Month: September 2023

Daily News 1 Sep 2023

The real costs of wind power prove the sums don’t add up

By Paul Homewood

It appears that the Editor of the Telegraph has told Jeremy Warner and Ben Marlow to wake their ideas up.

For years they have been blindly churning out renewable energy propaganda. All of a sudden, they have both seen the light!

Someone get a grip. UK energy policy is once again coming apart at the seams, with growing doubts over whether net zero or even energy security goals can be met.

Only now are the true economic costs and practical difficulties of going carbon-free becoming fully evident, and it’s not a pretty sight. Yet still policymakers don’t seem to get it; either that or they are being deliberately misleading on the ease with which it can be delivered.

All pretence at “leading the world” in the application of renewables is meanwhile going up in smoke, as one-time champions pare back their ambitions for the UK market in the face of rising costs, oppressive planning laws, and better opportunities elsewhere. Rival jurisdictions, particularly the US and EU, are beginning to offer far superior incentives.

If you cannot beat them, do the opposite. Slowly, but surely, the Government is watering down its environmental agenda, which sadly but inevitably frequently clashes with the parallel goal of enhanced economic growth – the latest example being so-called “nutrient neutrality” water pollution rules which act as a barrier to more housebuilding.

Yet on paper at least, and indeed legally, the overarching environmental goal of net zero by 2050 – together with the staged targets set for getting there – remains sacrosanct, even though most practically minded people have long thought there is not a snowball’s chance in Hades of actually meeting it. A giant leap of faith in the transforming powers of technology is demanded to think it can be.

As if to confirm the gaping chasm between ambition and reality, the latest round of auctions for UK renewable energy licences, the outcome of which is due to be announced late next week, has plainly hit the rocks.

Having already abandoned a key UK offshore wind development because of rising costs, the Swedish utility Vattenfall has indicated that it won’t be participating in the Government’s so-called Auction Round Five.

Similarly with the UK energy group SSE, which has said it will not be entering its Seagreen offshore development into the auction, citing a low, officially set, strike price, and dramatically rising costs.

Under pressure from the renewables industry, the Government has announced a slight increase in the promised subsidy below strike prices, but it’s unlikely to make a difference.

Presumably there are at least some bidders still in the running; even so, officials will struggle to get the capacity hoped for, putting in jeopardy the target of 50GW of offshore wind by 2030. Current capacity stands at just 14GW, so there is a way to go.

This in turn raises doubts about the Government’s separate target of complete decarbonisation of the electricity network by 2035. This, too, looks unrealistic. British energy policy is once more in a chaotic mess. It was ever thus.

As it is, policymakers have set strike prices so low that investors are struggling to see how they might make a return. No surprise that prices should be forced down like this, for the green energy transition is not just about saving the planet. It is also meant to deliver much lower energy costs.

This, too, is turning out to be a pretence. It’s true that in the past seven or eight years, the notional cost of renewable energy has plummeted. The price of offshore wind output has, for instance, fallen by around two thirds, from £100 per megawatt hour to less than £40. There you go, say ministers in response to net zero sceptics; it’s cheaper than coal.

Would that it was, but the claim is in fact a statistical illusion. The manufacturing, installation and maintenance costs alone have been surging since the war in Ukraine. To these we must also add the costs of upgrading the National Grid to bring the new sources of electricity from where they are generated to where they are used.

Littering the countryside with pylons is understandably running into local opposition. Billions may have to be forked out to compensate affected communities, or in finding alternative, more expensive, transmission routes. It could make HS2 look cheap by comparison.

But to gain a proper understanding of the real costs of wind, and to a lesser extent, solar, we need to factor in another of their characteristics – that they are intermittent.

In order to function effectively, the grid needs a constant balance between supply and demand; if the wind isn’t blowing, or even if it is blowing too strongly, thereby overloading the grid, there is a problem.

Lots of conventional backup capacity is required to deal with the shortfalls that result from intermittency – capacity that can be brought online quickly at the flick of a switch when needs arise.

