The Swedish environmental activist Greta Thunberg (holding sign) marches in a 2019 protest organized by students. As a teenager, Thunberg became known for her boldness in confronting adult politicians for their inaction on climate change due to global warming.
Credit: © Alexandros Michailidis, Shutterstock

April 22 is Earth Day, an annual observance to increase public awareness of environmental issues. Each year on Earth Day, millions of people throughout the world gather to clean up litter, protest threats to the environment, and celebrate progress in reducing pollution.

Earth Day began in the United States. In 1969, the U.S. Senator Gaylord A. Nelson suggested that a day of environmental education be held on college campuses. The following year, the lawyer and environmentalist Denis Hayes, then a recent graduate of Stanford University, led hundreds of students in planning and organizing the observance of Earth Day on April 22, 1970. About 20 million people participated in this celebration.

The observance of Earth Day in 1970 helped alert people to the dangers of pollution and stimulated a new environmental movement. That same year, Congress created the Environmental Protection Agency to set and enforce pollution standards. Congress also passed the Clean Air Act of 1970, which limited the amount of air pollution that cars, utilities, and industries could release. Other new environmental laws soon followed.

One modern champion for the environment is the Swedish activist Greta Thunberg. She has worked to convince politicians to take action against climate change due to global warming. Global warming is an observed increase in Earth’s average surface temperature. As a teenager, Thunberg became known for her boldness in confronting adult politicians for their inaction on climate change. She has called upon leaders to reduce emissions of greenhouse gases, mainly carbon dioxide. Such gases trap heat in the atmosphere, warming the planet’s surface.

Thunberg was born in Stockholm, Sweden, on Jan. 3, 2003. She was diagnosed with autism spectrum disorder at a young age. As a child, she showed an interest in environmental issues. She convinced her family to reduce their carbon footprint by becoming vegan and giving up air travel. Carbon footprint is a measure of the greenhouse gas emissions associated with human activities.

In 2018, at the age of 15, Thunberg protested for action on climate change outside the Swedish parliament, inspiring other student protesters. Together, they organized school strikes to demand action on climate change. In August 2019, Thunberg sailed across the Atlantic Ocean from Plymouth, in the United Kingdom, to New York City, in the United States, on a “carbon neutral” voyage. Thunberg sailed aboard a yacht that got its electric power from solar panels and underwater turbines. While in the United States, she addressed the United Nations as part of its Climate Action Summit. During her speech, she announced that she and a group of other children were filing a lawsuit against five nations not on track to meet their emission-reduction targets under the Paris Agreement. The Paris Agreement is a global treaty designed to fight global warming.

Tulips are colorful garden flowers that bloom in the spring. Tulip leaves and the flower stem grow directly out of a bulb.
Credit: Derek Fell

Spring has sprung! Sunday, March 20th, was the vernal equinox, the official marker of the spring season in the Northern Hemisphere. The equinox occurs when the sun is directly above Earth’s equator. When the sun is in this position, all places on Earth receive approximately 12 hours of sunlight. The term equinox comes from a Latin word meaning equal night.

The equinoxes occur on March 19, 20, or 21 and on September 22 or 23. In the Northern Hemisphere, the March equinox marks the start of spring and is often called the vernal equinox. The position of the vernal equinox is called the first point of Aries. The word vernal means of spring. The September equinox marks the beginning of autumn and is called the autumnal equinox. The seasons are reversed in the Southern Hemisphere.

The equinoxes are the two moments of the year when the sun is directly above the equator. As Earth moves in its orbit around the sun, the position of the sun changes in relation to the equator, as shown by the dotted lines in this diagram. The sun appears north of the equator between the March equinox and the September equinox. It is south of the equator between the September equinox and the next March equinox.

The time interval from the March equinox to the September equinox is longer than that between the September equinox and the next March equinox by several days. This time difference results from the earth’s elliptical (oval-shaped) orbit around the sun. The earth moves faster in its orbit when it is closer to the sun. The distance between the earth and the sun is shortest in January. Therefore, the earth completes the semicircle from the September equinox to the March equinox faster than it does the opposite semicircle.

Historically, the year began with spring in many cultures. Evidence of this practice in ancient Rome remains part of the modern calendar. Counting March instead of January as the first month of the year, we find that September, October, November, and December are the seventh, eighth, ninth, and tenth months. The prefixes sept-, oct-, nov-, and dec- come from the Latin words for 7, 8, 9, and 10.

