Black Sea which are largely responsible for regional precipitation inputs and influence Mediterranean Sea Surface Temperatures (SST's). The relative strength of these systems also limits the amount of cold air arriving from northern regions during winter. Other influencing factors include the regional topography, as depressions and storms systems arriving from the Mediterranean are funneled through the low land around the Bosphorus, Pontic and Caucasus mountain ranges acting as wave guides, limiting the speed and paths of cyclones passing through the region. There are some islands in the Black sea that belong to Bulgaria, Romania, Turkey, and Ukraine: The Black Sea is connected
Caspian Sea around 4 million bbl/day. Additionally, Iran has an estimated 988.4 trillion cubic feet of natural gas, around 16 percent of total world reserves, which makes it to play a key role in the global energy security equation. Russia's economy ranks as the twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2015. Russia's extensive mineral and energy resources are the largest such reserves in the world, making it second leading producers of oil and natural gas globally. The Caspian Sea region presently is a significant, but not major, supplier of crude oil to world markets, based