[Alupis]

And yet nobody really knows for sure how quickly climates changed in the past, or how fast they're supposed to change, or if they always change at a similar rate.

On some level, what people advocate doing is creating climate change to benefit humans, which is kind of the antithesis of what climate science activists claim they want.

I'm confident we don't understand the earth and climate well enough to "engineer" it to our will.

I cannot imagine what a pole reversal would look like today. The truly scary thing is contemplating just how many things depend on, or assume polar north is where it is today.

Even more scary, there's absolutely nothing anyone can do about polar reversal, and absolutely nothing humans do that is provoking it. It's just a natural phenomenon, during which things will indeed become extremely unpleasant.

[dragonwriter]

> how fast they're supposed to change.

The idea that this is even a coherent question is Creationist, because it presupposes a purposeful design.

[Alupis]

Interesting take - it was not my intention to insert a philosophy here such as Creationism.

My point was if we're saying something is changing at an alarming rate - then the natural question would be what is a normal rate?

One of the problems with observational science is we cannot ever really know for sure.

[dragonwriter]

> My point was if we're saying something is changing at an alarming rate - then the natural question would be what is a normal rate

Danger can be alarming even if on a wide enough time window its not unusual (that the current warming is unusual on any timeline as narrow as, say, “the history of human civilization on Earth” is clear, though.)

[Alupis]

> the history of human civilization on Earth

We actually don't even know that much. Written records only go back so far, and the ability to measure say temperature in any relatively accurate way is a modern invention. Majority (or all?) dependable temperature data starts around 1900...

If it's alarming because within recent human history something is changing quickly - well fine, but that's not how this stuff is being offered.

Even so, the question remains - is it an actual problem? Has human activity created the change, accelerated change, or was the change inevitable (ie. caused by polar reversal)? These are difficult questions to answer absolutely.

Even if we could answer these questions confidently - should we do anything about it? Would our actions to "combat" climate change cause unknown side effects? Probably... how do we square those potentially negative impacts with the "good" changes we've created?

It's pretty complicated. Anyone offering absolutes or hysterics should be taken skeptically in my opinion.

[paisajerelicto]

Wikipedia has a pretty good summary of climate proxies (1). E.g., tree rings, coral, pollen, forams/ostracods/coccolithophores/radiolaria, varves/lake sediments, water isotopes, membrane lipids, etc. See also Wikipedia article re. temperature proxies, 'Paleothermometer'(2).

So, yes, we do have proxies for past climates and rates of change. Yes, there have been some pretty spectacular excursions in climate (e.g., the entry into the Younger Dryas happened within 50 years, and brought the climate of Nome, Alaska to San Francisco). However, I saw a research presentation that compared the rate of change in the Paleocene-Eocene Thermal Maximum (PETM) to Homo sapiens' injection of CO2 into the atmosphere, and the rate of our injection beat the PETM, and it may very well exceed any such injection in Earth's history (the latter is my speculation).

(1) Proxy (climate), https://en.wikipedia.org/wiki/Proxy_(climate) (2) Paleothermometer, https://en.wikipedia.org/wiki/Paleothermometer

[Alupis]

Tree rings tell us there were years where there was more or less rainfall relative to what that tree/forest normally sees - but it does not provide a measurement of how much water/rainfall there was. Different geographical regions experience different norms over time as well.

Same with temperature. We can infer there were hotter years, and colder years within those regions all throughout history. Being able to say the temperature averaged say 30*C was not possible until relatively recently.

It's all observational science, and we can't observe all of the factors unfortunately so we have to infer a great deal.

[seadan83]

Agree on absolutes and hysterics.. Though, if the data tells us very bad things are on the horizon, how can that not be discounted as hysterics?

> Majority (or all?) dependable temperature data starts around 1900...

I don't think this is quite true. We don't need a thermometer measurement to know historical temperature.

"After analyzing enough ice core slices, which may each represent anywhere from a week to a year of time, a researcher can look for patterns to track changes in the atmosphere's composition and temperature, and what activity on Earth shaped it... The ratio of "light" oxygen-16 to "heavy" oxygen-18 in a sample, for instance, reveals the global temperature when the ice formed; " [1]

[1] https://www.climate.gov/news-features/climate-tech/climate-c...

[aatharuv]

I think the question we need to ask is how fast climate can change and how much can climate change.

For which I'd say, at a rate and total amount of change low enough to be compatible with the survival of human civilization, not having mass deaths, and keeping ecosystems intact, even if changed.

Civilization developed during a time of relatively stable weather. Rapid instability can cause mass dieoffs which at the very least will cause havoc with our food supply -- think fish. Or what's happening with peach production in Georgia.

We need to stop the bleeding (by going carbon neutral), and in parallel think about how to mitigate the problems, and reverse the changes.

[seadan83]

"For example, bubbles of air in glacial ice trap tiny samples of Earth’s atmosphere, giving scientists a history of greenhouse gases that stretches back more than 800,000 years. The chemical make-up of the ice provides clues to the average global temperature." [1]

Is NASA incorrect about this?

This XKCD visualizes the historic rates of temperature change in a pretty compelling way: https://xkcd.com/1732/

> I cannot imagine what a pole reversal would look like today. The truly scary thing is contemplating just how many things depend on, or assume polar north is where it is today.

I would ask in response - do magnetic poles impact climate change? (I presume you are talking about the magnetic polar north & south).

According to NASA the magnetic poles have essentially no impact on climate change: "Some people have claimed that variations in Earth’s magnetic field are contributing to current global warming and can cause catastrophic climate change. However, the science doesn’t support that argument. In this blog, we’ll examine a number of proposed hypotheses regarding the effects of changes in Earth’s magnetic field on climate. We’ll also discuss physics-based reasons why changes in the magnetic field can’t impact climate." [2]

What other impacts do the magnetic poles have?

It is very interesting to me that the magnetic poles move by "34 miles (55 kilometers) per year" [2]. That is a pretty reasonably steady and fast rate of change. Seems like navigation equipment and anything else that relies on polar north should already be baking this in. After a decade, it's 340 miles of movement.

[1] https://earthobservatory.nasa.gov/features/GlobalWarming/pag...

[2] https://climate.nasa.gov/explore/ask-nasa-climate/3104/flip-...

[defrost]

> What other impacts do the magnetic poles have?

Animal migration | navigation and sheilding from cosmic gamma rays and high energy solar flux.

On that last point for humans an instantanous reversal is not the big issue, it would be the transition from one state to the next that could conceivably see long (ish) periods either unprotected from high energy cosmic rays and|or some areas enduring concentrated gamma rays focused in by changing magnetic field lines.

> Seems like navigation equipment and anything else that relies on polar north should already be baking this in.

Have been for a century at least (in a rough fashion), the World Magnetic Model (WMM) and the International Geomagnetic Reference Field (IGRF) date back to the 1960s or so and have their parameters updated on a five year epoch to provide a detailed fine resolution surface field model with local vecotors and rates of change.

https://www.ncei.noaa.gov/products/world-magnetic-model

https://www.ncei.noaa.gov/products/international-geomagnetic...