Spring looks different around the world. The Northern Hemisphere has spring weather from late March through May. In the Southern Hemisphere, spring weather begins in September and lasts through November. The number of daylight hours increases during spring, particularly in the polar regions, and the temperature rises. Nature awakens in spring. Flowers bloom, and hibernating animals leave their winter sleeping places. Many cultures have festivals that celebrate the arrival of spring. Find your own way to celebrate spring this year. Spring is a new beginning, enjoy the flowers, longer days, and warmer weather!

Brontosaurus.
Credit: © Emiliano Troco

Sauropods were the most spectacular of the dinosaurs. Their long necks supported small heads that took in needles and leaves. Despite such a nutrient-poor diet, they reached sizes and lengths unparalleled in any other terrestrial (land-dwelling) animals. How—and why—did they get so large? A recent study may have discovered a lead to unraveling the physiology of these amazing animals. 

Over tens of millions of years, the arrangement of the continents has shifted through the action of plate tectonics. Geologists can trace how a location has moved over the face of Earth to determine its paleolatitude. The paleolatitude is the position of a point on the Earth’s surface in relation to the equator at a time in the distant past. Both latitude and paleolatitude are measured on a scale of 0° (the equator) to 90° (the poles). Higher latitudes experience cooler temperatures and less sunlight in winter. 

Dinosaurs reigned during the Mesozoic Era—a time of warmer climates. Despite the planet being largely ice-free, regions near the poles still faced cold winters and weeks or months without sunlight. Nevertheless, dinosaurs have been found at high paleolatitudes, including in Antarctica and Alaska. At least some of these dinosaurs remained there through the winter. 

Sauropod fossils, however, are conspicuously absent from these polar locations. No sauropod fossil has been discovered from a paleolatitude higher than about 65°. Instead, these chilly climates were strictly occupied by meat-eating theropods and some plant-eating dinosaurs called ornithischians. 

Some paleontologists (scientists who study prehistoric life) suspected the absence of fossils suggest that sauropods preferred warmer climates. But others thought that sauropods might not have fossilized well near the poles for some reason, or that the fossils are still waiting to be discovered. 

A team led by Alfio Alessandro Chiarenza of the University of Vigo in Spain analyzed the paleolatitude of all the places where sauropod fossils have been found. The team published their findings last month in the scientific journal Current Biology. They determined that the absence of sauropods at high paleolatitudes was not due to incomplete sampling. Chiarenza’s team used models of the Mesozoic climate and found that sauropods preferred savanna-type habitats. Sauropod ranges were tightly constrained by the lowest predicted temperature. 

Why didn’t (or couldn’t) sauropods brave the cold? They might have cooled down too quickly, despite their massive sizes. Many theropods—and possibly some ornithischians—had downy or hairlike feathers that could be used to keep them warm. Sauropods lacked any such insulation. Furthermore, a sauropod’s long necks and tails might have lost heat quickly when exposed to bitter-cold winds. 

Sauropods buried their eggs in the earth to keep them at a stable temperature. But this method probably would not have kept the eggs warm enough in cold climates. In contrast, theropods sat on their eggs and ornithischians covered their eggs in rotting plants. Both of these approaches could keep the eggs warm even in cold climates. 

Chiarenza’s team proposes that sauropods did not possess as high of a metabolism as theropods and ornithischians. Historically, scientists have classified animals as endothermic (“warm-blooded”) or ectothermic (“cold-blooded”). Endothermic animals tend to produce more of their own body heat, while ectothermic animals tend to rely more on their environment for heat. This is a false division, since every animal is somewhat reliant on its environment for heat. But animals classified as endothermic can usually survive in cooler temperatures. Reptiles, the classic endotherms, are concentrated near the equator. 

In many ways, this makes a lot of sense. A lower metabolism would have enabled sauropods to survive on less food. Their huge size would cause them to lose less heat to their environment, much like a well-insulated building. Growing evidence suggests that the ancestor of dinosaurs and crocodilians (a group of reptiles) had a high metabolism, but crocodilians “slowed down” when dinosaurs took over most environmental niches. A similar changed might have occurred in sauropods as well, enabling them to attain colossal sizes. Sometimes slow and steady wins the race. 

Part of a roof lays in front of a home, destroyed by a powerful tornado in Defiance, Missouri on Sunday, December 12, 2021. A tornado hit the small town west of St. Louis on Friday, December 10, 2021, destroying 25 homes and killing one.
Credit: © Bill Greenblatt, UPI/Alamy Images

Devastating tornadoes tore through Arkansas, Illinois, Kentucky, Mississippi, Missouri, and Tennessee on Friday, Dec. 10, 2021. At least 22 tornadoes were reported throughout the 6 states. The storm started with a powerful thunderstorm, which meteorologists believe generated the tornadoes. The largest of the tornadoes broke United States history as the longest tornado. From touch down to the point where the tornado picked back up, the tornado measured 227 miles (365 kilometers).

