Why do some new scientific ideas bowl you over and others leave you unimpressed or even skeptical? It is undoubtedly a mix of several factors. These probably include: the novelty of the idea (which can either increase or decrease its appeal), the strength of the evidence, the consequences (emotional or intellectual) for you of accepting or declining the idea, and your personality (whether novelty appeals to you or not, your tendency to be sceptical or not), and perhaps chance factors relating to your mood (such as, to use an old expression, “which side of the bed you got up on” that morning).
I found myself wondering about this, asking myself when I first began to worry that “climate change”, triggered by fossil fuel emissions, was a real thing and would be a devastating one for contemporary life on our planet. The immediate recent stimulus for thinking about it was reading three recent articles in the popular press. This got me to wonder about when I first read about climate change and started thinking about it. Those musings took me back to my youth.
It was the summer of 1969, just before humans first walked on the moon, and I was 24 at the time, a graduate student in genetics. What had grabbed my attention was an article in Nature, one of the two top journals in science then (and now), which I then read regularly. It pointed out carbon dioxide (CO2) had been greatly accumulating, (This was a fact not receiving much public attention at the time though of course scientists were well aware of it.) This was taking place first in the atmosphere and then in the oceans, where it was causing increasing acidification. The article’s focus was on the oceans and the claim was that acidification posed a potential threat to all forms of sea life, especially animal life, if it continued long enough. The warning was appropriate since there was no reason to doubt that fossil fuels would be burnt at increasing rates, given the nature of the industrial world and the demands of the world economy. The article made a prediction, based on the calculations of the authors, that the world’s oceans would become unlivable for much animal life by the year 1977. Wow! I do not recall that word sprang to mind but, in effect, that was my reaction. I remember thinking something like “So I have only another 8 years or so before the natural world is destroyed?” That feeling was not dissimilar to that of young people today who feel they are members of “the last generation”.
These were new thoughts to me and plenty disturbing. To put this anecdote in context, recall that 1969 was about two decades before the term “global warming” had become common currency and well before people were talking about “climate change” due to fossil fuel consumption.
Of course, the basic scientific ideas were not new. A few people in the 19th century were already aware of the basic problem of CO2 increase and, likewise, a few perceptive people in the mid-20th century (e.g. the distinguished ecologist, Evelyn Hutchins; see On ecological succession and its larger context). After all, if one burns oil or coal for energy, one generates CO2, which will go into the atmosphere. Since CO2 holds heat energy longer than the major component gases of the atmosphere, N2 and 02, incoming solar radiation would increase the temperature of the atmosphere due to the energy retention by CO2. This in turn could potentially affect life on Earth, both plants and animals.
The effects on the oceans were appreciated later but these too were fairly straightforward. CO2, dissolved in water, forms carbonic acid (H2CO3), when one CO2 molecule interacts with a water molecule, H20. Carbonic acid rapidly breaks down into a proton, that is one positive hydrogen atom (H+), and a carbonate molecule (HC03-). It is the protons that create the extra acidity in ocean water.
There is nothing complex about any of this; it is high school level chemistry and physics. It is the implications of what this all means when these things are happening at a massive scale throughout the world that are serious and complicated (in their many downstream consequences), which need to be considered. The immediate victims of rising acidity in the oceans --we are talking about what seem like relatively modest increases, from a few per cent to the present average increase of 26% more protons in sea water relative to pre-industrial levels – are invertebrates, especially shell fish, whose shells tend to dissolve in more acid water. Those animals are often a critical part of the diet of other animals but if one disrupts one level of an ecosystem, you set in motion changes that will affect all.
What, one may ask, is the significance of that old paper (or indeed this anecdote) today? One might well conclude that it has none. After all, the paper’s big prediction – that 1977 might mark the end of the oceans as we had known them, with their rich animal life -- was falsified. Fifty six years after the paper appeared and 48 years since 1977, the presumed doomsday year, the oceans remain rich, if somewhat depleted, of the different forms of life that they had in the 1960s and 1970s. Clearly, the oceans have been more resilient, more able to absorb excess CO2, than had been believed. Hence, something was wrong in the calculation that led to the prediction of the paper, presumably something in the premises. (I have not tried to locate the paper nor go over the analysis, nor would I be the best person to identify the problem in the calculation.)
Nevertheless, this was one of the first, perhaps the first, paper to point out the dangers of ocean acidification due to rising CO2 in the atmosphere. Its prediction about the speed of the oceans’ death was clearly wrong but the authors were right in identifying the problem. There is of course a lot of new scientific literature on the topic but as evidence for my statement here I just offer the title of one of the popular press articles on climate change and ocean health that caught my attention: “The ‘evil twin’ of climate crisis: scientists warn about ocean acidification”. 1
Of course, acidification is just one problem of the oceans due to climate change. Two more are “marine heat waves” and “ocean deserts”. Though “heat waves” and “deserts” are not terms we normally associate with marine environments, sadly, they now apply.
