Temporary dead zones are located where the condition of hypoxia occurs for hours or days. This means that the oxygen level of the ocean might remain normal but at times for hours or days, the oxygen level will be below 2 mg per liter. Many temporary dead zones are going to become permanent dead zones due to global warming. If this condition continues to spread, many oceans in the world will end up becoming dead zones and greatly affect marine life. The chart (left) shows that the oxygen level-below 2 mg/L is only during the summer months. Many temporary dead zones even occur for a period of days in other times of the year as well.