Sea Level: How Do We Measure Global Ocean Levels And Do Rising Oceans Change That Benchmark?

Every summer you go down the shore, but lately you’ve begun to notice that the beach seems narrower each time you visit. Is that the sea level rising, or is the sand just being swept away? Speaking of sea levels, you keep hearing that they rise higher every year — but how exactly is that measured? After all, you can’t exactly use a ruler. As it turns out, there are a number of clever systems in place that can accurately measure the global sea level down to less than an inch and a half.

Not only are waves always rippling across the ocean’s surface, but tides periodically roll in and out, making any single instantaneous measurement of sea level hopelessly inaccurate. Even if you plan to take hundreds or thousands of measurements over the course of weeks or months, taking the individual measurements is still difficult. Pick a nice, stable rock in the surf, mark a line on it, and return every hour for two weeks to hold a tape measure up to it. At best you’ll get within six inches on each reading, no matter what you’ll get wet, and at worst the rock will move and you’ll get a damp notebook full of useless numbers. So let’s take a look at how the pros do it.

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Targeting Rivers To Keep Plastic Pollution Out Of The Ocean

Since the widespread manufacture of plastics began in earnest in the early 1950s, plastic pollution in the environment has become a major global problem. Nowhere is this more evident than the Great Pacific Garbage Patch. A large ocean gyre that has become a swirling vortex full of slowly decaying plastic trash, it has become a primary target for ocean cleanup campaigns in recent years.

However, plastic just doesn’t magically appear in the middle of the ocean by magic. The vast majority of plastic in the ocean first passes through river systems around the globe. Thanks to new research, efforts are now beginning to turn to tackling the issue of plastic pollution before it gets out to the broader ocean, where it can be even harder to clean up.
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Cousteau’s Proteus Will Be The ISS Of The Seas

The Earth’s oceans are a vast frontier that brims with possibilities for the future of medicine, ocean conservation, and food production. They remain largely unexplored because of the physical limits of scuba diving. Humans can only dive for a few hours each day, and every minute spent breathing compressed air at depth must be paid for with a slower ascent to the surface. Otherwise, divers could develop decompression sickness from nitrogen expanding in the bloodstream.

An illustration of the Conshelf 3 habitat. Image via Medium

In the 1960s, world-famous oceanographer Jacques Cousteau built a series of small underwater habitats to extend the time that he and other researchers were able to work. These sea labs were tethered to a support ship with a cable that provided air and power.

Cousteau’s first sea lab, Conshelf 1 (Continental Shelf Station) held two people and was stationed 33 feet deep off the coast of Marseilles, France. Conshelf 2 sheltered six people and spent a total of six weeks under the Red Sea at two different depths.

Conshelf 3 was Cousteau’s most ambitious habitat design, because it was nearly self-sufficient compared to the first two. It accommodated six divers for three weeks at a time and sat 336 feet deep off the coast of France, near Nice. Conshelf 3 was built in partnership with a French petrochemical company to study the viability of stationing humans for underwater oil drilling (before we had robots for that), and included a mock oil rig on the nearby ocean floor for exercises.

Several underwater habitats have come and gone in the years since the Conshelf series, but each has been built for a specific research project or group of tasks. There’s never really been a permanent habitat established for general research into the biochemistry of the ocean.

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DARPA Enlisting Nemo And Dory To Find You

The ocean is a hostile environment for man-made equipment, no matter its purpose. Whether commercial fishing, scientific research, or military operations, salt water is constantly working to break them all down. The ocean is also home to organisms well-adapted to their environment so DARPA is curious if we can leverage their innate ability to survive. The Persistent Aquatic Living Sensors (yes, our ocean PALS) program is asking for creative ideas on how to use sea life to monitor ocean activity.

Its basic idea is simple: everyday business of life in the ocean are occasionally interrupted by a ship, a submarine, or some other human activity. If this interruption can be inferred from sea life response, getting that data could be much less expensive than building sensors to monitor such activity directly. Everyone who applies to this research program will have the chance to present their own ideas on how to turn this idea into reality.

The program announced it will “study natural and modified organisms” (emphasis ours.) Keeping an open mind to bio-engineering ideas will be interesting, but adding biohacking to the equation also adds to the list of potential problems. While PALS will keep its research within contained facilities, any future military deployment obviously will not. Successful developments in this area will certainly raise eyebrows and face resistance against moving beyond the lab.

But such possibilities are still far away in a future that many never arrive, as is common with DARPA initiatives. Very recently we talked about their interest in brain stimulation and we’ve been fascinated by many DARPA initiatives before that. If PALS takes off, their living sensor nodes might end up face to face with the open-source underwater glider project that won this year’s Hackaday prize.

[via Engadget]

An Interview With Alex Williams, Grand Prize Winner

Alex Williams pulled off an incredible engineering project. He developed an Autonomous Underwater Vehicle (AUV) which uses a buoyancy engine rather than propellers as its propulsion mechanism and made the entire project Open Source and Open Hardware.

The design aims to make extended duration missions a possibility by using very little power to move the vessel. What’s as remarkable as the project itself is that Alex made a goal for himself to document the project to the level that it is fully reproducible. His success in both of these areas is what makes the Open Source Underwater Glider the perfect Grand Prize winner for the 2017 Hackaday Prize.

We got to sit down with Alex the morning after he won to talk about the project and the path he took to get here.

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