The huge extent to which Europe has exported its global warming pollution is evident from two sharply contrasting reports on how much greenhouse gas emissions have fallen or risen since world leaders signed up to huge reduction targets in the Kyoto protocol.

The European Environment Agency reported that by the end of last year emissions produced by the current 27 member countries have fallen by more than 17% since 1990, putting them "well on track" to meet the target to meet the EU's own pledge of a 20% reduction by 2020 . The original 15 EU member states who signed Kyoto have dropped their emissions by 6%, giving them "a headstart to reach and even over-achieve" their target under the treaty of an 8% reduction. Emissions from the current 27 member countries have fallen by more than 17% since 1990, putting them "well on track" to meet the target to meet the EU's own pledge of a 20% reduction by the same date, added the report.

However a report due to be published soon by the Policy Exchange thinktank has measured the emissions generated by goods and services consumed by those countries and found that it has increased by more than 40%.

As a result, "demonstrating success in reducing carbon levels is questionable," said Simon Less, the thinktank's head of environment and energy.

Although the Kyoto agreement only measures production, the stark difference in the figures highlights a key controversy in negotiations about a new treaty – which will continue at a big UN meeting in Cancún, Mexico, in December: some developing countries, such as China, argue they should not be held responsible for emissions generated by consumption in rich nations.

An early study, published in 2009 in the journal Geophysical Research Letters, calculated that one third of China's carbon emissions were a result of producing goods for export. At that time, the UK's department for energy and climate change, told the Guardian "the footprint associated with the UK's consumption has risen", but argued for the "internationally agreed criteria" used by the UN to measure production. The biggest barrier to international targets based on consumption is fair measurement, given different methods of production, fuel use, and other variables.