Archives par mot-clé : Cycle(s)

Oscillations of the baseline of solar magnetic field and solar irradiance on a millennial timescale

by Zharkova et al., June 24, 2019 in ScientificReportsNature


Abstract

Recently discovered long-term oscillations of the solar background magnetic field associated with double dynamo waves generated in inner and outer layers of the Sun indicate that the solar activity is heading in the next three decades (2019–2055) to a Modern grand minimum similar to Maunder one. On the other hand, a reconstruction of solar total irradiance suggests that since the Maunder minimum there is an increase in the cycle-averaged total solar irradiance (TSI) by a value of about 1–1.5 Wm−2 closely correlated with an increase of the baseline (average) terrestrial temperature. In order to understand these two opposite trends, we calculated the double dynamo summary curve of magnetic field variations backward one hundred thousand years allowing us to confirm strong oscillations of solar activity in regular (11 year) and recently reported grand (350–400 year) solar cycles caused by actions of the double solar dynamo. In addition, oscillations of the baseline (zero-line) of magnetic field with a period of 1950 ± 95 years (a super-grand cycle) are discovered by applying a running averaging filter to suppress large-scale oscillations of 11 year cycles. Latest minimum of the baseline oscillations is found to coincide with the grand solar minimum (the Maunder minimum) occurred before the current super-grand cycle start. Since then the baseline magnitude became slowly increasing towards its maximum at 2600 to be followed by its decrease and minimum at ~3700. These oscillations of the baseline solar magnetic field are found associated with a long-term solar inertial motion about the barycenter of the solar system and closely linked to an increase of solar irradiance and terrestrial temperature in the past two centuries. This trend is anticipated to continue in the next six centuries that can lead to a further natural increase of the terrestrial temperature by more than 2.5 °C by 2600.

Sun spotless for 33 days straight – airline travelers getting dosed with up to 70 times more radiation

by A. Watts, June 21, 2019 in WUWT


Are we in a solar grand minimum? We’ve seen this before, but now predictions are for an extremely weak solar cycle ahead.

Today is the summer solstice in the northern hemisphere. The sun has been without a single observable sunspot now for over a month – 33 days according to NOAA and SIDC data.

 

Daily observations of the number of sunspots since 1 January 1977 according to Solar Influences Data Analysis Center (SIDC). The thin blue line indicates the daily sunspot number, while the dark blue line indicates the running annual average. The recent low sunspot activity is clearly reflected in the recent low values for the total solar irradiance. Compare also with the geomagnetic Ap-index. Data source: WDC-SILSO, Royal Observatory of Belgium, Brussels. Last day shown: 31 May 2019. Last diagram update: 1 June 2019 . [Courtesy climate4you.com]

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Cycles of Rapid Climate Warming

by Jim Steele, May 28, 2018 in WUWT


The globally averaged temperature rose 1.5°F from 1880 to today. Various narratives suggest the rise since 1950 was driven by increasing concentrations of CO2. The rising temperature before 1950 was considered natural. Since 1990, Arctic temperatures rose 2 to 3 times faster than the global average. So, are rapidly rising Arctic temperatures evidence of an impending climate crisis?

Astute students of climate history recall rapid Arctic warming has happened often and naturally. During the last Ice Age when CO2 concentrations were just half of today’s, 25 abrupt warming events happened. Arctic temperatures rose 9°F, and sometimes as much as 14°F in just 40 years. These rapid warming episodes are now called Dansgaard–Oeschger events (D-O events) in honor of the researchers who first detected them in Greenland’s ice cores. These D-O episodes affected global climate, changed ocean currents along California’s coast and altered the range of European forests.

What caused such abrupt warming? Basic physics dismisses changes in greenhouse gases or solar insolation because neither radiative effect induces such rapid warming. The most reasonable explanation suggests episodes of ventilating heat, that had accumulated in the Arctic Ocean, rapidly warmed the air.

