N. Atlantic Staying Cool

Science Matters

RAPID Array measuring North Atlantic SSTs.

For the last few years, observers have been speculating about when the North Atlantic will start the next phase shift from warm to cold. Given the way 2018 went and 2019 is following, this may be the onset.  First some background.

. Source: Energy and Education Canada

An example is this report in May 2015 The Atlantic is entering a cool phase that will change the world’s weather by Gerald McCarthy and Evan Haigh of the RAPID Atlantic monitoring project. Excerpts in italics with my bolds.

This is known as the Atlantic Multidecadal Oscillation (AMO), and the transition between its positive and negative phases can be very rapid. For example, Atlantic temperatures declined by 0.1ºC per decade from the 1940s to the 1970s. By comparison, global surface warming is estimated at 0.5ºC per century – a rate twice as slow.

In many parts…

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Continuous observations in the North Atlantic challenges current view about ocean circulation variability

Reblogged from Watts Up With That:

Guest Blogger / May 11, 2019

Kevin Kilty

May 10, 2019

[HiFast Note:  Figures A and B added:

Figure A. OSNAP Array Schematic, source:  https://www.o-snap.org/]

Figure B. OSNAP Array, source:  https://www.o-snap.org/observations/configuration/]

Figure 1: Transect of the North Atlantic basins showing color coded salinity, and gray vertical lines showing mooring locations of OSNAP sensor arrays. (Figure from OSNAP Configuration page)

From Physics Today (April 2019 Issue, p. 19)¹:

The overturning of water in the North Atlantic depends on meridional overturning circulation (MOC) wherein warm surface waters in the tropical Atlantic move to higher latitudes losing heat and moisture to the atmosphere along the way. In the North Atlantic and Arctic this water, now saline and cold, sinks to produce north Atlantic Deep water (NADW). It completes its circulation by flowing back toward the tropics or into other ocean basins at depth, and then subsequently upwelling through a variety of mechanisms. The time scale of this overturning is 600 years or so².

The MOC transports large amounts of heat from the tropics toward the poles, and is thought to be responsible for the relatively mild climate of northern Europe. The heat being transferred from the ocean surface back into the atmosphere at high latitudes is as large as 50W/m², which is roughly equivalent to solar radiation reaching the surface at high latitudes during winter months².

In order to evaluate models of ocean overturning oceanographers have relied upon hydrographic research cruises. But the time increment between successive cruises is often long, and infrequent sampling cannot measure long term trends reliably nor gauge current ocean dynamics.

To get a better handle on MOC behavior an array of sensors to continuously monitor temperature, salinity, and velocity measurements known as the Overturning in the Subpolar North Atlantic Program (OSNAP) was recently deployed across the region at multiple depths. Figure 1 shows sensor moorings in relation to the various ocean basins of the North Atlantic. Figure 2 shows data from the first 21 months of operation, and displays a rather large variability of overturning in the eastern North Atlantic between Greenland and Scotland that reaches +/-10 Sverdrup (Sv=one million cubic meters per second) monthly, and amounts to one-half the MOC’s total annual transport. Researchers had thought that such variability was only possible on time scales of decades or longer.

Figure 2: Twenty-one months of observational data showing large month to month variation in MOC flows.

The original experimental design for sensor placement in OSNAP was predicated on much smaller variability of a few Sv per month³. The report does not address what impact this surprising level of transport variability has on validity of the experiment design; but the surprisingly large variations in flow challenge expectations derived from climate models regarding the relative amount of overturning between the Labrador Sea and the gateway to the Arctic between Greenland and Scotland.

As one oceanographer put it, the process of deep water formation and sinking of the MOC is more complex than people believed, and these results should prepare people to modify their ideas about how the oceans work. This improved data should not only help test and improve climate models, but also produce more realistic estimates of CO₂ uptake and storage.

References:

1. Alex Lopatka, Altantic water carried northward sinks farther east of previous estimates, Physics Today, 72, 4, 19(2019).

