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79 votes

Why do climate experts from the UN/IPCC rarely mention Grand Solar Minimum?

The IPCC do mentions solar minimums and maximums, as part of extremely careful treatment they do of the reconstructions and predictions for the changes in solar irradiance. The Assessment Report 5, ...
Camilo Rada's user avatar
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55 votes
Accepted

How it's possible to measure temperature 2000 years ago with such precision?

How it's possible to measure temperature 2000 years ago? Sans the technology used by Bill and Ted ("Bill and Ted's Excellent Adventure"), it obviously is not possible to directly measure ...
David Hammen's user avatar
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40 votes

Why do climate experts from the UN/IPCC rarely mention Grand Solar Minimum?

I think the main question has already been answered. But I would like to add to the fallacy that: History shows solar activity is the main driver of our climate, among other factors. The Sun is ...
Max M.'s user avatar
  • 401
28 votes

Was Judea as desertified 2000 years ago as it is now?

There has always been a strong north-south rainfall gradient from approximately the Golan Heights (high rainfall), through Judaea and southwards into the arid Sinai desert. We know that this gradient ...
Gordon Stanger's user avatar
22 votes

Could the Paleocene–Eocene thermal maximum have been caused by intelligent life forms?

tl;dr: No, we can't exclude that for sure. But we would expect to see some fossil records from such a civilization, which we don't. Yes, pretty much this. To elaborate, I would refer to your ...
Gimelist's user avatar
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16 votes
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How did CO₂ originate on Earth before there was life?

The answer is Volcanos. There might be other inorganic processes capable to produce $\text{CO}_2$, but on Earth, the main inorganic source of $\text{CO}_2$ are volcanoes. In some period of Earth's ...
Camilo Rada's user avatar
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11 votes

Was Judea as desertified 2000 years ago as it is now?

tldr: It was also dry back then, which is why the people living there were rebels and not the rich elite. I'd like to add a few points to Gordon's answer. First of all, Masada is on the western edge ...
Gimelist's user avatar
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10 votes

Does general relativity influence climate (vs Newtonian mechanics)

In short: No. Unless multi-million timescales are considered. The reason we keep teaching Newtonian mechanics, is because it is a VERY accurate approximation of a more general theory (general ...
Camilo Rada's user avatar
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10 votes
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Is there any evidence for higher air pressures in the geological past?

Yes, there is. But the data is still very sparse and errors are large. Past atmospherics pressures have been estimated by at least three different methods: Isotopic composition of fluid inclusions ...
Camilo Rada's user avatar
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10 votes
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Did climate cool down when underground hydrocarbons stocks formed?

Possibly One thing you have to understand is that natural carbon sequestration via the formation of fossil fuel is VERY slow, it can take millions of years to build up the coal we burn in a day. In ...
John's user avatar
  • 7,016
8 votes

Why did the carboniferous period have so much atmospheric oxygen?

The Carboniferous was when the growth of woody plants took off. Non-plant life had not yet evolved the ability to consume lignins, the key chemical components that makes woody plants "woody". Lignins ...
David Hammen's user avatar
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8 votes

3 Billion years ago, the earth was covered with Carbon Dioxide. Where did it go?

It went into: Limestone Mostly made out of calcium carbonate (CaCO3) Coal Oil and gas Living biomass Subducted into the mantle Occasionally coming back as diamonds Or as volcanic gas All ...
Gimelist's user avatar
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8 votes
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Underground temperature record

There are many underground temperature measurements. Monitoring of permafrost is one instance where underground temperature has been monitored for many years. In Europe there are many boreholes ...
Peter Jansson's user avatar
7 votes
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How Warm Was the Paleocene?

Redrawn after Zachos et al. 2001. This is a plot of the Cenozoic variations of $\delta\ce{^{18}O}_{Cibicidoides}$ according to Zachos et al. 2001 (this is a bit outdated now but the Paleocene is ...
plannapus's user avatar
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7 votes
Accepted

What are the ranges of natural (or pre-industrial era) levels of CO2 in the atmosphere in ppm and tons?

