Climate Change and the Thermohaline Circulation

 Sea Ice, Svalbard, Norway

In my previous article on Climate Change and Carbon, I discussed the impact that carbon emissions have on climate change and global warming.  I discussed international agreements, global temperature, carbon sequestration, carbon dioxide as a sensitive indicator of climate change, and global health as a factor in how we interact with a changing world.

In this article I discuss the thermohaline circulation and its interrelationship with climate change. The thermohaline circulation may be explained by chaos theory, as a "bifurcation point", a sensitive indicator which may keep the planet under one paradigm, or place it into another paradigm, presenting planetary challenges.

Planetary cycles (Milankovitch Cycles)  indicate a trajectory at this time towards planetary cooling, or glaciation, reflecting a continuing decrease in  axial tilt (obliquity) .  This long term  cycle (41,000 years) presents psychosocial difficulties for those who are not accustomed to thinking on a scale involving geologic time. Such a scale seems way too far off to appear relevant, eclipsing by orders of magnitude scales such as 100-year floods or 500-year volcanic eruption intervals such as at Mt Rainier as discussed in my 2011 blog article.

At the same time as underlying very long term planetary cycles (e.g. obliquity) are pointing us towards planetary cooling, our earth is warming with the effects of climate change. We are in the throes of opposite systems colliding, facing very different issues.  The immediate climate change issues are important, however considering the long term factors is also relevant to the discussion.  Global health issues are tied up in both discussions, as evolution may take a variety of paths in response to planetary indicators.

My blog article, Climate Change and global health discusses some of the ramifications of health effects of climate change, including those depicted as coastal flooding.  A trend towards glaciation, a Mini-Ice Age or even in the extreme, a Snowball Earth would bring on very different changes, and adaptations and implications for global health.

The oceans are an important factor to consider in assessing such developments.  The Earth goes between icehouse and greenhouse cycles.  These cycles can be captured via examination and measurement of calcite and aragonite seas. A graph, shows the emergence of an aragonite threshold during the current period, which might indicate the emergence of a period of glaciation.  Aragonite seas  contain high magnesium calcite, and less abundantly, aragonite while calcite seas  have lower magnesium content, which increases as a threshold is reached.

The calcites  are inorganic carbonate precipitates, with calcium carbonate (CaCO3) being most common precipitate.  Other precipitates include aragonite and vaterite.  These precipitates emerge in a number of areas, including shells of marine organisms, including  plankton, foraminafera and trilobytes  (where calcite was responsible for development of eyes).
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There are a number of planetary adjustment factors that act to keep the planet in balance.  The National Oceanographic and Atmospheric Administration (NOAA) has a wide variety of information for the general public on science,  research and further  information regarding the thermohaline circulation , the ocean  and its role in climate.   The thermohaline circulation is central to the issue of planetary climate control.

Positive feedback loops work to increase the risk of global warming.  This effect occurs as the sea ice extent decreases, exposing open ocean and thus decreasing the planetary albedo.    Higher albedo is associated with higher reflectivity, or less heat retention, while lower albedo is associated with lower reflectivity and greater heat absorption.

As more heat is retained by the Earth, especially in the polar regions (the Arctic and the Antarctic), warming increases.  With increased warming comes melting, of sea ice, icebergs and glaciers, This melting may impact Arctic regions  such as Greenland and Arctic Ice, as well as the Weddell Ice Shelf in Antarctica.and Antarctic Sea Ice.  Ice may be lost from glaciers, resulting in the formation of tabular icebergs, and calving of those icebergs, which may increase melting, just as a bag of ice cubes melts faster than block ice.

The melting that occurs increases the flow of fresh water into the oceans.  This is particularly felt in the Arctic, where the thermohaline circulation travels northward from the warmer Gulf Coast of North American waters to cold North Atlantic Arctic waters.

The infusion of fresh water in the North Atlantic may disrupt the sinking of the saltier water in the North Atlantic, which develops as the result of formation of sea ice (as sea ice forms, it forms from fresh water and the surrounding water gets saltier, and sinks to deeper depths).  This infusion of fresh water in the North Atlantic could result in disruption of the thermohaline conveyor belt, thus impeding the delivery of warm water from the Gulf to northern areas in both North America and Europe, resulting in much harsher winters.  A shutdown of the thermohaline circulation could have very serious impacts on global climate.