The upshot is likely to be a high degree of duplication in generating capacity. This will obviously very considerably add to the costs of the renewable element. It’s disingenuous to say wind is cheaper than fossil fuels.

Potentially, storage could provide a solution to the intermittency problem, yet for the moment it doesn’t exist at the scale needed to do the trick. If Britain cannot guarantee to keep the lights on, nobody is going to want to set up shop here.

What about batteries? This may seem unduly pessimistic, but it stretches credulity to believe that they can ever really be the solution. Is there even enough lithium in the world to provide the level of battery power needed to supply the National Grid when the wind stops blowing?

There are alternatives, nuclear being the most obvious, but many environmentalists are as opposed to it as they are to coal, gas and oil, and here in the UK, policy on new nuclear capacity, as on much else, falls woefully short.

It is as much as we can do even to get the money-eating leviathan of Hinkley Point C up and running. Next comes Sizewell C, which scarcely promises to be much better. As Britain’s ageing fleet of existing nuclear power stations reaches the end of its life, merely replacing what’s closing down seems to be beyond us.

And to phase out the 80pc of UK energy demand currently satisfied by fossil fuels, we would need far, far more. Yet the Government continues to procrastinate. Shamefully, it is still faffing around with an international competition to decide who gets to build Small Modular Reactors, never mind how to finance them.

The last two auction rounds lulled the Government into a false sense of security on the economics of renewables. Both were hugely successful in attracting bidders at apparently highly competitive prices.

But things have changed. Having been ahead, Britain is slipping behind. Next week’s announcement on the outcome of the fifth round auction threatens to be a rude awakening.

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September 1, 2023 at 12:27PM

Daily News 1 Sep 2023

Observational and theoretical evidence that cloud feedback decreases global warming

Guest Post by Willis Eschenbach

Well, I decided to take a shot at publishing my views on the cloud feedback response to increases in surface warming. I wrote it up and sent it for peer review to the Journal of Climate.

The reviewers said that it seemed like I was looking at changes in location, not changes over time. So I re-wrote it and sent it back in.

They wrote back and said ok, changes helped, and oh, by the way …

… it’ll cost you $1,546 to get it published.

I can assure you that I harnessed the awesome power that comes from splitting the infinitive. In a far-too-loud voice, I uttered various speculations regarding the ancestry, sexual habits, and personal hygiene of the Owners, Editors, and Reviewers. I fear I went so far as to encourage them to engage in auto-fornication … for all of which I’m truly sorry. It’s just what goes on in 2023, and I’m still not used to it.

So instead, I figured I’d start by publishing it here, and invite people to suggest changes, to point out inconsistencies, and to generally be some combination of Editors and Reviewers of the paper. Please be kind in your comments, I’m just a fool whose intentions are good.

With that as a prologue, here’s the current state of the paper.

Observational and theoretical evidence that cloud feedback opposes global warming

Willis Eschenbach

Independent Climate Researcher, Occidental, California

Corresponding author: Willis Eschenbach

ABSTRACT

Cloud radiative response to a change in surface temperatures is a key component in accurately estimating future temperature changes. Changes in surface temperature lead to different cloud responses in different parts of the planet. However, the overall effect of these changes has been very poorly constrained. (Boucher 2013) Using data from satellite observations, here I develop two independent methods to estimate how the clouds in different areas respond to a surface temperature increase. Both methods show a global net surface cloud radiative cooling effect. The size of the cooling obtained in this manner is a minimum value of total cloud cooling, because more cloud-related cooling occurs as a result of a temperature-related increase in thermally-driven tropical and extra-tropical thunderstorms which cool the surface in a variety of non-radiative ways. In addition, using theoretical arguments, I show that it is unlikely that the cloud response amplifies global warming.

