Читать книгу Oceans For Dummies - Joseph Kraynak - Страница 70

According to the ancient Greek philosopher Heraclitus, “The only constant in life is change,” and this holds true for the ocean.

First, let’s look at the physical shape of the ocean. The ocean is continually changing shape, albeit at a v-e-r-y s-l-o-w pace. For example, thanks to plate tectonics — the movement of the seven humongous slabs of rock that form Earth’s crust as we know it (see Chapter 6 for details), the Atlantic Ocean is spreading apart, and the Pacific Ocean is shrinking. Or consider that the Baja Peninsula off the coast of Mexico is slowly “unzipping” from the mainland, and the Red Sea is expanding as the African and the Middle Eastern tectonic plates part company. Both of these movements are happening at about the same rate that your fingernails grow.

And at some time in the near future (like 50 to 200 million years from now), a new supercontinent will form again as the continents smoosh (a totally scientific term) back together. It’s already been named — Amasia. Scientist are debating where the supercontinent will actually settle, but wherever it lands, it looks as though the continents will be reunited, and it feels so good.

Now on to the depressing stuff.

If humans continue conducting business as usual, and burning fossil fuels at the current rate, Earth will continue to warm, which means the ocean’s temperature will steadily increase, not to mention that the excess carbon in the atmosphere will result in a decrease in pH in the surface ocean, resulting in what is known as ocean acidification. This combination of factors is already resulting in rising sea levels, shifting currents, extreme weather, and a collapse of biodiversity. Just as humans can survive a fever a few degrees higher than normal but die at temperatures over about 106.7 degrees Fahrenheit, so too can most ocean life tolerate an ocean that warms by a few degrees but when it becomes just a little warmer than that, ecosystems collapse, species migrate or just die out and the entire balance of the ocean is ruined.

All of this is BAD for us! Many coastal cities around the world are in the direct path of severe flooding as a warming ocean means rising sea levels. In terms of fishing, we’re currently on a path to eating our way down the food chain, and the lower you go, the more disruptive that fishing is, because we humans end up outcompeting the fish for the food they need to live. It’s not a stretch to say that we’re at risk of fishing ourselves out of fish.

Ocean acidification is another huge threat. The ocean is facing potential catastrophic damage from a change in pH (the measure of hydrogen ion concentration in seawater). Before the Industrial Revolution (that is, before humans began to burn fossil fuels), the average pH in the surface ocean was 8.2. In today’s ocean, the pH of surface water has dropped below 8.1 because of increased carbon dioxide produced by burning coal, oil, and natural gas. If global warming can be held to 2 degrees Celsius (3.6 degrees Fahrenheit) above the pre-industrial temperature, the average pH will drop to 7.9. A drop of 0.3 pH units might not sound very important, but that is not the case. pH is based on a logarithmic scale (like the Richter scale used to measure the magnitude of earthquakes). A decrease of 0.3 pH units is equivalent to a 45 percent increase in hydrogen ion concentration. If global warming continues to 4 degrees Celsius (7.2 degrees Fahrenheit), which some scientists have argued may occur by 2100 if humanity fails to take any action to achieve net zero carbon emissions by 2050 the average pH of surface ocean water could drop to 7.6. Although seawater at a pH value of 7.6 is still alkaline (seawater pH would have to decrease below 7 to be considered acid), the hydrogen ion concentration would be 280 percent higher than it was before the Industrial Revolution. This would have a devastating effect on many forms of marine life that are adapted to seawater with higher pH (lower hydrogen concentration). This would not be good, like Doomsday not good.

A warming ocean is also disrupting weather because the ocean plays a huge role in controlling the weather. Those disruptions are already beginning to have an impact on agriculture and the availability of fresh water, which is kind of important because you know … food and water. Already, people around the world are suffering from major shifts in temperature and rainfall that are wreaking havoc on crops and drinking water supplies.

Crap.

On the flip side, the ocean is incredibly resilient, and humans are smart, not that we always act on what we know, but we are Earth’s most innovative species. We have many tools that we know work to help the seas recover and thrive. One of the best tools is the establishment of Marine Protected Areas (MPAs), and there’s a major global push to protect 30 percent of our ocean by 2030 called 30x30. Although these MPAs may be impacted by warming water and the lowering of pH, setting aside safe places for nature has been proven to help stem biodiversity loss and build resilience in nature.

In addition, better fisheries management can restore our fisheries to healthy sustainable levels — enough to feed us while also supporting diverse marine populations.

Our greatest ally in the fight to protect the ocean is the ocean itself. In fact, the ocean already has slowed global warming from greenhouse gasses by absorbing much of the heat and pulling in heat-trapping carbon dioxide from the atmosphere. By restoring critical ocean habitats such as mangrove forests, seagrass meadows, and marshes (see Chapter 21), we can create natural systems that will help us reduce excess carbon in the atmosphere.

Some people used to think that the ocean was too big to fix, but as former NOAA director Jane Lubchenco says, “It’s time to stop thinking of the ocean as a victim of climate change and start thinking of it as a powerful part of the solution.” Here are some of the ways the ocean can help reduce global warming:

 The ocean can serve as a power source to reduce our reliance on fossil fuels. People are already harvesting energy from wind, waves, and tides. The ocean is also the largest collector of solar energy, and through ocean thermal energy conversion (OTEC) and other technologies, people are using that heat to produce electricity. (See Chapter 19 for more about tapping the ocean for energy.)

 The ocean is the biggest heat sink and carbon sink on the planet, meaning the ocean absorbs a huge amount of the heat and carbon before they significantly impact life on Earth. If we maintain and in some cases restore a healthy blue carbon ecosystem, the ocean can continue to sequester and store carbon, doing much of the heavy lifting required to reduce carbon in the atmosphere.

 Sustainable aquaculture (land-based aquatic farming) and mariculture (ocean-based aquatic farming) of both marine plants and animals can help grow food, establish new habitats create new jobs, and absorb some extra carbon as well.

The good news is that by working together in partnership with the ocean, there is the very real possibility that we can stop the downward spiral we have set ourselves upon, restore the ocean to abundance, and rebuild a thriving future for all living creatures both above and below the ocean’s surface.