A large flood caused by heavy rains and melting mountain snow recently hit America’s Yellowstone National Park. It caused widespread damage and resulted in many changes.

It changed the path of a river popular for fishing and also devastated hundreds of homes, bridges and roadways in nearby communities. It drove more than 10, 000 visitors out of the park. Luckily, no one was reported hurt. However, the park could remain closed for up to one week. The water also washed away camp structures, flooded small towns and cut power to parts of southern Montana and northern Wyoming.

The Yellowstone River was running at a historically high level of 4. 9 meters as it flowed past Billings, Montana’s largest city. The city got its water from the river and was forced to close its treatment plant (工厂) because it couldn’t operate effectively with water levels that high. Billings officials said the city only had a 24-hour supply of water. They were asking people to save water until the river could drop and the plant could restart operations.

Yellowstone officials said, “The northern half of the park is likely to remain closed over the summer. This will greatly affect local economies that depend on summer tourists. But we have faith in the park repairs and economic recovery.”

This season, the bushfires in Australia have burned more than 12.35 million acres of land. At least 25 people have been killed and 2000 homes destroyed. According to the BBC, this is the most casualties （伤亡）from wildfires in the country since 2009. The University of Sydney estimates that 480 million animals have died in South Wales alone.

Zeke Hausfather, an energy systems analyst and climate researcher at Berkeley Earth, said warmer temperatures and extreme weather have made Australia more susceptible to fires and increased the length of the fire season. “The drier conditions combined with record high temperatures in 2019 created main conditions for the disastrous fires. Australia’s fires were worsened by the combination of those two. 2019 was the perfect storm for being the warmest year on record for Australia and the driest year on record for Australia,” Hausfather added on Friday.

Kevin Tenberth, a senior scientist at the US National Center for Atmospheric Research, said warmer ocean temperatures also contributed to more variable weather around the world. Trenberth believes the global warming contributed to energy imbalances and hot spots in the oceans, which can create a wave in the atmosphere that locks weather patterns in places, causing longer rain events in Indonesia, for example, and at the same time contributing to drought in Australia. He said that once an area experiences drought conditions for two months or more, it increases the risk of fires catching and spreading. Those changing weather patterns due to global warming make drought events longer.

Climate experts stress that climate change is not the only factor in the severity of wildfires. How land is managed can also impact the amount of fuel available for   controlled burns and other factors can impact the risk to people and property, such as warning systems and the type of development in a given area. Changing those policies has great potential to limit future damage from wildfires along with changes to how fire management resources are dispatched（派遣）.

A very dangerous situation happened in California last week. More than 12 wildfires broke out in the state. Most of them began on October 8, in Northern California. They grew rapidly. The fires were made bigger by winds of up to 50 miles per hour and dry air in the area.

At least 20 people have been killed, the state government said. About 200 have been injured. At least 3,500 homes and businesses have been destroyed. About 50,000 people have been required to escape. Many left in a hurry, without time to take their personal things. “All the good stuff(东西)—I’m never going to see it again,” Jeff Okrepkie said. He escaped from his Santa Rosa home. It was destroyed soon after he left.

The fires burned through parts of eight counties(郡，县). These include Sonoma and Napa. The areas are important to California’s economy(经济). They are home to many of the state’s vineyards(葡萄园) and wineries(酿酒厂). In 2016, California’s wineries made more than $57 billion.

October is when wildfires usually produce the most ruins in California. But it is unusual for so many fires to start at once. Up to now, the government has not given a cause for any of the fires, many of which were still burning.