Governor Charlie Baker’s decision to return the legislation with amendments was expected after lawmakers overwhelmingly approved an identical version of the bill that had died on Baker’s desk early last month. But on Sunday, legislative leaders expressed willingness to consider and potentially incorporate some of Baker’s proposals.

The bill would require the state to reduce its carbon emissions by 50 percent below 1990 levels by the end of the decade and effectively eliminate those emissions by 2050.

Long considered too risky, solar geoengineering is now being more seriously considered as the threat of climate change grows more dire. But critics say such a test would set a dangerous precedent.