I continue to be perplexed about how difficult it is for people to see the magnitude of the problems that our continued release of CO2 (carbon dioxide) into the atmosphere are having, and will continue to have, on the global environment. I don’t blame the difficulty of comprehending the magnitude of the problem on “the public,” but I certainly blame it on “the media.” The media primarily focus on the topic of greenhouse gases creating “global warming” resulting in slightly (one or two degrees) warmer weather, brief periods of extreme weather and a slow increase in sea levels. Most people now believe that we are experiencing a period of increased variability in global weather, and they agree that is probably results in more extreme weather. But they don’t seem to comprehend the severity of the situation and don’t want to believe that people are contributing to the changes.
Many people think we are experiencing a natural, temporary, increase in temperature – something that happens all the time. They don’t believe that we (mankind) can cause problems sufficient to drive such as big system. They take the position that while there probably is global warming, and that warming is probably making the weather worse and perhaps causing a small rise of sea levels, they believe that none of this has anything to do with us. It is a “natural” occurrence and therefore there is nothing we can do about it.
The thing is, there are additional potentially catastrophic outcomes from releasing huge quantities of CO2 into the atmosphere than bigger storms, more uncomfortable temperatures and slightly higher sea levels. While the media sometimes hint at these issues, they don’t get the full throated messaging that they deserve. I find it astounding that given the potential severity of the problems created by the release of these gases we continue with the status quo. Dramatically limiting the release of greenhouse gases (most notably CO2 and CH4 (methane)) can be accomplished inexpensively with very little disruption to our lifestyle, and will result in many other positive health and economic outcomes. Doing so will result in an enhanced, healthier and less expensive lifestyle. Even if it turns out that all of the dire predictions turn out to be false, it is still worth our while to stop polluting the atmosphere with by releasing vast quantities of these chemicals. I don’t understand why we (Society and Government) are so timid about making the necessary changes.
For now I am going to leave discussion of exactly how these gases can be economically reduced to a later time. Right now I just want to point out that changing our carbon footprint has many positive outcomes, including improving our health, while saving money and resources. Vastly reducing our carbon footprint has enough positive results to make it worthwhile even if doing so has no impact on global warming, wild weather or a rise in sea levels.
It is important that the public and our leaders better understand the full range of potentially negative impacts of continuing the current practices of releasing greenhouse gases to the atmosphere. It isn’t just about warming the air, melting ice, changing weather or creating slightly deeper oceans. I am writing this article in the hope of illustrating a few of the other problems. However, my choice of topics is by no means exhaustive, there are MANY other problems associated with our current practices, including potential health impacts from air pollution.
Ocean Acidification:
One of the potentially devastating outcomes of increased CO2 levels has to do with impacts on the ocean food-chain caused by the acidification of the oceans. When CO2 is absorbed by seawater, a series of chemical reactions occur resulting in the seawater becoming more acidic. Approximately 30% of the CO2 released to the atmosphere is absorbed by the oceans. Increased acidity causes carbonate (CO3) ions to be relatively less abundant. Carbonate ions are an important building block of structures such as sea shells and coral skeletons. Decreases in carbonate ions can make building and maintaining shells and other calcium carbonate structures difficult for calcifying organisms such as oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton.
The problem with difficulties for species such as clams and oysters is just the tip of the iceberg. Many of the calcareous plankton form the bottom of the ocean food-chain web that other species of ocean creatures depend upon, and which we also depend upon. For example, calcareous plankton are extremely sensitive to ocean acid levels and the availability of carbonate ions to form their shells. There appears to be a sharp range of pH below which these creatures can no longer effectively reproduce and live. Studies find that is happening in many locations, and appears to be worsening as the pH of the oceans continues to fall due to the absorption of carbon dioxide by the water. Losing a large part of the bottom of the food web does not bode well for the ocean ecology.
Many larval fish are also quite sensitive to acid levels, failing to mature when the pH is too low (the water is too acidic). Low pH levels not only interfere with shell growth not only interferes with maintaining shell mass, it can dissolve existing shells on living organisms. An example of the kind of problems expected, in a recent study when pteropod shells were placed in sea water with pH and carbonate levels projected for the year 2100, the shells dissolved after 45 days. Researchers have already discovered severe levels of pteropod shell dissolution in the Southern Ocean, which encircles Antarctica. Pteropods are an important part of many food webs and eaten by organisms ranging in size from tiny krill to whales. A NOAA-funded study has documented that ocean acidification along the U.S. Pacific Northwest coast is impacting the shells and sensory organs of some young Dungeness crab, a prized crustacean that supports the most valuable fishery on the West Coast.
