And human life can only rely on fresh water, although the earth's water resources are circulating all the time, seawater evaporates, convects, condenses and precipitates under the action of solar energy, which seems inexhaustible.
However, if the speed of human consumption of fresh water resources is faster than this cycle speed, it will cause a shortage of fresh water resources. Therefore, although saving water in the early years has not been mentioned much in recent years, we still can't deliberately waste water resources.
Especially in recent years, we often hear that many freshwater lakes have been disappearing, shrinking or even disappearing directly because the ecological environment has been destroyed by human production and life and the climate in some areas is abnormal.
Recently, however, according to the data provided by satellites, scientists found that the number of lakes in the world has surged by 53% in just 30 years, the area of all lakes has increased by 565,438+0% as a whole, and the overall water volume has increased by 48%.
There are more lakes, the climate is wetter, and the inland is no longer dry. It seems to be good news, but it is not. The appearance of these lakes is caused by abnormal climate, rather than the increase of global rainfall and the improvement of ecology.
The area with blue line in the above picture is Imga Lake near Mount Everest, and its size is 1989 as shown in the above picture.
However, by 20 19, its area has almost tripled compared with 1989, and the overall water volume has also increased significantly. The whole process of change is like this after 30 years:
Like the lake above, there used to be many. Some are new, and some are much larger than the original area.
We can see that these lakes are located near towering mountains or glaciers. The formation of lakes and the increase of water quantity are caused by glacier degradation caused by global warming.
Scientists estimate that from 1994 to 20 17, glaciers around the world, including the Antarctic and Antarctic ice sheets, especially those in alpine mountains, have lost more than 650 million tons of mass.
In the past, we know that most of the water has flowed into the ocean, and the melting of glaciers accounts for 35% of the factors leading to sea level rise. In addition, as the temperature rises, the sea water expands and the sea level rises.
But now it seems that some water melted by glaciers is actually stored in glacial lakes or groundwater systems. It is impossible to accurately estimate how much water there is at present.
This discovery is the data of glacial lake changes on the earth, which was analyzed by researchers from 250,000 photos of the earth taken by NASA satellites in the past 30 years, ranging from 1990 to 20 18 years.
The research results were published in the journal Nature Climate Change.
Then why is this bad news?
This discovery and the data analysis of glacial lakes around the world will enable us to more accurately predict the speed of sea level rise in the future.
This also shows that the rate of glacier degradation caused by global climate change is faster than we realized before. Faster glacier degradation will also accelerate the deterioration of the earth's environment.
The first is that fresh water resources will be threatened. In fact, most of the water resources of rivers and lakes in the inland areas of the earth come from glaciers in the mountains, except for precipitation collection.
If glaciers are in a roughly balanced state with the formation and melting of seasons, the fresh water resources on which our lives depend will continue.
But now the fact is that these glaciers are degenerating much faster than they were formed, which means that we have consumed our future water resources in advance.
If these glaciers disappear in a short time, saving water in the future may not be a simple slogan.
Secondly, the melting of glaciers will accelerate climate warming, which will accelerate the melting of glaciers and arctic permafrost. This is a vicious circle.
The chief culprit of climate warming must be the greenhouse gases produced by human activities, but the melting of glaciers will reduce the albedo of the earth to sunlight, so the heat absorbed by the earth's surface will become stronger and stronger, which will aggravate the temperature rise.
Finally, the glacial lake added in recent decades is of little use to us because its place is inaccessible.
However, the increase in the number and quantity of glacial lakes directly threatens the lives of millions or even tens of millions of people.
Compared with the common lakes in our life, glacial lakes are often located in higher places. These glacial lakes are mainly blocked by dams made of some ice or loose rocks.
Just like the dammed lake formed during the earthquake, with the increase of water volume, the dam will burst one day, and a large amount of water will pour down in a short time, causing large-scale floods in the downstream.
The author also mentioned that in the last century, the eruption of this glacial lake also caused the destruction of downstream villages and infrastructure and thousands of casualties.
It is estimated that more than 3,000 glacial lakes, large and small, have formed in the Himalayan region, of which 33 glacial lakes have threatened nearly 7 million people downstream.