"The strength of the 2009 recession affected all economic sectors in the EU," the report said. "Consumption of fossil fuels fell compared to the previous year, mainly for coal."
Greenhouse gas emissions in Europe fell to the equivalent of 4.6 billion tonnes of carbon dioxide in 2009 from 4.96 billion in 2008.
The 7.2% fall - of 354 million tonnes, or almost as much as the annual emissions of either Spain or Poland - was far steeper than any other declines since 1990, when rich nations started compiling data.
The report did not signal how far emissions might have rebounded since the return to economic growth in 2010.
Figures show that CO2 discharges in the EU's emissions trading scheme rose 3.5% in 2010.
The EEA report simply noted that "the recession in 2009 accelerated, temporarily, the downward trend in total greenhouse gas emissions".
This fifth-successive greenhouse gas fall in a row has put the EU's emissions 17.6% below the 5.59 billion tonnes which were emitted in the UN's base year of 1990.
The 17.6% figure is also close to the EU's 2020 target of a 20% cut below 1990 levels, and will strengthen the hand of the EU's climate action commissioner, Connie Hedegaard, who would like to see the 2020 goal extended.
The EU's formal position is that the target could be deepened to 30% if other industrialised nations follow suit.
In March, Germany, Britain and other member states called for the 20% target to be strengthened now.
The European Commission's Low-Carbon Roadmap for 2050 shows how honouring the EU's target of a 20% increase in energy savings by 2020 would, of itself, lead to emissions cuts of at least 25%.
For the 15 EU members with emissions goals under the UN's 1997 Kyoto Protocol, emissions fell by 6.9% in 2009, taking their emissions output 12.9% below 1990 levels - and almost 5% lower than the goal set at Kyoto for 2012.
Most of 2009's emissions cut was caused by a steep decrease in carbon emissions from public electricity and heat production, and by reductions in manufacturing activity.
Other nations' emissions also fell in 1990, because of recession. In the US, greenhouse gas emissions plummeted by 6.1%, and in Russia by 3.2%.
(EurActiv with Reuters.)