The term Energy descent refers to descent from the peak of peak oil. See for example . Oil descent might be a more precise term. Precisely what will happen during the inevitable decrease in oil production depends on whether or not effective methods of capturing solar energy are developed.
The global economy, and the modern 'way of life', is built upon affordable, abundant conventional oil.
ASPO The Association for the Study of Peak Oil & Gas, founded by Colin Campbell: a network of scientists studying the decline of oil and gas production. The site is good for news, but hard to navigate. APSO holds annual conferences.