One of the most famous, there are four long ice ages, and its names are listed below:
Poyang Lake Ice Age137-10.5 million years ago.
105-65438+Dagu Ice Age 200,000 years ago.
Lushan ice age10-320,000 years ago.
Dali ice age 1- 1 1 ten thousand years ago.
When the ice age comes, the global temperature will drop. In every ice age, the temperature in Antarctica will drop by about 1 1 Celsius compared with the current temperature. As a large amount of seawater freezes, the sea level will shrink and the land area will expand. At the same time, tropical and subtropical regions will also shrink.
The earth's climate repeats the cycle of ice age and warm period. After the cold ice period lasts about 6.5438+ten thousand years, there will be a warm ice period of 6.5438+ten thousand years. At present, the earth is in a warm period, which has lasted for about 654.38+0.5 million years. The biggest difference between the current warm period and the previous one is that it is currently in a jumping period of hot and cold. Therefore, scientists believe that it is analyzed and used according to the nonlinear law of jumping.
Since the birth of the earth, the temperature on the earth has experienced a cycle of warm period and ice period every tens of thousands of years. According to geological data, it has happened more than 30 times in 800 thousand years. The temperature between two glacial periods is warmer, which is called interglacial period. Therefore, the earth's climate is changing gradually at a slow speed, and it is not static.
One of the most famous, there are four long ice ages, and its names are listed below:
Poyang Lake Ice Age137-10.5 million years ago.
105-65438+Dagu Ice Age 200,000 years ago.
Lushan ice age10-320,000 years ago.
Dali ice age 1- 1 1 ten thousand years ago.
When the ice age comes, the global temperature will drop. In every ice age, the temperature in Antarctica will drop by about 1 1 Celsius compared with the current temperature. As a large amount of seawater freezes, the sea level will shrink and the land area will expand. At the same time, tropical and subtropical regions will also shrink.
The earth's climate repeats the cycle of ice age and warm period. After the cold ice period lasts about 6.5438+ten thousand years, there will be a warm ice period of 6.5438+ten thousand years. At present, the earth is in a warm period, which has lasted for about 654.38+0.5 million years. The biggest difference between the current warm period and the previous one is that it is currently in a jumping period of hot and cold. Therefore, scientists believe that it is analyzed and used according to the nonlinear law of jumping.
The ice age, also known as the ice age, refers to the fact that the land and sea of the earth were covered with ice in some years, and these frozen areas were much wider than the current frozen areas. During the ice age, ice covered most parts of the world, and the climate in these areas was very cold. There is a lot of ice in the ocean, and thick ice condenses on the ground. At the same time, because more water is stored in the ice, the sea level is relatively low everywhere.
There may have been several ice ages in two geological periods called Precambrian (600 million years ago) and the end of Ordovician (about 450 million years ago). In today's Sahara desert, we can still see the remains of the Ordovician ice age-there are scratches on a large area of stones, which were left by the ice passing by. Scientists have determined that the earth has had eight glacial periods and eight warm periods in history.
During the ice age, many places in Europe, North Asia and North America were covered with large areas of ice and snow, and the current ice sheets and ice sheets were left at that time. The movement of the ice sheet changed the land. The ice sheet scraped off a large area of rocks, and the scraped stone chips accumulated on the edge of the ice sheet, which was called moraine. The weather gets warmer, the ice sheet melts, the ice sheet narrows, moraine is left on the ground, and moraine is melted by the ice sheet.
In addition, some scientists predict that the next ice age of the earth will appear as early as 6.5438+0.5 million years later, provided that human activities have no serious impact on the earth during this period.
Ice age refers to the period when a large area of land on the surface was covered by glaciers. In the past life history of the earth, ice ages have appeared repeatedly; At least 800 thousand years ago, the earth had experienced more than 30 ice ages.
How cold was the earth during the ice age?
Actually, it sounds a little unexpected. During the ice age, the temperature may have dropped by only four or five degrees Celsius in the past 100,000 years. But please note that this is only a global "average" figure. When the ice age comes, the polar ice sheet will expand, and the distribution of subtropical areas will move to the equator. In some areas, such as coastal areas, or equatorial areas with strong sunshine all the year round, the temperature change may be small. However, in some areas, such as inland, desert areas or areas with other special topography and environment, the temperature drop is very obvious.