Global-scale multidecadal variability missing in state-of-the-art climate models

by S. Kravstov et al. 2018, in Nature


Reliability of future global warming projections depends on how well climate models reproduce the observed climate change over the twentieth century. In this regard, deviations of the model-simulated climate change from observations, such as a recent “pause” in global warming, have received considerable attention. Such decadal mismatches between model-simulated and observed climate trends are common throughout the twentieth century, and their causes are still poorly understood. Here we show that the discrepancies between the observed and simulated climate variability on decadal and longer timescale have a coherent structure suggestive of a pronounced Global Multidecadal Oscillation. Surface temperature anomalies associated with this variability originate in the North Atlantic and spread out to the Pacific and Southern oceans and Antarctica, with Arctic following suit in about 25–35 years. While climate models exhibit various levels of decadal climate variability and some regional similarities to observations, none of the model simulations considered match the observed signal in terms of its magnitude, spatial patterns and their sequential time development. These results highlight a substantial degree of uncertainty in our interpretation of the observed climate change using current generation of climate models.

Modern Climate Wavelet Patterns

by Renee Hannon, December 17, 2018 in WUWT


Wavelet analyses of modern global temperature anomalies provides an excellent visualization tool of temperature signal characteristics and patterns over the past 150 years. Scafetta recognized key temperature oscillations of about 9, 20 and 60-years using power spectra of global surface temperature anomalies. There has been much discussion about the 60-year quasi-oscillation both in WUWT and publications.

Detrending the temperature time series and removing the 60-year underlying trend enables insights into the interplay of interannual and decadal scales. Wavelet analyses reveals these periodic signals have distinguished patterns and characteristics that repeat over time suggesting natural external and internal influences. Interannual wavelet patterns that consist of 9-year and 3 to 5-year quasi-oscillations are repeated and dominate over 70% of the instrumental record. The 3 to 5-year discontinuous breakouts are coincident to El Niño and La Niña events of the El Niño-Southern Oscillation (ENSO). A period of quiescence from 1925 to 1960 is devoid of most wavelet signals suggesting different or transitional climate processes.

Cycle du carbone, l’éclairage de trois nouvelles publications

by Uzbek, 11 septembre 2018 in Climat,Environnemen,Energie


Trois nouvelle études publiées en août 2018 apportent un éclairage nouveau sur le cycle du carbone. La première, publiée dans la revue Nature [1] montre que le taux de croissance du CO2  dans l’atmosphère est très sensible aux changements observés dans le stockage de l’eau terrestre. Les deux autres publiées respectivement dans Nature Geoscience [2] et dans Nature [3] montrent une tendance à l’augmentation du puits de carbone terrestre grâce notamment  aux modifications de l’usage des sols sous l’influence des activités humaines.

Statistical study of past temperature records suggest possible undetected natural climate forcing cycles

by Anthony Watts, September 18, 2018 in WUWT


Godfrey Dack writes in with this:

Everyone will be familiar with the difficulty of listening to a conversation held with a friend in a crowded room with many other conversations going on at the same time. So it is with many fields of scientific investigation where it is difficult to tease a particular trend out from masses of data. In the first case, we could call the friend’s conversation ‘The Signal’, and the background conversations ‘The Noise’.

In looking at climate data, trends (the signal) can be graphically represented by a (generally) smooth curve, usually flanked by a range of experimentally predicted or actually measured values (the noise). Joining up every point on a graph of such data would give a jagged line which could be thought of as a combination of many alternating functions over a wide range of frequencies.

Beyond Milankovitch

by Donald Rapp, September 8, 218 in Climate Etc.


On the terminations of Ice Ages.

Terminations occur on solar up-lobes

There is no doubt that there is merit in the widely accepted Milankovitch theory that Ice Ages and their terminations are controlled by solar input to the NH in mid-summer. It is also clear that relying on the solar input to the NH alone, does not adequately account for the occurrence of terminations of Ice Ages. The variation of solar input to high latitudes is modulated by precession, which produces continual up-lobes and down-lobes in solar input with a ~ 22,000-year period. While every termination is accompanied by the 5,500-year rising portion of an up-lobe in the solar input to high latitudes, many strong up-lobes do not produce a termination….

