As in the first experiments, EBF emission was again dependent on plant genotype and size with FS9 plants emitting more EBF then FS11 plants (F = 191.10, p < 0.001) and larger plants emitting more EBF than smaller plants (F = 13.38, p < 0.001).
And although U.S. emissions did decline in recent years, Claussen noted in her statement that "U.S. greenhouse gas emissions are again on the rise, and much stronger efforts are needed to rein them in and achieve steep long-term reductions".
But in 2012 and 2013, CO2 emissions rose again to 841m tons.
The dramatic fall in the price of oil over the last few months will also be an important factor in whether emissions rise again next year, as cheaper oil is associated with increasing greenhouse gas levels.
The recommendation that global emissions need to peak and decline before 2020 is an important additional element — one which might be helped by the current recession but which nevertheless requires significant action in the short term to prevent emissions rising again in tandem with economic recovery.
Greenhouse gas emissions in 2011 fell to record lows, 21% down on 1990 levels, largely due to warm weather reducing the use of gas – but more recent data has revealed that emissions rose again by 3.5% in 2012, due to a colder winter and more use of coal for electricity.
The Bush administration acknowledged for the first time in a new report that "greenhouse gases" will build significantly over the next twenty years, due largely to oil refining, power plants and car emissions, but again rejected an international treaty to slow global warming.
Meanwhile, global emissions rose again last year as global growth bounced back after the slump of 2009.
4. Are we seriously not going to update our emissions targets again until 2025?
"But at the same time, with emissions peaking again last year... everything was pointing to an increased temperature.