Climate Change and Carbon

Plume from Stack, Longview, Washington

Global Warming and Climate change are important topics.  Recent talks at the United Nations have highlighted the concern about these planetary issues that go beyond borders and seek to unite people in discovering means to solve the emerging problems.

The United Nations climate change site indicates that 2014 is on track to being among the hottest on record.  Christiana Figueres, Executive Secretary of the UN Framework Convention on Climate Change states "Fortunately our political climate is changing too with evidence that governments, supported by investors, business and cities are moving towards a meaningful, universal climate agreement in Paris 2015 - an agreement that keeps a global temperature rise below 2 degrees C by putting in place the pathways to a deep de-carbonisation of the world's economy and climate neutrality or 'net zero' in the second half of the century."

A recent article in Scientific American discusses United Nations climate talks in Paris last December. As the article indicates "(The planet's surface has warmed about 0.85 degrees C (1.5 degrees F) since 1880, worsening floods, storms and deadly heat waves.) The 2 degrees C target has since become a keystone goal of the negotiations."

NASA's, Global Climate Change: Vital Signs of the Planet displays information about climate change. including graphs and latest measurements.  This information shows steadily increasing recorded carbon dioxide levels in recent history, with inputed history obtained from ice cores indicating significant variation from historical levels over three glaciation periods. Ice cores have been drawn from the Arctic, Antarctic and mountain glaciers.  The measured value as of January 2015 showed 399.73 parts per million (ppm), just under 400 ppm. At current rates it should exceed 400 ppm in February 2015.

Snow Hill Island, Antarctic Peninsula, Antarctica

 NASA's Climate Change site provides information on Global Temperature.  Five year averages in global temperature are measured relative to a 1951-1980 average temperature baseline, indicating a dip in global temperature around 1910 and a steady rise since then.

Global Warming concerns have fostered considerable research  on climate change issues, seeking ways to mitigate the impacts of climate change, providing potential solutions.  Climate change and environmental issues have been addressed at local, state, federal and international levels.   The CIA World Factbook provides a list of Current Environmental issues and international agreements which countries listed are a "party to" and/or "signed, but not ratified".

I discuss some of the issues relating to climate change, including global health in other blog articles relating to Climate Change and Global Health  and Avian Flu.

Carbon, and especially carbon dioxide are sequestered in a number of areas on the planet, including in the rocks and in the oceans.  Other greenhouse gases, such as methane, are sequestered in areas such as Arctic Tundra, and in the oceans.  The questions remain as to how much capacity does our planet have to sequester carbon, without over stressing the resource with storage demands and whether there is a risk that carbon which has been already sequestered might be released back into the environment.

An outgassing of carbon dioxide at Lake Nyos (1986), in Africa, illustrates the problem which can occur with a body of water that is saturated with carbon dioxide.  Lake Nyos lies above a pocket of magma and is one of only three lakes saturated with carbon dioxide.  Lake Nyos is not the size of the ocean, however.

It is clear that carbon, and carbon dioxide are keystone issues in addressing global warming and climate change.  Global warming is especially sensitive to changes in carbon dioxide, as increases in carbon dioxide can also lead to increases in water vapor in the atmosphere, as indicated by a NASA report. Water vapor is the most abundant greenhouse gas.  Thus, increases in carbon dioxide in the atmosphere can act in a positive feedback manner to increase the greenhouse effect.

Just as carbon dioxide is a sensitive indicator in the atmosphere, and may represent a bifurcation between different climatological paradigms, one pursues, seeks and finds answers as to the equivalent impact that changing carbon dioxide atmospheric concentrations have on the human body, which is also a sensitive indicator of climate change. These findings have implications for Global Health, as well the psychosocial milieu in which mankind experiences climate change.

These are all very serious issues worthy of further research, consideration and action. The key question is the manner in which homeostasis is achieved, given the climate change issues.