It has been over 150 years since the Great Chicago Fire. The 1871 fire killed an estimated 300 people. It turned the heart of the city, wood-frame buildings quickly constructed on wooden sidewalks, into ruins, and left 100,000 people homeless. Like the Great Fire of London in 1666, the San Francisco Earthquake of 1906, and Hurricane Katrina in 2005, the Great Chicago Fire reminds us that big cities can still be frail.

But that same night, about 250 miles north of Chicago, more than 1,200 people died in and around Peshtigo. It was the deadliest wildfire in U.S. history. Survivors said the fire moved like a hurricane, jumping across Green Bay to light forests on the opposite shore.

Chicago’s fire came to be seen as a disaster that also led to the invention of steel skyscrapers, raised up on the city’s ashes. It has overshadowed the Peshtigo Fire. And for years, the two were seen as separate disasters. However, many of those houses and sidewalks that burned in Chicago had been built with trees grown around Peshtigo.

Chicago’s fire was long blamed - falsely - on an Irish-immigrant family’s cow kicking over a lantern. Some people thought the Peshtigo Fire started when pieces of a comet (彗星) landed in the forest, which has never been proven.

What we understand better today was that the Midwest was historically dry in the summer of 1871. When a low-pressure front with cooler temperatures rolled in, it produced winds, which can fan sparks (火星) into wildfires. The fires themselves generated more winds. Several parts of nearby Michigan also burned during the same few days ; at least 500 people were killed there.

At present, all of those fires on an autumn night in 1871 might help us see even more clearly how rising global temperatures and severe droughts, from Australia to Algeria to California, have made forests easier to burn, and people more likely to be harmed by the climate changes we’ ve helped create.

The morning of March 2, 2012, was a busy one for the students in Mrs. Goodknight’s class in Henryville, Indiana. There was morning meeting with poems to read, jokes to share, and tests to prepare for. “It was just an ordinary day,” says student Lyric Darling, 12.

At noon, while students played basketball under a sunny sky, a huge tornado (龙卷风) was forming 50 miles away. Around 2:25 p.m., 20 minutes before school was supposed to let out, a huge tornado touched down in Fredericksburg, 20 miles away. As word spread, parents rushed to the school. Teachers rushed to get kids onto buses or into waiting cars. By 2:45, the skies were darkening.

“I was crying,” says Lyric. “All around me, kids were crying.” Two buses returned to the school with students whose parents had not been home. Teachers brought the kids to the office, where they all took cover under desks. Suddenly the power went out. And then the tornado attacked the school, filled with wood and trees and glass. The tornado was over the school for less than one minute. In that time, it almost completely destroyed the school. Teachers were about to lead the group out of the office when a second tornado was upon them. When it finally ended, the group made its way out of the building.

Over the next few hours, parents arrived, overjoyed to find their children. The next day, it was clear: All of Henryville’s people were safe.

There were so many sad and frightening stories. Some students saw the tornado with their own eyes. Some lost their homes. But many described how the community (社区) came together to help and support each other. “You learn what’s important,” Mrs. Goodknight says.