Questions tagged [paleoclimatology]
Paleoclimatology concerns climate and climate variability before the onset of instrumented measurements.
90
questions
5
votes
2
answers
126
views
Why was the ice age more severe in North America than in Eurasia?
I've been looking at reconstructions of the extent of ice at the last glacial maximum, while each map differs slightly (two shown below), most show a massive North American ice sheet, extending as far ...
11
votes
3
answers
3k
views
How were the sea levels around western Europe during the Medieval Warm Period?
The Medieval Warm Period (MWP) or Medieval Climatic Anomaly was a time from about 950 to 1250 when climate was warmer than in the timespans immediately before and after.
My question is if this ...
1
vote
2
answers
231
views
Have we looked for human-like signals in the geological record?
This is somewhat of a follow up to some interesting discussion here about using synthetic radioisotopes to define the start of the anthropocene. It is also sort of related to a question asked here, ...
3
votes
1
answer
104
views
Verification statistic for ice core temperature reconstructions
1 Do ice core temperature reconstruction studies have a calibration step, or is the relationship between Oxygen-18 and mean global temperature considered linear enough that this is not required?
2 ...
7
votes
1
answer
1k
views
Underground temperature record
Max/min Thermometer readings from a weather station with Stevenson screen are subject to noise from many sources and represent the max/ min at that one point in space.
It's well known that underground ...
3
votes
1
answer
44
views
Reconstructing lake level from organic and magnetic sediment data
I would like to understand why any of the following conditions in a layer of a lacustrine sediment core appear to imply that the lake level was low at the relevant time:
low C/N ratio
low δ13C
low ...
13
votes
2
answers
332
views
How did CO₂ originate on Earth before there was life?
To start life there has to be $\ce{CO2}$.
$\ce{Solar energy + 6CO2 + 6H2O -> C6H12O6 (sugars) + 6O2}$
$C_6H_{12}O_{6} + O_2 \longrightarrow H_2O + {CO}_2 + \text{Energy}$
So to start this cycle, ...
7
votes
1
answer
70
views
Why aren't diatoms' shells used as a temperature proxy, but foraminifera shells are?
Changes in oceanic oxygen isotope ratios (18O to 16O) are reflected in the shells of ancient foraminifera.
However, I have not read of diatom shells being used, despite the fact that they were (and ...
17
votes
5
answers
3k
views
Could the Paleocene–Eocene thermal maximum have been caused by intelligent life forms?
I was intrigued to learn recently of the Paleocene–Eocene thermal maximum from this blog of John Baez. For those who haven't seen, it's the sharp spike labelled "PETM" in this graph (from ...
12
votes
3
answers
7k
views
How were we able to measure carbon dioxide levels in earlier climates?
It is said that carbon dioxide levels were much higher during the Cretaceous and Eocene periods: which proxies are used to determine paleo-pCO2?
5
votes
0
answers
330
views
how old are the gulf stream and the NAC?
After reading about the NAC (North Atlantic Current) weakening in the news, we got to wondering about its history and that of the gulf stream. Specifically, how and when did they start? Were there ...
1
vote
1
answer
170
views
Will a new glacial age take place on Earth or Holocene will become a new climatic epoch?
Pleistocene shows a switch between glacial and interglacial ages.
However, humanity is burning fossil fuels and increasing atmosphere's $\ce{CO2}$ content.
Should we expect a new glacial age after ...
3
votes
1
answer
71
views
Does deforestation increase global temperatures or just local temperatures?
Did human-caused deforestation impacted climate and rainfall patterns in the past?
I'm asking this because I don't know much about the impact of forest cover loss and evapotranspiration on global ...
5
votes
0
answers
124
views
Biomes that existed during the Paleocene-Eocene Thermal Max (PETM)
I understand that you could fill multiple books with descriptions of the PETM and the mechanisms that incited the event. I have always wondered what regions of the world were covered in what types of ...
17
votes
2
answers
4k
views
How accurate are climate proxies in giving us a clear picture of global average temperatures throughout Earth history?
Since reliable modern records of climate only began in the 1880s, proxies provide a means for scientists to determine climatic patterns before record-keeping began, though it appears that the the ...
1
vote
0
answers
35
views
From ice core analysis to temperature curves
In ice cores a lot of data are measured and analyzed and can be plotted versus depth, for example
age of layers
thickness of layers
concentration of spurious gases
concentration of solids
delta ...
23
votes
2
answers
2k
views
What was the Amazon like during Green Sahara?
It is said that the Amazon rainforest receives up to half of its nutrients via mineral dust from the Sahara desert. But a few thousand years ago, the Sahara desert was much more fertile, having a ...
