December 23, 2019

Saturday, December 21, was the winter solstice in the United States and the rest of the Northern Hemisphere. In the Southern Hemisphere—which includes Australia, New Zealand, and other lands south of the equator—the solstice marks the beginning of summer. In Australia, summer is a season known for bushfires. Such wildfires are common in Australia, due in part to the country’s hot and dry climate. Many wildfires start in the remote countryside known to Australians as the bush. Bushfires can be extremely destructive, especially if they reach urban areas. The fires often kill people and destroy property and farmland. They also devastate forests, along with the koalas and other animals that live there.

Police in Jimboomba, Queensland, rescued this koala and her joey from a bushfire in late November 2019. Many other koalas were not so lucky. Credit: Jimboomba Police

A number of major bushfires have plagued Australia in 2019. Late last summer, in February, bushfires consumed more than 50,000 acres (20,000 hectares) of land in northern New South Wales. Far more destructive bushfires ignited again in New South Wales in September, burning nearly 5 million acres (2 million hectares) there and in neighboring Queensland. Some of those fires lasted for weeks, while others continue to burn, turning skies black or orange, causing severe damage, and killing a number of people. The bushfires also killed thousands of vulnerable and slow-moving koalas trapped by the rapidly spreading flames.

Bushfires are relatively common in Australia. These fire-damaged buildings are seen alongside a house that survived Christmas Day bushfires near Melbourne in 2015. Credit: © Julian Smith, EPA/Landov

Koalas live only in the forests of Queensland, New South Wales, and Victoria, in eastern Australia. They are found in significant numbers in only a few areas, and the animals are protected by law. Bushfires, however, ravage the koala’s natural habitat and its population. Koalas cannot escape the fast-moving fires, and their only defense is to climb to the top of a tree, curl into a ball, and hope the flames do not rise to reach them. Koalas sometimes survive this way, but they often burn their paws and claws descending charred trees, leaving them unable to climb properly again.

Koalas are not officially listed as endangered, but the population in New South Wales and Queensland has decreased by more than 40 percent since 1990. The animals are threatened by deforestation and habitat loss, as well as the effects of climate change, which is causing longer and more intense heat waves and droughts, leading to more frequent, intense, and longer-lasting bushfires. Beyond the flames and smoke of the fires, many koalas die from lack of water or exposure to prolonged periods of high temperatures. Australia just suffered through the driest spring in its history, and a brutal heat wave peaked on Dec. 19, 2019, when the highest ever nationwide average temperature—107.4 °F (41.9 °C)—was recorded.

February 11, 2019

Last week, monsoon rains dumped record amounts of water in northern  Queensland, Australia, flooding roads, swelling rivers above their banks, and causing landslides. The coastal city of Townsville received more than 3.3 feet (1.0 meters) of rain, raising the level of water held by the Ross River dam to dangerous levels far above its capacity. On February 3, city officials opened the dam’s gates, intentionally flooding several neighborhoods to ease pressure on the dam and keep it from collapsing. Crocodiles, snakes, and other wildlife followed the waters into the flooded streets, appearing in places they are not typically found. Boats and other vehicles capable of navigating high waters rescued many people and pets trapped by the flooding. Two people are known to have died in the flooding.

Floodwaters inundate the Townsville, Australia, suburb of Idalia on Feb. 4, 2019. Credit: © Ian Hitchcock, Getty Images

Some Queensland farmers welcomed the rainfall. Drought conditions have been widespread in recent months across Australia (where summer is from December to February), and the farmers hoped the rain would help their crops. The monsoon flooding came at the tail end of the hottest month ever recorded by Australia’s Bureau of Meteorology. On February 1, the agency reported that the average January temperature across the continent exceeded 86 ºF (30 ºC). The Australian Capital Territory, New South Wales, the Northern Territory, and Victoria all set new high temperature records for the month of January. Some parts of western Queensland and New South Wales had weeks of temperatures above 104 ºF (40 ºC). Numerous farm and wild animals died in the extreme heat, as did many fish in overheated lakes and rivers.

Despite the monsoon rains in Queensland, much of Australia remains in a drought. Scientists believe that such extreme weather events will become more frequent in coming years as a result of global climate change.

