In general, the world supply of oil and natural gas matches the demand for these fuels. Consequently, any real or even perceived threat to supply can cause oil, petroleum products, and or natural gas prices to rapidly rise days to months in advance of when the threat might materialize. Natural disasters are an example of such threats and here in the US, the biggest and most common are hurricanes. In 2014, the US got approximately 16% of its oil and approximately 4% of its natural gas from production in the offshore Gulf of Mexico. Furthermore, about 45% of US refining capacity is located along the Gulf coast. When a hurricane passes into the Gulf, exploration and production platforms within a wide swath of the hurricane's projected path are shut down and evacuated. Offshore oil and gas transmission pipelines are also closed so as to minimize spills from infrastructure that might be damaged by waves and or sea floor avalanches that such storms can trigger. And coastal refineries where the hurricane may make landfill greatly reduce or even curtail operations. The prospect of disrupted supply that these shutdowns would cause can set off price jumps a week or more in advance of a hurricane. And if a storm cripples oil and gas infrastructure off shore or on the coast, prices can remain high for weeks to months afterwards. This is, in fact, what happened in 2005 when the U.S. Gulf of Mexico was hit by four hurricanes, including Katrina and Rita which were category five hurricanes, or the largest they come. Geopolitical conflicts are another supply threat that triggers significant, short-term price volatility particularly for oil, but also for natural gas. In 1991, for example, Desert Storm, the first of the two recent wars in Iraq, caused oil prices to jump almost $20. A third short-term influence on prices is unforeseen impacts on economic growth. In general, if data show that the gross domestic product of the world, or even a large hydrocarbon consuming nation, is increasing faster than expected, oil demand may increase faster than expected as well. And the anticipation drives oil prices up. The reverse happens when economic growth unexpectedly stagnates or declines. Under these circumstances, prices fall in anticipation of a previously unforeseen reduction in demand. This is in fact what happened immediately following the September 11th terrorist attack on the U.S. in 2001. Finally, in the case of oil, there's a fourth factor that can instigate rapid price changes, and that is announcements of significant changes in the supply of crude oil from the organization of petroleum exporting countries or OPEC. OPEC provides 40% of the oil consumed by the world, and 60% of the oil that is traded internationally. Being a cartel, OPEC tries to manage its supply so as to keep world oil prices as high as possible without crimping global demand given other factors at play in the world. The most influential country in OPEC is Saudi Arabia. It is both OPEC's largest oil producer, and the world's only swing producer. Saudi Arabia has been able to rapidly bring on or take off of the world market up to two million barrels of oil per day. When world supply of oil relative to demand is tight, changes in output by OPEC, and particularly by Saudi Arabia, can cause significant price swings. These changes can also be used by OPEC to stabilize world prices if they are rising too fast. However, when global demand for oil is weak, OPEC's influence on oil prices is greatly reduced. At these times, cutbacks in production have had much less influence on price, and have even spurred individual OPEC countries to exceed their assigned production quota. In an effort to maintain the oil revenues they need to fund the domestic government services.