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Uh-oh. Ocean temperatures are rising much faster than we've been thinking

Courtesy of the Commonwealth Scientific and Industrial Research Organisation
An Argo float is deployed in the ocean.

First of two parts.

An intriguing and important-sounding new research paper caught my eye on Sunday, with its finding that the world’s oceans have been warming at a much faster pace than is generally recognized.

Because seawater holds more than 90 percent of the excess heat that arrives from the sun but, thanks to greenhouse gases, isn’t promptly returned to space, that conclusion seemed to fall somewhere between stunning and alarming. Because it had been published in Science Advances, a journal of the American Association for the Advancement of Science, its credibility was clear.

The basic outline of the research was straightforward:

  • While surface air temperatures have been noted in countless places around the world for a very long time, until about 10 years ago the record on ocean temperatures was sparse, to say the least. Measurements were taken from commercial vessels and the occasional research ship, but not so frequently and usually only in shipping lanes where the boats happened to be going anyway.
  • Starting in 2005, however, readings started to flow from an array of sensors known as Argo floats: cylindrical gizmos that drift freely while changing their buoyancy on a predetermined schedule, sinking to depths of up to 7,000 feet or so, then returning to the surface to send their data to satellites.
  • The array now runs to about 3,500 floats, and their measurements — when extrapolated across the entire sea surface, and compared to pre-Argo readings — suggest that ocean warming in the past half-century has been understated in most modeling by about 13 percent.

But when I reached the discussion of methods that enabled these conclusions, I was instantly out of my depth. A typical passage explained that the researchers, led by Lijing Cheng of the Chinese Academy of Sciences in Beijing, had “used an ensemble optimal interpolation method combined with covariances from Coupled Model Intercomparison Project phase 5 multimodel simulations to provide an improved prior guess.”

Luckily the research team included John Abraham, a professor of mechanical engineering at the University of St. Thomas who has a deep interest in global warming and its impacts. He also has a gift for making climate science intelligible to nonscientists, and does so periodically in a column for The Guardian called “Climate Consensus — the 97%.”

Courtesy of John Abraham
John Abraham

So I asked for an interview and we ending up talking for a good long while about the new paper, its troubling implications and Abraham’s enduring optimism that we still possess the means to work out way out of this mess.

Following are excerpts from that conversation, which began with my asking if the new paper demonstrates that the oceans’ role is the aspect of global warming that remains least well understood and the most difficult to address in climate modeling. Abraham’s answer was characteristically clear and concise: No.

Why the ocean matters so much

There are other things that are less understood — but the oceans are so important that any misunderstanding we have there is more important than any misunderstanding elsewhere.

For example, cloud changes are not well understood. Is the Earth going to become cloudier? Are the clouds going to become brighter, less bright? That is not very well understood.

But let’s say we’re off in clouds by, oh, 50 percent. That is paltry compared to being off in the oceans by 50 percent, because the oceans are taking up 93 percent of the global warming heat, and if we’re off by just a little bit it has big implications. So I would say that the oceans are the part that’s most important to understand correctly.

I asked Abraham to explain why knowing the rate of ocean warming was so important, given that we’re already monitoring, analyzing and projecting trends in air temperatures at the Earth’s surface, and up to the outer reaches of the atmosphere. He said there were two distinct reasons:

Number one, if you want to predict how fast the Earth will warm in the future, you have to know its current rate of warming. And the only way you can do that is via the oceans. The oceans are a proxy for the entire planet, and understanding how fast they’re warming tells us how fast the world is warming — where we’re going to be in 10, 20, 100 years.

From a more immediate standpoint, warming of the oceans affects the climate we experience today. Oceans cover 70 percent of the planet and they dominate the weather. The clouds that form, the currents of air, are driven by the oceans; oceans can affect rainfall and drought.

