Total global proved oil reserves, excluding oil sands, have grown substantially over the past two decades from 998.4 billion barrels at the end of 1988 to 1,068.5 billion barrels at the end of 1998 to 1,258 billion barrels at the end of 2008. The total was down slightly from the 1,261 billion barrels at the end of 2007. The largest percentage decrease in reserves in the past twenty years was in North America which was down almost 30% from 100 billion barrels in 1988. The largest percentage increase in reserves over the past twenty years was in Africa which was up 113% from 59 billion barrels in 1988 due to substantial reserve increases in Libya, Angola and Nigeria.


Total global proved natural gas reserves have grown substantially over the past two decades from 998.4 Tcf at the end of 1988 to 1,068.5 Tcf at the end of 1998 to 6,534 Tcf at the end of 2008. The total was up 4.5% from reserve volumes at the end of 2007 mostly due to the development of new reserves of natural gas in Turkmenistan.