1. Introduction

Clouds have a central role in modulating the global energy balance. They have long been recognized as being the major source of uncertainty in climate projections. Although a variety of evidence has been presented, a narrow constraint on how clouds respond to projected warming has remained elusive. Indeed, there is still no widespread agreement even on the sign of the cloud response to warming. Part of the challenge is that net cloud radiative feedback involves cloud effects on both solar (shortwave [SW]) and terrestrial (longwave [LW]) radiative fluxes. (Ceppi et al. 2017, Gettleman and Sherwood 2016)

2. Theoretical Arguments

A most unusual yet generally unremarked feature of the climate system is its amazing stability. Here is the maximum temperature range over a 22-year period for each 1° latitude by 1° longitude gridcell.

Fig. 1. Maximum variations in monthly temperature (trough to peak) during the period Mar 2000 – Feb 2022.

Here, we see temperature swings of over 30°C in the poles, 29°C over the land, 9°C over the oceans, and 14.8 °C for the globe as a whole. But despite those large intra-annual swings, after 12 months the temperature always returns to nearly the same value. Over the same Mar 2000 – Feb 2022 period, the CERES data reveals annual average global surface temperature changes of only about 0.5°C, which is only three percent of the intra-annual variation.

And as another example, over the entire 20th Century the temperature only increased by a paltry 0.8°C, which is only a mere 0.3% temperature rise in 100 years.

Figure 2. Annual temperature ranges for the globe (red line) and monthly temperature ranges for parts of the globe. Red line shows range of 20th Century global average annual temperatures, around 0.3%.

As Figure 2 above shows, this amazing longer-term stability cannot be from thermal inertia, given the far larger monthly intra-annual swings. This overall steady-state condition argues strongly for the existence of natural thermoregulatory phenomena opposing any change in the overall steady-state temperature.

This is supported by Le Chatelier’s Principle. Le Chatelier enunciated a simple principle that governs systems that are in a steady-state condition. Le Chatelier’s principle asserts that a disturbance applied to a system at a steady state may drive the system away from its equilibrium state, but will invoke a countervailing influence that will counteract the effect of the disturbance. (Gorshkov et al. 1990) This principle strongly suggests that if the global average temperature changes, the clouds and other phenomena will act to counteract the temperature change, not to reinforce it.

3. Observational Data Analysis

The net cloud radiative effect (CRE) at the surface is composed of the clouds’ effect on two different types of radiation. The first is solar (shortwave) radiation, which is both reflected and absorbed by clouds. The second is thermal (longwave) radiation, which is both radiated and absorbed by clouds. The net surface CRE, which I’ll call “CRE” for simplicity, is the total of the two effects at the surface where we live. In general, clouds cool the surface. Figure 2 shows the global variations in the CRE. In Fig. 2 we see that the clouds warm the poles and the deserts, and cool everywhere else.

Fig. 3. Surface cloud radiative effect, on a 1° latitude x 1° longitude basis.

The short-term change in surface CRE with temperature is easily calculated using the CERES data. Figure 4 shows that result.

Figure 4. Short-term trends in surface cloud radiative effect as a function of temperature. Trends are ordinary least squares linear regression slopes.

However, that doesn’t tell us what we need to know, which is how the clouds respond to a long-term change in surface temperature. Despite that, there are two ways that we can use observational data to measure that response.

Both of them depend on a simple idea—as a long-term average for each gridcell, over thousands of years, the temperature and the corresponding cloud radiative effect have reached a steady state condition. All of the various phenomena affecting the CRE, such as relative humidity, boundary-layer inversion strength, CAPE (Convective Available Potential Energy), oceanic subsidence and upwelling, and other factors now oscillate around long-term average values for each given gridcell. Thus, the average relationship between temperature and CRE for each gridcell represents the long-term steady-state relationship.

The first way to see what will happen if the surface temperature warms is a gridcell-based scatterplot of CRE and temperature.

Fig. 5. Scatterplot, 22-year averages of CRE versus surface temperature. Each dot is a 1° latitude by 1° longitude gridcell.

