If we don't give guidance on how emission cuts will be made – by putting in place a coherent set of three targets – the door will be left open for false solutions like nuclear power, the replacement of coal with natural gas and unsustainable bioenergy, or carbon capture and storage. These technologies will not deliver sufficient long-term emissions cuts.
Nuclear is too dangerous and unpopular, as Fukushima shows us. It is also prohibitively expensive. There are two large-scale nuclear projects underway in the EU: Olkiluoto in Finland and Flamanville in France. Both are five years behind schedule and two or three billion Euros over budget.  And there is no safe, long-term solution for the storage of radioactive waste. Nuclear cannot deliver safely, or within the required time period.
Energy companies are currently pursuing several bioenergy sources with a worse carbon footprint than fossil fuels.  These also represent a false solution and accelerate instead of mitigate climate change. Burning whole trees for electricity in coal installations is extremely inefficient and makes no environmental sense. And burning crop based biofuels for energy contributes to significant greenhouse gas emissions due to the destruction of natural carbon sinks as a result of agricultural expansion. It also fuels conflicts over land use. New targets for 2030 must exclude such unsustainable forms of bioenergy.
On its own, a greenhouse gas reduction target for 2030 risks encouraging the replacement of coal power plants with natural gas. Natural gas is less dirty than coal but it still locks Europe into an unsustainable, carbon intensive fossil fuel system.
Unconventional gas sources – such as shale gas – are also not a solution. The lifecycle greenhouse gas emissions from burning and extracting shale gas make it even more damaging than coal.  The International Energy Agency estimates the development of shale gas would drive climate change ‘well above the widely accepted 2°C target’. On top of this, unconventional gas is linked to air and water pollution, and significant health threats. Development of shale gas requires significant investment, which has already reduced available capital for renewables projects in the US. 
Carbon capture and storage (CCS) is not a viable alternative. CCS is a 20th century concept, designed for cheap and plentiful fossil fuels. And because extra energy is needed to capture, transport and store CO2, CCS increases reliance on fossil fuels. It is a hot topic for big energy companies because it represents the hope that they can keep alive the current energy model. Rather than being a solution, it risks perpetuating the problem. The fundamental fact is that we have to make the transition to an energy system which does not rely on fossil fuels.
Haberl H. et al. (2012) “Correcting a fundamental error in greenhouse gas accounting related to bioenergy”, Energy Policy, 45, Pages 18–23: http://www.sciencedirect.com/science/article/pii/S0301421512001681
 IEA(2012), Golden Rules for a Golden Age of Gas, page 91: http://www.worldenergyoutlook.org/media/weowebsite/2012/goldenrules/WEO2012_GoldenRulesReport.pdf
 Bloomberg New Energy Finance. http://about.bnef.com/bnef-news/clean-energy-investment-fell-11-as-governments-cut-subsidies/