The Mayan calendar is interpreted to precisely describe on the very day the present fourth era, having started on 11 August 3114 BC and ending on the 21 December 2012. It actually does not describe the end of the world that we know and of mankind on earth in December 2012, but is interpreted as a transition point to a new kind of civilization. A Mayan inscription from the 7th century, found in Tortuguero, an archaeological site in Tabasco, Mexico, predicts the descent of the Underworld God Bolon Yokte to induce such a renewal process on earth. The astronomical knowledge of the Mayas is admirable because on the 21st of December 2012 our sun will be in a rare conjunction with the Milky Way. This constellation is calculable and has no negative effects on our planetary system, despite all the rumors about the imminent end of the world.
The real latent risks to life on earth are unpredictable impacts of asteroids and eruptions of super volcanos. Both have struck the Earth in the past and there is a chance that both may threaten life again. Many specialized scientists around the globe look out for early warning signs and started to think about possible countermeasures. It is not yet possible to control such a situation by any means. Today we at best could calculate the impacts and try to minimize the casualties.
A self-made problem is the accelerated process of global warming by the exaggerated output of greenhouse gases. As a consequence the provision of enough drinking water could soon become the major challenges for scientist and engineers. Without drinking water, the mass migration of peoples is unavoidable, provoking political tensions that could culminate in tragedy and misery.
However, there are more forthcoming events that cause risks to life and deserve to be mentioned.
Astronomers expect the Earth's average tilt to increase about 0.4 degrees over the next 10 million years, superimposed on the variation of about 2 degrees by precession and ecliptic, with its mean cycle of 41.000 years. Simulations show this additional impact because of the increasing distance between the earth and the moon. Changes of the tilt influence the climate by changing seasonal temperature differences and the consequences for the polar ice caps, the winds and the oceanic currents. Most of the ice ages of the past presumably have been caused by this change of the tilt.
Strong earthquakes, like in Japan on the 11th of March 2011, can arithmetically shift the Earth's axis by several inches, shortening days by microseconds against the continuous slowing down of Earth's rotation speed, but this has no measurable effects. This rotation speed already varies in the range of milliseconds, merely caused by atmospheric winds and oceanic currents. Therefore, earthquakes cause terrible regional disasters, but have only a negligible influence on our planet's stability overall.
The loss of the Earth's magnetic field would cause a similar critical radiation as permanent strong solar flares into the direction of our planet, much stronger than the recently observed powerful but for Earth harmless eruptions of 6th of March and 16th of April. Intensive sun activities can be expected in spring 2013, because of an irregular 11-year cycle of a magnetic poles reversal, detectable by an increasing number of colder dark sunspots on the sun's photosphere. The sun's magnetic field does not completely disappear during a reversal phase; it is in a state of complete chaos. The dark sunspots are extremely strong local magnetic poles. The Earth's magnetosphere is then hit by strong solar flares, some with enough disruptive power for satellites and terrestrial power grids, and increasingly provoking displays of aurorae by the initiated geomagnetic storms.
The reversal of magnetic poles is a scientifically documented part of our planet's history. These processes occur at random intervals from about 0.1 million years to 50 million years, with an average of about 250.000 years and the tendency of increasing frequency. However, the last reversal occurred about 780.000 years ago, apparently making the start of this process overdue. Currently, the Earth's overall geomagnetic field is becoming weaker, which may be a sign for an approaching reversal process. Research results show a 10-15% decline over the last 150 years, even accelerating in the past few years. The pole reversal approximately needs 4.000 years to 10.000 years, much longer than on the sun. During this phase, Earth is strongly exposed to the solar winds, which probably have caused DNA-mutations in the past as a contribution to the evolution. Scientist will carefully observe all changes of the Earth's geomagnetic field during the next years and elaborate precautions for the long overdue reversal period.
Trying to cope with the scheduled catastrophes, there will be again and again phases when people will have to completely revise contemporary classical views on science, but the majority will not remain in procrastination because of a special scientific reason: all structures in our cosmos show two undisputed aspects: All systems become more and more complex, leading to a wider and wider variety of existence, culminating in the marvelous composition of the human brain. A strong anthropic principle is not derivable, stating that the physical laws of nature compel the universe to develop compatible environments for conscious life. However, the laws and the given constants of nature astonish all scientists because they are perfectly matched to strongly support the further development of intelligent life with the desire to survive. It is not important whether these natural laws and the adjustment of their constants occurred accidentally, or if they turn out to be an inherently fixed feature of nature. The fact is that they are perfectly matched.
An unpredictable and global danger for all species came with the appearance of humans on earth, fighting with innovative lethal weapons for their superior right to stay. The human race probably will continue to stay for many more generations on the verge of self-destruction because of cultivating deliberate death as an accepted political option. This historically developed attitude may fade with the currently developing global consciousness, in case our blue planet can manage to feed and emotionally satisfy 10 and more billion people in near future without collapsing. This sociological issue is as serious as the other latent risks that could strike the human race and challenges scientists and politicians today and in future just as much.