It’s not climate change, it’s ocean change!


Redrawn by John Cook with data from Murphy et al 2009.

The oceans are choking on greenhouse gases. Our emissions are changing ocean temperature, pH and circulation with wide-ranging effects on biological productivity and ecosystem health. These are among the conclusions of five review articles published in a special feature on the oceans in a recent issue of Science magazine.

Last fall, the world was saturated by coverage of the oil spill in the Gulf of Mexico. Yet the impacts of this tragedy are localized, short-term and trivial compared to the broader effects of climate change.

The oil spill damaged the lives and businesses of many innocent people. Remarkably, however, every day we are releasing several thousand times as much carbon as the Gulf spill did by driving, flying and consuming and by heating and cooling our energy-inefficient houses. Hundreds of years from now, when BP is forgotten and the gulf wetlands have healed, ocean life will still be affected by the fossil fuels we are burning today.

Nearly all of the debate – or at least what is depicted in the media as a debate – about global warming has focused on land surface temperatures. However, over 85 percent of the extra energy trapped by soaring greenhouse gases has gone into the ocean.

We all call this man-made catastrophe “global warming” or “climate change,” but “ocean warming” and “ocean change” are really more descriptive of what is happening.

One value of the Gulf spill is that it highlighted how tightly coupled the health of ecosystems and human economic well-being really are. In retrospect, the costs of preventing the spill by installing more reliable safety systems are paltry in comparison to the economic losses in the tourism and fisheries sectors. The same is true for mitigating climate change. Mitigation that cost less than 1 percent of GDP over the next few decades are matched against massive impacts on people and industry, especially in coastal areas of the world.

Greenhouse gas emissions are rapidly changing the physical properties and key biological process in the ocean. For example, declining primary productivity is affecting ocean food webs, fisheries and the ability of the ocean to naturally absorb and store greenhouse gases.

Other ominous signs loom. Deepwater dead zones have expanded, probably due to both local nutrient pollution as well as climate change. The melting of Arctic sea ice will allow thousands of species from the north Pacific to colonize the Atlantic. This will be the first mixing of the distinct biota of these regions in nearly a million years. Similar changes are expected in Antarctica, where warming is enabling marine predators to invade shallow-water ecosystems for which the freezing temperatures have been an effective barrier for 40 million years.

To avoid these uncertain worlds, a growing number of scientists from a range of fields have advocated that we keep the concentrations of atmospheric carbon dioxide below 450 ppm (parts per million). To achieve this, we need to cut global emissions by 5 percent per annum starting right now.

A tall order. However, we have no other alternative given the extremely high costs of inaction.

The good news is that there are plenty of solutions at hand, including investment in renewable energy systems or avoiding deforestation. National support for creating competitive renewable energy supplies would cause the required changes to ripple through global economies. Halting deforestation in Brazil and Indonesia would eliminate nearly 20 percent of greenhouse gas emissions. Protecting and restoring coastal vegetation, including mangroves, salt marsh and sea grasses – dubbed “blue carbon” – would maintain or increase the ability of marine ecosystems to capture and permanently store carbon dioxide. Furthermore, all of these solutions have huge benefits for people and biodiversity.

The world’s scientists are calling for society and policymakers to wake up to the perils of our current greenhouse gas emission pathway. This is not merely the consensus of scientists; it is a consensus of evidence. Inaction might be justified if the impacts were trivial or there was nothing we could do to avoid these catastrophic futures. However, with so many affordable solutions in front of the world’s nations, continued inaction is no longer an excuse.

An earlier version of this post, co-written with Ove Hoegh-Guldberg, was originally published at ClimateShifts.

Download the paper Ove and I wrote about the biological changes we are seeing in the oceans due to anthropogenic climate change here (it is Hoegh-Guldberg and Bruno 2010).

And watch an awesome movie about the paper and ocean changes here.

3 Responses to “It’s not climate change, it’s ocean change!”

  1. […] Ocean winds are not exactly the first thing you think about when the topic of climate change comes up. Yet if they do continue to increase, the knock on effects will be large and costly. Yet another reason I like to call it "Ocean Change" rather than "Climate Change".  […]

  2. Rick Elkus says:

    Hi John,
    I think your focus on the oceans is perhaps the most important contribution to the AGW/Climate Change discussion is have seen. I wish more were aware of it and studied it. Also, your focus on heat vs. temperature is critical since for a given square meter, the heat capacity in the top 2.6 meters of the ocean is equal the entire atmosphere above that same area. So those that would average temperature anomalies in water and air make a very large mistake. Bottom line, it the ocean heat change stupid. Your graph certainly tells that story.

    However, I do note that your graph ends in about mid 2003 and it is now 2011. I think that the missing period (2003-2011) tells an even more interesting story – that the fundamental IPCC models are seriously flawed since they did not and do not explain the flat to declining heat content of the oceans during that period. As your article suggests, nothing in the air or land can possibly equate to a significant shift in the oceans. If you are interested in a further detailed analysis of this point, please see an excellent paper by DiPuccio at

    Your focus on a simple metric (ocean heating – not temperature) makes a potentially complex and confusing hypothesis quite simple and false. The benefit of this conclusion is that we can start the investigation for other hypotheses that are relevant to our time and as yet not falsified.

    Long live the scientific method!

    • John Bruno says:

      Dear Rick, I appreciate your interest in this topic. But reading the junk science on Watts Up With That is not exactly going to expand your mind. Roger Pielke and thus William DiPuccio and thus you (since you swallowed their canard without hesitation) are wrong about a few key facts. Most importantly, the theory of Anthropogenic Climate Change (ACC) DOES NOT predict or require monotypic (linear, never fluctuating) warming. This is a myth. In fact climate models do predict short periods of no temperature change and even cooling. In the case of ocean heat, this is simply because ocean heat content is indeed influenced by much more than greenhouse gas concentrations. Various natural cycles and events including ENSO can affect ocean heat over the short term (link); hence the wiggles in the slow rise in heat over the longer, multi-deacde term. Recall ACC is a theory about climate, ie, long term trends over many decades to centuries. The theory does not pertain to most aspects of short term fluctuations in physical parameters, ie, weather, like ocean heat. So the presence of such year to year variation (and short periods of no cooling) does not refute ACC.

      Note my article does NOT suggest “nothing in the air or land can possibly equate to a significant shift in the oceans”

      For a more recent graph, see my post on ocean heat here and also John Cooks post on it here. (the latter debunks the DiPuccio article your comment was based on – Iv’e been down this road before Rick).

      Finally, regarding the “ocean cooling meme” take a look here, as you will see one of many analysis did find slight cooling over a 4-5 year period. But several others found slight warming or no change. Part of this confusion is due to the difficultly oceanographers are having in accurately measuring ocean heat and some problems in switching over to the ARGOS platform. The recent discovery of very deep water warming is also complicating the matter since the accurately track short term changes in heat content, we cannot simply focus on the top 700m of the seas, as we assumed until recently.

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