Still recycling long-debunked arguments from 25 years ago, I see. You lot desperately need some new material.

The early 1900s warming wasn't caused by multiple factors. Solar output increased, volcanoes were relatively quiet for a while, and natural variability in the oceans all played a part. As even deniers will selectively point out, climate is multifactorial.

But the situation changes once you get to the late 20th century. From the 1970s onward, solar activity isn't increasing. It's flat. Yet temperatures keep climbing. That's where the “iT's ThE sUn” explanation collapses.

When scientists test this properly, they don't just eyeball graphs. They run simulations with different drivers switched on and off. If you exclude greenhouse gases, the late-century warming largely disappears in those simulations. Put them back in, and the models produce the upward trend we actually observed.

You don't have to think climate models are perfect to see the pattern. Solar variability can help explain some earlier fluctuations. It does not account for the sustained warming over the past five decades. The timing simply doesn't line up.

Stick to mechanical engineering, Tom. You make a terrible scientist.

On and on the climate change rubbish goes. It doesn't really matter who says what anymore. The lunatics are still in charge, thanks to silly voters, and life just gets harder and harder for said silly voters. Silly voters get the governments they deserve, along with the ever-increasing costs caused by lies that climate change is caused by the silly voters' use of cheap, reliable fossil fuels.

I've always been rather partial to the view that changes in temperatures over the eons are primarily caused by the big yellow thing in the sky. But not just by the heat from it but also the solar winds that spew forth thereby affecting the level of cosmic rays that hit the earth. Those cosmic rays are intimately involved in the creation of clouds which in turn heavily affect the earth's albedo. Many scientists are working on this, the most prominent and among the first was Svensmark.

The theory not only relies on changes in the sun but also changes in the solar system's position vis-a-vis other bodies in the Milky Way. As we rotate around the galactic centre there are changes in the level of cosmic rays that hit the earth. Some work has been done on aligning that with ice ages.

The earth's climate is a massively complex system Asserting that it was controlled by a change in the levels of CO2 from 3 parts per 10,000 to 4 parts per 10,000 was always dubious. That it even got off the ground is an indictment of current science.

ttbn frets that the rubbish goes on. But as I've been pointing out in other threads, the whole scam is currently unravelling. It'll take a while because of the careers and money invested in the continuation of the climate industry, but it is and will happen.

"When scientists test this properly, they don't just eyeball graphs. They run simulations with different drivers switched on and off. If you exclude greenhouse gases, the late-century warming largely disappears in those simulations. Put them back in, and the models produce the upward trend we actually observed."

You need to show us where this has happened. More importantly, you need to show that the simulations have been correctly calibrated by showing that they are able to recreate past temperature changes and correctly predict future changes.

mhaze,

The cosmic ray-cloud hypothesis isn't new. Svensmark has been advancing versions of it for decades. It's been tested.

The basic idea is that solar activity modulates cosmic rays, which influence cloud nucleation, which alters albedo. Interesting chain. The problem is scale.

Yes, cosmic ray levels move up and down. We can track that. But the changes are modest, and the supposed cloud response hasn’t lined up in any consistent way with the modern temperature rise. Researchers have tested the link repeatedly and the effect, if it exists, looks far too weak to account for the late-century warming.

More importantly, solar activity hasn't increased since the mid-20th century. Cosmic ray flux hasn't shown a long-term trend that matches post-1970 warming either. The timing problem remains.

Regarding simulations, this isn't hypothetical. Detection and attribution studies have been running since the 1990s. Models are tested by hindcasting. They are run using only natural forcings (solar + volcanic), and then with anthropogenic forcings added.

With natural forcings alone, late-century warming is not reproduced. With greenhouse gases included, it is. That result has been replicated across multiple independent modelling centres, not a single "climate industry" lab.

Models may not be perfect crystal balls, but they successfully reproduce:

- 20th century temperature evolution
- Stratospheric cooling alongside tropospheric warming
- Ocean heat uptake

If CO2 were irrelevant, you would not see the specific vertical and spectral fingerprints that we do.

Invoking complexity doesn't invalidate radiative physics. It just makes the system harder to simulate precisely.

Like I was saying: you lot desperately need some new material.

Lots of assertions there JD. But not a single concrete piece of evidence.

As usual.
As expected

mhaze,

You're asking for "concrete evidence", which is fair enough, but you've made several claims yourself:

- That cosmic rays are driving modern warming
- That galactic position is relevant to current trends
- That the "scam is unravelling"
- That models aren't properly calibrated

You haven't provided evidence for any of those.

I've referenced measurable observations: solar output trends, atmospheric temperature structure, and ocean heat content. Yet you - someone who manages to find papers appearing to contradict the mainstream consensus on any given topic - somehow need me to point you in the right direction?