The power of superstorm Sandy was driven by ocean temperatures off the East Coast. Temperatures off the West Coast have driven California’s drought and now the heavy rainfall, because when the ocean warms the atmosphere holds more water and you get more rainfall. Another example — the record flooding in Duluth a while back.

Heat isn't stored forever

I asked Abraham if this wasn’t a different view from one that seemed to dominate some years ago, which held that the oceans’ ability to absorb heat amounted to an unexpected lucky break because they were basically storing the warmth and slowing the rise in surface temperatures.

The oceans are a buffer in two ways: They soak up heat and they soak up carbon dioxide. And were it not for the oceans we’d be in a heck of a lot more trouble right now. The buffering gives us time to take action.

But it’s not like the heat stays there forever; it’s always leaving, too. We’ve just seen the three hottest years in a row, as measured in the atmosphere — 2015, 2015, 2016 — and those records were set because of heat transfers from the ocean.

Earth’s temperatures are steadily increasing because of greenhouse gases, but we get some fluctuations. Some years it will be a little hotter, some years a little colder. The oceans have cycles, and those cycles deposit or withdraw energy to or from the atmosphere, which shows up as a temporary short-term warming or a temporary short-term cooling — the biggest way this happens being the El Niño-La Niña cycle.

So it’s a zigzag curve, still going up and up, with the overall rise being driven by global warming, and the variations driven by the oceans.

We talked for a while about the Argo floats, which he called the gold standard for measuring ocean temperature, and I asked if he could explain for nonscientists how data from a few thousand floats covering less than 30 percent of the global ocean could be extrapolated to reach reliable overall findings about the temperature trend.

We found that we don’t actually need sensors everywhere, because ocean temperatures are stable — not in time, but in space. The technical term would be homogeneous, but what I mean is that temperatures are the same across hundreds of miles. And so we can actually ascribe a large region of ocean water to a single sensor. But then we checked it to see if we’d gotten accurate results, and found that we did.

We used satellite measurements — called top-of-atmosphere measurements — of how much energy is escaping through the atmosphere. We already know how much energy is coming into the system. And the difference matched quite closely our calculation of how much is being absorbed by the ocean.

We also used satellite measurements of sea-level rise. We know that ocean water expands when it’s heated, and that about 40 percent of sea level rise is from thermal expansion. So using altimeter measurements from the satellites, we get almost exactly what we would predict from the Argo temperatures.

In 2016 we published another paper that compared computer models of the climate to ocean heat content, and found that these also matched almost exactly.

Courtesy of the Integrated Marine Observing System
Abraham called Argo floats the gold standard for measuring ocean temperature. Here’s how the system works.

Light bulbs and A-bombs

I had not seen that paper, but had read a Guardian column Abraham had written about the findings, with rather a deft use of “social math” to quantify the heat it takes to raise the global ocean temperature by amounts the paper measured in factions of a watt per square meter. I asked him if it was still valid, and he said it was, so I’ll close today’s piece by quoting it:

This is the equivalent of 5,400,000,000,000 60-watt light bulbs running continuously day and night. Another way to look at this is the Earth is gaining the equivalent of approximately six Hiroshima bombs of heat every second, day and night.

Thursday: How Argo data debunk the notion that global warming has slowed or even paused since 1998.

* * *

This paper, “Improved estimates of ocean heat content from 1960 to 2015,” can be read and downloaded here [PDF] without charge.

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Comments (10)

Informative.

Interesting article. I am glad we are getting consistent ocean data as it will be valuable in the future.

Couple things, though...

Argo readings are only 12 years old. A 13% conclusion cannot be made with only 12 years of data. It would seem that 13% would be well within error margins. Even the article says the ocean has natural cycles.

The Duluth storm mentioned could have happened in any year since the beginning of time. Such storms may be more common due to global warming, but to claim global warming caused the storm, is unscientific and inaccurate.

Response...

Thanks for the comment. A few corrections. Our paper had temperature measurements back to 1958, not just 12 years. We just used different sensors prior to 2005. The long term trend cannot be explained as natural.

