Tampering can be dangerous. Nature can be vengeful. We should have a great deal of respect for the planet on which we live. — Carl-Gustaf Rossby
But as the [IUCN] study points out, 90% of the extra heat that our greenhouse gases trap is actually absorbed by the oceans. That means that the upper few meters of the sea have been steadily warming more than a tenth of a degree celsius per decade, a figure that’s accelerating. When you think of the volume of water that represents, and then try to imagine the energy necessary to raise its temperature, you get an idea of the blowtorch that our civilization has become. — Bill McKibben
The scale of ocean warming is truly staggering with the numbers so large that it is difficult for most people to comprehend. — from the IUCN report Explaining Ocean Warming: Causes, scale, effects and consequences
If there’s one simple fact about past Earth climates that should keep you awake at night, it’s this — warming the world ocean eventually produces a killing mechanism that is unrivaled by any other in Earth’s deep past. Great asteroids, gamma-ray bursters, earthquakes, tsunamis and volcanism — none of these can rival the vast damage to life on planet Earth that is resulting from ocean warming.
As a study of the sciences, this assertion would be merely an academic one if the human race weren’t now involved in a great injection of an unprecedented volume of greenhouse gasses into the Earth’s airs. As a critical new ocean report from the International Union for Conservation of Nature (IUCN) points out, these gasses are trapping an extraordinary amount of heat at the top of the world’s atmosphere. In turn, the atmosphere is transferring the lion’s share of this heat — more than 90 percent — into the waters of our world.
The Extreme Amount of Heat Energy Piling up in Our Warming Ocean
As a result, the surface of the world ocean is warming by 0.1 degree Celsius per decade. That may not sound like much, but it takes about four times the amount of energy to warm one gram of water by 0.1 C as it does one gram of air. This property, called specific heat, is a defining aspect of water. Water has the highest specific heat of any common substance.
(Since the 1970s, about 300 zettajoules’ (ZJ) worth of heat energy has accumulated in the Earth System due to fossil-fuel burning and related greenhouse gas emissions. That’s about 5 Hiroshima bombs worth of heat accumulating every second. Most of that energy has gone into the world’s oceans. So much heat is bound to have consequences, and these impacts are starting to show up in the form of declining ocean health, melting sea ice and glaciers, shifting climate zones and weather patterns, worsening droughts and storms, and threats of Earth System carbon feedbacks. Image source: Explaining Ocean Warming.)
Liquid water is also far denser than air. And this density generates an even higher impact heat energy transfer multiplier. So not only does it take four times more energy to warm a similar weight of water vs air, once warmed, that water contains that higher level of specific heat energy in a much more tightly concentrated package. And when that high heat concentration liquid water comes into contact with other substances — like ice in the form of ocean contact, or air in the form of evaporation, or frozen hydrates on the sea bed — it can pack a serious heat punch.
The vast volume of water in our oceans, therefore, serves as a kind of heat and energy regulator. It takes a lot of energy to warm it up, but once it does, serious environmental changes start to happen as a result. In other words, the temperature of the global ocean could be viewed as the point on which the whole of the Earth climate system pivots. Once the oceans are set in thermal motion, serious changes to the rest of the world are going to take place. To get an idea how much energy the oceans now contain, of how much potential they now have to dramatically alter our world, consider that if these vast waters were not present, the atmosphere now would have already warmed by 36 degrees C due to the heat-trapping effect of greenhouse gasses already in our atmosphere.
Heating Seas Ultimately Become Killer Seas
There’s a starker message to convey here, one that focuses on this simple yet dire question — how do warming oceans kill? In basic terms, they become toxic and anoxic. Warming oceans melt ocean-contacting glaciers. The glacial melt forces seas to rise and forms a freshwater lid on the global ocean, breaking down ocean conveyor belts and preventing mixing. This freshwater lid also deflects heat toward the ocean bottom. This process in turn helps to thaw methane hydrates. Warm waters that don’t mix and that are filled with bubbling hydrates become very oxygen-poor.
(Massive algae bloom covers tens of thousands of square miles of open water in the Barents Sea during August of 2016. As glaciers melt, oceans stratify and warm; as water oxygen levels drop, and as hydrates vent due to warming, such blooms result in significant reductions to ocean health and a related global mass-extinction threat. Image source: LANCE MODIS.)