Despite this scatterplot including both land and ocean and covering from the topics to both poles, there is a clear pattern. Looking from the left to the right in the scatterplot, the slope of the black/white line shows the direction and amount of change in the CRE as the temperature increases. There are four different zones.

The coldest zone encompasses the Antarctic and Greenland ice caps. Where the average monthly gridcell temperature is below -20°C, you are in one of those two locations. There, increasing temperatures lead to increasing cloud warming. This represents less than 4% of the planetary surface.

The next zone is from -20°C to 10-15°C. In this zone, increasing warming results in increasing cloud cooling. The third zone is from 10-15°C to about 25°C. In this zone, increasing temperature leads to increasing cloud warming.

Finally, in the warmest parts, increased surface warming leads to greatly increased cloud cooling. At its greatest, an increase of 1°C leads to up to 40 W/m2 of increased cloud cooling (reduction in downwelling surface radiation).

Now, this shows us the overall pattern of the relationship between temperature and CRE. It is extremely non-linear. But it is a general indication, with lots of scatter around the trend line. It also shows areas from all around the world combined.

What this method doesn’t show is either the detailed spatial pattern or the area-weighted global average response of the CRE to increasing temperature. For this I use a second method.

The second method looks only at the average values of the gridcells in the area immediately around each gridcell. Consider a gridcell in the ocean as an example. Nearby gridcells to the north, south, east, and west of that chosen gridcell will have different long-time average values for temperature and CRE. So we can determine the long-term effect by looking at the local relationship between average temperature and average CRE. For each gridcell, I have used a box that is 9° latitude by 9° longitude, centered on the chosen gridcell, and I’ve used a linear regression of that block of data to determine the value for the center gridcell. I’ve analyzed the land and the ocean separately, to avoid mixing different regimes. However, this seems to make little difference. The result is shown in the following Pacific- and Atlantic-centered graphics.

Fig. 6. Changes in surface cloud radiative effect per 1°C change in surface warming. The lower panel is the same as the upper but with an Atlantic-centered view. All values used in the calculation are the average of the full 22 years of the CERES record.

This shows two views, one Pacific and one Atlantic centered, of the detailed location and size of changes in CRE from 1°C surface warming. Globally, there is an area-averaged net cooling of -1.7 W/m2. The main cooling occurs over the ocean, with an area-averaged cooling of -2.4 W/m2. The land is the only area which is even slightly positive, with an area-averaged warming of +0.3 W/m2

These results are in good agreement with those of Ramanathan and Collins (Ramanathan, V., & Collins, W. (1991)), although the proposed mechanisms are different, and these results are for the planet while Ramanathan and Collins only looked at the Pacific Warm Pool.

3. Stability And Uncertainty

If this metric is indeed a measure of the long-term change in CRE with warming, it should change very little from year to year. The boxplot below shows 22 CRE feedback values for each geographical area listed in Figure 6, one for each year of the CERES record.

Figure 7. Boxplot, change in CRE from 1°C surface warming. Data for each of the 22 years in the CERES record.

As expected, there is very little variation in the results despite the shortness (one year) of each dataset. This indicates that even a 22-year average will give accurate values for the change in surface CRE per 1°C warming. As in Figure 6, the only large area that shows positive feedback is the land, and the feedback is quite small.

4. Data Details

I used monthly gridded Clouds and the Earth’s Radiant Energy System (CERES) Energy Balanced and Filled Edition 4.1 data (Loeb et al. 2018). The CERES record is quite stable (Loeb et al. 2016), which makes it an excellent record for this type of analysis. All of the CERES data used covers the 22-year period from March 2000 to February 2022.

