Changing Water, Changing Climate

Although much of the ocean’s abyss seems dark, still and silent, water is nevertheless always flowing, and in specific directions. Vast, slow currents called conveyors help create and govern the climate we experience.

They are easy to envision: the sun warms the sea’s surface at the equator, and the expanding water is driven away from it in the form of northerly and southerly surface currents. Much of this water cools as it flows towards the poles, becoming denser and sinking to the ocean floor. It then returns along the seabed in the opposite direction, to be raised and energized once more at the equator. 

Transport of warm water revealed by the sea surface temperature distribution around the Gulf Stream in 2005. NASA

The Gulf Stream, which governs the climate of eastern North America, Greenland and much of northern Europe, is one example of this action. By adding more heat to surface waters, global warming will change its course, speed and influence. The implications of this for the ecosystem and society are so complex that even the best computer models can so far only give a vague picture. 

Transformations Over Time

We think of time globally — in terms of years, decades or at most a century, those periods in which we personally might have some influence — but humanity as a whole has begun to act on a planetary scale. It is vital that we grasp the concept of planetary time, because in the last 350 years we have set several new planetary transformations in motion.  

The top bar of this visual encompasses the whole age of the planet; the middle one just the history of life; and the bottom one just everything since the Cretaceous. Note that in the top one, our period is too short to even show.

We have done this by releasing over a very short period huge amounts of energy into the planetary system that had been gradually concentrated underground over unimaginable time periods. The consequences of this will play out not just over decades or centuries, but over millennia.

We need, therefore, to start seeing ourselves and our actions in relation to a time scale that, by our embodied animal nature, we cannot easily conceive.  

Into the Abyss

The deep ocean floor makes up by far the largest part of the Earth’s surface, yet we know surprisingly little about it. We have mapped the Moon and Mars far more accurately than most of the seabed.

Studying the anatomy, physiology and genetics of these abyssal ocean organisms expands our knowledge of the effects of evolution over deep time, thereby allowing us to more clearly understand the faster developments we see in more dynamic and accessible environments.

The cup sponge Hyalonema sp. The cup sponge is a type of glass sponge with a stalk of long glass spicules supporting the “goblet” head. Glass sponges are some of the oldest colonial animals (metazoans) on Earth, arising after bacteria and single-celled organisms. NOAA

But there are growing signs of human influence in even the greatest depths, and people everywhere should be seriously concerned about that. 

Over hundreds of millions of years, the inhabitants of the cold, dark abyss have survived far worse things than human influence, and as we explore and encounter more of them, we can more fully grasp how far that influence is likely to extend.

Tubeworm community on a thermal vent. NOAA

Extreme Deep

The crinoids, mollusks, sponges, worms and other invertebrates we find on the abyssal plain today have been there in one form or another since the dawn of animal life. They barely looked up when the various mass extinctions wiped out large parts of life on Earth; that the sun was blotted out for centuries did not bother them much, as they had never seen it.

Evolution certainly takes place in the abyss, as it does everywhere, but all the processes of life there tend to move at a far slower pace. 

A deep-sea Chimaera, most closely related to sharks. Although their evolutionary lineage branched off from sharks nearly 400 million years ago, they have remained an isolated group ever since. NOAA Okeanos Explorer Program

Through learning about gradual changes, cycles and transformations that occur over millions of years, a greater knowledge of the abyss can help people grasp both the concept of planetary time and the scope of human influence. 

Written by Paul Callomon, the Academy’s collection manager of Malacology and General Invertebrates

Leave a Reply

Your email address will not be published.