Antarctica is a continent almost entirely covered by ice and snow. Snow, huge glaciers, extremely low temperatures, violent winds and cute penguins have always been the standard for Antarctica. However, since last year, the snow in parts of Antarctica has not taken the usual path and turned red like watermelon juice. At that time, it attracted the attention of many people on the Internet. Just a few days ago, there were reports that the snow in Antarctica had "changed" again. What has actually happened?
How does the red snow come from?
According to research by scientists, the source of these red colors is not due to the change in the color of the snow itself, but from a creature- polar snow algae .
The ice and snow in Antarctica basically contain this kind of algae, but the distribution is uneven in the area. This kind of snow algae is very suitable for living in cold regions like Antarctica. When the temperature is extremely low, the polar snow algae will be dormant, and they will not show any special color to the outside. When the temperature rises to a certain range, they will be dormant. "Wake up" from the dormant state.
After "waking up", the polar snow algae will synthesize carotenoids through photosynthesis. Carotenoids contain pigments, which will appear red under different light conditions. Different colors such as orange or yellow. When part of the Antarctic region has a large temperature increase, and at the same time there is sufficient sunlight, and the growth and reproduction of snow algae populations have obtained sufficient conditions, the ice and snow in this part of the region will show a combination of red, orange, and yellow colors. Like "watermelon juice" poured on the snow.
Why has the frequency of red appearance increased in recent years?
In fact, the "Watermelon Snow" in Antarctica is not a natural phenomenon that has only appeared in recent years. It appeared and recorded a long time ago. For example, in the 4th century BC,The ancient Greek philosopher Aristotle once described this phenomenon in "The Short Stories of Nature". At the same time, there are other types of algae in the ice and snow in Antarctica. These algae will show other colors during their physiological activities, such as green and black. Therefore, there is not only "watermelon snow" in Antarctica, but also in some areas. Special phenomena such as "green snow" and "black snow" will also appear.
Not only in the Antarctic, but also in low-temperature areas such as the North Pole and alpine glaciers. Sometimes such "color snow" formed by the "resurrection" of different algae occurs. Inside, the originally low temperature suddenly rose a lot, reaching the conditions for algae growth and reproduction. This is a normal natural phenomenon, but under normal circumstances, it is impossible for these algae to reproduce on such a large scale. When local algae populations If the number does not reach a certain scale, the color reflected by the ice and snow will not be so obvious, and it will not be noticed by people.
Judging from the conditions required for the growth of polar snow algae, the sudden rise in temperature is an important reason. Of course there are several other important factors. One is light, no photosynthesis, algae It is impossible to synthesize substances with characteristic colors like carotenoids. The other is that they need nutrients. Algae also belong to plants. In addition to sunlight, they also need to take in a certain amount of nutrients such as inorganic salts from the environment. Therefore, the outbreak of snow algae in the polar regions requires rising temperatures, suitable light, and the input of necessary nutrients, all of which are indispensable.
It can be seen that the polar snow algae has been erupting regularly in recent years. On the one hand, Antarctica is indeed heating up, which means that its average temperature is on the rise. From the monitoring data of relevant monitoring points in Antarctica over the years, the average temperature of Antarctic region has increased more than the global average, especially in spring and summer, where the year-on-year increase is more obvious.
On the other hand, with the impact of human activities, especially the intensity of human use of natural resources and energy, the concentration of some organic and inorganic particles discharged into the environment is always high. With an upward trend, these particles migrated to Antarctica along with atmospheric circulation, ocean currents, etc., providing a sufficient source of nutrients for the growth and reproduction of polar snow algae and other algae, creating a more favorable environment for the outbreak of algae.
What impact will the outbreak of algae in Antarctica bring?
Although the South Pole and North Pole are at very high latitudes, because Antarctic continent is covered with thick ice and snow, the reflection of solar radiation is very strong, and 50%-80% of solar radiation is reflected back by ice and snow. This is an important reason why the temperature in Antarctica is generally lower than that in the Arctic. However, when the number of algae in the snow is large, the reflection efficiency will be significantly reduced. According to preliminary estimates, the presence of snow algae in the polar regions will reduce the reflectivity of snow and ice to solar radiation by 13%-20%.
The decrease in the reflectivity of sunlight means that the ability of ice and snow to absorb solar radiation is improving, thereby increasing the rate of ice and snow melting. Therefore, in a sense, the frequent occurrence of "watermelon snow" is not a pollution problem, but it is not a good phenomenon for the Antarctic ice sheet, which means that during the period of periodic temperature rise, the ice The melting rate of the cover will be significantly accelerated, and it is very likely to become one of the driving forces behind the acceleration of the melting of the Antarctic ice cover or even partial disappearance of the Antarctic ice cover under the background of global warming.
At the same time, the accelerated melting of Antarctic ice and snow will have a collateral impact on the various creatures that live here.For example, the active range of Antarctic krill is further compressed, and it continues to move closer to the Antarctic continent. The active areas of those animals that use krill as their main food (seals, blue whales, etc.) will change accordingly, and some individuals cannot get enough. Lose weight or even die from food, which affects the stability of a series of ecosystems. In addition, the accelerated melting of Antarctic ice and snow will also cause more severe sea level rise. Some coastal areas will be threatened by seawater intrusion. Ocean , ocean current and atmospheric circulation will also change, which will affect the global Climate stability, which in turn causes extreme climate disasters of varying degrees in other regions.
In summary, although the Antarctic "watermelon snow" has existed since ancient times, it has entered the industrial revolution, especially in recent decades, and the impact of human beings on the natural environment has been increasing. Under the direct and indirect influence of the “Watermelon Snow”, the frequency of “watermelon snow” has increased significantly, and it has become a landmark event of global warming, which undoubtedly sounded the alarm for us.
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