Climate has much to do with the lifespan of a worker bee. The queen is mainly present in the hive except to mate and gather food so that she can hybernate. Many worker bees are subjected to the climate and less than ideal weather conditions as they gather food for the hive. Cold temperatures or storms can cause stress and shorten the lifespan of worker bees that are designated gatherers.
Worker bees are more likely to be attacked by predators than queen bees because they spend more time outside of the hive. It's not uncommon for a worker bee to be killed or die unexpectedly. Predators include many types of animals and birds, other insects, and even humans. Queen bees may also fall victim to predators, but it's much less likely due to the difference in duties and the relative safety within the hive.
The queen bee is allowed to hybernate through the winter and to stay in the hive to produce eggs. She lives a relatively sheltered, sedentary life and is protected by the worker bees. The function of the worker bees is much more dangerous than that of the queen bee, and they often work alone without the protection of the hive. In addition many do not hibernate to survive the winter.
A worker bee's function is to supply and protect the hive while the queen is meant to repopulate and ensure the future of the species. Most hives have many many worker bees and only one queen bee. Nature ultimately determines the longevity of the two lives and they are built different physically, which affects how long they each live. The queen's job is important for the continuation of the species as well as overseeing the hive, and because she does it alone she is designed to live longer.