Most of the destruction occurred in western Kentucky. Although tornadoes can occur any time of the year, they are more common in spring and summer. Tornadoes rarely form in Kentucky in the month of December. In Mayfield, Kentucky, a tornado hit a candle factory where 110 people were working the night shift. The building collapsed in the storm. Reports show eight people from the factory were killed in the storm and six people are still missing. At least 64 people have been confirmed dead in Kentucky with more than 105 people still missing. Rescue efforts are still underway to locate missing people. On Sunday, President Joe Biden approved Kentucky’s request for assistance from the Federal Emergency Management Agency (FEMA).

More than a dozen people were killed from the storms in Illinois, Tennessee, Arkansas, and Missouri. The storms hit an Amazon warehouse in Illinois, killing six people. One tornado tore through a nursing home in Arkansas, killing one resident. Rescue workers and family members are still searching for missing people throughout the wreckage. Thousands of businesses, houses, and schools have been damaged. Across the affected states, more than 50,000 people have been without electricity since the storm Friday night. Rescue efforts have been complicated because many power lines and cell towers were damaged in the storms.

The elk with a tire around its neck was first spotted in July 2019 by a Colorado wildlife officer in Mount Evans Wilderness.
Credit: Jared Lamb, Colorado Parks and Wildlife

School, homework, canceled activities, and retail shortages may have you feeling tired. But wildlife officials in October reached out to help an elk that was literally tired—the elk had spent two years with a tire stuck around its neck.

The bull (male) elk got a real weight off his shoulders on Oct. 9, 2021, when Colorado Parks and Wildlife officers removed the tire from around his neck. The oddly accessorized elk was originally spotted in July 2019 by a wildlife officer conducting a count of bighorn sheep and mountain goats in Mount Evans Wilderness. The Mount Evans Wilderness covers some 74,401 acres (30,109 hectares) of woods about 40 miles (64 kilometers) west of Denver. Officials had made four attempts to remove the tire over the previous week but were unsuccessful.

Officers do not know how the elk got the tire stuck on his neck. In Colorado, wildlife officials tranquilize about ten bull elk and buck (male) deer each year to remove objects from their necks. Many wild animals get stuck in basketball hoops, hammocks, buckets, laundry baskets, holiday decorations, and other objects. Wildlife officials asked residents of central Colorado to keep an eye out for the elk and to alert them to any sighting. There had been six sightings of the tired elk over the previous two years, mostly on trail cameras. Officials had been working tirelessly to locate and help this particular elk until resident Patrick Hemstreet reported the elk was in a herd of 40 just outside his house in Pine, Colorado. Hemstreet texted Dawson Swanson, a wildlife official who lives nearby.

The American elk is a large deer. The bull stands about 5 feet (1.5 meters) high at the shoulder and may weigh from 700 to 1,100 pounds (320 to 500 kilograms). Its rounded antlers can span more than 5 feet (1.5 meters). The antlers of a grown bull will have a total of about 12 to 14 points. Antlers grow during the spring and summer and are shed in late winter, so wildlife officials believe the elk got the tire stuck either in the winter or early spring. Cows, female elks, are smaller and do not have antlers. During September and October, bulls fight one another to gain control over harems, groups of cows. This activity distracts the elks from the presence of humans around them, making it a convenient time for officers to get the tire off.

Once the officers tranquilized the elk, they determined the animal was about 600-pounds (275 kilograms) in weight and 4 1/2 years old. The officers tried to cut the tire, but they were unable to do so when its steel reinforcement belts broke their saw. Luckily, there was still room around the elk’s neck to remove the tire after cutting off the antlers. The inside of the tire was packed with over 10 pounds (4.5 kilograms) of soil and pine needles. The elk’s neck was in good condition despite carrying around the heavy tire with debris for so long, and the elk’s antlers will grow back. After officials revived the elk, it quickly woke up, stood up, and walked away—tired no more. The officials kept the antlers and retired from their search.

A diver swims over the two-masted schooner Walter B. Allen, which sank in Lake Michigan 1880.
Credit: Tamara Thomsen, Wisconsin Historical Society

Off the lakeshore in Wisconsin, dozens of ships lie under the surface. In October 2015, the National Oceanic and Atmospheric Administration (NOAA) announced a new national marine sanctuary. In June 2021, the NOAA officially designated the Wisconsin Shipwreck Coast National Marine Sanctuary in Lake Michigan. Marine sanctuaries are protected waters, habitats, and archeological sites. In this case, NOAA’s sanctuary protects archeological, cultural, historic, and prehistoric artifacts, along with all historic shipwreck sites that served an important role in maritime heritage. The NOAA and the state of Wisconsin are co-managing the sanctuary.

