Temperature, the Ocean, and the Water Cycle

Dear readers,

While the last entry introduced you to the temperature-CO2 debate that is still raging, this entry and the next will focus on why CO2 levels and rising temperatures are extremely important independent of past geological climate data. And, as promised, this will take us right back to the oceans:) While it is entirely likely that our planet is warming due to both natural (changing solar intensity) and anthropogenic causes (increased greenhouse gases), the fact that it is warming is significantly changing the oceans and the water cycle.

As the USGS reports, the ocean is the world's greatest storehouse of water, containing about 96.5% of all the water on earth. As the ocean surface temperatures rise, the water cycle will be affected, leading to more evaporation and water vapor entering the atmosphere. Since water vapor is the most abundant greenhouse gas, making up 36-72% of our atmospheric greenhouse gases, increased atmospheric water vapor can amplify the warming effect by increasing the absorption and trapping of thermal radiation. This is called a positive feedback loop. Increased temperatures increase the atmospheric water vapor concentration, which in turn raises temperatures. Positive feedback loops are extremely common in biological systems and may significantly amplify the effects of climate change. Therefore, if pushed by increasing temperatures, the oceans may inadvertently help drive climate change through the water cycle, leading to the next mass extinction event. 

But temperature and water vapor aren't the only culprits. Come back next time to discuss the effect of the second most abundant greenhouse gas, CO2, on the oceans.

-N. Gallo

Cool fact. The Amazon River is the largest river in the world by water volume, containing about 1/5 of the world's total river flow. However, of the total water on Earth, it makes up < 0.4%. In comparison, the oceans make up 96.5% of the Earth's water, thus playing a very important part in the water cycle.
(photo credit: http://www.eltourismo.com/wp-content/uploads/2010/07/Amazon-River.jpg)

For more information on the ocean's role in the water cycle, check out this USGS article title "The Water Cycle: Water Storage in Oceans," which can be accessed here: http://ga.water.usgs.gov/edu/watercycleoceans.html