But the almost certain rejection of many of the amendments by the Commons means it will have to come back again.
The amendments shift in part the burden of responsibility for compliance from the environment minister to the prime minister and set annual indicative targets within the five year carbon budgets.
Campaigners have failed to get the 2050 target raised to 80 percent but claimed partial victory with the inclusion of a clause committing the government to hold temperature rises to two degrees -- a goal they say is equivalent to 80 percent.
In what they hailed as a major victory the amended bill also sets a strict limit on how many carbon emission permits the government can buy in from abroad to cover any shortfall in the national reduction performance.
The government had fought against a limit on foreign carbon credits which would give it broad leeway to underperform its own legal targets.
"The Lords' amendments do improve the bill, which means many won't make it through the Commons," said Greenpeace climate campaigner Charlie Kronick.
The European Union's Emissions Trading Scheme has turned carbon into a commodity through issuing emission permits which can be bought and sold by companies.
Also under the Kyoto climate change accord's Clean Development Mechanism countries and companies can buy into low emission developments to offset their own emission overshoots.
Scientists say global average temperatures will rise by between 1.8 and 4.0 degrees Celsius this century due to carbon emissions from burning fossil fuels for power and transport, causing floods and famines and putting millions at risk.