Let us take a quick look at the heat wave phenomenon first. Some of you may remember reports of record near-shore ocean temperatures in Canada and in New Zealand just a few years ago, in the early 2020s, but they were just the harbingers, nor even the earliest, of an increasingly frequent aberration. More recent reports of unseasonably warm seas, with massive die-offs of marine life, have focused on Britain, Ireland, the Mediterranean, Australia, the American northeast, and Spain. It is truly a world-wide phenomenon and reflects the transfer of excess heat in the atmosphere, due to global warming, to the surface layers of the oceans. Indeed, the change in temperatures can be so strong that a new term has been coined to describe the phenomenon: super marine heat waves. 2
As with increasing marine acidification, the effects are believed to travel up the food chain. Warmer surface waters lead to reduced transfer of nutrients in the sea from deeper regions which in turn means reduced phytoplankton productivity, which in turn reduced the small invertebrates that make up the zooplankton, which then had a knock-on effect on fish reproduction. This then can affect whale populations. It is believed that an earlier period of excess marine temperatures in the Northern Pacific, from 2014-2017, termed “the Blob”, was responsible for about a 20% reduction there of the Northern Humpback Whale populations by 2021; they had been recovering from the end of commercial whaling in that region in the 1980s.
As with acidification, the effects further up the food chain of heat waves may seem delayed, relative to the initial effects but much of this delayed effect undoubtedly reflects the vastness of the oceans, which cover about 2/3 of the planet’s surface and the consequent difficulties of monitoring them and getting accurate counts of the populations of the various life forms, even the largest, the whales. In contrast, the cumulative effects of commercial whaling on whale numbers, were relatively easy to measure and assess. In contrast, ocean acidification and heating are more subtle, more indirect, killers.
The third phenomenon mentioned above, “ocean deserts”, is directly related to the other two, marine acidification and heat waves, though probably predominantly so far to the latter. As its name suggests, it simply refers to the tremendous depletion of large swathes of the ocean of marine life. Again, the immediate effects are on the small organisms of the sea, the phytoplankton and the zooplankton, with follow-on effects on the ecosystem, in particular the fish and any marine mammals that live there, coming a little later. 3
Yet, the marine desertification phenomenon can take place in two ways. The first is simple die-back of animal life due to direct effects of temperature or other factors. The second is due to fast “blooms” of different forms of phytoplankton, which are normally held in check and do not dominate in a region. However, sometimes factors combine, such as higher temperatures plus excess nutrients released into the marine environment. The resulting explosion of growth can be quick and be followed by a rapid die-off of the new forms but when the latter happens, toxins can be released that inhibit the growth of the normal life forms of the area. And sometimes the toxins are released during the bloom phase. The famous “red tides”, an explosion of growth of a certain dinoflagellate protist, is an example of the latter. Full recovery of the marine region can take years, just as regions on land that have been subjected to ecological destruction can take many years to recuperate, if they ever do.
The following rule of thumb holds for ecosystems in general, whether terrestrial or marine: destruction can and often does happen relatively fast, while restoration, whether by wholly natural processes or involving human activities tends to be much slower. Yet it is also true that with ecosystems, the initial stages of destruction can be missed by human observers because many ecosystems have a strong degree of resilience, with the initial events of degradation proceeding almost unobserved. By the time they are perceived, things may be moving too fast to apply the brakes. There is a famous line from a Hemingway novel that is applicable here. A character is asked how he went bankrupt, and he replies that at first it was gradual, and then became sudden. The loss of ecosystems often happens with the same kinetics.
In this short article on the health of the oceans, and the loss of that health due to climate change, I have not tried to cover everything, just three of the major factors. Four others that I have not discussed but which deserve a mention, however, are: overfishing (see, for instance, Sharks! Coming back from the depths), marine plastic pollution, the deaths of coral reefs all around the world (reefs are estimated to support about a billion people and much economic activity), and the possible/likely changes in major ocean currents. Only the last two will be caused, if they occur, by global warming, but all four are serious problems that threaten the health of the oceans.
The sociologically interesting thing about this whole topic is that we – the human race – already know a lot about the sources of these problems. We also understand something about possible solutions or, at least, things that can be done to ameliorate the problems. The question is whether the powerful nations of the world, on whom the responsibility primarily rests, will have the will and the wisdom to save the oceans and our world. The answer to that question is unclear though the present indications are not hopeful. I urge my readers to do whatever you can to lend your voices to support all measures to limit climate change, however little it may seem at the moment. Death or radical change of the oceans would be catastrophic for all life on Earth and this is an all-hands-on-deck situation.
See Bachelor, L. (2025). The ‘evil twin’ of climate crisis: scientists warn about ocean acidification. The Weekly Guardian, 13 June, 2025, pp. 30-31.
The article is Erdenesanna, D., Stevens, H. (2025). Ocean heat waves spread. The New York Times, international edition. 18 June, 2025, p. 11
See Erdenesanna, D. (2025). Ocean deserts expand as water warms. The New York Times, international edition, 12 March, 2025, p. 18.