since 1888, according to a report published Monday.

The data by research group Carbon Brief claimed 2018's decline marked the longest series of annual emissions reductions on record. However, the 1.5 percent decrease was the smallest in the six-year run, which Carbon Brief said could signal the end of the downturn.

According to the report, the U.K.'s CO2 emissions in 2018 were an estimated 361 million tons — 39 percent lower than they were in 1990. With the exception of three years on record — when mass strikes took place in 1893, 1921 and 1926 — last year's emissions were the nation's lowest since 1888.

The organization's findings were based on an analysis of official data from the British government.