July 26, 2018

The baobab, one of the world’s most unusual and iconic trees, is in danger. The gigantic baobab, known as the “tree of life,” can live as long as 3,000 years. But the hardy trees are suddenly dying in unusual numbers, many long before their expected life spans. Climate change has increased the occurrence of such weather anomalies as droughts, floods, and lightning storms, all of which can harm or kill baobab trees. A destructive mold called black fungus is also appearing more frequently on baobab trees. The tree is further threatened by the loss of its natural habitat to agriculture and development. Habitat loss and illegal hunting have also greatly reduced the population of African elephants, the animals largely responsible for spreading the tree’s seeds. If no action is taken to protect the baobab and its environment, certain species of the tree could be extinct within 100 years.

These giant baobabs form part of the magnificent Avenue of the Baobabs in the Megabe region of western Madagascar. Credit: © Monika Hrdinova, Shutterstock

Baobab is the name of a group of trees that grow in tropical and subtropical regions of the Eastern Hemisphere, especially in Madagascar. The best-known type of baobab is found on the African mainland. It has an extremely thick, often bulging, trunk. This tree may grow to 80 feet (24 meters) tall with a trunk from 30 to 50 feet (9 to 15 meters) in diameter. The tree has white flowers that open at night and are pollinated by bats. The fruit, called monkey bread, is almost 1 foot (30 centimeters) long. It dangles from the tree like a lantern from a long, ropy stem. The fruit holds many seeds buried in a mealy pulp. The pulp, which is rich in vitamin C, serves as food for both animals and people, and it is also used to flavor cool drinks. People sometimes use the leaves and bark in medicines. They make paper, cloth, and rope from the bark fibers. The giant trees also provide shade in the hot climates where they grow, serving as cool gathering places for animals and humans alike.

African elephants, who are themselves in danger, help propagate baobabs by eating the tree’s fruit and seeds (antelopes, baboons, and other animals also contribute). The seeds pass through the animal’s digestive system, and they are then dropped in ready-made fertilizer. Elephants tend to walk great distances in search of food and water, and a single tree’s seeds can thus be spread out over many miles. Ironically, elephants are also known to damage or kill baobab trees in times of severe drought. Elephants sometimes rip apart a baobab’s trunk to get at the tree’s bountiful water supply inside.

Adrian Patrut, a chemist at Babeș-Bolyai University in Romania, has led an international research study on baobab trees since 2005. Patrut pioneered a radiocarbon technique to date baobabs, which do not have the tell-tale age rings found in most trees. Patrut and his team have kept close tabs on the largest and oldest baobabs in southern Africa. They found that 9 of the 13 oldest recorded baobabs (between 1,100 and 2,500 years old) and 5 of the 6 largest have died in the past 12 years—an alarming death rate among these long-living trees. Parts of many other baobabs have also died. The trees have multiple core systems within their massive trunks, allowing parts of the tree to die while the rest lives on.

Of the nine species of baobab trees, six are endemic to the African island of Madagascar. Of those six, half are on the Red List of Threatened Species compiled by the International Union for the Conservation of Nature and Natural Resources (IUCN). The numbers of three Madagascar baobabs—Adansonia grandidieri, Adansonia perrieri, and Adansonia suarezensis—have dropped more than a 50 percent since the 1950′s. A. perrieri and A. suarezensis are considered critically endangered. The numbers of the remaining baobab species that live in mainland Africa, the Arabian peninsula, and Australia are also on the decline.

December 12, 2014

After more than two years of extreme drought, California has been hit by the most powerful storm to cross the state in at least a decade.  A weather system known as a “pineapple express” hammered the north and center of the state with hurricane-force winds and up to 10 inches (25 centimeters) of rain yesterday. (A “pineapple express” is characterized by “an atmospheric river”–a strong and persistent flow of atmospheric moisture–that extends from the waters adjacent to the Hawaiian Islands to the Pacific Coast of North America.)

The storm left more than 220,000 people in northern California without electric power today after heavy rains and high winds slammed the region yesterday. For several hours, San Francisco received more than 1 inch (2.5 centimeters) of rain per hour. Some 240 flights were cancelled at the San Francisco airport, and flooding shut down the city’s Bay Area Rapid Transit system in some areas. The San Francisco Bay Ferry company was forced to cancel all ferry trips across the bay due to the foul weather. The National Weather Service in Sacramento yesterday issued a rare blizzard warning for higher elevations in northern California, and wind gusts in the Sierra Nevada mountains topped 140 miles (225 kilometers) per hour.