Can living things survive?
The temperature drop has changed the flora on the earth's surface, and indirectly or directly changed the living environment of animals, making many animals face extinction or forced migration. Of course, species that can adapt to the changed environment will survive.
When was the last time?
With the arrival of the ice age, the temperature gradually dropped. The last ice age occurred about 18000 years ago. According to the research results of scientists, the climate was cold at that time, and about one third of the world's land was covered with 240 meters thick ice.
The earth has an ice age. Is there a "Jehol Age"?
Between the end of the glacial period and the next glacial period, it is the "interglacial period"; The interglacial climate was warm, just like the earth is in the interglacial period now. Apart from the glacial and interglacial periods, there is no third hot period with extremely high temperature.
Ice in the ice age was not directly frozen in the ocean, but the glaciers on the land expanded, and a large amount of ice was stranded on the land, so it was difficult to return to the ocean, and the water body in the ocean decreased, so the sea level dropped.
Four major ice ages in the world.
The name of foreign ice age: the name of China ice age (ten thousand years) and its geological age.
Kunitz Glacier Poyang Glacier 137- 150 Late Jurassic
M Glacier: Cretaceous in dagu glacier 105- 120.
Lisi Glacier Lushan Glacier 10-32 Tertiary Oligocene
Woolm Glacier Dali Glacier 1- 1 1 Quaternary Pleistocene
There is a change period of 400,000 years, but it has never been observed. Therefore, geophysicists and meteorologists think that Kirkeby's cosmic ray theory is controversial, but it is not too crazy and worth studying.
Is the ice age caused by the change of the total amount of cosmic rays that hit the earth? According to research, the influence of cosmic rays acts on clouds, and then the earth's climate changes dramatically. The change of beryllium-10 content in deep-sea sediments is studied. Beryllium-10 is produced when cosmic rays hit air molecules in the earth's atmosphere, so the cosmic ray flux can be inferred from the beryllium-10 content. They believe that these data show that the cosmic ray flux is similar to the cycle of the ice age.
The more cosmic ray flux, the more cloud cover and the colder the climate. On the contrary, when the cosmic ray flux is low, the cloud cover is also low, so the climate is warming. At first, these scientists thought that the cosmic ray flux would change when the intensity of the solar wind (the charged particle stream emitted by the sun) changed.
In addition to the intensity change of solar wind (the influence scale is 10 ~ 1000), two new mechanisms that may lead to the change of cosmic ray flux are added: one is the change of the earth's magnetic field (the influence scale is1000 ~10000), and the other is the particle flow from outside the solar system.
Among them, one of the changes of the earth's magnetic field is the orbital modulation of the geomagnetic mechanism, that is, the direction and intensity of the earth's magnetic field will change with time; This change was recently discovered by measuring the long-term variation of the geomagnetic field. The 220,000-year beryllium-10 data of Kirkeby et al. also show this change, and stalagmites found in northern Oman in Arabian Peninsula and Austrian Alps in Europe also confirm that this situation does exist. The left picture shows the change of beryllium-10 content in deep-sea sediments over the past 220 thousand years (red line, that is, the change of cosmic ray flux GCR). Blue indicates the global average temperature, the area above the line indicates that the climate is warmer than now, and the area below the line indicates that it is colder than now. The figure on the left shows the geomagnetic changes measured in various ways, and the red line is still Beryllium-10, indicating that there is a fairly consistent trend.
At present, the accepted standard "sunshine model of ice age cycle" was put forward by Serbian astrophysicist Milutin Milankovi in 19 12. The ice age was caused by the change of sunlight reaching the earth. The main reason for the change of sunlight is that the orbit shape of the earth around the sun changes periodically and gently. However, although the solar exposure theory can explain the prehistoric climate change cycle of about 465,438+0,000 years, it cannot explain the observed climate change cycle of 654,380+0,000 years. In addition, this theory also predicted the change period of 400,000 years, but it has never been observed.