Recently, the second round of cold wave process in the second half of this year will sweep most of Our country. According to the forecast of the Central Meteorological Observatory, the cold air can be described as "all-round", which not only affects the long time and cools down fiercely, but also carries wind and rain and snow, and may reach the cold tide standard. At that time, it is estimated that only the quilt jacket can withstand the chill from Siberia.
With another arrival from La Niña, coupled with the assistance of cold air, 2021 will usher in another cold winter, in fact, not only China, from the Irish Sea to Hudson Bay, from Reykjavik to Halifax, this winter in the Northern Hemisphere has come earlier than in previous years.
In fact, the world is currently in the midst of a great ice age, so does that mean that global warming has stopped?
Geologists refer to the period in Earth's history when the atmosphere and the long-term low temperatures on the surface led to the massive expansion of polar and mountain ice sheets, and even covered the entire continent, as the Great Ice Age. Each Great Ice Age lasts tens of millions of years.
Since the formation of the Earth, there have been at least 5 great ice ages, each lasting tens of millions of years. At the height of the Great Ice Age, the Arctic and Antarctic ice sheets covered a very wide area, exceeding 30% of the total surface area. In contrast, during the Great Ice Age, the Earth was in what geologists call the Greenhouse Period, when there were no continental glaciers (including the North and South Poles) on earth.
We are now in the Quaternary Great Ice Age, which began 2.58 million years ago, during which the Antarctic continent and Greenland formed a permanent ice sheet, and the northern part of Eurasia and north North America also had a large continental ice sheet, and mountain glaciers appeared widely at high latitudes or high altitudes throughout the world. The main effect of this ice age is the erosion and sedimentation of glaciers on the continents, changing the direction of the river system, producing millions of lakes and changing the elevation of the sea level, developing rainy lakes far from the edge of the glaciers, and the balance of the earth's crust, affecting the ocean, floods, and biological species.
The alternating periods of cold and warm within the ice age are called the paraglacial period and the interglacial period (the short and warm period between the ice ages, called the interglacial period). The time scale is tens of thousands of years, and we are now in the midst of an interglacial period in which the Earth began in the Holocene. This interglacial period began 11,000 years ago. This led to the fading of the ice sheet of the last ice age. The remaining ice sheets of the last glacial period also cover 10% of the land area, existing in Antarctica and Greenland, and during the interglacial period due to reduced precipitation, rainy lakes tend to evaporate into salt flats.
So, the world is in the Great Ice Age, which is not inconsistent with global warming, because the macro scale is different, and more than 85% of the time in the Earth's 4.6 billion-year history has been the greenhouse period. From this perspective, the Great Ice Age was just an "interlude" of the greenhouse period, but as mentioned earlier, the term "interlude" is for billions of time scales.
That is to say, during the millions of years of the Quaternary Ice Age, the Earth's temperature was generally low, and the global warming we are talking about refers to the industrial revolution to the current climate change.
The temperature may rise a little during this time, and scientists also hope to keep the Earth's climate at these two or three hundred levels, and this time scale is just a moment for the Great Ice Age.
That is to say, the temperature was lower overall during the Great Ice Age, and there will be small fluctuations during this time, and global warming is one of them. At present, global warming has not stopped, and the famous scientist Milankovich calculated the changes in the eccentricity, axis inclination and precession of the orbit of the Earth over the past millions of years, and found the relationship between these parameters and the climate patterns on the earth, especially the ice age.
Approximately every 26,000 years of the inclination of the Earth's orbit completes the full precessive cycle of one orbit. At the same time, elliptical orbital rotations also guide changes between seasons and orbits in a slow 21,000 years. This is the famous Milankovic cycle.
According to scientists' calculations, the solar heat radiation received by the Earth is nonlinear due to the Milankovic cycle; greenhouse gas concentrations are increasing. Calculations of future global temperatures suggest that if co2 concentrations increase to 750 ppm (currently 398 ppm by volume), the interglacial period could last 50,000 years and global warming would occur. If co2 drops to 210 ppm, then the next ice age will occur after 15,000 years. According to ice core studies of seabed sediments and ice sheets, climate change is not flat. Isotopic components in ice cores have shown that the transition from warm to cold can be completed within a decade or two.
So why is it that global warming, our winter temperature continues to break records, and the "extremely cold" weather has become more? Like January 6, 2021, the lowest temperature in Beijing is -18 °C, according to statistics, the lowest temperature in Beijing since 2000 is -17 °C, which has also become the lowest temperature record since the 21st century.
This is because with the intervention of human activities, the process of global warming has accelerated, and global warming has changed the global atmospheric circulation situation, affecting the local climate through the interaction of the ocean and the atmosphere, land and atmosphere. For example, the Arctic sea ice situation. The cold air affecting our country originally originated from the Arctic, and the polar vortex that hovered over the Arctic would "lock" the cold air in the polar region.
At the same time, the Arctic region is the most sensitive region for global climate change response, and its surface temperature is warming at a rate of 2 to 3 times that of the world, which is known as the Arctic amplification effect. In the context of global warming, the Arctic sea ice decreases, and the polar vortex will weaken and split, favoring the Eurasian region, and it is difficult to "fix" the cold air and move south from it.
Therefore, the frequent occurrence of extreme cold events is a typical response to global warming. Climate warming has led to a more unstable climate, with frequent extreme weather and climate events such as cold waves, heavy rains and floods, and high temperature heat waves.
Therefore, for the earth that has existed for 4.6 billion years, a million years is just a beard. But for human society itself, climate upheavals on the million-year scale are out of reach, 50,000 years of time, if measured by humans, is too long, and the next 100 years, it is closely related to human beings, after all, the global average temperature rises by 6 degrees, for the earth, is an ordinary thing, but for humans and other organisms, it will bring extinction disasters.
Therefore, based on the time scale belonging to human beings, how to protect the environment is particularly important.