  The goal of this paper is to address A. Shumakovitch's conjecture about the
existence of $\Z_2$-torsion in Khovanov link homology. We analyze torsion in
Khovanov homology of semi-adequate links via chromatic cohomology for graphs
which provides a link between the link homology and well-developed theory of
Hochschild homology. In particular, we obtain explicit formulae for torsion and
prove that Khovanov homology of semi-adequate links contains $Z_2$-torsion if
the corresponding Tait-type graph has a cycle of length at least 3.
Computations show that torsion of odd order exists but there is no general
theory to support these observations. We conjecture that the existence of
torsion is related to the braid index.