Secondly sure, floods can happen and do happen naturally but they have become more common in this warmer world. Scientists predicted and are now seeing an increase in floods like the Duluth flood.

John Abraham

A question to Prof. Abraham

So the oceans are warming much faster than expected… and the Arctic ice is also melting fast… But now the science says that the ice loss is, in big part, driven by natural swings, not just people https://www.yahoo.com/news/arctic-ice-loss-driven-natural-swings-not-jus.... But isn’t it similar to what all those “deniers” were saying?

“Temperatures off the West Coast have driven California’s drought and now the heavy rainfall, because when the ocean warms the atmosphere holds more water and you get more rainfall.” OK, ocean warms the atmosphere and it holds more moisture – pretty simple… except it doesn’t explain why there was a drought before that, does it? And of course, Duluth, I think, is pretty far away from the ocean so why was it flooded then?

And here is another obvious question. We all know that warm water breeds hurricanes and Mr. Gore predicted many more of them in the future. Reality is quite different and we have not seen a major hurricane for a while. Can Professor Abraham explain that to us?

Wow how to respond

Okay a lot here but a quick response in reverse order.

The best science says hurricanes should become less frequent but more powerful. This trend is actually being observed.

The cause of he California drought was because of higher temperatures, driven in large part by humans. Warmer air evaporates water more quickly drying things out faster, pretty basic. I have an article soon to be published in the Guardian which discusses this very topic. Probably in next two days.

The rain in places like Minnesota does come the from oceans. Water evaporates, gets carried by the atmosphere, and falls as rain far away from the ocean.

The actual article you link to says natural variability MAY be responsible for less than half of arctic is loss. Your statement forgets the "may" and the "less than half" part.

John Abraham
From my iPhone.

Thank you but I have more

Thank you for your explanations. So if you don’t mind, I’ll ask some more questions.

I remember Gore’s saying “more hurricanes” but, regardless, there have not been ANY hurricanes hitting the US. How can that be explained? And why would warmer waters produce fewer hurricanes?

Warmer “ocean warms the atmosphere [which] holds more water and you get more rainfall.” “Warmer air evaporates water more quickly drying things out faster.” Do those two processes happen at the same time? And if not, why one year it creates droughts and another one – more rain? Shouldn’t those two processes compensate each other rather than create both phenomena, almost like nature wants to punish us and gives us everything bad it can do… which is hard to believe. Also, logically, if higher temperatures lead to both rain and droughts, lowering temperatures would lead to less moisture in the atmosphere and, therefore, less rainfall but we will not see more droughts because water evaporate less? And sure, water is carried by the atmosphere to Duluth and we have a lot of rain… but why not drought at the same time as in California for the same reason?

I am sorry but it all looks like a desire to attribute anything bad to the global warning… which brings me to another question: There must be something good somewhere brought by higher temperatures. Again, logically, higher crop in Canada, longer navigation in the Arctic, fewer deaths on the roads from long cold winters?

Yes, you are correct, the article I linked said that nature MAY be responsible for some of ice loss but isn’t it the same as saying that people MAY be responsible for that? I mean in climate science, everything actually just MAY occur due to certain reason… It’s not like in physics where laws are pretty much set (and even there in some cases the result is not certain, I believe). Shouldn’t we stop acting as we know things for sure? A couple powerful volcano eruptions, reduced Sun activity, a new invention, basically anything that is beyond our ability to predict, will throw everything off... Just like an automobile invention made predictions made in 1850 for horse power needs in 1950 obsolete…

Second response....

It isn't true that there are no hurricanes hitting the USA. Just a few months ago we had Matthew. Others recently are Irene Isaac Sandy and Arthur. Hurricanes are made powerful by warmer water because the extra heat in the water helps evaporation processes which are the source of energy for the hurricanes. This is pretty basic stuff.