However, the problem of reducing the bottom of the food chain is not the end of the story. In addition to the obvious potential impacts on the diversity and abundance of marine plants and animals, there are also many known, and unknown, physical changes brought about by acidification of oceans. One change that is important to the increase in atmospheric CO2 levels is caused by the reduced calcification affecting the ocean’s biologically driven sequestration of carbon from the atmosphere to the ocean interior and seafloor sediment. A surprising impact of decreased pH in the oceans is that it changes the acoustic properties of seawater, allowing sound to propagate further, and increasing ocean noise. This impacts all animals that use sound for echolocation or communication.
Loss of Ice Shelves:
The recent rapid melting and breakup of giant ice shelves in the Antarctic have been well publicized, but without clear descriptions of the potential impacts of these vast areas of floating ice. The concern of rise in ocean levels resulting from the melting of floating ice has been correctly debunked because melting of floating ice does not change water levels. When the ice melts, the water level remains the same. However, entrance of grounded (ice supported by the ground) ice into the oceans can have dramatic impacts on sea levels. The issue isn’t sea level rise from melting floating ice making up vast ice shelves; it is that the ice shelves are blocking huge grounded glaciers from sliding into the sea. These glaciers are large enough to cause dramatic sea level rises. For example, the Thwaites Glacier alone holds enough ice to raise global sea levels two feet. It’s also a bottleneck protecting the larger West Antarctic ice sheet (grounded ice), which would raise sea level 10 feet if it were slide into the ocean. The sliding could be caused by the melting and/or breakup of a single ice shelf; which is already happening with the disintegration of the Thwaites ice shelf expected within the decade. We don’t know how rapidly the West Antarctic ice sheet could move once freed – but we know there is the potential for catastrophic flooding should it occur. Similar changes are happening throughout the Antarctic and arctic regions. Ice is melting rapidly, and unpredictably – creating unpredictable risks from sea level induced flooding around the world. (Since I wrote this I found out that the Thwaites Ice Sheet appears to be moving over “rippled” ground that might slow the slide of the glacier into the sea – but that is just one threat among others so while I might be over exaggerating the current threat from that particular glacier, the concept is still of concern.)
Current projections of sea level rise above the 2020 average range from about 2 feet to 10 feet by the end of the century (which is about my current lifetime). These projections are based upon many assumptions concerning future rates of rise of global temperature. Perhaps more importantly, the projections assume that glaciers melt in place rather than by movement (sliding) of blocks of ice into the sea. As long as most of the glaciers stay where they are and just melt, then those rather alarming projections are likely to be accurate. However, there is a great deal of uncertainty in projections of future sea levels. The conservative projection of approximately 2 feet within 75 years is based upon a linear projection of historical data. The estimate of up to 10 feet of rise by the turn of the century assumes an increasing rate of global warming. However, neither of these takes into consideration the potential for the physical movement of large amounts of ice that could far overshadow the rate of melting. I believe the amount of rise by the end of the century will be closer to 15 feet (or more) in a period of time about the same as from when the Beatles were popular and now, and will continue at the elevated rate for many years beyond that. But who knows? Perhaps we will be lucky.
Surprisingly, the threat of huge increases in sea levels may not be the worst outcome of the melting of the ice sheets.
Ice sheets (floating sea ice) are decreasing in size and breaking up because they are melting from the bottom. The warming of the oceans is resulting in warmer sea water that is rapidly melting the floating ice, preventing new ice from forming each winter. This in turn results in the release of large quantities of fresh water, making the adjacent ocean much less salty, and therefore less dense.
Under “normal” conditions, Southern Polar Region experience the formation of large ice shelves when the oceans freeze in winter, forming large quantities of frozen fresh water ice. Converting ocean water to salt free ice “squeezes” salt out of the newly formed ice, increase the salt concentration and density of the adjacent ocean water. The cold, heavier salty water then falls toward the ocean floor forming the extra-salty Antarctic Bottom Water (AABW) that moves slowly toward the subtropics as part of the driving force for what is known as thermohaline circulation. The thermohaline circulation weaves around and through the oceans of the world, upwelling in some regions and descending in others – injecting much needed nutrients into ocean waters, and transporting large quantities of heat from one region to another.