A Pineapple Express (circled in red)—basically a river in the atmosphere—dumps huge amounts of rain on California in a short time. During this meteorological event, southwest winds bring warm, moist air to the U.S. West Coast. (National Climate Data Center at the National Oceanic and Atmospheric Administration)

The fast-moving storm is currently pounding southern California, leaving some 70,000 people across the region without electric power and triggering rockslides and mud flows. In some areas of the Los Angeles metropolitan area, rain was falling at a rate of 2 inches (5 centimeters) per hour.

Additional World Book articles:

• Climate
• How the Ocean Affects Climate (a special report)
• Weather Terms—Cloudy or Clear? (a special report)

September 16

Three of 11 wildfires—the Boles, Courtney, and King fires—burning in drought-stricken California have caused thousands of residents to evacuate their homes.  More than 150 structures have been destroyed by the wildfires in the last few days.

A map from the U.S. Drought Mitigation Center shows how extensive the drought is in California (dark red-brown represents extreme drought on the map). Drought has been a contributing factor in the nearly 5,000 wildfires that have burned in the state through mid-September in 2014. This figure represents 1,000 more fires than occur on average in a year, and September and October are the peak months for California wildfires. (Copyright 2014 National Drought Mitigation Center)

The severe drought afflicting California began in January 2012. Currently, 80 percent of the state is affected by extreme drought, characterized by widespread water shortages and restrictions and major loss of agricultural crops. The drought also means that grass and foliage in the state are extremely dry.

Unusually high temperatures—record-high, triple-digit temperatures— began in California on September 12. Yesterday, very high winds created the perfect conditions for raging wildfires. The winds spread the burning embers much faster than firefighters could extinguish them.

In the last 24 hours, the Boles wildfire in northern California destroyed 100 homes in the small town of Weed and caused at least 1,500 to evacuate. Some 300 acres (121 hectares) surrounding the town were burned. The interstate running through Weed was closed for a time and power to the town was knocked out.

Courtney and King fires in central California led to hundreds more evacuations on the same day. The King fire burned over 8,600 acres (3,480 hectares) by today. The Courtney fire has also burned over 300 acres.

Temperatures are predicted to drop in California by this weekend, but the ferocity and number of wildfires this week have strained fire departments across the state.

Additional articles:

• Weather (2013-a back in time article)
• Wildfires (A U.S. Geological Service website)

April 28, 2014

The entire state of California is now suffering from moderate to exceptional drought conditions, according to a recent report from the United States Drought Monitor (USDM). The drought is the worst in the 15-year history of the USDM, which is a joint project by the National Drought Mitigation Center, the National Ocean and Atmospheric Agency, the U.S. Department of Agriculture, and drought observers across the country. The USDM found that the area of California experiencing “extreme drought” has jumped from zero percent in April 2013 to 76.68 percent this month. The area experiencing “exceptional drought” has risen from zero percent to 24.77 percent during the same period. Government officials are deeply concerned about the effect of the drought on drinking water for California communities as well as the state’s valuable agricultural industry. California produces more agricultural products than any other U.S. state. A vast farming region, the Central Valley, is the leading region in the United States for growing fruits, nuts, and vegetables.

Although winter is normally California’s wettest season, 2013 was the driest year in that state’s recorded history, the U.S. National Weather Service (NWS) has reported. The state’s snowpack (snow that accumulates on mountaintops during the winter) was measured at less than one-third of its historical average, according to April data collected by NASA‘s Airborne Snow Observatory.

All of California is now experiencing drought. (U.S. Drought Monitor)

The immediate cause for California’s parched condition is a weather phenomenon that meteorologists have nicknamed the Ridiculously Resilient Ridge. This massive wall of high-pressure air is nearly 4 miles (6.4 kilometers) high and 2,000 miles (3,200 kilometers) long. The ridge, which developed in December 2012, has prevented Pacific winter storms from coming ashore in California. Instead, the storms have been deflected to Alaska and British Columbia. “It’s like the Sierra–a mountain range just sitting off the West Coast–only bigger,” Bob Benjamin, a NWS forecaster told the San Jose Mercury News. “This ridge is sort of a mountain in the atmosphere. In most years, it comes and goes.” This time, however, it came and stayed. Some scientists have speculated that climate change may be keeping the ridge in place.

