What causes ice age climate change11.06.2021
What Triggers Ice Ages?
Sep 01, · What causes an ice age and glacial-interglacial cycles? Many factors contribute to climate variations, including changes in ocean and atmosphere circulation patterns, varying concentrations of atmospheric carbon dioxide, and even volcanic eruptions. Sep 01, · Ice ages are driven by a complex, interconnected set of factors, involving Earth's position in the solar system and more local influences, like carbon dioxide levels.
An ice age is a long period of reduction in the temperature of the Earth 's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and greenhouse periodsduring which there are no glaciers on the planet. Earth is currently in the Quaternary glaciationknown in popular terminology as the Ice Age.
In the terminology of glaciologyice age implies the presence of extensive ice sheets in both northern and southern hemispheres. The amount of heat-trapping gases emitted into Earth's oceans and atmosphere is predicted to prevent the next glacial period, which otherwise would begin in around 50, years, and likely more glacial cycles.
InPierre Martel —an engineer and geographer living in Genevavisited the valley of Chamonix in the Alps of Savoy. He reported that the inhabitants of that valley attributed the dispersal of erratic boulders to the glaciers, saying that they had once extended much farther.
In the carpenter and chamois hunter Jean-Pierre Perraudin — explained erratic boulders in the Val de Bagnes in the Swiss canton of Valais as being due to glaciers previously extending further. When the Bavarian naturalist Ernst von Bibra — visited the Chilean Andes in —, the how to fix sunburn peeling attributed fossil moraines to the former action of glaciers.
Meanwhile, European scholars had begun to wonder what had caused the dispersal of erratic material. From the middle of the 18th century, some discussed ice as a means of transport. The Swedish mining expert Daniel Tilas — was, inthe first person to suggest drifting sea ice in order to explain the presence of erratic boulders in the Scandinavian and Baltic regions. He regarded glaciation as a regional phenomenon. Only a few years later, the Danish-Norwegian geologist Jens Esmark — argued for a sequence of worldwide ice ages.
In a paper published inEsmark proposed changes in climate as the cause of those glaciations. He attempted to show that they originated from changes in Earth's orbit. Esmark's discovery were later attributed to or appropriated by Theodor Kjerulf and Louis Agassiz.
During the following years, Esmark's ideas were discussed and taken over in parts by Swedish, Scottish and German scientists. Andersen In a paper published inBernhardi speculated about former polar ice caps reaching as far as the temperate zones of the globe. Inindependently of these debates, the Swiss civil engineer Ignaz Venetz — explained the dispersal of erratic boulders in the Alps, the nearby Jura Mountains, and the North German Plain as being due to huge glaciers.
When he read his paper before the Schweizerische Naturforschende Gesellschaftmost scientists remained sceptical. De Charpentier transformed Venetz's idea into a theory with a glaciation limited to the Alps.
His thoughts resembled Wahlenberg's theory. In fact, both men shared the same volcanistic, or in de Charpentier's case rather plutonistic assumptions, about the Earth's history. Inde Charpentier presented his paper before the Schweizerische Naturforschende Gesellschaft. He began to wonder where such masses of stone had come from. During the summer of he made some excursions to the Bavarian Alps. Schimper came to the conclusion that ice must have been the means of transport for the boulders in the alpine upland.
In the winter of to he held some lectures in Munich. Schimper, de Charpentier and possibly Venetz convinced Agassiz that there had been a time of glaciation. They mainly drew upon the preceding works of Venetz, de Charpentier and on their own fieldwork.
Agassiz appears to have been already familiar with Bernhardi's paper at that time. The audience was very critical and some opposed to the new theory because it contradicted the established opinions on climatic history. Most contemporary scientists thought that the Earth had been gradually cooling down since its birth as a molten globe. In order to persuade the skeptics, Agassiz embarked on geological fieldwork.
De Charpentier felt that Agassiz should have given him precedence as it was he who had introduced Agassiz to in-depth glacial research. It took several decades before the ice age theory was fully accepted by scientists. This happened on an international scale in the second half of the s, following the work of James Crollincluding the publication of Climate and Time, in Their Geological Relations inwhich provided a credible explanation for the causes of ice ages.
