the peak oil theory is reduced demand from various options and technologies substituting oil. US federal funding to develop algae fuels increased since 2000 due to rising fuel prices. Many other projects are being funded in Australia, New Zealand, Europe, the Middle East, and elsewhere and private companies are entering the field. Oil industry representatives John Hofmeister, president of Royal Dutch Shell's US operations, while agreeing that conventional oil production would soon start to decline, criticized the analysis of peak oil theory by Matthew Simmons for being "overly focused on a single country: Saudi Arabia, the world's largest exporter and OPEC swing producer." Hofmeister pointed to the large reserves at the US outer continental shelf, which held an estimated of oil and natural gas. However, only 15% of those reserves were currently exploitable, a good part of that off the coasts of Texas, Louisiana, Mississippi, and Alabama. Hofmeister also pointed to unconventional sources of oil such as the oil sands of Canada, where Shell was active. The Canadian oil sands—a natural combination of sand, water, and oil found largely in Alberta and Saskatchewan—are believed to contain one trillion barrels of oil. Another trillion barrels are also said to be trapped in rocks in Colorado, Utah, and Wyoming, in the form of oil shale. Environmentalists argue that major environmental, social, and economic obstacles would make extracting oil from these areas excessively difficult. Hofmeister argued that if oil companies were allowed to drill more in the United States enough to produce another , oil and gas prices would not be as high as they were in the late 2000s. He thought in 2008 that high energy prices would cause social unrest similar to the 1992 Rodney King riots. In 2009, Dr. Christof Rühl, chief economist of BP, argued against the peak oil hypothesis: Rühl argued that the main limitations for oil availability are "above ground" factors such as the availability of staff, expertise, technology, investment security, funds, and global warming, and that the oil question was about price and not the physical availability. In 2008, Daniel Yergin of CERA suggest that a recent high price phase might add to a future demise of the oil industry, not of complete exhaustion of resources or an apocalyptic shock but the timely and smooth setup of alternatives. Yergin went on to say, "This is the fifth time that the world is said to be running