[AlphaEsponjosus]

No. The energy consumption does not need to decrease, the source must be more eficient. We have nuclear energy, despite the propaganda, nuclear energy (specially the Thorium reactors) produce very little waste and pollute less than fosil fuels or even solar panels. You do not need to discover a new source of energy to stop climate change. The problem is that people keep thinking in how much it will cost.

Again, GDP measures how much money is spent within a country, if there are several intermediaries in a supply chain, the cost of products and services increases and the GDP tends to rise.

If a country change direction and leans towards nuclear energy, the GDP (that is in fact a terrible measure) will increase cause the new expenditures.