Questions tagged [paleoclimatology]

Paleoclimatology concerns climate and climate variability before the onset of instrumented measurements.

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Is the atmospheric composition still changing naturally?

Earth's atmosphere has gone through "dramatic" composition changes over millions of years. A well-known example is the Great Oxidation Event. Currently the atmosphere is 78% nitrogen, 21% ...
luchonacho's user avatar
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Cryogenian Earth and biodiversity

After the glaciations of the Cryogenian, Earth underwent a period of intense biodiversification which ultimately saw the emergence of the first animals of the succeeding Edicaran. What was it about ...
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Effect of eccentricity and axial precession on glaciation/deglaciation

Having learned about the Milankovitch cycles, I've found two entirely separate explanations from different sources on how the combination of precession and eccentricity changes affect glaciation vs ...
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Why is it that the Holocene's temperature is much more stable than the Pleistocene?

I'm currently in university for environmental science, and in a lecture on paleoclimate our professor showed some graphs of climate in the Holocene and Pleistocene periods (included below), then ...
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How could oxygen levels have ever been higher if there is so little carbon dioxide present?

Assumptions: Essentially all oxygen that's ever been present in the atmosphere originated from oxygenic photosynthesis. The production of an oxygen molecule during photosynthesis leads to the ...
Alessandro Power's user avatar
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Ocean oscillations with long time periods

I heard that some ocean oscillations act on a time scale of a millennium. Is this true, or at least argued by some oceanographers? If so, what are they and what causes them? If not, what are the ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
Victor1995's user avatar
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
Kurt Hikes's user avatar
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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. ...
Keith McClary's user avatar
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
polcott's user avatar
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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 ...
polcott's user avatar
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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 ...
Tanishq Kumar's user avatar
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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 ...
Jef Grailet's user avatar
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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 ...
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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 ...
Thomas's user avatar
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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 ...
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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 ...
JohnWDailey's user avatar
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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 ...
Jonathan L.'s user avatar
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Why do climate experts from the UN/IPCC rarely mention Grand Solar Minimum?

I've read many papers about Grand Solar Minimums and Glassberg Minimums, known to science for a very long time, and studied and monitored with many public funds. History shows solar activity is the ...
daniel brastaviceanu's user avatar
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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 ...
Pablo's user avatar
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What were CO2 levels in Carboniferous?

What were CO2 levels in early and late Carboniferous, an what were mean levels? Who are the sources for these figures?
Richard Lawson's user avatar
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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 ...
acypher's user avatar
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How Hot was the Oligocene?

When studying the paleoenvironment of the Oligocene epoch, a period in Earth's history spanning from 34 to 23 million years ago, I had a really hard time understanding what the climate was like in ...
JohnWDailey's user avatar
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322 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 ...
cr0's user avatar
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13 votes
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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, ...
Marcel Plan B's user avatar
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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?

I understand why foram shells contain more $^{18}\text{O}$ when there are ice sheets present, since $^{16}\text{O}$ evaporates more readily and gets trapped in the ice, increasing the relative ...
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Does general relativity influence climate (vs Newtonian mechanics)

That may sounds like a silly question but here it is. One of the early great successes of general relativity was to explain the discrepancy between the prehilion advance of Mercury predicted by ...
TT Farreo's user avatar
11 votes
2 answers
275 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 ...
Camilo Rada's user avatar
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For how long have the great karst springs of the Aachtal been active?

Aachtal, along with Lonetal, is a valley in the Swabian Jura, Germany, and the site of many famous archaeological sites of the upper Pleistocene. It also hosts a series of very large karst springs (...
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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 ...
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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 ...
0tyranny0poverty's user avatar
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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 "...
The_Sympathizer's user avatar
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Is there a reconstruction of paleoclimate sea level air pressure?

In paleoclimateology graphs of both temperature and atmospheric composition versus time are common. Where can I find a reconstruction of sea surface pressure versus time? I have found one paper that ...
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