A council has declared a climate emergency and committed itself to improve sustainability in the county.
A full meeting of Hertfordshire County Council unanimously backed the environmental strategy.
The council will consider the environmental impact on its operations and services.
Leader of Tory-controlled Hertfordshire County Council David Williams said: "I'm pleased that we've made this important declaration."
He added: "As a county council we're well-placed, not just to reduce our own environmental impact but to help the whole county become more sustainable."
A Sustainable Hertfordshire Strategy will be presented to the council's cabinet before the end of the year.