Geological evidence for ice ages comes in various forms, including rock scouring and scratching, glacial morainesdrumlinsvalley cutting, and the deposition of till or tillites and glacial erratics. Successive glaciations tend to distort and erase the geological evidence for earlier glaciations, making it difficult to how many calories in a bowl of tomato soup. Furthermore, this evidence was difficult to date exactly; early theories assumed that the glacials were short compared to the long interglacials.
The advent of sediment and ice cores revealed the true situation: glacials are long, interglacials short. It took some time for the current theory to be worked out. The chemical evidence mainly consists what is food lion phone number variations in the ratios of isotopes in fossils present in sediments and sedimentary rocks and ocean sediment cores.
For the most recent glacial periods, ice cores provide climate proxiesboth from the ice itself and from atmospheric samples provided by included bubbles of air. Because water containing lighter isotopes has a lower heat of evaporationits proportion decreases with warmer conditions. This evidence can be confounded, however, by other factors recorded by isotope ratios.
The paleontological evidence consists of changes in the geographical distribution of fossils. During a glacial period, cold-adapted organisms spread into lower latitudes, and organisms that prefer warmer conditions become extinct or retreat into lower latitudes.
This evidence is also difficult to interpret because it requires 1 sequences of sediments covering a long period of time, over a wide range of latitudes and which are easily correlated; 2 ancient organisms which survive for several million years without change and whose temperature preferences are easily diagnosed; and 3 the finding of the relevant fossils. Despite the difficulties, analysis of ice core and ocean sediment cores  has provided a credible record of glacials and interglacials over the past few million years.
These also confirm the linkage between ice ages and continental crust phenomena such as glacial moraines, drumlins, and glacial erratics. Hence the continental crust phenomena are accepted as good evidence of earlier ice ages when they are found in layers created much earlier than the time range for which ice cores and ocean sediment cores are available.
Outside these ages, the Earth seems to have been ice free even in high latitudes;   such periods are known as greenhouse periods. Rocks from the earliest well-established ice age, called the Huronianhave been dated to around 2. Several hundreds of kilometers of the Huronian Supergroup are exposed 10 to kilometers 6.
Marie to Sudbury, northeast of Lake Huron, with giant layers of now-lithified till beds, dropstonesvarvesoutwashand scoured basement rocks.
Correlative Huronian deposits have been found near Marquette, Michiganand correlation has been made with Paleoproterozoic glacial deposits from Western Australia. The Huronian ice age was caused by the elimination of atmospheric methanea greenhouse gasduring the Great Oxygenation Event. The next well-documented ice age, and probably the most severe of the last billion years, occurred from to million years ago the Cryogenian period and may have produced a Snowball Earth in which glacial ice sheets reached the equator,  possibly being ended by the accumulation of greenhouse gases such as CO 2 produced by volcanoes.
The Andean-Saharan occurred from to million years ago, during the Late Ordovician and what do kidney stones feel like when they pass Silurian period.
The evolution of land plants at the onset of the Devonian period caused a long term increase in planetary oxygen levels and reduction of CO 2 levels, which resulted in the late Paleozoic icehouse.
Its former name, the Karoo glaciation, was named after the glacial tills found in the Karoo region of South Africa.
There were extensive polar ice caps at intervals from to million years ago in South Africa during the Carboniferous and early Permian Periods. Correlatives are known from Argentina, also in the center of the ancient supercontinent Gondwanaland.
Since then, the world has seen cycles of glaciation with ice sheets advancing and retreating on 40, and ,year time scales called glacial periodsglacials or glacial advances, and interglacial periods, interglacials or glacial retreats.
The earth is currently in an interglacial, and the last glacial period ended about 10, years ago. All that remains of the continental ice sheets are the Greenland and Antarctic ice sheets and smaller glaciers such as on Baffin Island.