1
vote
1
answer
106
views
Were Carboniferous plants more efficient sequestering $\ce{CO2}$ than present plants?
The Carboniferous was a period where CO2 levels fell drastically.
Source: Geologic history of seawater: A MAGic approach to carbon chemistry and ocean ventilation
I think the main reasons are ...
7
votes
1
answer
191
views
Why is it that "With higher CO2, the dry gets drier and the wet gets wetter"?
The Phys.org article CO2 dip may have helped dinosaurs walk from South America to Greenland quotes Dennis Kent, "adjunct research scientist at Columbia University's Lamont-Doherty Earth ...
2
votes
1
answer
250
views
How many extreme shifts in climate has Earth gone through in its existence?
As the Earth formed, it went through cycles of essentially hotter and colder periods. Extremely volcanic times and ice ages, in feedback loops contributing to one another. CO2 swinging from high to ...
9
votes
6
answers
579
views
Any historical examples of destructive climate warming?
Summation: Local cooling climate changes, since the last ice age seem relatively common and all seem to cause significant harm to human population. But I can't find instances of the reverse, warming ...
1
vote
1
answer
126
views
How much of the Earth's surface was covered with water during the Mesozoic?
When the Earth was at its warmest, and there were no ice caps at all, not even during the winter, and thermal expansion meant a certain amount of water took up more space, what ratio of Earth's ...
4
votes
1
answer
81
views
Frost in trees in the middle of summer (of 536)
It was so cold that frost formed inside trees in the middle of summer.
Traces of this have been found in Russia, among other places. It is very rare for trees to freeze internally during the summer.
...
41
votes
2
answers
9k
views
How it's possible to measure temperature 2000 years ago with such precision?
I saw this graph about the global temperature, it goes back for 2000 years.
How is it possible to measure temperature 2000 years back with such a precision of like ~0.1 C?
The image from Reddit post I ...
8
votes
1
answer
624
views
Release mechanism for methane clathrate at the PETM
The Paleocene-Eocene Thermal Maximum (PETM) is a well-studied warming event near the Paleocene-Eocene boundary.
It is characterized by its extreme warming rate: from onset to recovery the event lasted ...
17
votes
3
answers
4k
views
Is there any evidence for higher air pressures in the geological past?
I was curious about how the Earth's overall air pressure has varied over time, and tried to take a look around the internet. However, Google pops up a lot of sites with questionable science proposing ...
10
votes
3
answers
441
views
Did climate cool down when underground hydrocarbons stocks formed?
As far as I understand, the dominant theory of modern climate change says that recent warming is mainly caused by the massive burning of hydrocarbons that used to be stored in solid form mostly ...
3
votes
1
answer
99
views
Earth History Book
I'm a PhD student studying the (current) climate of the Earth. I'm also quite interested in the history of planet Earth, although I have little academic background in that area. Is there a good ...
3
votes
1
answer
83
views
In the 800 kyr $\ce{CO_2}$ record, how detectable would a short-term peak be?
It is stated in https://cdiac.ess-dive.lbl.gov/trends/co2/ice_core_co2.html that the temporal uncertainty for the glacier $\small\mathsf{CO_2}$ records is less than $\small\mathsf{5~\%}$ at any given ...
11
votes
2
answers
267
views
Would a volcanic winter trigger an oceanic "spring"?
There is large amounts of observations supporting the effects of volcanic eruptions on climate: A long term subtle warming effect due to $\small\mathsf{CO_2}$ and a short term, but more intense ...
5
votes
2
answers
259
views
At least by theoretical biology - could there be, or should there have been, or was a "southern Taiga" on earth?
All data I have ever encountered about the Taiga "pole surrounding", vast, cold forests comprised mainly of Pinophyta trees, was about the ...
2
votes
2
answers
220
views
Why rely on climate models as opposed to paleoclimate data?
Something I hear often from climate scientists, and indeed even politicians, is that we "don't understand climate change very well". And, I'm sure this is true since the climate is a complex adaptive ...
0
votes
0
answers
25
views
Can any natural process explain this rate of CO2 increase? [duplicate]
Can any natural process explain this rate of CO2 increase?
[![1000 years of CO2][1]][1]
[1]: https://i.stack.imgur.com/MO0mK.png
The prior similar question used different data as its basis.
This ...
0
votes
0
answers
71
views
Does anyone have any data indicating a faster rate of CO2 increase?
Pieter Tans 2019-10-07(lead scientist of NOAA's Global Greenhouse Gas Reference Network):
Based on the best historical data that we have available CO2 is probably increasing at a rate at of least ...
