Why does global warming cause the temperature to rise instead?

According to the analysis of various climate models, global warming will increase the ocean temperature, accelerate the melting of icebergs, and make more fresh water flow into the ocean, while the increase of ocean surface temperature and the decrease of seawater salinity may slow down or even completely stop the thermohaline circulation. If there is no thermohaline circulation, the heat energy from the equator will not be transported to the North Atlantic, that is, eastern North America and western Europe will become cold.

Many paleoclimatic data clearly show that abrupt climate changes did occur in history. Among many abrupt climate change events, the most famous one is the New Fairy Tree event which happened before 12000.

At that time, the world had just passed the last ice age and was warming slowly and continuously. But just about 12900 years ago, the temperature in the high latitudes of the northern hemisphere suddenly began to drop again, and the whole region soon returned to the low temperature state similar to the ice age. This state lasted about 1300 years before the temperature began to rise again.

This cooling process does look very similar to that described in The Day After Tomorrow. According to paleoclimatic data, in addition to the new fairy tree incident, there have been more than 20 similar incidents in the past 654.38 billion years. Therefore, from the point of view of whether climate change is possible, there is no problem in the description of the film.

The film's explanation of "the process of climate change" is also reasonable. At present, the scientific community's more recognized explanation for climate change is that "the global heat balance is broken due to the slowdown or stop of the ocean hot-salt circulation."

What is "Ocean Hot Salt Circulation"? We know that the density of seawater is mainly controlled by temperature and salinity. The colder and saltier the water is, the denser it is. On the contrary, the warmer the sea water is, the lighter it is and the less dense it is. Ocean thermohaline circulation is a zonal circulation driven by different temperature and salinity distributions of seawater. The water in the North Atlantic is cold and salty, so the water in this place will sink, then flow to the low latitude and rise to the sea surface, and finally return to the North Atlantic through the surface circulation. Through this process, the hot salt circulation will transport excess heat from low latitude to high latitude, so the ocean hot salt circulation plays a great role in maintaining the global heat balance. During global warming, many land glaciers will melt, and a large amount of fresh water will be imported into the North Atlantic, which will reduce the density of local seawater and prevent it from sinking into the deep sea, so the hot salt circulation will slow down or stop. In this way, the global heat balance will be broken and the high latitudes will become very cold. The process of "the scene after tomorrow" in the film basically conforms to this process.

But the film itself also has many places that are not in line with scientific facts.

For example, according to the available data, the occurrence of climate change is likely to be a process of decades to hundreds of years, rather than a few days depicted in the movie. The reason why the film compresses this "hundred years" process into "a long time" is entirely for the development of the story. If the plot is advanced according to scientific facts, the film will become a historical series. In addition, the sudden change of climate in the film is accompanied by many extreme weather phenomena, among which the most impressive is the N-in-one super storm. According to the existing historical data and climate knowledge, such a strong storm is basically impossible to happen under the condition of climate change.

Besides, the super storm surge that flooded new york in the film is also untenable. If the wind really causes a storm surge of 100 meters, then the wind speed needs to reach supersonic speed.

In short, the extreme weather in the film is a plot added to construct the doomsday scene, not a real response to the actual situation. It is worth mentioning that with global warming, extreme weather will indeed increase, but scientists believe that its intensity and frequency will not reach the level in the film anyway.

Although many years of observation show that the hot salt circulation tends to weaken, compared with many paleoclimate data, this weakening is still not obvious. Scientists believe that climate change is unlikely to happen in the next 100 years, so readers basically don't have to worry too much about the day after tomorrow in their lifetime.

Reference: Network Link