This creates a massive current of sea water moving energy and nutrients in a giant watery conveyor belt. These currents moderate global temperatures and mix nutrients resulting in the marvelous diversity and productivity of the oceans. If those conveyor belts stop functioning they will have immediate and dramatic impacts on all aspects of the world. There is already a dramatic slowdown of the deep ocean currents caused by the melting of ice shelves. We can only that there is not a “tipping point” after which the currents cease to flow.
The global conveyor belt, shown in part here, circulates cool subsurface water and warm surface water throughout the world. The Atlantic Meridional Overturning Circulation is part of this complex system of global ocean currents. This illustration is captured from a short video produced by NOAA Science on a Sphere.
The Thermohaline Circulation influences the climate all over the world. The impacts of the decline and potential shutdown of the Atlantic Meridional Overturning Circulation (AMOC) could include losses in agricultural output, ecosystem changes, and the triggering of other climate tipping points. Other likely impacts of AMOC decline include reduced precipitation in mid-latitudes, changing patterns of strong precipitation in the tropics and Europe, and strengthening storms that follow the North Atlantic track. Finally, a decline would also be accompanied by strong sea level rise along the eastern North American coast.
Methane Hydrates:
And then there are the methane hydrates waiting patiently on the ocean floors around the world. Methane hydrates (more specifically clathrate hydrate) is a solid material in which a large amount of methane is trapped within an ice-like crystal structure of methane and water. It mainly forms in water and sediment depths below 300 – 500m. While it is unknown how much of this material is susceptible to disassociation due to increased global temperatures, it is potentially a very large quantity. The current research indicates that it is unlikely for a massive turn-over event that suddenly releases vast quantities of methane to occur. It is more likely to be a gradual release as the temperature increases at the depth of the upper levels of hydrates as the ocean temperature increased due to global warming. Apparently very little of this methane will make it to the atmosphere. Instead it will be converted to CO2 that then increases the acidity of the ocean and eventually gets released into the atmosphere while decreasing the ability of the ocean to act as a carbon dioxide “sink” – adding to the global warming problem.
Conclusion:
These are just a few issues that are caused by increased levels of CO2 in the atmosphere. Many potentially devastating outcomes are either independent of global warming, or amount to additional feed-back loops that increase the greenhouse effect even though they are not “primarily” caused by the release of burning fossil fuels. They are potent sources of greenhouse gas that are sequestered by nature, but will be released as global temperatures increase. I just mentioned a couple of these naturally occurring carbon sinks that we be (and are) impacted by warming that is man-made. The release of vast quantities of methane from tundra as it thaws due to global warming is another well known “natural” source that is released from sequestration as temperatures increase.
Whether or not the increased levels of methane and carbon dioxide are responsible for the observed increase in global temperatures is not important for determining whether or not it is necessary to reduce (or eliminate) human created sources of carbon dioxide. There are so many other negative impacts from the burning of fossil fuels and the release of carbon dioxide that the question of whether it is a significant driver of global warming is a moot point. The global ecosystem can’t survive as we know it with the continued increase in atmospheric carbon dioxide levels regardless of it causing global warming. We are facing multifaceted existential threats, any of which can (and probably will) destroy civilization as we know it and lead to the extinction of thousands of species (perhaps including ours). The magnitudes of the threats are such that in order to survive, we MUST take immediate and dramatic action.
An interesting point about taking the necessary actions is that they are inexpensive, easily implemented and result in enhanced health and quality of life for everyone. They aren’t draconian changes tending to destroy our life styles or cause health problems. They are changes that make life better, cleaner and more affordable. In the process, they create millions of good quality, high paying jobs. As far as I can determine, there are few (or no) downsides to taking action right now. We know what has to be done, we have the technologies to do it, and it will improve our lives in many important ways – not the least is to clean up the air and water.
The real question is what will it take to convince people to take the necessary actions? That might be a great topic for a follow on blog – “why don’t we take action to save the environment?”