[Yardstick]

The temperature of the oil will actually drop as it goes from high to low pressure (that’s why they had trouble with ice crystals in the cap), and it will pull heat from the nearby water which will cool it. But the mass of the oil is miniscule compared to that of the surrounding sea, and the cooling of the water will be insignificant, except in a very localized way. If you put a drop of cold oil into a bucket of water, the temperature doesn’t change much.

[justa-hairyape]

The water temp issue is actually a complex problem. Yes, if the oil is very cold, could be below the freezing point of water actually, its overall effect on the water temp of the gulf will be small at first. The key is the accumulative effects over time. And also localized affects will have much greater magnitudes then average affects. How an oil slick modifies the solar warming of water is also complex. The oil absorbs more light so it will get warmer then the water, but the water below gets less light and less thermal warming. When the oil slicks warms, it will give some of the the energy to the water and some to the atmosphere. Gonna have to crunch the numbers on that one. Oil slicks cover a significant portion of the water surface and are growing. My guess is solar heat is being trapped at the water surface due to the oil, some of that concentrated heat gets radiated back to the atmosphere at night, some is lost to the atmosphere due to wind during the day and the net result is that the water below is cooling.