The definition of the Quaternary as beginning 2. The term Late Cenozoic Ice Age is used to include this early phase. The maximum extent of the ice is not maintained for the full interval. The scouring action of each glaciation tends to remove most of the evidence of prior ice what is 1000 pesos worth in us dollars almost completely, except in regions where the later sheet does not achieve full coverage. Within the current glaciation, more temperate and more severe periods have occurred.
The colder periods are called glacial what country is mt aconcagua inthe warmer periods interglacialssuch as the Eemian Stage. The glacial cycles of the late Paleozoic ice house are likely responsible for the deposition of cyclothems. Glacials are characterized by cooler and drier climates over most of the earth and large land and sea ice masses extending outward from the poles.
Mountain glaciers in otherwise unglaciated areas extend to lower elevations due to a lower snow line. Sea levels drop due to the removal of large volumes of water above sea level in the icecaps.
There is evidence that ocean circulation patterns are disrupted by glaciations. The glacials and interglacials coincide with changes in orbital forcing of climate due to Milankovitch cycleswhich are periodic changes in the Earth's orbit and the tilt of the Earth's rotational axis. The earth has been in an interglacial period known as the Holocene for around 11, years,  and an article in Nature in argues that it might be most analogous to a previous interglacial that lasted 28, years. Moreover, anthropogenic forcing from increased greenhouse gases is estimated to potentially outweigh the orbital forcing of the Milankovitch cycles for hundreds of thousand of years.
Each glacial period is subject to positive feedback which makes it more severe, and negative feedback which mitigates and in all cases so far eventually ends it. An important form of feedback is provided by the Earth's albedowhich is how much of the sun's energy is reflected rather than absorbed by the Earth. Ice and snow increase Earth's albedo, while forests reduce its albedo. When the air temperature decreases, ice and snow fields grow, and they reduce forest cover. This continues until competition with a negative feedback mechanism forces the system to an equilibrium.
InEwing and Donn  hypothesized that an ice-free Arctic Ocean leads to increased snowfall at high latitudes. When low-temperature ice covers the Arctic Ocean there is little evaporation or sublimation and the polar regions are quite dry in terms of precipitation, comparable to the amount found in mid-latitude deserts.
This low precipitation allows high-latitude snowfalls to melt during the summer. An ice-free Arctic Ocean absorbs solar radiation during the long summer days, and evaporates more water into the Arctic atmosphere.
With higher precipitation, portions of this snow may not melt during the summer and so glacial ice can form at lower altitudes and more southerly latitudes, reducing the temperatures over land by increased albedo as noted above. Furthermore, under this hypothesis the lack of oceanic pack ice allows increased exchange of waters between the Arctic and the North Atlantic Oceans, warming the Arctic and cooling the North Atlantic. Current projected consequences of global warming include a largely ice-free Arctic Ocean within 5—20 years.
Such a reduction by reducing the effects of the Gulf Stream would have a cooling effect on northern Europe, which in turn would lead to increased low-latitude snow retention during the summer.
Ice sheets that form during glaciations erode the land beneath them. This can reduce the land area above sea level and thus diminish the amount of space on which ice sheets can form. This mitigates the albedo feedback, as does the rise in sea level that accompanies the reduced area of ice sheets, since open ocean has a lower albedo than land.
Nov 06, · These large-scale climate shifts consist of colder ice ages followed by much warmer interglacial periods, characterized by melting ice sheets and higher sea levels. The causes of . Apr 19, · While scientists continue to research whether an extended solar minimum could have contributed to cooling the climate, there is little evidence that the Maunder Minimum sparked the Little Ice Age, or at least not entirely by itself (notably, the Little Ice Age began before the Maunder Minimum). Current theories on what caused the Little Ice Age consider that a variety of events could have contributed, with natural fluctuations in ocean circulation, changes in land use by humans and cooling. Instead of sweating, people around the world may soon be shivering as high temperatures hasten the coming of the next ice age. Currently, huge volumes of fresh water are being poured into the North Atlantic by melting glaciers, disrupting the conveyer belt of ocean currents such as the Gulf Stream, which is responsible for keeping the UK and Western Europe balmy.