I doubt that.

Would you like me to google the supporting papers for you?

Lots of assertions there JD. But STILL not a single concrete piece of evidence.

As usual.
As expected

Now he's asking me to go off and find papers that support his assertions. What a joke.

No, mhaze, I didn't ask you to.

//Now he's asking me to go off and find papers that support his assertions. What a joke.//

I simply pointed out that you were capable of doing so.

(Sounds like someone's getting a little cranky.)

//But STILL not a single concrete piece of evidence.//

I offered to google it for you. Can I take it this is a 'Yes, please do'?

"Henrik Svensmark's ground-breaking theory, often termed cosmoclimatology, offers a compelling explanation for how solar winds influence Earth's climate through cosmic rays. Developed in the 1990s at the Danish National Space Center, it posits that variations in solar activity modulate the influx of galactic cosmic rays, which in turn affect cloud formation and global temperatures.

At its core, the mechanism is elegant: During periods of high solar activity, marked by increased sunspots and stronger solar winds, the Sun's magnetic field intensifies, deflecting more cosmic rays away from Earth. Fewer cosmic rays mean reduced ionization in the atmosphere, leading to fewer cloud condensation nuclei. This results in diminished low-level cloud cover, which normally reflects sunlight back to space. Consequently, more solar radiation reaches the surface, warming the planet. Conversely, low solar activity allows more cosmic rays to penetrate, promoting cloud formation and cooling effects, as seen during the Little Ice Age when solar minima coincided with colder global temperatures.

Empirical evidence bolsters this view. Svensmark's analysis of satellite data revealed a strong correlation—up to 0.92—between cosmic ray flux and global cloud cover variations over solar cycles. Laboratory experiments, such as those at CERN's CLOUD project, have confirmed that cosmic rays enhance aerosol nucleation, supporting the cloud-seeding hypothesis. Historical reconstructions further align solar activity proxies with climate shifts, explaining warming trends since 1750 without over-relying on anthropogenic factors.
This theory amplifies the Sun's role beyond mere irradiance changes, estimating solar forcing at 1.0–1.5 W/m² over cycles—far greater than IPCC estimates. It challenges conventional models by integrating astronomical phenomena with terrestrial climate, fostering a holistic understanding of natural variability. Svensmark's work invites re-evaluation of climate dynamics, emphasizing the Sun's profound, underappreciated influence on our world."

http://www.thegwpf.org/content/uploads/2019/03/SvensmarkSolar2019-1.pdf

mhaze,

The document you linked isn't a journal paper. It's a GWPF policy report. So it hasn't gone through the standard anonymous peer review process that attribution studies in the mainstream literature do.

Svensmark is a serious physicist and the cosmic ray-cloud idea is a legitimate hypothesis. CLOUD at CERN did show that ionisation can enhance nucleation of very small particles in controlled conditions. That part is interesting.

The harder part isn't whether ions can help nucleation. It's what happens next.

Showing enhanced nucleation in a chamber is not the same as demonstrating a sustained, multi-decadal shift in global cloud cover large enough to explain late-20th-century warming. Moving from microphysics to global radiative forcing is the real leap, and that's where the evidence becomes much less clear.

Then there's timing. Cosmic ray flux has been directly measured since the 1950s. It tracks the 11-year solar cycle. What it does not show is a strong long-term trend since the 1970s that mirrors the steady temperature rise. The modern warming curve and the cosmic ray record simply don't line up on that timescale.

As for attribution, this isn't about eyeballing graphs. Models are run with natural forcings only and then with greenhouse gases included. The natural-only runs don't reproduce the late-century warming trend. Add greenhouse gases and the models track the observed rise much more closely. That pattern has been reproduced across multiple modelling groups.

The sun clearly influences climate. The question is whether solar-modulated cosmic rays explain the magnitude and timing of recent warming. At this stage, the peer-reviewed literature says they don't.

In the ongoing debate over the drivers of global warming, two prominent theories emerge: the mainstream CO2-driven greenhouse effect and Henrik Svensmark's cosmic ray hypothesis. While the CO2 theory attributes recent temperature rises primarily to human emissions trapping heat, Svensmark's model offers a more comprehensive, natural explanation that aligns better with historical and empirical data, making it preferable for understanding climate dynamics.

Svensmark's theory holds that galactic cosmic rays (GCRs) play a pivotal role in cloud formation. When solar activity is high, the sun's magnetic field strengthens, deflecting more GCRs from Earth. Fewer GCRs mean reduced ionization in the atmosphere, leading to fewer cloud condensation nuclei and thus thinner cloud cover. This allows more sunlight to reach the surface, amplifying warming. Conversely, low solar activity permits more GCRs, increasing clouds and cooling the planet. This mechanism explains not just 20th-century warming but other climate events, such as the Medieval Warm Period and Little Ice Age, without relying on anthropogenic factors.