For surface temperature, I have used the CERES surface upwelling longwave dataset, converted to temperature using the Stefan-Boltzmann equation. For verification of the calculated CERES surface temperature data, I have compared it with the results using the Berkeley Earth gridded land/ocean data record (Rohde and Hausfather 2020). The area-weighted average difference between the two is only 0.43°C. This difference is not surprising because the Berkeley Earth dataset is a combination of air temperature over land and sea surface temperature. On the other hand, the CERES data is surface temperature everywhere. Below is the same calculation shown in Figure 5 but using the Mar 2000 – Feb 2022 Berkeley Earth Data in place of CERES data for that same period. Note that there is very little difference between this and Figure 5 above which uses CERES data.

Figure 8. As in Figure 3, but using Berkeley Earth surface temperature data in place of CERES data.

5. Final Thoughts

As mentioned above, the cloud radiative effect is only one of the ways that the clouds affect the surface temperature. In addition, thunderstorms cool the surface by means of:

• Increased surface albedo over the ocean due to the white surface foam, spume (foam driven aloft by the wind), and spray.

• Increased evaporative cooling due to the thunderstorm-generated winds at the base, as well as from the provision of dry air to the surface.

• Increased evaporation from the increase in surface area on the millions of spray droplets.

• Cold wind and rain directly cool the surface.

• Increased albedo due to the tall cumulonimbus towers, particularly in the afternoons.

• Increased radiation to space due to the lack of water vapor in the dry descending air between the thunderstorms.

Tropical thermally driven thunderstorms increase with increasing temperatures. As a result, the cloud radiative cooling (CRE) is enhanced by increased thunderstorm production, and the CRE cooling estimates represent a minimum value.

Acknowledgments.

All of this work is my own. However, I owe immense thanks to all of the outstanding scientists who have preceded me. I have no conflicts of interest.

Data Availability Statement.

The underlying CERES EBAF 4.1 data is NASA/LARC/SD/ASDC, 2022. CERES Energy Balanced and Filled (EBAF) TOA and Surface Monthly means data in netCDF Edition 4.1., accessed 11 December 2022, https://ift.tt/J5X74fp.

The underlying Berkeley Earth data is Berkeley Earth, 2022, Monthly Land + Ocean Average Temperature with Air Temperatures at Sea Ice, accessed 17 December 2022, https://ift.tt/Jp0Axj3

REFERENCES

Boucher, O. et al., 2013: Clouds and aerosols, Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (Cambridge University Press, Cambridge, UK, 2013), pp. 571–657.

Ceppi, P, F. Brient, M. D. Zelinka, D. L. Hartmann, 2017: Cloud feedback mechanisms and their representation in global climate models. Wiley Interdisc. Rev. : Clim. Change 8, e465.

Gettelman, A., Sherwood, S.C., 2016: Processes Responsible for Cloud Feedback. Curr Clim Change Rep 2, 179–189. https://ift.tt/Zc3MWuw

Gorshkov, V.G., Sherman, S.G. & Kondratyev, K.Y., 1990: The global carbon cycle change: Le Chatelier principle in the response of biota to changing CO₂ concentration in the atmosphere. Il Nuovo Cimento C 13, 801–816 https://ift.tt/eSI9fVt

Loeb, N. G. et al., 2018: Clouds and the Earth’s Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Top-of-Atmosphere (TOA) Edition-4.0 data product. J. Clim. 31, 895–918.

Loeb, N., N. Manalo-Smith, W. Su, M. Shankar, S. Thomas, 2016: CERES top-of-atmosphere Earth radiation budget climate data record: Accounting for in-orbit changes in instrument calibration. Rem. Sens. 8, 182.

Ramanathan, V., & Collins, W. (1991). Thermodynamic regulation of ocean warming by cirrus clouds deduced from observations of the 1987 El Niño. Nature, 351(6321), 27–32. doi:10.1038/351027a0 https://ift.tt/f514dOs

Rohde, R. A. and Hausfather, Z., 2020: The Berkeley Earth Land/Ocean Temperature Record, Earth Syst. Sci. Data, 12, 3469–3479, https://ift.tt/AwRoD4I.