Additional World Book articles:

• Irrigation
• Losing Ground (a Special Report)
• Parched Earth (a Special Report)

February 6, 2014

The Republican-controlled U.S. House of Representatives passed legislation yesterday designed to address California’s current water shortage. The House bill would, among other things, roll back environmental protections and halt restoration of a dried-up stretch of the San Joaquin River in order to revive salmon runs. Republican members of the House blamed the water shortage on liberal environmentalist policies, arguing that fish were being put ahead of farmers. “We have listened to the environmental left for 40 years, and this is where it’s gotten us,’’ declared Representative Tom McClintock (R., California) on the floor of the House. Another California representative, Ken Calvert, said, “Congress can’t pass a bill to make it rain, but we can pass a bill to put an end to the water shortages that have been caused by misguided regulatory decisions.” Fully 33 percent of available water in California is used for the irrigation of crops. Democrats responded that the problem is simply a lack of rain.

Along with other parts of the West, California is undergoing a third straight year of severe drought. In late January, California Governor Jerry Brown declared a drought emergency, pointing out an extreme need for the conservation of water. He asked Californians to voluntarily reduce their water consumption by 20 percent. This is “perhaps the worst drought California has ever seen since records began being kept about 100 years ago,” stated Brown at a news conference. “We can’t make it rain, but we can be much better prepared for the terrible consequences that California’s drought now threatens, including dramatically less water for our farms and communities and increased fires in both urban and rural areas.”

Much of California's urban water comes from the spring melt of snow from the Sierra Nevada in eastern California. This winter's snowpack is dangerously low. (© Shutterstock)

The months of December through April are usually California’s rainy season, but not this year. Vegetation that typically rehydrates with rain during this period has continued to get dryer, becoming ever more dangerous. In January 2013, there were no wildfires in California; in January 2014, there were more than 400.

Much of the state’s urban water supply comes from the spring melt of the Sierra Nevada snowpack. While a good deal of the United States east of the Rockies has received above-normal amounts of snow this winter, California has received far less than normal. In late January, the California Department of Water Resources (DWR) reported that the Sierra snowpack was only 12 percent of the average amount for this time of the year, a record low. “If we don’t get more storms in here that actually dump some reasonable snowpack by April 1 . . .  [state reservoirs are likely to be] “alarmingly dry during the summer,” warned Dave Rizzardo, chief of DWR’s snow survey section.

Additional World Book articles:

• The Colorado River: Lifeline in the Southwest (a special report)

• How the Oceans Affect Climate (a special report)

• When the Rains Stop (a special report)

November 21, 2013

Drought has driven at least 50 emus into the center of the Queensland city of Longreach in Australia in search of food and water. “Out in the paddocks, there is not a lot of food for them, because emus are really seed eaters,” a Longreach official told ABC News. In early November, the Queensland government declared a little over 62 percent of the state officially in drought. During the past year, much of Queensland has received less than 65 percent of its normal average rainfall. Higher-than-normal temperatures have also made surface water harder to find. Numerous wildfires are burning across the state.

The emu is a large flightless Australian bird. It stands about 5 1/2 feet (1.7 meters) high, weighs about 100 pounds (45 kilograms), and has brownish-black feathers. (© Worakit Sirijinda, Shutterstock)

Longreach officials said there are no plans to remove the swift-running birds from the town. “People just have to be mindful when they see them and be careful and give them right of way,” said a police official, “It doesn’t hurt to slow down and let them cross, because they are under a lot of pressure at the moment looking for food and water for their families.”

Additional World Book articles:

• Outback
• Bushfires in Australia

September 9, 2013

Human activities influenced at least some of the extreme weather events that occurred across the world in 2012, according to new research on the causes of 12 events that occurred on 5 continents and in the Arctic. The research, Explaining Extreme Events of 2012 from a Climate Perspective, included 19 studies conducted by 78 scientists working in 11 countries. All of the events would have occurred even without rising global temperatures, with “natural weather and climate fluctuations” playing “a key role in the intensity and evolution” of the events, the scientists concluded. However, they also reported compelling evidence that human activity—particularly the release of large amounts of carbon dioxide and other heat-trapping greenhouse gases from the burning of fossil fuels—contributed to about half of the events.

