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Why natural cycles only play small role in rate of global warming

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Re: Why natural cycles only play small role in rate of global warming

#11

Post by snowwrestler »

taneq wrote: post #8
inflatableDodo wrote: post #6

Earlier quoted context omitted.

If you look to the paper the article is about - 'A limited role for unforced internal variability in 20th century warming.' - it does seem to demonstrate that natural cycles play small role and the way it is set up it doesn't have to look at all natural cycles to do that. >Using a two-box impulse response model, we demonstrate that multidecadal ocean variability was unlikely to be the driver of observed changes in gl…

It still seems ass-about to me. The study doesn't show that natural cycles don't do much, it shows that in our models the external forcing they added is sufficient to cause the observed results. We already know there's more going on than our models account for (consider the post-9/11 discovery of global dimming from airliner exhausts, as one example). There are probably a heap of effects pushing the measured temperat…

It's worth noting that the 9/11 U.S. insolation study showed a human-created mitigating factor, not a causal factor. That is, it showed that high-altitude contrails create clouds high enough to raise the average albedo and reflect solar energy that otherwise would reach the surface. This is, to some extent, "hiding" a portion of the true warming one would expect from the current mix of the atmosphere and solar activity.

That doesn't offer evidence either way for a hypothesis that there are natural processes yet undescribed that could surprise us with their contribution to warming. Discovering one new thing about a complex phenomenon doesn't make it more likely that another new thing is out there to be discovered. If anything, it makes it less likely, on the theory that there are a finite number of factors contributing to a result of given significance in a deterministic system--in this case, global average temperature trend.

And anyway, what we're really worried about is long-term warming, and this paper is not about that. It's about factors that contribute to temperature variance on shorter time scales during the known long-term warming. From the article:

> However, the relative influences of natural drivers of climate change – such as volcanic eruptions, ocean cycles, and the sun – on warmer and cooler phases superimposed on the long-term warming trend is still an area of active research.

There are two levels to the question of global warming. One is the overall, global question--are we making the surface of the Earth warmer by burning fossil fuels? This is a relatively simple question to answer, so simple that it was first proposed over a century ago, basically when thermodynamics was being invented. Very little contemporary research goes toward answering this question; it has basically been answered.

The other level is: can we predict the consequences of this warming at time scales and resolutions relevant to human society? This is an incredibly complex endeavor and where the bulk of contemporary time and resources are spent (including this paper).

Re: Why natural cycles only play small role in rate of global warming

#12

Post by apo »

The first graph ("External factors explain nearly all global temperature change") shows what appears to be temperature precisions of less than 0.1 degree C, yet reports no error bars.

How is it that a graph like this is even acceptable, given the importance of the conclusions? How does this study account for the inevitably poorer precision and accuracy of measurements made over 100 years ago? How are systematic errors (differences in measuring procedure, differences in time of day precision, etc.) accounted for?

A paper from Cowton/Way is available, but it appears to focus on filling in gaps from lack of data at the poles:

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/qj.22...

Where is the readily-accessible explanation for how the underlying dataset accounts for so many unknown factors?

Re: Why natural cycles only play small role in rate of global warming

#13

Post by Jill_the_Pill »

ocschwar wrote: post #4
Roark66 wrote: post #3

The headline of this post is bullshit. The author of the article doesn't prove "natural cycles" play small role. He claims that the data he analyses points to the conclusion one specific 60-70 year old cycle of oceanic origin has far less impact on climate than commonly accepted. He talks about one mechanism, there are plenty of other natural mechanisms that affect the climate in various ways. Quoting the article: >T…

There are other cycles, most of which are right now in a cooling phase, and yet we are warming. So those cycles (i.e. Milankovich cycles) can be written off already

Or, rather than written off, treated as mitigating factors.

Re: Why natural cycles only play small role in rate of global warming

#14

Post by microcolonel »

apo wrote: post #12

The first graph ("External factors explain nearly all global temperature change") shows what appears to be temperature precisions of less than 0.1 degree C, yet reports no error bars. How is it that a graph like this is even acceptable, given the importance of the conclusions? How does this study account for the inevitably poorer precision and accuracy of measurements made over 100 years ago? How are systematic error…

When there is effectively a religious commitment to the assertions you're making, why worry about justifying them?

Re: Why natural cycles only play small role in rate of global warming

#15

Post by lenticular »

GorgeRonde wrote: post #10
Bucephalus355 wrote: post #2

This was an interesting article and the author has strong data. I would want to know about the Younger Dryas [1] period though. This is a warming period about 12,000 years ago when some of the most devastating geological events we know of happen. This includes the outburst floods of glaciers holding back bodies of water larger than Lake Erie (Lake Agassiz [2] for example) and a temperature differential in Greenland o…

It was almost certainly caused by one or multiple comet fragment impacts. Sources: https://scholar.google.fr/scholar?as_ylo=2018&q=hiawatha+cra...

No, speaking as a former glaciologist, that's not likely to be true. The parent poster is correct. Younger Dryas featured multiple advances and retreats, which is inconsistent with an impact. Multiple impact over many centuries just isn't that statistically likely, and we would see better evidence of it.

Instead, the most probably cause is freshwater pulses coming out of the melting Laurentide ice sheet changing circulation in the Atlantic. This is actually quite well supported.