0
votes
1
answer
212
views
Is there any natural phenomenon that can account for the 100 fold faster CO2 rate increase?
"Based on the best historical data that we have available CO2 is probably increasing at a rate at of least 100 times faster than at any time in the last 800,000 years." Pieter Tans lead scientist of ...
3
votes
1
answer
211
views
If today's Earth becomes warmer, how will it compare to the Earth of the Cretaceous period?
Most pessimistic scenarios about climate change predicts a global rise of temperature of several Celsius degrees over the course of the 21st century if no action is taken. While such a shift in ...
8
votes
1
answer
155
views
Is there conclusive evidence to refute an earlier oxygenation of the Earth's atmosphere?
The Great Oxygenation Event (sometimes called the Great Oxidation Event (GOE), as in the journal Nature) occurred around 2.2 to 2.45 billion years ago (Frei et al. 2009). However, in the article A ...
16
votes
2
answers
387
views
Did the impact event that caused the Chicxulub-Crater definitively and single-handedly cause the Cretaceous-Paleogene extinction?
Opinions abound on the web. What is the state of the current science regarding this theory and what is the best evidence? Is the theory gaining or losing traction? If it's losing what's the best of ...
4
votes
1
answer
417
views
3 Billion years ago, the earth is covered with Carbon Dioxide. Where did it go?
Oxygen gas began to appear on the earth surface about 2 billion years ago by photosynthesis. Carbon Dioxide was converted into carbohydrates in the process. Where did these carbohydrates go?
If they ...
19
votes
1
answer
1k
views
What was the ocean circulation like during the time of Pangaea?
So Enderton and Marshall (2009) wrote an interesting paper on the ocean circulation of various aquaplanets covered with certain terrain: e.g. an aquaplanet with a small ridge of land that ranged from ...
1
vote
0
answers
24
views
How do you interpret Oxygen Isotope changes?
In a paper I am reading, the authors note "large (5-7%) negative shifts in the oxygen isotopic composition of geologic proxy materials" (Davis 2008, pg. 102) in several regional basins. This is then ...
10
votes
1
answer
439
views
What makes a nuclear winter so extreme and destructive?
This may be a sort of, pertinent to the times, and disturbing question, inspired by the difficulties surrounding North Korea and the situation with it and nuclear weapons.
I've heard of this idea of "...
6
votes
1
answer
318
views
Geological evidence about climate change: has there ever been a period with a rate of climate change as great as it is today?
Most statistics about climate change are based on climate data over the last 150 year (as long as records have been kept). This seems irrelevant in terms of the geological time scale of temperature ...
4
votes
2
answers
5k
views
What was the density and composition of Earth's atmosphere during the Cretaceous warmest period?
There was time during the age of dinosaurs when the polar regions were ice free. The earth was obviously much warmer but a run-away greenhouse effect did not occur.
This was most likely because the ...
5
votes
2
answers
2k
views
Why did the carboniferous period have so much atmospheric oxygen?
Even if all the carbon dioxide (which makes up less than 1% of the atmosphere) in the air were sequestered by plants, would the atmosphere not remain about 21% oxygen? Why did the carboniferous period ...
4
votes
0
answers
198
views
Did the Azolla Event 49 Million Years Ago Result in an Extinction Event?
55 million years ago, the world was literally a jungle. With such high temperatures, rainfall and humidity, life could proliferate. But 49 million years ago, something drastic happened: The Azolla ...
10
votes
1
answer
585
views
How was the Marinoan Glaciation triggered?
The Marinoan Glaciation (a.k.a. Elatina Glaciation) was a glaciation that is thought to have occurred towards the end of the aptly-named Cryogenian period at ca. 650Ma. It is particularly known as one ...
19
votes
3
answers
938
views
How do we know that we are NOT in an "Ice Age?"
Historically, the earth has had five "Ice Ages" Each of them lasted millions, tens of millions, or hundreds of millions of years.
The last ice age reportedly ended perhaps 10,000 years ago. That ...
4
votes
1
answer
276
views
What caused the Carbon Dioxide Variations observed in the 800,000-year polar ice record?
I have seen several graphs showing the prehistoric temperatures and CO2 concentrations derived from ice-core data. My understanding is that CO2 and temperature correlate. I assume that Milankovich ...
4
votes
1
answer
579
views
What are the ranges of natural (or pre-industrial era) levels of CO2 in the atmosphere in ppm and tons?
Are the levels of natural (before the industrial revolution) levels of CO2 and ppm known? Also as a related question, should the "natural" levels be considered before the industrial revolution or ...