Carbon dioxide emissions have plummeted amid the coronavirus pandemic in the largest drop since World War II, however any environmental advantages are expected to only be temporary until the global economy restarts, a new report says. Global carbon emissions from six sectors of the economy—such as transportation and commerce—have dropped 17 percent between January and early April compared to the same period in 2019, according to the journal Nature Climate Change. The improvements were mainly attributed to less cars on the road and a substantial drop in air traffic. The average decline in carbon emissions could clock anywhere between 4.4 percent and 8 percent by the end of 2020.

“I can’t celebrate a drop in emissions driven by unemployment and forced behavior,” said study co-other Rob Jackson. “We’ve reduced emissions for the wrong reasons.” The study asserts that long-term, systematic changes are needed to sustain any environmental improvements.