2. J. Robert Toggweiler, The Ocean’s Overturning Circulation, Physics Today, 47, 11, 45(1994).

3. Susan Lozier, Bill Johns, Fiamma Straneo, and Amy Bower, Workshop for the Design of a Subpolar North Atlantic Observing System, URL= https://www.whoi.edu/fileserver.do?id=163724&pt=2&p=175489, accessed 05/10/2019.

Retreating Greenland glacier is growing again

Tallbloke's Talkshop

Jakobshavn glacier, West Greenland [image credit: Wikipedia]
Without jumping to hasty conclusions, this is an interesting development not predicted by the IPCC’s supposed experts. Natural ocean/climate oscillations are implicated. Against assumptions, rising carbon dioxide levels cannot explain these latest observations.

A new NASA study finds a major Greenland glacier that was one of the fastest shrinking ice and snow masses on Earth is growing again, reports The GWPF.

The scientists were so shocked to find the change, Khazendar said: “At first we didn’t believe it.

“We had pretty much assumed that Jakobshavn would just keep going on as it had over the last 20 years.”

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Hurricanes & climate change: 21st century projections

Climate Etc.

by Judith Curry

Final installment in my series on hurricanes and climate change.

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China And The Pause

Reblogged from the GWPF:

Dr David Whitehouse, GWPF Science Editor, 08/03/19

Chinese climate scientists: The so-called hiatus in global temperature is illuminating, significant and real.

Chinese climate scientists are clearly off-message. They keep referring to the global warming hiatus which so many scientists and activists – those who shout on twitter and prowl the comment sections of off-colour articles on the subject – know has been trounced and discredited again and again. They clearly ought to have a word with the emerging science powerhouse that is China.

Writing recently in “Science of The Total Environment,” Li and Zha of Nanjing Normal University, say the global hiatus has played a prominent role in their thinking and they see it reflected in China. Using satellite data they found a hiatus in China between 2001-15. They found warming in western and southern China and a 15-year cooling trend in northern China. For China as a whole they estimate that the warming rate is just -0.02°C per decade. They conclude that, “there is a regional warming hiatus, a pause or slowdown in China, and (it) implies that greenhouse gas induced warming is suppressed by other natural forcing in the early 21st century.”

There is also Li et al writing in Climate Dynamics who are a little more forceful saying, “since the late 1990s, the global warming has ground to a halt, which has sparked a rising interest among the climate scientists. The hiatus is not only observed in globally average surface air temperature, but also in the China winter air temperature trend, which turns from warming during 1979-1997 to cooling during 1998-2013.” They attribute the effect to the melting of Arctic sea ice.

Gan et al (Lanzhou University and South Dakota State University), reporting in Earth and Space Science say that the hiatus, if not cooling, is seen over the Northern Hemisphere finding that the daily temperature minimum experienced an “obvious” decline in North America during the warming slowdown period. They relate the changes in daily temperature minimum to the Atlantic Multi-decadal Oscillation.

He at al (National Science Review) note that carbon budgets in ecosystems in China are coupled with changes in climate. They point out that in the past decade China has experienced changes in the characteristics of its summer monsoon as well as “decelerated warming.” They point out that in general changes in China’s ecosystems are poorly documented.

Looking at East Asian surface temperatures Xie et al in Climate Dynamics suggest that the effect of the North Atlantic Oscillation, operating through its influence on the African-Asian multi-decadal teleconnection pattern, will mean that East Asian surface ait temperatures will remain at their current levels or slightly cooler between 2018 -2034, and will then increase.

Elsewhere in the world Wanatabe et al in Nature Scientific Reports say that the Indian Ocean Dipole – an inter-annual mode of climate variability in the Indian Ocean – has intensified with 20th century global warming. However, the data shows a global-warming hiatus between the late-1990s and 2015. They say it is presently unclear how this global warming hiatus, as they put it, will affect regional ocean parameters.

All of these interesting papers come from mainstream journals, and all are food for thought. The so-called hiatus in global temperature is illuminating, significant and real.