What we have now is the end product of a couple hundred years starting with the age of iron and coal and progressing to the burning of oil and gas. Whatever standard of living people have now is powered by fossil fuels, which provide the great majority of the 400 quadrillion BTUs of energy used globally each year.

Constraining fossil fuel use will result in a significant decline in GDP per capita if it is done rapidly enough to significantly reduce global warming.

Here is US energy sources and uses. Note that solar, hydro, wind, geothermal, and biomass are pretty small.

Those that do, corporations and the populations of some industrialized states, use far more than they need. Much of the economy produces things that really are useless or even harmful. Also, an increasing amoung of the world's wealth is being concentrated into fewer and fewer people. I consider that to be completely unnecessary production.

The US uses a little under 20% for its 5% of world population. The consumption per capita is lower in almost all other countries, which means that the smaller amount per capita that they use is for more vital and less wasteful purposes than in the United States.

http://en.wikipedia.org/wiki/List_of_countries_by_energy_consumption_per_capita

Admittedly, some of the lowest energy per capita countries use a lot of biomass. But that is denuding their countries of forests and is doing the carbon balance and climate no good.

I made that pretty clear.

The average human being doesn't use much even if there is a big (usually foreign) factory in his or her area. The average person is a farmer and lives at a low technology level. Also, you are skewing the figures by not looking at the immense amount of coal the USA uses.

Urban populations exceeded rural ones in about 2008.

China is the world's largest producer and consumer of coal, accounting for a little less than half the world's production. 3844 million short tones out of world production of 8440 million short tons.

US was in second place consuming 1003 million short tons.

http://www.eia.gov/countries/

When you say "half the world," is that by population or state (country)? I notice, for instance that all of Australia and the USA is green, while most of their population is on the coasts.

to renewables.

Any dramatic limiting should probably be paired with a paradigm shift in how we see civilization

And devote the remaining energy to rail, buses, communal baths, communal cooking, and the production and distribution of unprocessed food.