Happy February, Speak Up For Blue crew! February is a short month, meaning we don’t have that long to enjoy it. In the spirit of this urgency, we decided to begin the month by speaking about sea level rise. First off, sea levels are rising. Not only are sea ice and glaciers melting, but the water itself is chemically expanding. This thermal expansion is a neat but currently inconvenient property of water molecules. Sea level rise can also be influenced by periods of seafloor expansion and the global water cycle (rain becomes groundwater or ocean water which evaporates and ultimately becomes rain again). Because of the complex relationship between climate change and these direct causes of sea level rise, it has been difficult for researchers to predict just how much sea levels will rise across the globe throughout the next few decades. Therefore, a few scientists decided that the next best thing would be to actually measure how much sea levels have risen since 2002 using historical data and see if they could figure out just how much of this was due to thermal expansion (or steric expansion).
Led by Dr. Rietbroek, a team of German researchers found that thermal expansion’s contribution to sea level rise was about 1.38 millimeters per year. While this may not seem like a large number, scientists previously estimate sea level rise due to thermal expansion was a measly 0.7 – 1.0 mm per year. The study also concluded that the overall mean sea level rise rate between 2002-2014 was about 2.7 mm. Much like a college freshman who just discovered 24-hour delivery, our seas are expanding at a faster rate than originally predicted. The study also reiterated that local sea level rise can vary from region to region. Areas of the western Pacific, for example, are facing much faster sea level rise than the eastern Pacific. While the Phillipines and Indonesia have seen an annual rise in sea levels of 14.7 mm/yr and 8.3 mm/yr, respectively, the west coast of the United States has seen virtually no net rise in sea levels over the past decade. These fluctuations are largely due to the contribution of thermal expansion in each region. Then you have areas like the northwest Atlantic, which has seen a rise in sea levels of about 5.3 mm/yr but mostly due to “ocean bottom pressure variations” (Rietbroek et al. 2016).
The good news is that there is something we can do to reduce or eliminate this sea level rise. The two main causes of current sea level rise (thermal expansion and melting sea ice) are results of an associated rise in sea surface temperatures. By reducing your carbon footprint and your carbon emission contribution, you can do your part to ensure that sea level rise does not get worse over the next few years. Go for more walks or bike rides rather than taking your car everywhere; turn down the thermostat in your home and turn off the lights when you aren’t using them. These will not only use less energy (thereby decreasing your carbon footprint), they’ll also save you money. Call them Life Hacks and become a superstar on Buzzfeed if you want, the important thing is that we are all doing our part to keep our ocean ecosystems healthy and prevent adverse impacts of climate change.
Enjoy the Podcast!