Image of the Sun showing a solar prominence a large, bright feature extending outward from the Sun's surface. Through its lifetime, the Sun naturally goes through changes in energy output. Some of these occur over a regular year period of peak many sunspots and low activity fewer sunspots , which are quite predictable. But every so often, the Sun becomes quieter for longer periods of time, experiencing much fewer sunspots and giving off less energy. This is called a "Grand Solar Minimum," and the last time this happened, it coincided with a period called the "Little Ice Age" a period of extremely low solar activity from approximately AD to in the Northern Hemisphere, when a combination of cooling from volcanic aerosols and low solar activity produced lower surface temperatures.
Anomalous periods like a Grand Solar Minimum show that magnetic activity and energy output from the Sun can vary over decades, although the space-based observations of the last 35 years have seen little change from one cycle to the next in terms of total irradiance. Solar Cycle 24, which began in December and is likely to end in , was smaller in magnitude than the previous two cycles. On occasion, researchers have predicted that coming solar cycles may also exhibit extended periods of minimal activity.
The models for such predictions, however, are still not as robust as models for our weather and are not considered conclusive.
But if such a Grand Solar Minimum occurred, how big of an effect might it have? In terms of climate forcing — a factor that could push the climate in a particular direction — solar scientists estimate it would be about Thus, a new Grand Solar Minimum would only serve to offset a few years of warming caused by human activities.
What does this mean? The warming caused by the greenhouse gas emissions from the human burning of fossil fuels is six times greater than the possible decades-long cooling from a prolonged Grand Solar Minimum. Even if a Grand Solar Minimum were to last a century, global temperatures would continue to warm. The Sun powers life on Earth; it helps keep the planet warm enough for us to survive.
During each cycle, the Sun undergoes various changes in its activity and appearance. Levels of solar radiation go up or down, as does the amount of material the Sun ejects into space and the size and number of sunspots and solar flares. The current solar cycle, Solar Cycle 24, began in December and is less active than the previous two. Warming from increased levels of human-produced greenhouse gases is actually many times stronger than any effects due to recent variations in solar activity.
For more than 40 years, satellites have observed the Sun's energy output, which has gone up or down by less than 0. Since , the warming driven by greenhouse gases coming from the human burning of fossil fuels is over 50 times greater than the slight extra warming coming from the Sun itself over that same time interval.
As mentioned, the Sun is currently experiencing a lower level of sunspot activity. Some scientists speculate that this may be the beginning of a Grand Solar Minimum — a decades-to-centuries-long period of low solar activity — while others say there is insufficient evidence to support that position. During a grand minimum, solar magnetism diminishes, sunspots appear infrequently and less ultraviolet radiation reaches Earth. While scientists continue to research whether an extended solar minimum could have contributed to cooling the climate, there is little evidence that the Maunder Minimum sparked the Little Ice Age, or at least not entirely by itself notably, the Little Ice Age began before the Maunder Minimum.
Current theories on what caused the Little Ice Age consider that a variety of events could have contributed, with natural fluctuations in ocean circulation, changes in land use by humans and cooling from a less active sun also playing roles; overall, cooling caused by volcanic aerosols likely played the title role.
Several studies in recent years have looked at the effects that another Grand Solar Minimum might have on global surface temperatures. These studies have suggested that while a grand minimum might cool the planet as much as 0. There would be a small decline of energy reaching Earth; however, just three years of current carbon dioxide concentration growth would make up for it.
In addition, the Grand Solar Minimum would be modest and temporary, with global temperatures quickly rebounding once the event concluded. Moreover, even a prolonged Grand Solar Minimum or Maunder Minimum would only briefly and minimally offset human-caused warming. The above graph compares global surface temperature changes red line and the Sun's energy that Earth receives yellow line in watts per square meter since Eleven-year averages are used to reduce the year-to-year natural noise in the data, making the underlying trends more obvious.
Over the same period, global temperature has risen markedly. It is therefore extremely unlikely that the Sun has caused the observed global temperature warming trend over the past half-century.