So, there it is. All comments, criticisms, and improvements gladly considered. This site provides one of the best peer-review processes on the planet.

Please remember that when you comment, you need to quote the exact words you are discussing. That way, we can all be clear about your subject.

Finally, a couple of requests.

First, I’d still like to get this sucker published. Does anyone know of a reasonably high-impact-factor journal that does NOT charge $1,546 to publish a paper?

And second, does anyone want to take this paper over and shepherd it through the review process? This method worked out very well for Craig Loehle and me. With some assistance from me, he rewrote parts of my post on extinctions entitled Where are the Corpses?, he arm-wrestled the journals, and we got it published as Historical bird and terrestrial mammal extinction rates and causes, with him as the Lead Author. So far, about 150 citations, with more each month.

Anyone interested? Any “publish or perish” folks out there not interested in perishing? Because I truly hate dealing with the journals …

My very best wishes to all, enjoy this marvelous world where we are given so little time.

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September 1, 2023 at 12:04PM

Daily News 1 Sep 2023

Geophysical consequences of celestial mechanics

by Vincent Courtillot, Jean-Louis Le Mouel and Fernando Lopes

Sources of variability of some terrestrial and solar phenomena.

As former members of the geomagnetism department at IPGP (Institut de Physique du Globe de Paris), we have always retained an interest in solar-terrestrial relationships. Being in charge of geophysical observatories, we have always paid the foremost attention to long series of observations and as a consequence to methods of time series analysis. As of some five years ago, we have undertaken a systematic study of several long series of observations recorded around the globe (“long” means from several decades up to three centuries).

The research program has been quite productive, with the publication of some 24 articles in the past five years (all freely available online; references at the end of this note). The papers have been published in a very diverse set of journals, mostly in geophysics and astrophysics (in a broad sense). Because we came from the solid Earth geophysics community, it was not always easy at first to be recognized. Thus, we published in those journals where our French IPCC colleagues published, such as Cryosphere or Earth and Planetary Science Letters, MDPI or Frontiers. As a result, readers may have found it uneasy to grasp the wider picture. This short note is intended to try and draw this wider picture, to stress some of its consequences in the spirit of the paper’s title, and to give full references to the papers published in the frame of the program.

We have first determined the spectral content of many long series of observations, using either the Wavelet Method (WM) or Singular Spectrum Analysis (SSA). These series include global mean temperature and pressure of the lower atmosphere, a number of climate-related indices, solar activity through sunspots, length of the day, geomagnetic indices, extent of high latitude sea-ice, and more…
SSA allows one to decompose (in a way that a posteriori makes sense) a time series into a smooth trend and a series of components characterized by specific periodicities or pseudo-periods, based on which the series can be filtered and reconstructed.

We first applied the method to the series of sunspot numbers. The series could be satisfactorily reconstructed from simply a (rather flat) trend and two components with periods 11 years (Schwabe cycle) and 90 years (Gleissberg cycle). More interestingly, these components allow one to construct a precise and robust model of solar activity and to predict (so far rather accurately) the ongoing sunspot cycle and beyond [ref 1, 2, 3].

We have next determined the SSA components of the length of day (or Earth’s rotation velocity) and motions of our planet’s pole of rotation. To the Schwabe and Gleissberg cycles could thus be added the Hale (~22 years) and Jose (~160 years) cycles [ref 4, 5, 6]. We also analyzed tide gauges and sea-level change [ref 7, 8]. In all these series we could recognize the signatures of the four Jovian planets (Jupiter, Saturn, Uranus and Neptune): i.e. their periods of rotation and many of their “commensurable” periods. This argues for a mechanism involving exchanges of angular momentum between the Sun, Earth and planets. Variations in the inclination of the rotation axis due to this coupling in turn affect insolation, much in the way exemplified by Milankovic cycles at much longer periods (from tens of thousands to millions of years). We propose to extend the concept of Milankovic cycles to the much shorter periods we have analyzed [ref 9, 10].

