“In my opinion, the rate of ocean heat storage is the most fundamental number for our understanding of long-term climate change,” James Hansen.
Climate change is heat trapped by greenhouse gases that produce an energy imbalance between the energy flowing in and out of the upper atmosphere. As shown in the following skepticalscience.com visual for global warming components for the period 1993 to 2003 calculated from IPCC AR4 18.104.22.168, only slightly more than 2% of this heat actually remains in the atmosphere.
By far the majority is going into the ocean and according to the latest study, two-thirds of that is accumulating in the upper 700 meters, with another 15 percent below 2,000 meters, and 20 percent in between.
Further the rate of accumulation of this heat the past 18 years matched that of the previous 133 years.
Because of their great mass and heat capacity the ocean’s have thermal inertia. They are slow to heat and once warmed will be slow to cool down.
On average they are about 1 or 2 degrees warmer than the atmosphere, so on average they transfer heat to the atmosphere. This happens only at the surface however so heat that has migrated below 700 meters, often considered the deep ocean, is essentially as out thermal communication with the atmosphere as if had been sent into space. At least until it returns to the surface at and average return rate of about 4 meters per year.
Some scientists consider this “unrealized” global warming because it is a delayed response to the radiative forcing of the greenhouse gases. By most estimates it will take about 1000 years for the atmosphere and ocean to come back into equilibrium once we stop adding greenhouse gases to the atmosphere because this is about the full transit cycle of the thermohaline circulation.
The latest study however suggests that policy decisions made in the next few years to decades will have profound impacts on global climate, ecosystems and human societies — not just for this century, but for the next ten millennia and beyond.
At Paris policy makers expressed a strong desire to limit temperature increase to 1.5 degrees Celsius above pre-industrial levels even though by the time they made that commitment 1 degree had already been surpassed.
Eight years ago Ramanathan and Feng estimated 2.4°C was already baked in over the next 1000 years including the 0.8° that had been reached by that time.
The 1.6 degrees (more than the aspirational target) over and above consisted of 0.7°C due to the ocean heat lag, 0.9°C due to a hidden deferred warming from aerosols that will be ‘unmasked’ when fossil air pollution or fossil energy production stops, plus another 1.0°C that will accumulate in the least time it will take to stabilize greenhouse gas emissions that are currently the highest they have been in 66 million years.
“Because our carbon release rate is unprecedented over such a long time period in Earth’s history, it also means that we have effectively entered a ‘no-analogue’ state,” said co-author Richard Zeebe of the Nature article that says, we are now emitting 10 gigatons of carbon annually, “This represents a big challenge for projecting future climate changes because we have no good comparison from the past.”
So we are currently up 1.0°C, effectively head for another 1 even with a best effort to get off fossil fuels, and the latest study confirms the cooling effects of aerosols have masked approximately one-third of the global warming that is attributable to increased greenhouse gas concentrations, without even accounting for the release of unrealized ocean heat.
The Paris commitment was a fraud as James Hansen suggested because it has no basis in science. The most current study says, “Given the required rate and magnitude of this transition to renewable energy, it is unlikely that the <2 °C goal can be met.” And calls for as rapid as possible expansion of renewable energy to keep to within 2.5–3 °C.
In fact making false promises like those implied at Paris is probably more insidious than baseless declarations that global warming is a hoax.
Making matters worse, James Hansen’s latest work says we are in for a perilous climate shift within decades, not centuries, based on a 2 degree increase.
Nevertheless effective environmental policy in the developed nations is evolving at an electoral cycle pace leaving both fossil fuel providers and their investors as well as nascent clean energy innovators circling the economic drain.
Further in the estimation of the IEA, two years of climate inaction cost the world $8 trillion, which I make to be $127,000 every second wasted.
The only recent bright spot on the environmental scene has been when global warming temporarily stalled. When about 30% of the warming heat was dumped below 700 meters in the ocean due to wind changes, especially in the Pacific, associated with decadal weather patterns associated with La Niñas. There have been 3 such periods in the past 50 years; from 1977 to 1986, from 1987 to 1996, and 2001-2012.
After each of these however temperatures jumped as the bulk of the heat that went no deeper than 300 meters returned to the surface.
The obvious conclusion therefore, IMHO, is to move as much surface heat as possible deeper than 700 meters, making it as “unrealized” as possible for as long as possible.
The second law of thermodynamics provides that the production of energy can be derived from such movement.
And the thermohaline circulation perpetuates the ocean potential to produce this energy because the heat source is replenished by solar energy that warms the tropical surface and in winter, when the poles freeze, cold, dense, saline enriched, water sinks and flows back towards the tropics to complete the cycle (which is a heat engine in its own right) and replenishes the cold sink.
Heat pipe OTEC would generate power by moving heat from the surface to the intermediate layer.
James Hansen’s latest work is predicated on the proposition that ice melt is causing a feedback that will shutdown the thermohaline leading to accelerated sea level rise and superstorms.
Heat pipe OTEC would short-circuit the heat movement that is setting this process in motion and at sufficient levels would boost the thermohaline.
The oceans are a global warming buffer. We need to use them effectively to produce energy that unrealizes as much global warming as possible or face the real, serious and imminent consequences.
Abstract, Oceanography: Leading the hiatus research surge, published online by Nature Climate Change, 24 March 2016, “The recent slowdown in global warming challenged our understanding of climate dynamics and anthropogenic forcing. An early study gave insight to the mechanisms behind the warming slowdown and highlighted the ocean’s role in regulating global temperature.”
You could have read the same in this forum off and on the past three years but more importantly you could have read as well about the practical implications of the same for clean energy and climate mitigation.