Emissions estimates were also increased by switching the modeling from a consumption-based, meaning emissions taken from power generated in state and out of state, to production-based, which relies on data from in-state power sources.

The SEI report was initiated by Brown University, in part because some of the data for calculating reductions in a 2016 report by the state’s Executive Climate Change Coordinating Council (EC4) were 20 years old and considered outdated.

“In the twenty years since, climate science has advanced rapidly, and it suggests that impacts are coming faster even than some of the worst predictions,” according to the SEI report.

“So we wanted to know, if we updated some of those numbers with more current science and more realistic estimates about the leakage rates from our old pipes here in New England from natural-gas distribution, what would be the impact,” said Timmons Roberts, professor at the Institute at Brown for Environment and Society.

Roberts explained at the Sept. 12 meeting of the EC4 that the new report was commissioned after Brown University students asked Gov. Gina Raimondo to follow the lead of other states and commit to eliminating greenhouse-gas emissions. Raimondo said she wanted to see evidence that zero-carbon could be achieved. To find out, Brown University president Christina Paxson agreed to fund the SEI study and hire four students as staff.

The 65-page Deeper Decarbonization in the Ocean State also showed that current emissions are understated by shortening the impact of greenhouse gases, such as methane, from 100 years to 20 years.

“We probably only have about 20 years to act if we want to ratchet down greenhouse-gas emissions in a way that is necessary to assure that we avoid the most catastrophic consequences of climate change,” said Jason Veysey, SEI’s lead scientist on the report.

Rhode Island has non-binding goals of cutting climate emissions 10 percent below 1990 levels by 2020, 40 percent by 2035, and 80 percent by 2050.

Based on 2016 data, the state is currently 11 percent below 1990 levels. Transportation continues to account for the largest segment, with 36 percent of emissions. Electricity consumption accounts for 26 percent, and residential heating accounts for 17 percent.

A full report from the Rhode Island Department of Environmental Management (DEM) on state emissions sources is expected by the end of the year.

“The point of this is to say we need to look seriously at emissions that we are producing now and what their effects are going to be in this next critical period, and that should inform the discussion about what the mitigation agenda should be,” Veysey said.

To get there, the state can use existing technology, such as electric vehicles, electric heat pumps, and a zero-carbon electric grid. Even with such changes, the state would still produce greenhouse-gas emissions from airplanes and boat travel.

“If you want to cut your emissions quickly,” Veysey said, “the very first thing you need to do is you need to stop buying fossil-fuel equipment.”