Media Raises False Alarms of Ocean Cooling
The usual suspects, such as BBC, the Guardian, New York Times, Washington Post etc., are reporting that the Atlantic gulf stream is slowing down due to climate change, threatening an ice age.
That’s right, warmists are now claiming fossil fuels do cooling when they are not warming. As usual, the headlines are not supported by the details.
The AMOC is back in the news following a recent Ocean Sciences meeting. This update adds to the theme Oceans Make Climate. Background links are at the end, including one where chief alarmist Michael Mann claims fossil fuel use will stop the ocean conveyor belt and bring a new ice age.
Actual scientists are working away methodically on this part of the climate system, and are more level-headed.
H/T GWPF for noticing the recent article in Science Ocean array alters view of Atlantic ‘conveyor belt’ By Katherine Kornei Feb. 17, 2018.
Excerpts with my bolds:
The powerful currents in the Atlantic, formally known as the Atlantic meridional overturning circulation (AMOC), are a major engine in Earth’s climate.
The AMOC’s shallower limbs—which include the Gulf Stream—transport warm water from the tropics northward, warming Western Europe.
In the north, the waters cool and sink, forming deeper limbs that transport the cold water back south—and sequester anthropogenic carbon in the process.
This overturning is why the AMOC is sometimes called the Atlantic conveyor belt.
Fig. 1. Schematic of the major warm (red to yellow) and cold (blue to purple) water pathways in the NASPG (North Atlantic subpolar gyre ) credit: H. Furey, Woods Hole Oceanographic Institution): Denmark Strait (DS), Faroe Bank Channel (FBC), East and West Greenland Currents (EGC and WGC, respectively), NAC, DSO, and ISO.
In February at the American Geophysical Union’s (AGU’s) Ocean Sciences meeting, scientists presented the first data from an array of instruments moored in the subpolar North Atlantic.
The observations reveal unexpected eddies and strong variability in the AMOC currents.
They also show that the currents east of Greenland contribute the most to the total AMOC flow. Climate models, on the other hand, have emphasized the currents west of Greenland in the Labrador Sea.
“We’re showing the shortcomings of climate models,” says Susan Lozier, a physical oceanographer at Duke University in Durham, North Carolina, who leads the $35-million seven-nation project known as the Overturning in the Subpolar North Atlantic Program (OSNAP).
Fig. 2. Schematic of the OSNAP array. The vertical black lines denote the OSNAP moorings with the red dots denoting instrumentation at depth. The thin gray lines indicate the glider survey. The red arrows show pathways for the warm and salty waters of subtropical origin; the light blue arrows show the pathways for the fresh and cold surface waters of polar origin, and the dark blue arrows show the pathways at depth for waters that originate in the high-latitude North Atlantic and Arctic.
The research and analysis are presented by Dr. Lozier et al. in this publication Overturning in the Subpolar North Atlantic Program: A New International Ocean Observing System
Images above and text excerpted below with my bolds.
For decades oceanographers have assumed the AMOC to be highly susceptible to changes in the production of deep waters at high latitudes in the North Atlantic.
A new ocean observing system is now in place that will test that assumption.
Early results from the OSNAP observational program reveal the complexity of the velocity field across the section and the dramatic increase in convective activity during the 2014/15 winter.
Early results from the gliders that survey the eastern portion of the OSNAP line have illustrated the importance of these measurements for estimating meridional heat fluxes and for studying the evolution of Subpolar Mode Waters.
Finally, numerical modeling data have been used to demonstrate the efficacy of a proxy AMOC measure based on a broader set of observational data, and an adjoint modeling approach has shown that measurements in the OSNAP region will aid our mechanistic understanding of the low-frequency variability of the AMOC in the subtropical North Atlantic.
Fig. 7. (a) Winter [Dec–Mar (DJFM)] mean NAO index. Time series of temperature from the (b) K1 and (c) K9 moorings.
Finally, we note that while a primary motivation for studying AMOC variability comes from its potential impact on the climate system, as mentioned above, an additional motivation for the measure of the heat, mass, and freshwater fluxes in the subpolar North Atlantic arises from their potential impact on marine biogeochemistry and the cryosphere.
Thus, we hope that this observing system can serve the interests of the broader climate community.
Fig. 10. The linear sensitivity of the AMOC at (d),(e) 25°N and (b),(c) 50°N in Jan to surface heat flux anomalies per unit area. Positive sensitivity indicates that ocean cooling leads to an increased AMOC—e.g., in the upper panels, a unit increase in heat flux out of the ocean at a given location will change the AMOC at (d) 25°N or (e) 50°N 3 yr later by the amount shown in the color bar. The contour intervals are logarithmic. (a) The time series show linear sensitivity of the AMOC at 25°N (blue) and 50°N (green) to heat fluxes integrated over the subpolar gyre (black box with a surface area of ∼6.7 × 10 m2) as a function of forcing lead time. The reader is referred to Pillar et al. (2016) for model details and to Heimbach et al. (2011) and Pillar et al. (2016) for a full description of the methodology and discussion relating to the dynamical interpretation of the sensitivity distributions.
In summary, while modeling studies have suggested a linkage between the deep-water mass formation and AMOC variability, observations to date have been spatially or temporally compromised and therefore insufficient either to support or to rule out this connection.
Current observational efforts to assess AMOC variability in the North Atlantic.
The U.K.–U.S. Rapid Climate Change–Meridional Overturning Circulation and Heatflux Array (RAPID–MOCHA) program at 26°N successfully measures the AMOC in the subtropical North Atlantic via a trans-basin observing system (Cunningham et al. 2007; Kanzow et al. 2007; McCarthy et al. 2015).
While this array has fundamentally altered the community’s view of the AMOC, modeling studies over the past few years have suggested that AMOC fluctuations on interannual time scales are coherent only over limited meridional distances.
In particular, a breakpoint in coherence may occur at the subpolar–subtropical gyre boundary in the North Atlantic (Bingham et al. 2007; Baehr et al. 2009).
Furthermore, a recent modeling study has suggested that the low-frequency variability of the RAPID–MOCHA appears to be an integrated response to buoyancy forcing over the subpolar gyre (Pillar et al. 2016).
Thus, a measure of the overturning in the subpolar basin contemporaneous with a measure of the buoyancy forcing in that basin likely offers the best possibility of understanding the mechanisms that underpin AMOC variability.
Finally, though it might be expected that the plethora of measurements from the North Atlantic would be sufficient to constrain a measure of the AMOC within the context of an ocean general circulation model, recent studies (Cunningham and Marsh 2010; Karspeck et al. 2015) reveal that there is currently no consensus on the strength or variability of the AMOC in assimilation/reanalysis products.
Read rest at Science Matters
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