Additional energy is needed to desalinate water. More water is needed given more manufacturing. Cement adds to carbon emissions.
Fossil fuels are also needed for renewable energy plus infrastructure plus consumer goods. Not only fossil fuels but various minerals, fresh water, cement, etc., are needed. These will face the same problems as fossil fuels.
The issue isn't whether or not conservation is praiseworthy and insufficient but whether it is logical. Given a world with physical limitations, it is.
The purpose is not to produce more hydrocarbons but to adjust to a world with physical limitations.
It doesn't delay the inevitable. Rather, it takes place after one realizes that the inevitable (i.e., physical limitations catch up with increasing consumption) is delayed.
And the Jevons paradox takes place because the global economy is capitalist, and that requires increasing production and consumption of goods to ensure more profits, which in turn are churned back into the economy to produce and consume more. That global economy cannot continue due to physical limitations.
The switch to renewables is meant to address both peak oil and global warming. In which case, the point that the latter doesn't matter is illogical.
The problem is that it's assumed that renewables can be used to replace fossil fuels. They can only to a certain extent because fossil fuels are needed to mine resources, manufacture components for renewables, infrastructure, and consumer goods, and even ship them.
More important, renewables, new oil, and other resources have low energy returns and quantity:
http://www.theoildrum.com/node/3786
The catch is that the global economy, which is capitalist, requires increasing energy quality and quantity. According to the IEA:
http://www.worldenergyoutlook.org/publications/weo-2010/
the world economy will need the equivalent of one Saudi Arabia in new oil every seven years just to maintain economic growth. At least 70 pct of the increased oil demand per annum must be replaced with renewables to deter the effects of global warming:
http://www.theguardian.com/environment/2011/nov/09/fossil-fuel-infrastructure-climate-change
but in the long term that will require (according to the report) oil producers going for maximum depletion rates, strong regulation by governments, and cooperation between economies. How likely is this given the fact that the complete opposite has been taking place for decades?
In addition, if more of the new oil consists of unconventional production, then even more oil will be needed:
http://www.theguardian.com/environm...um-geologist-peak-oil-break-economy-recession
and if more of the oil, minerals, water, cement, solar panels, etc., will be needed by a growing global middle class:
http://www.bbc.com/news/business-22956470