If It’s This Bad on Land, What’s it Like in the Oceans

The above government-prepared chart presents the steadily deteriorating impact of global warming just in the United States. Clearly, this process is mirrored across the globe. The threat to mankind is profound. From habitability to the increase in the frequency and severity of natural disasters as ugly punctuation to an existential challenge to life as we know it. Rising generations are expressing varying levels of panic knowing that they will feel the brunt of these horrific changes. And clearly, humanity is doing way too little, way too late. But if this is what we can see with little or no amplification, what is it like for life we cannot see easily? Life under the seas? As land temperatures rise, so too, of necessity do the temperatures in our oceans.

James Shelton, writing for the May 13th Yale News, paints the picture more clearly based on a recent cross-university study, focusing simply on mollusks as the oceans’ canary in the coal mine: “Writing in the journal Current Biology [the study is entitled Metabolic Tradeoffs Control Biodiversity Through Geological Time by Thomas Boag, William Gearty and Richard Stockey published in the May 6th issue of Current Biology], researchers at Yale, Stanford, and the University of Nebraska-Lincoln say mollusks such as clams, sea snails, and cephalopods will be particularly vulnerable in tropical regions if global climate projections hold true. 

“The researchers analyzed 145 million years’ worth of data, in increments of approximately 10 million years. They looked at geochemical data that reveal past ocean temperatures, fossil data of mollusks, and models for habitability and biodiversity.

“Their analysis suggests that by the year 2300, upper ocean temperatures (up to about 200 meters deep) in tropical latitudes will mirror those of ‘hothouse’ eras millions of years ago, when upper ocean temperatures rose well past 68 degrees Fahrenheit and sometimes past 85 degrees. These periods saw significant biodiversity loss at low latitudes, the researchers said.

“‘That’s when you start to see a dramatic decrease in species diversity,’ said lead author Thomas Boag, a postdoctoral fellow in Earth and planetary sciences at Yale who conducted the research as a graduate student at Stanford. ‘We’re already seeing a loss of diversity of species at the equator.’…Currently, sea surface temperatures near the equator top out at 82 or 83 degrees Fahrenheit.” 

“But the cause of species loss isn’t just a matter of temperature, Boag said. Rather, it is an intricate balance of ocean temperature, oxygenation of the water, and the physiological composition of species themselves that determines whether life thrives or begins to wither.

“That’s why global changes in species diversity in the ancient oceans don’t resemble a swinging pendulum between ‘hothouse’ and ‘icehouse’ periods, with the equator in the center. Indeed, the fossil record shows instances when species diversity peaked far away from the equator.”

While these many variables all contribute to the decline and demise of marine species of every kind, most of the damage can be traced directly to temperature rise. The study summary states this conclusion: “We therefore suggest that the effects of ocean temperature on the aerobic scope of marine ectotherms is a primary driver of migrating biodiversity peaks through geologic time and will likely play a role in the restructuring of biodiversity under projected future climate scenarios…

The earth has experienced wild shifts in global temperatures since life began. Fossil remains present a picture of what the earth faces in this current and growing cycle of global warming. What this study portends is not pretty. “Looking to the future, the new analysis places rising ocean temperatures and their interactions with dissolved oxygen in the ocean as the primary driver for stifling biodiversity. The researchers said their projections for 2100 and 2300 show the planet’s low latitudes — near the equator — are at particular risk… ‘Based on our model and past temperature extremes, 50% loss of modern, low-latitude diversity does seem possible in a worst-case climate scenario,’ Boag said.” Yale News. We do not have to wait until 2300 to see the massive impairment of life in the oceans. The trends are well-underway right now. 

I’m Peter Dekom, and as much as we know about the probable impact of continued global warming on the planet, think of how much we really do not know… yet!