Question: What cause black holes to slowly evaporate?
About the article "Black hole", section "Information loss paradox".

Candidate passages:
The Black Hole Era is defined as "40 < n < 100".
In this era, according to the book, organized matter will remain only in the form of black holes.
Black holes themselves slowly "evaporate" away the matter contained in them, by the quantum mechanical process of Hawking radiation.
By the end of this era, only extremely low-energy photons, electrons, positrons, and neutrinos will remain. 
Before Stephen Hawking came up with the concept of Hawking radiation, the question of black holes having entropy was avoided.
However, this concept demonstrates that black holes can radiate energy, which conserves entropy and solves the incompatibility problems with the second law of thermodynamics.
Entropy, however, implies heat and therefore temperature.
The loss of energy also suggests that black holes do not last forever, but rather "evaporate" slowly.
Small black holes tend to be hotter whereas larger ones tend to be colder.
All known black hole candidates are so large that their temperature is far below that of the cosmic background radiation, so they are all gaining energy.
They will not begin to lose energy until a cosmological redshift of more than one million is reached, rather than the thousand or so since the background radiation formed. 
In the future, the possibility of black hole production at the highest energy accelerators may arise if certain predictions of superstring theory are accurate.
This and other exotic possibilities have led to public safety concerns that have been widely reported in connection with the LHC, which began operation in 2008.
The various possible dangerous scenarios have been assessed as presenting "no conceivable danger" in the latest risk assessment produced by the LHC Safety Assessment Group.
If they are produced, it is theoretically predicted that such small black holes should evaporate extremely quickly via Bekenstein-Hawking radiation, but which is as yet experimentally unconfirmed.
If colliders can produce black holes, cosmic rays (and particularly ultra-high-energy cosmic rays, UHECRs) must have been producing them for eons, but they have yet to harm anybody.
It has been argued that to conserve energy and momentum, any black holes created in a collision between an UHECR and local matter would necessarily be produced moving at relativistic speed with respect to the Earth, and should escape into space, as their accretion and growth rate should be very slow, while black holes produced in colliders (with components of equal mass) would have some chance of having a velocity less than Earth escape velocity, 11.2 km per sec, and would be liable to capture and subsequent growth.
Yet even on such scenarios the collisions of UHECRs with white dwarfs and neutron stars would lead to their rapid destruction, but these bodies are observed to be common astronomical objects.
Thus if stable micro black holes should be produced, they must grow far too slowly to cause any noticeable macroscopic effects within the natural lifetime of the solar system. 
 "1040 years to 10100 years" Black Hole Era.
After 1040 years, black holes will dominate the universe.
They will slowly evaporate via Hawking radiation., §IVG.
A black hole with a mass of around 1 solar mass will vanish in around 2×1066 years.
As the lifetime of a black hole is proportional to the cube of its mass, more massive black holes take longer to decay.
A supermassive black hole with a mass of 1011 (100 billion) solar masses will evaporate in around 2×1099 years.
Hawking radiation has a thermal spectrum.
During most of a black hole's lifetime, the radiation has a low temperature and is mainly in the form of massless particles such as photons and hypothetical gravitons.
As the black hole's mass decreases, its temperature increases, becoming comparable to the Sun's by the time the black hole mass has decreased to 1019 kilograms.
The hole then provides a temporary source of light during the general darkness of the Black Hole Era.
During the last stages of its evaporation, a black hole will emit not only massless particles but also heavier particles such as electrons, positrons, protons and antiprotons., pp.
148–150.  
Because a black hole has only a few internal parameters, most of the information about the matter that went into forming the black hole is lost.
Regardless of the type of matter which goes into a black hole, it appears that only information concerning the total mass, charge, and angular momentum are conserved.
As long as black holes were thought to persist forever this information loss is not that problematic, as the information can be thought of as existing inside the black hole, inaccessible from the outside.
However, black holes slowly evaporate by emitting Hawking radiation.
This radiation does not appear to carry any additional information about the matter that formed the black hole, meaning that this information appears to be gone forever.
The question whether information is truly lost in black holes (the black hole information paradox) has divided the theoretical physics community (see Thorne–Hawking–Preskill bet).
In quantum mechanics, loss of information corresponds to the violation of vital property called unitarity, which has to do with the conservation of probability.
It has been argued that loss of unitarity would also imply violation of conservation of energy.
Over recent years evidence has been building that indeed information and unitarity are preserved in a full quantum gravitational treatment of the problem.