Judaism, however, differs from the Law of Karma in significant ways. First of all, the Law of Karma is strictly personal; an individual who steals will be stolen from, in this incarnation or the next or the next. The individual's dishonesty will revolve back only on him/herself. It cannot cause others to suffer. Although there is a concept of group karma, here too the boomerang flies back to the hands that threw it; only the perpetrators become the victims.
Judaism, on the other hand, credits human action with a much broader effect. A person stealing $100 in Tel Aviv lowers the moral fiber in Mexico City and could encourage massive embezzlement in Melbourne. Conversely, a person doing a mitzvah in Haifa may avert an auto accident in London or prevent complications during open-heart surgery in Los Angeles. The spiritual channels of effect run far below the surface, untraceable but powerful.
--snip--
A second major difference is that karma is inexorable; a misdeed once committed is, as they say in India, like the tusks of an elephant. It can never be retracted. Judaism, on the contrary, teaches the concept of teshuva. Teshuva means that a person can regret and change his/her mode of conduct, and when s/he does, the past actions are spiritually erased. In fact, if one does teshuva from pure love of God, the subterranean channel, the river of fire, turns into a positive force, a river of sweet water.
This is precisely what Judaism endorses as a response to disaster. The Talmud says that when one suffers, one should scrutinize one's deeds, implying that teshuva for wrong conduct can change one's fortune. And what if one is not directly affected, but only hears about a disaster that occurred in a distant place? The Talmud asserts that if a person even hears about a disaster such as an earthquake, one must relate to the tragedy by examining one's own deeds.
the entire article