Harmonic Analysis of Worldwide Temperature Proxies for 2000 Years

by H.J. Lüdecke and C.O. Weiss, April 27, 2017 in TheOpenAtm.Sci.J.


Abstract

The Sun as climate driver is repeatedly discussed in the literature but proofs are often weak. In order to elucidate the solar influence, we have used a large number of temperature proxies worldwide to construct a global temperature mean G7 over the last 2000 years. The Fourier spectrum of G7 shows the strongest components as ~1000-, ~460-, and ~190 – year periods whereas other cycles of the individual proxies are considerably weaker. The G7 temperature extrema coincide with the Roman, medieval, and present optima as well as the well-known minimum of AD 1450 during the Little Ice Age. We have constructed by reverse Fourier transform a representation of G7 using only these three sine functions, which shows a remarkable Pearson correlation of 0.84 with the 31-year running average of G7. The three cycles are also found dominant in the production rates of the solar-induced cosmogenic nuclides 14C and 10Be, most strongly in the ~190 – year period being known as the De Vries/Suess cycle. By wavelet analysis, a new proof has been provided that at least the ~190-year climate cycle has a solar origin.

Modulation of Ice Ages via Precession and Dust-Albedo Feedbacks

by Ralph Ellis, August 2018 in FriendsofScience


Why do ice ages occur? Surprisingly, even after many decades of paleoclimatic research we simply do not know for sure. Most scientists will agree that ice age cycles have something to do with precession: the slow wobble of the axis of the Earth. The ancient Egyptians and Greeks knew of precession and called it the Great Year, because it gives warm and cool seasons over its approximate 23,000-year cycle. But there is a problem with invoking the Great Year as the regulator of ice ages, because we should really get an interglacial warming every 23,000 years or so. And we don’t – they only happen every fourth or fifth Great Year.

But why should the global climate give a selective response to orbital warming and cooling? (Called ‘forcing’ in the climate trade.) This is one of the great unknowns of modern science.

Lightning strikes occur in time with the spinning Sun in 150 year old Japanese farm records

by Jo Nova, July 19, 2018 in JoNova


Remarkably, some Japanese families kept weather record diaries in the 1700 and 1800s, and some for as long as 150 years. The connections they reveal are tantalizing but so incomplete. We are trying to fish out primitive signals from murky water. The Sun turns around on itself every 27 days, so these researchers are looking for repeating patterns in lightning that fit, but the poles of the sun spin slower than the equator and the sun spots can take their own time. Hence, it’s not a neat “27″ days.

During periods of high solar activity, they found regular peaks in lightning activity with the right timing, from May to September when the cold Siberian air mass is not so influential.

Other studies we’ve discussed here have investigated long solar cycles on the 11 year or 200 year scales ….

The La Nina Pump

by Willis Eschenbach, July 16, 2018 in WUWT


Sometimes a chance comment sets off a whole chain of investigation. Somewhere recently, in passing I noted the idea of the slope of the temperature gradient across the Pacific along the Equator. So I decided to take a look at it. Here is the area that I examined.

I’ve written about this temperature gradient before, in a post called The Tao of El Nino. If you take time to read that post, this one will make more sense. …

June Solar Update

by David Archibald, July 6, 2018 in WUWT


We have only 300 years-odd of detailed solar observations with telescopes, half that of magnetic records, half again in the radio spectrum and less than that for most modern instrument records (and 12 years of Watts Up With That to interpret it). So as the months pass our knowledge of solar activity is still growing appreciably. The evidence points to a major transition of activity in 2006 which has returned us to the solar conditions of the 19thcentury. 19th century-type climate is expected to follow.

Figure 1: F10.7 Flux 1948 to 2018