Empirical evidence strongly supports Svensmark. Studies show a 0.92 correlation between GCR flux and global cloud cover, far exceeding CO2's explanatory power for pre-industrial variations. Over the solar cycle, energy entering Earth's system is 5-7 times greater than from solar irradiance alone, indicating amplification via clouds. Recent Japanese research on winter monsoons confirms GCRs' "umbrella effect," where increased rays boost low clouds, countering warming trends. In contrast, the CO2 theory struggles with these natural cycles; IPCC estimates solar forcing at a mere 0.05 W/m² since 1750, negligible next to greenhouse gases, yet ignores solar amplification.

"Svensmark's approach is preferable because it integrates astronomical influences with terrestrial climate, offering a holistic view. It suggests lower climate sensitivity to CO2 (around 0.25 K/Wm⁻² versus IPCC's 0.9), implying less alarm over emissions. By substantiating solar-GCR links through experiments like SKY2, it challenges CO2-centric models that overlook cosmic drivers. Ultimately, embracing Svensmark fosters a nuanced, evidence-based climate science, prioritizing natural variability over singular human culpability."

Thanks for the copy-and-paste, mhaze.

//two prominent theories emerge: the mainstream CO2-driven greenhouse effect and Henrik Svensmark's cosmic ray hypothesis.//

That framing is the first problem. This isn't a binary contest where one theory must replace the other. Solar forcing is already included in mainstream attribution work alongside volcanic forcing, aerosols and greenhouse gases. The question has always been magnitude, not existence.

//Studies show a 0.92 correlation between GCR flux and global cloud cover…//

That figure comes from early ISCCP cloud datasets over a limited period. Later work raised calibration issues with those satellite records, and the strength of that correlation weakened once those were addressed. Even Svensmark's own report notes long-term cloud dataset reliability problems. A short-window correlation during part of a solar cycle doesn't establish multi-decadal climate control.

//Over the solar cycle, energy entering Earth's system is 5-7 times greater than from solar irradiance alone…//

Yes, the solar cycle signal in ocean heat content appears larger than TSI alone would imply. That's interesting. But an 11-year oscillation is not the same thing as a sustained century-scale driver. The existence of a cycle does not automatically establish a secular trend.

//This mechanism explains not just 20th-century warming…//

Timing is the sticking point. Since the 1970s there has not been a sustained upward trend in solar activity, nor a sustained downward trend in cosmic ray flux that mirrors the steady rise in global temperature. If GCR modulation were the dominant modern driver, you would expect that alignment to be visible in the data.

//Svensmark's approach is preferable…//

Preference isn't the metric.

Attribution studies test forcings separately. When models are run with natural forcings only (solar + volcanic), they do not reproduce the late-20th-century warming trend. When greenhouse gases are included, the models track the observed rise much more closely. That pattern has been reproduced across multiple modelling groups.

The Sun clearly influences climate. That isn't disputed.

The narrower question is whether solar-modulated cosmic rays explain the magnitude and timing of recent warming better than greenhouse forcing. At present, the broader peer-reviewed literature does not support that conclusion.

Back to you...

"This isn't a binary contest where one theory must replace the other. "

There can only be one dominant theory.

BTW, can't help but notice that you haven't offered the slightest evidence for your myriad assertions.

"Thanks for the copy-and-paste, mhaze."

Well I used quotes where appropriate.

Climate attribution isn't a Highlander episode, mhaze.

//There can only be one dominant theory.//

Multiple forcings operate simultaneously. Solar variability, volcanic aerosols, internal variability and greenhouse gases all contribute. The question is which forcings explain the magnitude and timing of the recent trend.

//BTW, can't help but notice that you haven't offered the slightest evidence for your myriad assertions.//

1. Solar activity has not shown a sustained upward trend since the 1970s.

See IPCC AR6 WG1, Chapter 2 (solar forcing section). Satellite measurements of total solar irradiance since 1978 show cyclical variation but no long-term upward trend:
http://www.ipcc.ch/report/ar6/wg1/chapter/chapter-2

NASA – Solar Irradiance Data (TSI Composite Records):
http://lasp.colorado.edu/lisird/data

2. Cosmic ray flux has not shown a sustained downward trend over that same period.

Neutron monitor records (e.g. Climax, Oulu datasets) show the 11-year cycle clearly:
http://cosmicrays.oulu.fi

See Usoskin et al. (2017) for cosmic ray reconstructions and instrumental-era trends:
http://link.springer.com/article/10.1007/s41116-017-0006-9

3. Climate model runs using only natural forcings (solar + volcanic) do not reproduce the late-20th-century warming trend.

