Global warming and cosmic rays

Although the rise in global temperature has a profound and profound impact on the lives of all species on the planet, in the course of centuries, that phenomenon is nothing special: for three millennia. recently the fluctuation of the average temperature of the earth's surface has repeatedly reached such fluctuations (0.74 ± 0.18 ° C).

In the last century, our Earth has suffered from many unusual weather changes due to global warming. The average temperature of the earth's surface has increased by 0.74 ± 0.18 ° C. That is the undeniable fact. All measurements using different methods and tools confirm that.

In the twentieth century, global warming caused ice in the poles as well as on the fast-flowing rivers, leading to a sea level rise of about 17 cm. Climate change will inevitably lead to many economic and social consequences. People in the most affected areas are really worried about their future and destiny. Unfortunately, so far we have not understood the mechanism that governs climate change, so the forecasting work in this area often suffers great errors.

Figure 1. Earth temperature (top left), sea level (upper right picture) and the amount of greenhouse gases (left middle image) increase over time in the 20th century. Increasing the earth's temperature correlates with the change in the solar cycle more clearly than the increase in the concentration of CO2 in the air (right middle image). The periods of temperature rise in the last three thousand years are similar to the rise of temperature in the 20th century (below).

What is the main cause?

For decades, it has been suggested that the increase in the amount of greenhouse gases from the industrial age to the present is the main cause of global warming. Although carbon dioxide only contributes about 20% to the greenhouse effect (steam contributes more than 50%), it is a factor that causes global temperature rise: the amount of carbon dioxide released into the air increases in part. three in the second half of the twentieth century. Thus, as well as the rise in global temperature, the increase in atmospheric carbon dioxide is undeniable.

An important issue to note is that it is not possible to determine the exact extent of the relationship between the increase in carbon dioxide concentration in the atmosphere and the rise of the Earth's temperature. The increase in global temperature in the last century is still in the range of temperature fluctuations observed during the pre-industrial era. Assessing the effect of CO2 emissions into the atmosphere on the earth's climate is difficult. The more basic the effects (the transmittance of the atmosphere) are, the easier it is to evaluate them, the more secondary effects (feedback effects) are complex, confusing and unnoticeable. An example of a feedback effect: when the earth's surface temperature rises to 1 ^° C, the amount of water evaporated from the oceans will be higher, there will be more clouds and the temperature will decrease.

There are many feedback factors that must be taken into account as different types of clouds have different effects, the existence of the flora, etc. When taking into account all of these effects, the evaluation becomes very complicated. rather than simply increasing the amount of CO2, the temperature will increase. The problem is that the effect level of these secondary effects may be equivalent to the primary effect. So far there is no direct evidence that the amount of carbon dioxide released into the atmosphere from the industrial age is the main cause of global warming in the twentieth century, but no evidence exists receive that.

Through climate studies in the centuries before the twentieth century, there was a great correlation between the activity of the Sun and the Earth's temperature. Clearly, the luminosity change of the Sun cannot create this correlation because that transformation is very small. In fact, in order to assess the extent of the Sun's activity, a very important parameter is the number of sunspots - dark areas on the sun's surface due to the lower temperatures there. with the surrounding areas due to the strong magnetic field changes in the Sun. The number of black spots fluctuates according to the 11-year cycle (solar cycle).

However, it seems that cosmic rays can provide a suitable explanation for this relationship. Radiation from the Sun (solar wind and flames) varies greatly throughout the solar cycle but their energy is not enough to overcome the barrier created by the magnetic field, and therefore cannot play a direct role in controlling the earth's climate. However, they carry a much stronger magnetic field than the magnetic dipole magnetic field, affecting the magnetic field in the solar system and thus affecting the orbit of cosmic rays to Earth. . Cosmic rays, mainly proton components, have energy distribution following the exponential rule ~ E2,7 and their energy spectrum is cut at low energy areas by the barrier effect due to left magnetic field land cause.

Therefore, only cosmic rays with sufficiently large energies are capable of going deep into the atmosphere. This cutoff varies with latitude, reaching a maximum value of 17 GeV in Vietnam and about 4 GeV in Europe and North America. The changing Sun's activity will directly lead to threshold fluctuations that cut cosmic ray energy, resulting in a constant correlation between the rate of cosmic rays measured on the ground and the level of activity. of the Sun. So how do cosmic rays affect the earth's climate?

The role of cosmic rays?

Figure 2. The level of activity of the Sun in the last four centuries. The Sun's cycle of activity is an average of 11 years, but there are two periods (the Minority of the Maunder and the Dalton Minima). Correlation between cosmic ray flux and temperature fluctuation (bottom right) and with lower layer cloud (lower left).

Researching the process of cloud formation in the atmosphere helps us have an overview of the role of cosmic rays on the earth's climate. When cosmic rays enter the atmosphere they interact with atoms, molecules and create countless secondary charged particles - this phenomenon is called atmospheric showers. These particles affect almost the entire ionization process in the atmosphere. Cloud formation is a partial condensation of atmospheric water under proper temperature and pressure conditions. The process of condensation wants to happen quickly and smoothly, there must be condensed nuclei in the air for water molecules to stick to.

In fact, the active molecules and free radicals (size 10−9m - nanometers) group together to form condensate nuclei. In the early stages they grow up (diameter of tens of nanometers) mainly due to the accretion from other molecules and the later development process thanks to the agglomeration to form larger particles ( diameter of hundreds of nanometer to micrometer - 10−6m). When they reach this size, water molecules continue to cling and water droplets are formed, this process continues until the droplets reach a diameter of 10 to 100 micrometers: they form clusters. clouds.

If they continue to grow to reach a diameter of 1-2 mm, they will fall to the ground and form rain. Thus, all stages of the cloud formation process are characterized by accretion. The ionization process caused by cosmic rays in the air adds electrostatic attraction with much greater intensity than the intermolecular force (Van Der Waals force) that facilitates the accretion process. than. Unfortunately, the knowledge of the above phenomena is still limited, allowing us to accurately assess the role of cosmic rays in the process of cloud formation. Currently, many experiments in the world are underway to understand the mechanism that governs the earth's climate. If that is determined,

the increase in the Sun's activity makes the galactic cosmic ray flux decrease to Earth, leading to a decrease in the lower cloud layer, and its correlation with the rise in global temperature will be demonstrated. . But with the current knowledge, there is no basis to confirm that.

Need more time

Recently, global warming has become a topical political issue. But the debates stemming from this hot topic often take place in the atmosphere of intense controversy not conducive to scientific discussion, they are often affected by conflicts of financial and economic interests - society of nations. However, more than forty years after the Rome Club's first warnings, an encouraging result was achieved: people on the planet are gradually aware of the instability in balancing the conditions for human beings exist. Clearly, it takes more time for people to be fully aware of the entire climate system on Earth.