Does drying and wetting compensate? Not really because they don't happen at the same time. The increased wettness is associated with more heavy rainfalls. Increased dryness would not occur during rain. A rule of thumb to remember is that there will be less rain but it will come in heavier downpours. Please read my soon-to-be published Guardian article where I go into this more.

Sure, there are some positives with warmer weather like you mention, longer growing season in Canada. But the economic studies have asked whether there will be more good or more bad effects and all the reputable studies show more bad effects. For instance, raising sea level and ocean acidification are just bad.

Finally, climate is physics. I mean it is driven by the same physics that occurs in the lab. Your last paragraph is confusing.

Thank you very much

A very nice discussion...

It is obvious that there are fewer hurricanes in the last several years than before or at least not more despite these years being the hottest on record https://en.wikipedia.org/wiki/Atlantic_hurricane_season#Number_of_tropic... and it’s been long time since a big hurricane hit the US. Matthew was Category 1, Arthur in 2012 was Category 2, and we have to go to 2008 for another Category 2 hurricane… And nothing major https://weather.com/storms/hurricane/news/category-5-atlantic-drought-ni.... There may be no explanation for that and that is why this fact has not been mentioned lately in talking about climate.

You said that the cause of California drought was higher temperatures because water evaporates faster when it is warm. It is basic physics but a couple degrees will not make a big difference in evaporation so the reason for California drought was little rain, just like it has always been since the beginning of time. So why would there be more rain in some years and less rain in others if the Earth is warming steadily? If warm air carries more water, which is also basic physics, and air keeps getting warmer, there should be no fluctuations.

I have never seen any studies even considering positive effect. In fact, I have never seen even mentioning of positive effect like it is a taboo to mention it. Plus, I would guess that some areas will see more positive effects and some will see more negative ones, right? As for raising sea level, it is bad… for those who live next to the ocean. But why would people are allowed to rebuild their houses next to the water line (often, as I understand, from flood insurance payments) if it is not a matter of if but when their houses will be destroyed or damaged again. But of course, a big part of the Netherlands lies below the sea level … and they are fine.

Climate is physics… but it is not a lab – the scale and the number of factors is not comparable. Behavior of a physical system may be predicted but the more complicated it is, the more difficult it is to predict it but at least it may be compensated by better computers and better models. However, the more unknown parameters we have, the less precise predictions are and of course, they become even less reliable if we try to do it for longer periods of time.

If we want to predict where a space capsule will be in a few years, it is easy. However, if there is another celestial body behind Pluto that we don’t know about right now, and this capsule happens to go next to that, our trajectory prediction will be off. And the more time passes after that deviation, the farther away it will be from our predicted location.

That is what I meant in my last paragraph. There are plenty of things that we know may happen but have no idea when and if they will happen and how strong they will affect the outcome. But there are also plenty of things that we have absolutely no way of knowing about at all… and that makes our 100 year predictions illogical. We can say that if everything we assume will happen as assumed it will happen but the chances that everything will be as assumed for a 100 years are minimal.

I am all for renewable energy and recycling. I just don’t like when important decisions are made in a panic and when we are being frightened into agreeing with something which may or may not happen (everything just MAY occur). When I hear people saying that climate change is the biggest threat to mankind, I am puzzled.

That is why

It is disappointing that Professor Abraham did not respond to my latest post because this is one of the reasons people do not believe in dealing with climate change: No one is willing to answer specific reasonable questions….

So recently collected data

So recently collected data compared to non-existent data of a half-century ago leads to the guessed conclusion that ocean temperatures are rising more rapidly than we had previously guessed, and continually errant computer modeling supports that conclusion.

This is about science, and we need Ron Meador to explain it?

The science is settled, then?

So collected data compared to non-existent data of a half-century ago leads to the guessed conclusion that ocean temperatures are rising more rapidly than we had previously guessed, and continually errant computer modeling supports that conclusion.

This is about science, and we need Ron Meador to explain that to us?