The main components mentioned above are common (in whole or in part) to all the series we have analyzed [ref 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]. The fact that these series of components are found in the rotational mechanics of the planets and in many Earth-bound phenomena argues for a causal (forcing) relationship that can only work one way. The components one finds in sea level, pressure, temperature… must arise from a causal chain going (1) from Jovian planets to the Sun

We note that trends could actually correspond to still other pseudo-periodic components with much longer pseudo-periods (longer than the data interval). As a result, we argue that a very large part of the geophysical and atmospheric variations covered by the series we have analyzed appear to have an external origin (astronomical or gravitational). The perturbing effects of the giant planets correspond to a remarkable set of frequencies [ref 5, 19] that modulate (force) solar activity, variations in inclination of the Earth’s rotation, many terrestrial parameters among which sea level, oceanographic indices, sea – ice and finally temperature. These components have in general not yet been modeled.

These works shed light and are in turn illuminated by the works of giants, the Legendre, Laplace, Lagrange and Poisson, who revolutionized geophysics [ref 25, 26, 27, 28]. The core of their elegant physics explains well the careful observations gathered in the past 200 years.

The first results of our research program have been discussed in an informal seminar at the Paris Academy of Sciences last May. Some 20 academy members attended and a lively open discussion followed. We hope this open, truly scientific attitude prevails.

About the authors. Vincent Courtillot (courtil@ipgp.fr) and Jean-Louis Le Mouël are both emeriti professors of Geophysics at University of Paris, members of the Paris Academy of Sciences and former directors of Institut de Physique du Globe de Paris. Fernand Lopes (lopesf@ipgp.fr), also formerly at IPGP, now at Museum National d’Histoire Naturelle, is a Research Engineer with a PhD in geophysics and a specialty in computing, inverse problems and time series analysis.

JC note: This is an important body of work, addressing many “known unknowns” in the climate system. I encourage you to pick a paper, read it, and comment on it.

Papers published in the frame of this research :
• [ref 1] Le Mouël, J. L., Lopes, F., Courtillot, V. (2017). Identification of Gleissberg cycles and a rising trend in a 315-year-long series of sunspot numbers. Solar Physics, 292(3), 43.
• [ref 2] Le Mouël, J. L., Lopes, F., Courtillot, V. (2020). Solar turbulence from sunspot records. Monthly Notices of the Royal Astronomical Society, 492(1), 1416-1420.
• [ref 3] Courtillot, V., Lopes, F., Le Mouël, J. L. (2021). On the prediction of solar cycles. Solar Physics, 296, 1-23.
• [ref 4] Le Mouël, J. L., Lopes, F., Courtillot, V., Gibert, D. (2019). On forcings of length of day changes: From 9-day to 18.6-year oscillations. Physics of the Earth and Planetary Interiors, 292, 1-11.
• [ref 5] Lopes, F., Le Mouël, J. L., Courtillot, V., Gibert, D. (2021). On the shoulders of Laplace. Physics of the Earth and Planetary Interiors, 316, 106693.
• [ref 6] Lopes, F., Courtillot, V., Gibert, D., Mouël, J. L. L. (2022). On two formulations of polar motion and identification of its sources. Geosciences, 12(11), 398.
• [ref 7] Le Mouël, J. L., Lopes, F., Courtillot, V. (2021). Sea-Level Change at the Brest (France) Tide Gauge and the Markowitz Component of Earth’s Rotation. Journal of Coastal Research, 37(4), 683-690.
• [ref 8] Courtillot, V., Le Mouël, J. L., Lopes, F., Gibert, D. (2022). On sea-level change in coastal areas. Journal of Marine Science and Engineering, 10(12), 1871.
• [ref 9] Lopes, F., Courtillot, V., Gibert, D., Le Mouël, J. L. (2022). Extending the range of milankovic cycles and resulting global temperature variations to shorter periods (1–100 year range). Geosciences, 12(12), 448.

