But scientists appear to have little if any understanding of this magnetic field, or fields. — Metaphysician Undercover
At the bottom of the graph you see four purple blocks representing events that some geologists call ice ages. it doesn't really matter what we call these larger scale cold spells. The point is: we're in one. — Tate
The word "quaternary" refers to the idea that there were four ice ages in the past. We now call those glacial periods. — Tate
Do you have advice for how to make it clearer? — Tate
This graph shows the dramatic change that one little lifeform called cyanobacteria caused, almost resulting in the final mass extinction due to the loss of atmospheric CO2.
The whole globe was covered in ice. — Tate
The Snowball Earth hypothesis proposes that, during one or more of Earth's icehouse climates, the planet's surface became entirely or nearly entirely frozen. It is believed that this occurred sometime before 650 M.Y.A. (million years ago) during the Cryogenian period. Proponents of the hypothesis argue that it best explains sedimentary deposits that are generally believed to be of glacial origin at tropical palaeolatitudes and other enigmatic features in the geological record. Opponents of the hypothesis contest the implications of the geological evidence for global glaciation and the geophysical feasibility of an ice- or slush-covered ocean,[3][4] and they emphasize the difficulty of escaping an all-frozen condition. A number of unanswered questions remain, including whether Earth was a full snowball or a "slushball" with a thin equatorial band of open (or seasonally open) water.
The snowball-Earth episodes are proposed to have occurred before the sudden radiation of multicellular bioforms known as the Cambrian explosion.
This graph shows the dramatic change that one little lifeform called cyanobacteria caused, almost resulting in the final mass extinction due to the loss of atmospheric CO2. — Tate
oxygenation of the atmosphere about 2 billion years ago. — unenlightened
Well I put up links to help folks with terminology and timelines, and numbers of years ago are really useful for sorting things. — unenlightened
Informative as was your previous post. I thought you were a psychologist? Hopefully Tate you're getting "up to speed" and we can start discussing the climate crisis. — Benkei
I'm not sure what you're referring to. — Tate
The point was that radiant heat from the sun has the biggest influence over the earth's surface temperatures, and scientists seem to know very little about the sun's capacity to radiate heat. I suppose I'm off topic, and we need a different thread about the sun's influence on the earth's climate. — Metaphysician Undercover
In fact, we're in interglacial period. Which means, sooner or later, we're going to enter the ice age. But not yet. — L'éléphant
That is not happening: the ice caps are fast melting. The Artic one will be history soon, by 2040 or so. Then, in the absence of the moderating factor that the artic ice cap represents, summer temperatures in the northern hemisphere will most certainly shoot up.
Antarctica is a bigger piece but all models predict that summer ice there will be gone in a few centuries.
Tate's "ice age" (defined by the presence of ice caps) is ending. Because of us. -- Olivier5
From Ice Age, Interrupted article linkIn terms of the ebb and flow of the Earth’s climate over the course of its history, the next Ice Age is starting to look overdue. Periods between recent Ice Ages, or ‘interglacials’, average out to be around 11 thousand years, and it’s currently been 11, 600 since the last multi-millennial winter. Although it is almost impossible to predict exactly when the next Ice Age will occur (if it will at all), it is clear that a global freeze is not on the horizon; the amount of CO2 emitted by human activity and the enhanced greenhouse effect that results all but preclude it. But what if we weren’t around and CO2 was lower?
In a paper published in Nature Geoscience this week, new research proposes that the next Ice Age would have been kick-started sometime in the next thousand years, just round the corner in the context of the Earth’s lifespan, if CO2 was sufficiently low.
By looking at the onset of abrupt flip-flops in the temperature contrast between Greenland and Antarctica (extreme climate behaviour that would have only been possible if vast and expanding ice sheets were disrupting ocean circulation), the researchers believe they have been able to identify the fingerprint of an Ice Age activation, or the ‘glacial inception’.
By applying this fingerprinting method to an interglacial period with nearly identical solar radiation, or ‘insolation’, to our own - some 780 thousand years ago - the researchers have been able to determine that glacial inception would indeed be expected to occur sometime soon.
“The mystery of the Ice Ages, which represent the dominant mode of climate change over the past few million years, is that while we can identify the various ingredients that have contributed to them, it’s the arrangement of these ingredients, and how they march to the beat of subtle changes in seasonality, that we lack an understanding of,” says Dr Luke Skinner from the Department of Earth Sciences, who helped to conduct the research with Professor David Hodell and their colleague Professor Chronis Tzedakis from University College London.
Insolation, the seasonal and latitudinal distribution of solar radiation energy, changes over tens of thousands of years due to the variations in the Earth’s orbit around the sun. It has long been apparent that insolation changes have acted as a pace-maker for the Ice Ages. But, like a metronome paces music, it sets the beat of climate change but not its every movement. The changing concentrations of greenhouse gases, CO2 in particular, are evidently what determine when a shift in insolation will trigger climate change.
“From 8,000 years ago, as human civilization flourished, CO2 reversed its initial downward trend and drifted upwards, accelerating sharply with the industrial revolution,” says Skinner. “Although the contribution of human activities to the pre-industrial drift in CO2 remains debated, our work suggests that natural insolation will not be cancelling the impacts of man-made global warming.”
I'm sure you get the point. — L'éléphant
Tate's "ice age" (defined by the presence of ice caps) is ending. Because of us. -- Olivier5
poisoning the atmosphere with oxygen — unenlightened
It is the biggest influence. Easily overlooked, you're right. There's the grand solar minimum (solar minimum) that some say started two years ago and will cause cooling until around 2050? I don't know much about. — Tate
Rather, there have been wild fluctuations of climate through geological time far larger than can be accounted for by variations of insolation. The history of humanity has been one of unusual climate stability sufficiently long for the effects of milankovitch cycles to become noticeable. — unenlightened
You are losing track of the relative time scales here. The history of humanity is a point on the geological timescale. We could be living right smack in the middle of one of those "wild fluctuations of climate" that you mentioned and not notice it. — SophistiCat
But manmade global warming is likely to tip us out of the icehouse and into the hothouse which neither humans nor apes have ever experienced. — unenlightened
Get involved in philosophical discussions about knowledge, truth, language, consciousness, science, politics, religion, logic and mathematics, art, history, and lots more. No ads, no clutter, and very little agreement — just fascinating conversations.