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, ...
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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 ...
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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 ...
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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 ...
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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 ...
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16
votes
Accepted
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 ...
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12
votes
Is this scientific explanation of The Bible flood accurate?
Fishing through the links mentioned over at Christianity SE, I netted this scientific paper about freshwater and marine fish: Why are there so few fish in the sea?. Apparently the bulk (96%) of marine ...
- 1,207
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 ...
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10
votes
Accepted
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 ...
- 6,878
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 ...
- 17.6k
9
votes
Accepted
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 ...
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8
votes
Accepted
Current consensus on the Messinian Salinity Crisis
The present consensus is that the Messinian salinity crisis (MSC) took place in 5 stages:
0) Mediterranean restriction from the ocean; 1) Primary gypsum precipitation (starting 5.97 million years ...
- 1,723
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 ...
- 23.1k
8
votes
Accepted
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 ...
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7
votes
Why is the ocean paleotemperature trend downwards?
I recommend you read the original paper Lear et al. (2000). In it they explain that the results are controlled by processes in polar regions and likely associated with the polar surface temperature. ...
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7
votes
Accepted
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 ...
- 5,338
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 ...
- 17.6k
7
votes
3 Billion years ago, the earth is 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 ...
- 23.1k
7
votes
Accepted
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 ...
- 23.1k
7
votes
Accepted
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 ...
- 215
7
votes
Could the Paleocene–Eocene thermal maximum have been caused by intelligent life forms?
The answer by @Gimelist is a good list of hints we would see, although not all of them are equally convincing or strong, we would expect to see at least some of the signs.
The problem with any ...
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 ...
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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 ...
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6
votes
Accepted
Did the surfaces of the oceans freeze over entirely during the snowball Earth periods?
By looking at the recent literature on the question, I see neither a consensus or a definitive answer on the extent of the snowball earth.
Since the Neoproterozoic Snowball Earth event is more recent,...
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6
votes
Accepted
What's a frost-gley?
A frost-gley is a waterlogged permafrost soil. IOW, a gleysol that has undergone cryoturbation.
- 1,207
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 ...
- 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 ...
- 17.6k
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 ...
- 17.6k
5
votes
How has and how does the lithosphere affect climate change?
The timing of events in the lithosphere is not necesarily as large as tens to hundreds of millions of years (10s-100s My), and much shorter time scales also apply.
Few examples, from short to long ...
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5
votes
Accepted
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 ...
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