There is no such thing as a single "natural" level of $CO_2$: In Earth's history, there have been levels much higher and much lower than currently, and they are all natural. What we should consider ...
Camilo Rada's user avatar
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7 votes
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At least by theoretical biology - could there be, or should there have been, or was a "southern Taiga" on earth?

I'll define a boreal forest as a place that Has trees, i.e., long-lived woody plants that are capable of growing at least ten meters tall and that grow both upward by extending new branches and ...
David Hammen's user avatar
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7 votes
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Why is it that "With higher CO2, the dry gets drier and the wet gets wetter"?

To my best knowledge, the paper by Held & Soden (2006) is the first paper that discussed the concept of the rich get richer. They used the climate change experiments generated for the Fourth ...
ahmathelte's user avatar
7 votes

Could the Paleocene–Eocene thermal maximum have been caused by intelligent life forms?

(Deleted as I'm against it being used to train AI).
uUnwY's user avatar
  • 268
7 votes
Accepted

Why aren't diatoms' shells used as a temperature proxy, but foraminifera shells are?

Lacustrine diatoms are used extensively as reliable conventional proxies in Holocene (within the last 10,000 years) paleoclimate studies. According to this 2010 paper: (paleoclimate) Reconstructions ...
Knob Scratcher's user avatar
6 votes

Was Judea as desertified 2000 years ago as it is now?

Gordon Stanger covers the climate aspects well in his answer, but I thought I'd chime in with an answer to the "was it as much a desert as it is now?" While I'm not aware of any archaeological ...
kingledion's user avatar
  • 3,376
6 votes

What was the Amazon like during Green Sahara?

Here is a brand new (January 2021) study from Nature. It proposes that the Sahara has not been the main source of dust for the Amazon for the past 7,500 years of Holocene, but rather dust from North ...
Nick's user avatar
  • 61
6 votes
Accepted

Geological evidence about climate change: has there ever been a period with a rate of climate change as great as it is today?

Quick answer: yes. But please read the following comments and explanations: Most statistics about climate change are not based only in the 150 years of instrumental records. We have many good ...
Camilo Rada's user avatar
  • 17.7k
6 votes
Accepted

Why did the carboniferous period have so much atmospheric oxygen?

To complement @DavidHammen answer and address the point "where did so much oxygen come from?" I will elaborate on David's final remark The end result was a gradual increase in oxygen levels The ...
Camilo Rada's user avatar
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5 votes

What caused the Carbon Dioxide Variations observed in the 800,000-year polar ice record?

Six plus years after the fact, I find the accepted answer to be a bit insufficient. With that, but what specifically caused the CO2 to fluctuate? Notice in the two graphs how the temperature drop ...
David Hammen's user avatar
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5 votes
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Why the $\delta \, ^{18}\text{O}$ in foraminifera shells decrease with temperature even if the oceanic $\delta \, ^{18}\text{O}$ stay constant?

That is because the chemical reactivity of $^{18}\text{O}$ is slightly higher than that of $^{16}\text{O}$. For that reason, the biochemical reactions that produce calcium carbonate in foraminifera ...
Camilo Rada's user avatar
  • 17.7k
4 votes
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How were the sea levels around western Europe during the Medieval Warm Period?

In the global sense the sea level data are not entirely consistent, but then, there are always going to be apparent variations when you are comparing proxy data from different sources. As far as ...
Gordon Stanger's user avatar
4 votes

Is there any evidence for higher air pressures in the geological past?

All manner of isotopic analyses confirms that the chemical composition of the earth's atmosphere has fluctuated wildly in the past. Besides the Archean hypoxic atmospheres of 2.5 billion years ago, ...
Knob Scratcher's user avatar
4 votes
Accepted

How Hot was the Oligocene?

Short answer (this is essentially what the paragraph is saying): 55.5 to 33.9 million years ago ("mya" or "ma") the Earth cooled (Eocene period) 33.9 to 33.5 mya: temporary cooling minimum, glaciers ...
userLTK's user avatar
  • 5,897
4 votes
Accepted

Is there any natural phenomenon that can account for the 100 fold faster CO2 rate increase?

There are things that could do it, but they would be very noticeable. A whole string of thousands of the largest volcanic eruptions to ever occur on Earth. Volcanoes can briefly match human output, ...
John's user avatar
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