Opponents of the widening of the UK's main motorway have unfurled banners to promote their anti-pollution message.
The banners say 'no' to M1 widening
Banners with slogans such as "Climate Emergency" and "More roads = more cars" were draped over motorway bridges from Sheffield to Luton on Monday.
The No Widening M1 Alliance claim the £3.74bn project will cause environmental damage.
But the Highways Agency said the widening will improve journey time, road safety and reduce driver stress.
Too many cars
The protest coincides with the release of the Stern Review on climate change which said scientific evidence of global warming was "overwhelming" and its consequences "disastrous".
The banners were being displayed at locations in Sheffield, Nottingham, Derby, Leicester and Luton on Monday morning.
The protesters are calling for the money from the project to be invested in measures that will reduce road transport and its contribution to climate change.
Julie White, a spokesperson for the No Widening M1 Alliance said: "Road transport contributes 21% of UK CO2 emissions which cause global warming and rises every year as traffic increases.
"Higher levels of these gases are causing the climate to change at a speed never seen before in human history."
The widening plans for the M1 include four lanes in both directions between junctions 21 and 42 (Leicester to Leeds).
There is also widening planned for junctions 10 to 13 (Luton to Milton Keynes) and the M1 between junctions 6a and 10 (M25 - Luton) is being widened at the moment.
The Highways Agency is to expand three-lane sections into four with an additional crawler lane on hills for lorries to use.
Tony Turton, of the Highways Agency, said earlier: "Journey times are predicted to rise on this particular section between 50% and 60% by 2030.
"This project will create additional capacity to allow that traffic to flow efficiently."
Construction work is scheduled to begin in 2007.