Hegerl et al. (2007), IPCC AR5 Chapter 10, and IPCC AR6 WG1 Chapter 3 present detection-and-attribution analyses showing that simulations including only natural forcings (solar + volcanic) fail to reproduce observed post-1970 warming, whereas including greenhouse gases does.
http://archive.ipcc.ch/publications_and_data/ar4/wg1/en/faq-9-2.html

Additional support from IPCC AR5 detection & attribution chapter:
http://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter10_FINAL.pdf

Those are not rhetorical claims. They're published attribution findings.

So, where's the evidence for your claims?

http://i.giphy.com/1Zbeweu52ZaQE.webp

"When scientists test this properly, they don't just eyeball graphs. They run simulations with different drivers switched on and off. If you exclude greenhouse gases, the late-century warming largely disappears in those simulations. Put them back in, and the models produce the upward trend we actually observed."

Just another, YET another, one of assertions JD makes that he hopes to never have to provide evidence for. As as expect, he hasn't.

You need to show us where this has happened. More importantly, you need to show that the simulations have been correctly calibrated by showing that they are able to recreate past temperature changes and correctly predict future changes.

mhaze,

You've now said twice that I "haven't provided evidence." That's simply not accurate.

I linked sources that explicitly show the "natural forcings only" vs "natural + anthropogenic" comparison you asked for:

- IPCC AR4 FAQ 9.2: http://archive.ipcc.ch/publications_and_data/ar4/wg1/en/faq-9-2.html
- IPCC AR5 WG1 Chapter 10 (Detection & Attribution): http://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter10_FINAL.pdf

Both assess the same basic point: simulations using only natural forcings (solar + volcanic) do not reproduce the late-20th-century warming trend, including anthropogenic forcing does.

If you dispute that finding, say so and explain why. But repeating "no evidence" after citations have been provided isn't engagement.

You also shifted the standard to "show they're correctly calibrated" and "predict future changes." Hindcasting historical temperature evolution using known forcings is exactly what detection-and-attribution work tests, and that's what those chapters are assessing.

If you reject this category of evidence (assessment of the attribution literature), then spell out what category you would accept. Otherwise we're not talking about the same thing.

Still waiting on your evidence too, by the way. I take it we're not going to get it.

"You also shifted the standard to "show they're correctly calibrated" and "predict future changes." "

No. That was part of my original point. I guess you (ahem...) conveniently missed that. There's not much point in relying on this or that model to forecast the future if it can't hindcast the past.

"Still waiting on your evidence too"

Well go back and read all the stuff I posted and the links regards Svensmark. I guess you (ahem...) conveniently missed that.

Whether it was original or added later isn't the issue, mhaze.

//That was part of my original point.//

The issue is whether attribution studies test hindcasting. They do. That's exactly what the chapters I linked assess.

//There's not much point relying on this or that model to forecast the future if it can't hindcast the past.//

Agreed in principle.

That's why detection-and-attribution work compares model runs using historical forcings against observed 20th-century temperature evolution. The sources I linked show that simulations using only natural forcings do not reproduce the late-20th-century warming trend, whereas including anthropogenic forcing does.

//Well go back and read all the stuff I posted and the links regards Svensmark.//

I've read them.

They describe a mechanism. They do not demonstrate that natural forcings alone reproduce the observed late-20th-century warming. That's the specific claim under discussion.

I guess you (ahem...) conveniently missed that.

"The sources I linked show that simulations using only natural forcings do not reproduce the late-20th-century warming trend"

Again, referencing a model that hasn't been shown to correctly hindcast climate is useless.

mhaze,

The hindcast comparison you asked for is exactly what detection-and-attribution studies present.

//referencing a model that hasn't been shown to correctly hindcast climate is useless.//

For example:

IPCC AR5 WG1 Chapter 10 compares model simulations against the observed 20th-century temperature record using known historical forcings (see Figure 10.1):

http://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter10_FINAL.pdf

More recently, the same comparison appears in IPCC AR6 (Working Group I).

Those figures compare:

- observed global temperature
- simulations using natural forcings only (solar + volcanic)
- simulations including anthropogenic forcings

The result is straightforward.

Simulations using natural forcings alone do not reproduce the late-20th-century warming trend.

When greenhouse gas forcing is included, the models reproduce the observed temperature evolution much more closely.

That comparison is the hindcast test.

You asked for evidence that model simulations are evaluated by their ability to reproduce past climate behaviour. That is exactly what these attribution studies do.

Your links regarding Svensmark describe a proposed mechanism for solar-cosmic-ray influence on clouds. They do not demonstrate that natural forcings alone reproduce the observed late-20th-century warming trend.

That is the specific claim under discussion.

If you believe natural forcings alone reproduce the modern warming signal, point to the attribution study demonstrating that.

Otherwise the evidence remains as described above.