• [ref 10] Courtillot, V., Lopes, F., Gibert, D., Boulé, J. B., Le Mouël, J. L. (2023). On variations of global mean surface temperature: When Laplace meets Milankovi\’c. arXiv preprint arXiv:2306.03442. (in sub)
• [ref 11] Courtillot, V., Le Mouël, J. L., Kossobokov, V., Gibert, D., Lopes, F. (2013). Multi- decadal trends of global surface temperature: A broken line with alternating~ 30 yr linear segments?. Atmospheric and Climate Sciences, 3, 364-371.

• [ref 12] Le Mouël, J. L., Lopes, F., Courtillot, V. (2019). A solar signature in many climate indices. Journal of Geophysical Research: Atmospheres, 124(5), 2600-2619.
• [ref 13] Le Mouël, J. L., Lopes, F., Courtillot, V. (2019). Singular spectral analysis of the aa and Dst geomagnetic indices. Journal of Geophysical Research: Space Physics, 124(8), 6403-6417.
• [ref 14] Le Mouël, J. L., Lopes, F., & Courtillot, V. (2020). Characteristic time scales of decadal to centennial changes in global surface temperatures over the past 150 years. Earth and Space Science, 7(4), e2019EA000671.
• [ref 15] Dumont, S., Le Mouël, J. L., Courtillot, V., Lopes, F., Sigmundsson, F., Coppola, D., … Bean, C. J. (2020). The dynamics of a long-lasting effusive eruption modulated by Earth tides. Earth and Planetary Science Letters, 536, 116145.
• [ref 16] Le Mouël, J. L., Lopes, F., Courtillot, V. (2021). A strong link between variations in sea-ice extent and global atmospheric pressure?. The Cryosphere Discussions, 1-28.
• [ref 17] Lopes, F., Zuddas, P., Courtillot, V., Le Mouël, J. L., Boulé, J. B., Maineult, A., Gèze, M. (2021). Milankovic Pseudo-cycles Recorded in Sediments and Ice Cores Extracted by Singular Spectrum Analysis. Climate of the Past Discussions, 1-17.
• [ref 18] Lopes, F., Courtillot, V., & Le Mouël, J. L. (2022). Triskeles and Symmetries of Mean Global Sea-Level Pressure. Atmosphere, 13(9), 1354.
• [ref 19] Lopes, F., Courtillot, V., Gibert, D., Le Mouël, J. L., Boulé, J.B (2022). On pseudo- periodic perturbations of planetary orbits, and oscillations of Earth’s rotation and revolution: Lagrange’s formulation. arXiv preprint arXiv:2209.07213.
• [ref 20] Courtillot, V., Le Mouël, J. L., Lopes, F., Gibert, D. (2022). On the nature and origin of atmospheric annual and semi-annual oscillations. Atmosphere, 13(11), 1907.
• [ref 21] Lopes, F., Courtillot, V., Gibert, D., Mouël, J. L. L. (2023). On the annual and semi-annual components of variations in extent of Arctic and Antarctic sea-ice. Geosciences, 13(1), 21.
• [ref 22] Le Mouël, J. L., Gibert, D., Courtillot, V., Dumont, S., Ars, J., Petrosino, S., … Geze, M. (2023). On the external forcing of global eruptive activity in the past 300 years. arXiv preprint arXiv:2304.09564. (just accepted in Frontiers in Geosciences)
• [ref 23] Courtillot, V., Boulé, J. B., Le Mouël, J. L., Gibert, D., Zuddas, P., Maineult, A., … & Lopes, F. (2023). A living forest of Tibetan Juniper trees as a new kind of astronomical and geophysical observatory. arXiv e-prints, arXiv-2306. (in sub)
• [ref 24] Le Mouël, J. L., Lopes, F., Courtillot, V., Gibert, D., & Boulé, J. B. (2023). Is the earth’s magnetic field a constant? a legacy of Poisson. Geosciences, 13(7), 202.