Earth’s average surface temperature rose by about 1.4 Fahrenheit degrees (0.76 Celsius degree) from the mid-1800′s to the early 2000′s. Researchers have also found that most of the temperature increase occurred from the mid-1900′s to the 2000′s. Natural processes have caused Earth’s climate to change in the distant past. But scientists have found strong, clear evidence that human activities have caused most of the warming since the mid-1900′s.

A new reports suggests that coastal flooding from ocean storms will increase because of global warming. (AP/Wide World)

The difficulty in determining whether and to what degree human activities are influencing storms, heat waves, and other extreme weather events has made scientists cautious about linking global warming to any particular event. Recent advances in computer modeling and a greater understanding of climate data, however, have greatly improved scientists’ ability to distinguish natural weather factors from human-related factors. The new report has added to scientists’ understanding of the impact that climate change “adds, or doesn’t add, to any extreme event,” said Thomas R. Karl, director of the National Climatic Data Center in Asheville, North Carolina.

The scientists concluded that natural weather patterns were responsible for heavy rains that caused devastating floods in India, China, and Japan and for high summer rainfall in the United Kingdom in summer 2012. In addition, climate change only slightly influenced extreme rains in New Zealand in December 2011 and in Australia from October 2011 to March 2012.

In the United States, climate change had little effect on the drought that struck the midwestern United States in the summer, the scientists reported. However, human activities played a role in the accompanying heat waves that struck that region as well as the eastern United States. Temperatures during these hot spells are higher now than in the past and occur four times as often. The authors of the study also suggested that global warming will increasingly lead to more coastal flooding like that which occurred during Hurricane Sandy.

Some of the strongest evidence involved the record loss of sea ice in the Arctic. The scientists concluded that this loss resulted “primarily from the melting of younger, thin ice from a warmed atmosphere and ocean. This cannot be explained by natural variability alone.”

Additional World Book articles:

• The Great Meltdown (a special report)
• Methane (a special report)
• Meltdown: Climate Change in the Arctic (a special report)
• Probing the History of Climate Change (a special report)
• Twisted–More Terrible Storms (a special report)
• What We Know About Global Warming (a special report)

June 24, 2013

Pyramids, palaces, ball courts, and houses from an ancient Maya city overgrown by centuries of thick jungle vegetation have been discovered in a remote area of southeastern Mexico by scientists from Mexico’s National Institute of Anthropology and History. Occupied from about A.D. 600 until 900, the city has been newly renamed Chactun. The scientists reported that the city, which covered about 54 acres (22 hectares), is the first ancient Maya complex found in a now heavily forested area of Campeche province in the western Yucatán Peninsula. Also found at the site were plazas and altars as well as stone monuments called stelae. The name “K’inch B’ahlam,” which may refer to one of the city’s rulers, was carved on one stele.

The scientists discovered Chactun while examining aerial photographs of the area. Visiting the site required hacking their way along paths once used by loggers and workers who tapped the area’s rubber trees.

The Maya civilization reached its peak from about A.D. 250 to 900. During that time, known as the Classic Period, it was centered in the tropical rain forest of the lowlands of what is now northern Guatemala. By about 900, most of the Maya abandoned the lowlands and moved to areas to the north and south, including Yucatán and the highlands of southern Guatemala. In those areas, they continued to prosper until Spain conquered almost all of the Maya in the mid-1500′s. Scholars are still trying to discover the reasons for the collapse of Classic Maya society in the lowlands. Some experts point to a combination of such factors as overpopulation, disease, exhaustion of natural resources, crop failures, warfare between cities, and the movement of other groups into the Maya area.

In a study published in November 2012, a research team headed by environmental archaeologist Douglas Kennett of Pennsylvania State University concluded that a 100-year drought played a major role in the collapse of the Classic Maya society. The drought, which plagued the lowlands from 1020 to 1100, had followed a drying period that began in about 660. According to Kennett, Maya writings from this period link the drought to widespread famine, disease, and wars, among other disruptive events.

Additional World Book article include:

• Chichén Itzá
• Copán
  
• Mexico (History of)
• The Ancient Maya: Deciphering New Clues (a special report)
• Archaeology (1924) (a Back in Time article)