Climate Change is Affecting our Hydrosphere
Column in The Bargain Hunter Nov 20, 2020
by Randi Pokladnik
When we talk about climate change, we often fail to recognize the role that our oceans play in the bio-chemical cycles of the planet. We know from biology class that the planet is made up of spheres. The lithosphere includes the surface crust, the biosphere is all the living organisms, the atmosphere includes the layers of air surrounding and protecting the planet, and the hydrosphere contains all the solid, liquid and gaseous water of the planet.
The hydrosphere extends from Earth’s surface downward several kilometers into the lithosphere and upward about 12 kilometers into the atmosphere.
According to the U.S. Geological Survey, 97% of our planet’s water is salt water, and 3% is freshwater. Most of this freshwater is inaccessible. Over 68% of the freshwater is found in icecaps and glaciers, and just over 30% is found in ground water. Only about 0.3% is found in the surface water of lakes, rivers and swamps.
Climate change is dramatically affecting our hydrosphere, mainly our oceans. The Intergovernmental Panel on Climate Change Special Report on Ocean and Cryosphere (frozen water) cited these changes in our oceans: acidification, increases in water temperature, sea-level rise, loss of oxygen and sea ice retreat.
Scientists tell us the absorption of atmospheric carbon dioxide by Earth’s oceans has led to their “acidification.” What does this mean? Ocean water combines with carbon dioxide in the atmosphere to create carbonic acid, the same acid in your soda pop. The higher the concentration of carbon dioxide in the atmosphere above the water, the more carbon dioxide that is absorbed.
According to the National Oceanic and Atmospheric Administration, “In the 200 years since the industrial revolution began, our oceans have seen a drop in pH of about 0.1 pH units.” This might not seem like much, but remember, the pH scale is logarithmic, so that drop means a 30% increase in ocean acidity.
As the oceans acidify, the organisms that inhabit the oceans are negatively impacted. Oysters and clams that make hard shells are particularly affected by acidification. The carbonate ions that organisms use to make shells instead combine with the excess hydrogen ions from the acids. This means less carbonate to make shells. Also, the lower pH of acids can even dissolve shells. A similar reaction is happening to ancient monuments affected by acidic rain.
“In the Pacific Northwest, baby oysters have died off by the billions. Their tiny shells dissolved before they were fully formed.” This will affect an industry that brings $11 million into the Pacific Northwest economy.
The oceans have seen unprecedented increases in water temperatures. A map produced by scientists of NOAA and NASA shows temperature increases in the oceans from 1955-2010. The overall increase in ocean heat content during those 55 years is equivalent to 2.5 billion times the energy released from the bomb dropped on Hiroshima, Japan.
Data shows 90% of the heat increases on the planet have gone into the oceans, and they show significant warming at the surface, as well as in the depths of the oceans. The ocean warming also has led to sea-level rise as warmer water expands.
Another factor to consider is water has a high specific heat, meaning it holds heat for a long period of time. When water is warmed, it takes a long time for it to cool down. Ocean temperatures today are a result of the enormous amount of heat that has been absorbed in the past 55 years.
This heat can damage organisms. An example of this can be observed at Australia’s Great Barrier Reef. This reef is the largest coral reef in the world and home to more than 1,500 fish species. It is so large it can be seen from space and is one of the seven “natural” wonders of the world.
The reef is a source of food and provides protection from storms. In terms of its economic value, it represents $6.5 billion to the Australian economy, drawing more than 2 million tourists each year. In 2016 a massive heat wave killed 30% of the coral reef. This death, often called bleaching, happens when algae called zooxanthellae die. They are blue-green in color; therefore, once they die, the reef appears white. These algae have a symbiotic relationship with reef-building corals supplying energy and nutrients. Without them, the corals themselves often die.
Trout fishermen know trout like cold water, oxygen-rich streams. Warm water does not contain enough oxygen to support many fish species. As our oceans warm, they are losing oxygen gas. Andreas Oschlies, an oceanographer at the Helmholtz Center for Ocean Research Kiel in Germany, has a team that tracks worldwide oceanic oxygen levels. He said, “We were surprised by the intensity of the changes we saw, how rapidly oxygen levels are going down in the ocean and how large the effects on marine ecosystems are.”
The decline is worse in tropical regions, which show a 40% decrease in oxygen levels over the past 50 years, but even polar regions are seeing oxygen declines. These drops are especially harmful to zooplankton, which are the base of the ocean food web. Other species are affected and may not be able to reproduce as readily or get adequate food supplies. As oxygen-rich areas shrink, economically valuable fish like tuna, which globally generate $42 billion annually, are forced to find new habitats.
Lastly, climate change is affecting sea ice, which in turn is affecting sea levels. Since 1880 the mean sea level has risen about 8-9 inches, and a third of that increase has happened in the last 25 years. This rise is due to both thermal expansion of warmer water and also meltwater from glaciers and ice sheets.
The United Nations reported eight out of the 10 most populated cities are coastal cities and 40% of the USA’s population lives near a coastline susceptible to flooding. Meteorologists tell us that as the sea levels rise, storm surge is worse. We saw this with Hurricane Katrina and Superstorm “Sandy.” Warmer water means more intense storms too.
If we continue on this path with little to no changes, our oceans could see pH values as low as 7.8. The last time the ocean pH was this low was 14-17 million years ago. At that time the Earth was experiencing warming, as well as a major extinction event.
We know what past warming scenarios brought to the planet, yet we still are ignoring the issue and are reluctant to make any significant changes to our lifestyles. One might say we live in a country of “willful ignorance.”