As the land glaciers bleed out into the oceans, the stratified, oxygen-deprived waters become less and less able to support advanced life. The kinds of life warm, oxygen-deprived waters do support are poison-producing microbes. These microbes thrive in the warm, oxygen-poor waters. If ocean heating continues to progress, the warming seas will eventually fill up with their deadly byproducts. Among the most nasty of these is hydrogen sulfide. If enough of it is produced, it will spill out from the ocean into the nearby air, resulting in land animal mortality as well.
In microcosm, we saw a mild taste of some of these effects this past year in Florida as toxic algae blooms filled the warming state’s waterways and coastlines, even forcing some riverside marinas to close due to toxic gasses wafting up from the purple-green, oxygen-starved waters. These effects are a snapshot of a possible future for Earth’s oceans if we don’t get our act together yesterday.
El Niño Shifted, Ocean Hydrates Threatened
As alluded to earlier in this post, a new report, Explaining Ocean Warming, provides some pretty hard evidence that the oceans are on the move toward a much more harmful global climate state. The study, which has rightly received a great deal of media attention, issues a ‘shot across the bow’ warning to pretty much everyone living today. And it finds serious impacts to the ocean and linked climate systems due to a very rapid human-forced global warming.
These hard findings are worth reading directly:
- Sea-surface temperature, ocean heat content, sea-level rise, melting of glaciers and ice sheets, CO2 emissions and atmospheric concentrations are increasing at an accelerating rate with significant consequences for humanity and the marine species and ecosystems of the ocean.
- There is likely to be an increase in mean global ocean temperature of 1-4 degrees C by 2100. The greatest ocean warming overall is occurring in the Southern Hemisphere and is contributing to the subsurface melting of Antarctic ice shelves. Since the 1990s the atmosphere in the polar regions has been warming at about twice the average rate of global warming.
- There is likely to be Arctic warming and ice loss, and possibly the essential removal, in some years, of the summer Arctic sea ice within the next few decades.
- Over the last 20 years there has been an intensification and distinct change in the El Niño events, with a shift of the mean location of sea-surface temperature anomalies towards the central Pacific.
- Currently 2.5 Gt of frozen methane hydrate are stored in the sea floor at water depths of 200 to 2000 m. Increasing water temperature could release this source of carbon into the ocean and ultimately into the atmosphere.
These are all Earth-shattering scientific statements. For those who frequent this blog, points 1 through 3 are probably pretty familiar. The last two, however, require more in-depth explanation.
(Some scientific studies have pointed out that warming the world ocean will result in a shift of El Niño toward the central Pacific. A new ocean report finds that it’s already happening. Image source: Global Warming May Dent El Niño’s Protective Hurricane Shield, Increase Droughts.)
For a long time now, scientists have believed that El Niño wouldn’t be affected by climate change until the end of this century. But as with sea ice, it appears that such impacts may well be advancing faster than expected. As we’ve alluded to here, there’s been an apparent shift in El Niño toward the central Pacific over recent decades. This may well be a climate change-related shift. The fact that the IUCN report highlights this change is a sign that the broader sciences are starting to tackle the notion of early alterations to El Niño due to climate change as well.
However, the most ominous language here centers around methane hydrate. For years, there’s been adamant push-back against potential risks to hydrates coming from well-respected sections of the climate sciences. Nonetheless, those downplaying the threat of warming to hydrates have yet to produce any conclusive proof as to why warming the ocean bottom and applying heat to hydrates won’t result in at least some feedback from these carbon stores (especially under the higher-range warming scenarios). The IUCN report reiterates this risk by identifying 2.5 billion tons of frozen seabed methane at shallow and mid-ocean depths that will ultimately be exposed to warming — risking both an ocean and an atmospheric release.
These last points serve to underline some pretty basic facts, the chief of which is that pushing Nature, and heating up her life-blood world ocean waters, is a very, very dangerous game. And if this poignant new report sends any message at all it could simply boil down to this — turn back before it’s too late.
IUCN Report: Explaining Ocean Warming
Hat tip to Cate
Hat tip to George Hayduke