Younger Dryas was also confined to the parts of the northern hemisphere, mainly in higher latitudes. A large enough impact to significantly alter climate would see the resulting particulates globally mix in the atmosphere, resulting in more uniform cooling.

Instead, the fact that it was confined to parts of the northern hemisphere also supports the freshwater pulse hypothesis, since it is only a change in the transport of heat from the tropics to the pole, not a change in total heat.

The fact that freshwater pulses from the Laurentide ice sheet caused so much cooling is actually a concern with climate change. It's possible that it could happen again with melting of the Greenland Ice Sheet, at least a weakened version of it (the Laurentide Ice Sheet dwarfed the GIS).

Re: Why natural cycles only play small role in rate of global warming

#16

Post by jphenningsen »

apo wrote: post #12

The first graph ("External factors explain nearly all global temperature change") shows what appears to be temperature precisions of less than 0.1 degree C, yet reports no error bars. How is it that a graph like this is even acceptable, given the importance of the conclusions? How does this study account for the inevitably poorer precision and accuracy of measurements made over 100 years ago? How are systematic error…

Just from a first look, the caption of the figure references Figure 5 in Haustein et al 2019 [1]. You can see that this figure is way more detailed and includes a confidence interval. This article is clearly not a scientific publication but aimed at a broader audience. As for your other questions about the details of the methods used to gather and analyse this dataset, I am sure you can find plenty of information in the actual paper and references therein.

Generally speaking however let me comment that you will not be able to formulate a meaningful critique of the nitty gritty details you inquire about without the equivalent experience of at least a PhD in the specific subfield.

[1] https://sci-hub.tw/https://doi.org/10.1175/JCLI-D-18-0555.1

Re: Why natural cycles only play small role in rate of global warming

#17

Post by mikekij »

apo wrote: post #12

The first graph ("External factors explain nearly all global temperature change") shows what appears to be temperature precisions of less than 0.1 degree C, yet reports no error bars. How is it that a graph like this is even acceptable, given the importance of the conclusions? How does this study account for the inevitably poorer precision and accuracy of measurements made over 100 years ago? How are systematic error…

I'm so glad to see you bring this up. In my graduate physics training, I was taught to be extremely cautious about statistical significance, error propagation, and error bars. I remain skeptical of our conclusions about AGW, not because I have a political view on the subject, but because I'm skeptical that our temperature measurements from 120 years ago have a precision of less than 1 degree C.

But I (sincerely) assume that the climate scientists working in this space have compensated for this lack of precision in their conclusions. Right?

Re: Why natural cycles only play small role in rate of global warming

#18

Post by briantakita »

This article's claims fail the smell test. Ultimately we don't know what we don't know & simplistic overarching models are probably missing key components, many of which are non-linear. 200 years is a tiny window when it comes to cosmological time. The methodology of measurement & extrapolation of data also needs public scrutiny. Interpretations of geological events are ridden with conjecture to fit an overarching narrative.

Here's what we have evidence of. Earth receives the majority of it's energy from the Sun. The Sun has significant fluctuations. Earth is affected not only by infrared & visible EM, but also by higher frequencies of EM. Earth is also affected by magnetism from the Sun. Earth's Magnetosphere is affected by the Heliosphere. A weaker Magnetosphere means less protection from Cosmic Rays, Coronal Holes, CMEs, & other space weather. Cosmic Rays perturbs water, seeds clouds, induces volcanic eruptions & earthquakes. Volcanic ash & cloud cover increase albedo, which cools the earth.

The "year without a summer" in 1816 (~200 years ago), was caused by the Mt. Tambora eruption. The Carrington Event happened in 1859.

Re: Why natural cycles only play small role in rate of global warming

#19

Post by jolfdb »

jphenningsen wrote: post #16
apo wrote: post #12

The first graph ("External factors explain nearly all global temperature change") shows what appears to be temperature precisions of less than 0.1 degree C, yet reports no error bars. How is it that a graph like this is even acceptable, given the importance of the conclusions? How does this study account for the inevitably poorer precision and accuracy of measurements made over 100 years ago? How are systematic error…

Just from a first look, the caption of the figure references Figure 5 in Haustein et al 2019 [1]. You can see that this figure is way more detailed and includes a confidence interval. This article is clearly not a scientific publication but aimed at a broader audience. As for your other questions about the details of the methods used to gather and analyse this dataset, I am sure you can find plenty of information in…

"it's for a popular audience" is a bad justification for publishing misleading or wrong information that teaches people a wrong headed view of what a science is. It's not just poor quality, it's a actively harmful to culture and social progress. It's a supernormal stimulus, the journalism equivalent of replacing real foods by sugar and oil mixes -- it pushes people toward preferring wrong things over right things.

Re: Why natural cycles only play small role in rate of global warming

#20

Post by [deleted] »

microcolonel wrote: post #14
apo wrote: post #12

The first graph ("External factors explain nearly all global temperature change") shows what appears to be temperature precisions of less than 0.1 degree C, yet reports no error bars. How is it that a graph like this is even acceptable, given the importance of the conclusions? How does this study account for the inevitably poorer precision and accuracy of measurements made over 100 years ago? How are systematic error…

When there is effectively a religious commitment to the assertions you're making, why worry about justifying them?

[deleted]
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