Besides reading theology I have the opportunity to read some of my son's books on economics, especially on world economy and international trade. Not that I am interested in economics per se but globalization and international commerce are for all to read in the book of Revelation chs 17 and 18. Horst Siebert's The World Economy: A global analysis (2007) is very readable even for amateur observers of global trends.
The price of crude oil in 1960 was only 2 USD a barrel and in 1972 it was 10 dollars per barrel. Now it is 88 dollars per barrel and it has shot to more than 100 dollars a year or so ago. 7 years ago we still have 350 million people in India living on 1 USD a day. I just spent 27 NZD on a korean meal with my son tonight. We live in high income countries and we don't think twice spending 4 dollars on a cup of coffee money which could feed 2 Indian families of 5 or 6 for 2 days. The call to frugal living is part and parcel of practicing justice for where is justice when one lives in luxury while 2 billion people are still suffering poverty with per capita income of less than 1,500 USD a year.