By Henry Fountain Send us your questions about climate change by using the form at the bottom of our Climate Q. and A. This week’s question comes from a reader named Scott: When the last ice age retreated, the Earth’s crust sprang back up again as the weight of the ice was pressing down no more. Question: Would the melting of the ice caps cause the Earth’s crust to shift and cause more quakes or volcanic activity? Here’s another reason to be concerned about global warming: It might lead to more earthquakes, at least near the poles. In addition to the other problems that the eventual melting of the thick ice sheets in Greenland and Antarctica would create (soaring sea levels centuries from now, for one thing), it would remove a huge weight from the two land masses and affect stresses in the faults beneath them. “I would expect it,” said Göran Ekström, a geophysicist at Lamont-Doherty Earth Observatory, part of Columbia University, of the possibility that earthquakes might result. “That’s a very large stress change.” There are indications that this happened in the past, as the large ice sheets that covered much of the Northern Hemisphere and Antarctica during the last ice age began to retreat 12,000 years ago and the land began to rise (a process called postglacial rebound, which continues today). Scientists have found evidence in northern Scandinavia of large faults that ruptured after the ice retreated. Much more recently, relatively small changes in mass at or near the Earth’s surface have been thought to cause quakes. Several earthquakes in the 1970s and 1980s in a natural gas field in Uzbekistan, for instance, were believed to be the result of removing so much gas by drilling operations. And some scientists have linked a strong earthquake that struck Sichuan Province in China in 2008 to the filling of a reservoir behind a new dam. As for volcanoes, Dr. Ekström was less certain what the impact would be. There are indications, for example, that higher sea levels in the ancient past reduced volcanism at midocean ridges, as the extra weight of water acted to constrain molten rock, or magma. So loss of the ice sheets might be expected to lead to increased volcanic activity on the newly exposed land. “To the extent that a load should affect the magma bodies underground, there should be a connection,” Dr. Ekström said.