Archives par mot-clé : Cycle(s)

The 60-year oscillation revisited

by Javier, April 26, 2018 in WUWT


It is a well-known feature of climate change that since 1850 multiple climate datasets present a ~ 60-year oscillation. I recently wrote about it in the 7th chapter of my Nature Unbound series. This oscillation is present in the Atlantic Multidecadal Oscillation (AMO), Arctic Oscillation (AO), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), Length of Day (LOD), and Global (GST) and Northern Hemisphere (NHT) temperatures, with different lags.

To me this oscillation is not a cycle because prior to 1850 it had a more variable period and it is not well identified in LIA records. Since the origin of this oscillation is unknown, models have a hard time reproducing it and it is all but ignored by the IPCC. It is a big oscillation with an amplitude of ± 0.3 °C in NHT (0.1-0.2°C in GST; figure 2). While the long-term temperature trend is unaffected by it, there is a large effect on the 30-year trends. If this oscillation is considered, most of the climate alarmism vaporizes.

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It appears Solar Cycle 25 has begun – Solar cycle 24 one of the shortest and weakest ever

by A. Watts, April 12, 2018 in WUWT


Evidence of a Cycle 25 sunspot found

In our previous post: Solar activity crashes – the Sun looks like a cueball, 

Our resident solar physicist, Dr. Leif Svalgaard commented and provided a link to something reported by his colleagues, something that likely would not have been possible without the fantastic solar observations of NASA’s Solar Dynamic Observeratory (SDO).

It seems a small sunspot has been observed, that has the opposite polarity of cycle 24 sunspots.

Tools to Spot the Spots

by Willy Eschenbach, March 30, 2018 in WUWT


People have asked about the tools that I use to look for any signature of sunspot-related solar variations in climate datasets. They’ve wondered whether these tools are up to the task. What I use are periodograms and Complete Ensemble Empirical Mode Decomposition (CEEMD). Periodograms show how much strength there is at various cycle lengths (periods) in a given signal. CEEMD decomposes a signal into underlying simpler signals.

Now, a lot of folks seem to think that they can determine whether a climate dataset is related to the sunspot cycle simply by looking at a graph. So, here’s a test of that ability. Below is recent sunspot data, along with four datasets A, B, C, and D. The question is, which of the four datasets (if any) is affected by sunspots?

New paper tries to disentangle global warming from natural ocean variations

by A. Watts, March 15, 2018 in WUWT


This paper deals with the central argument that skeptics bring up about claims of global warming: How do you separate the temperature signal from the base components like natural variation, human land-use influence, micro-site bias, measurement errors and biases, and other factors to get the “true” global warming signal?

The answer is that you can’t, at least not easily.

With the surface temperature record, it’s somewhat easier since  you can observe some of those elements directly and separate them (such as we’ve done in our surfacestations project for land-use microsite biases), but in the ocean, everything is homogenized by the ocean itself. All you can look for is patterns, and try to disentangle based on pattern recognition. That’s what they are trying to do here.

Disentangling Global Warming, Multidecadal Variability, and El Niño in Pacific Temperatures
Authors
Robert C. Wills, Tapio Schneider, John M. Wallace, David S. Battisti, Dennis L. Hartmann

 

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Global SST data confirms cooling is on the way

by P Homewood, January 27, 2018 in NotaLotofPeopleKnowThat


I see that reality is beginning to intrude upon the dangerous global warming team. They say ” it is plausible, if not likely, that the next 10 years of global temperature change will leave an impression of a ‘global warming hiatus’.”
Climate is controlled by natural cycles. Earth is just past the 2003+/- peak of a millennial cycle and the current cooling trend will likely continue until the next Little Ice Age minimum at about 2650.See the Energy and Environment paper at
http://journals.sagepub.com/doi/full/10.1177/0958305X16686488
and an earlier accessible blog version at http://climatesense-norpag.blogspot.com/2017/02/the-coming-cooling-usefully-accurate_17.html

The Antarctic Centennial Oscillation: A Natural Paleoclimate Cycle in the Southern Hemisphere That Influences Global Temperature

by W.J. Davis et al., January 8, 2018 in Climate


We report a previously-unexplored natural temperature cycle recorded in ice cores from Antarctica—the Antarctic Centennial Oscillation (ACO)—that has oscillated for at least the last 226 millennia. Here we document the properties of the ACO and provide an initial assessment of its role in global climate.

See also here

Earth’s Rotation Is Mysteriously Slowing Down: Experts Predict Uptick In 2018 Earthquakes

by Tevor Nace, November 20, 2017 in WhoaScience


Scientists have found strong evidence that 2018 will see a big uptick in the number of large earthquakes globally. Earth’s rotation, as with many things, is cyclical, slowing down by a few milliseconds per day then speeding up again.

You and I will never notice this very slight variation in the rotational speed of Earth. However, we will certainly notice the result, an increase in the number of severe earthquakes.

Geophysicists are able to measure the rotational speed of Earth extremely precisely, calculating slight variations on the order of milliseconds. Now, scientists believe a slowdown of the Earth’s rotation is the link to an observed cyclical increase in earthquakes.

12 New Papers: North Atlantic, Pacific, And Southern Oceans Are Cooling As Glaciers Thicken, Gain Mass

by K Richard, September 11, 2017 in NoTricksZone


Contrary to expectations, climate scientists continue to report that large regions of the Earth have not been warming in recent decades.

According to Dieng et al. (2017), for example, the global oceans underwent a slowdown, a pause, or even a slight cooling trend during 2003 to 2013.  This  undermines expectations from climate models which presume the increase in radiative forcing from human CO2 emissions should substantially increase ocean temperatures.

The authors indicate that the recent trends in ocean temperatures “may just reflect a 60-year natural cycle“, the AMO (Atlantic Multidecadal Oscillation), and not follow radiative forcing trends.

Nature Unbound V – The elusive 1500-year Holocene cycle

by Javier,  September 15, 2017, in Judith Curry Climate Etc.


The existence of a 1500-year climatic cycle during the Holocene, related to the glacial Dansgaard-Oeschger cycle, is a matter of intense debate. However, by introducing precise timing requirements it can be shown that the 1500-year cycle displayed in Northern Hemisphere glacial records is also observed in Holocene records from all over the world.

The cycle is most prominently displayed in oceanic subsurface water temperatures, Arctic atmospheric circulation, wind deposits, Arctic drift ice, and storminess records.

The Effects of the Bray Climate and Solar Cycle

by Andy May, August 8, 2017 in WUWT


The Bray cycle is about 2450 years from beginning to end and the Bray Lows, which are the coldest portion of the cycle, are the most important events.

The world is currently within the Quaternary Ice Age and nearly as cold as it has ever been. The normal average temperature of the world is around 20°C, some 5°C warmer than today. To keep recent warming in perspective, it is important to understand that even if the worse predictions of the IPCC were to occur, we would only be returning to the average temperature of the last 560 million years

Phanerozoic Global Temperature from Scotese 2015,

link in the post (.pdf)

The 2400-year Bray cycle

by Javier, July 11, 2017 in ClimatEtc.


In our attempt to better understand the nature of our planet’s abrupt climate changes I have already reviewed the glacial-interglacial cycle, and the Dansgaard-Oeschger cycle’s that take place during glacial periods. I now start reviewing the millennial climate cycles that abruptly impact the slowly changing Holocene climate. The most significant and regular one is the ~ 2400-year Bray cycle.