The area is 726 square nautical miles (962 square miles or 2,492 square kilometers) along the coasts of Manitowoc, Port Washington, Sheboygan, and Two Rivers. The sanctuary protects 36 known shipwrecks. Of those, 21 are in the National Register of Historic Places. Because of Lake Michigan’s cold temperature and lack of salt, these shipwrecks are preserved with more integrity than usual, and some remain mostly intact. Researchers believe there are up to 59 shipwrecks in the sanctuary. Wisconsin spent three decades preserving historic maritime sites against human and natural activities. The sanctuary provides opportunities for archeological preservation, research, and education.

The shipwrecks have historical significance. They include the two oldest known shipwrecks in Wisconsin. From the 1800’s through the 1900’s, the Great Lakes were used to ship such goods as coal, grain, and manufactured goods. Hundreds of thousands of settlers used the lakes to move to the Midwest and West of the United States. Midwestern cities, farms, and industries grew as a result.

In this photograph from July 2021, One World Trade Center (left) and other New York City buildings are shrouded by smoke and haze from wildfires in western North America.
Credit: © Bjoern Kils, New York Media Boat/Reuters/Alamy Images

Have you looked at the sun or moon low in the sky in the past few weeks? You may have noticed them take on hues of orange and red. A hazy film may have blurred out the horizon. These visual effects were caused by smoke and haze from fires in western North America, in what is shaping up to be another record wildfire season. So far this year, wildfires have scorched nearly 3 million acres (1.2 million hectares) in the United States alone.

The Dixie Fire is the largest in California, burning almost 250,000 acres (100,000 hectares). It began near where the deadly Camp Fire burned in 2018, killing more than 80 people. Both fires were sparked by equipment from the utility company Pacific Gas and Electric Co. (PG&E). This month, PG&E announced its intent to bury 10,000 miles (16,000 kilometers) of power lines in areas of the state most at risk for wildfires. The project—which PG&E had long resisted—is estimated to cost at least $15 billion.

California usually dominates the wildfire season. The largest fire of the season, however, belongs to Oregon. The Bootleg Fire started on July 6 and has burned more than 400,000 acres (160,000 hectares). The fire persevered through rain and continues to defy efforts to contain it.

The Bootleg Fire threatened Mitchell Monument, dedicated to the only civilians killed on U.S. soil during World War II (1939-1945). Toward the end of the war, Japan released more than 9,000 bomb-carrying balloons, intended to land on the West Coast of the United States. The bombs caused mostly minor damage. But one bomb killed five members of a picnicking family near Bly, Oregon. Firefighters battling the Bootleg blaze worked to save the forest around the monument, including trees damaged by the bomb blast.

Nearby Idaho and Montana also have dozens of fires. The Canadian province of British Columbia declared a state of emergency due to the hundreds of wildfires raging there. The government of Mexico sent firefighters to the province to assist. Outside North America, fires burned in Greece, Turkey, Russia, and Italy.

Smoke from the North American fires drifted east on the prevailing winds, reducing air quality across the continent. Air quality was affected as far away as New York City. The smoke threatened people with such medical conditions as asthma, chronic obstructive pulmonary disease (COPD), and heart disease.

Climatologists and other experts blame the severe fire outbreaks on the intense drought gripping the western half of the continent. In June, a sizzling heat wave killed hundreds of people in Oregon, Washington, and British Columbia. Experts strongly suspect the drought and heat were intensified by climate change.

Credit: © Uwe Bergwitz, Shutterstock

Australia is famous for its unique culture, metropolitan cities, and unusual wildlife, among other things. Each week, this seasonal feature will spotlight one of Australia’s many wonders.

If you could eat 1,000 somethings in one day, what would you choose? Slices of pizza? Chunks of chocolate? Florets of broccoli?

The small Australian lizard called the thorny devil would choose 1,000 somethings that are a little… different.

The thorny devil, also called the thorny dragon or mountain devil, eats 1,000 ants in a day. And, it does this day after day, because the thorny devil feeds exclusively on ants.

Thorny devils live in dry, sandy areas, including deserts and sandy grasslands and scrublands. They are found from Australia’s interior to the coast of Western Australia.

Thorny devils reach up to 8 inches (20 centimeters) in length. They are covered in spines of keratin, a tough material also found in human hair and nails. Their skin has a banded appearance. The skin color changes with temperature. Thorny devils may appear olive to brown in the cool of the desert morning and evening. They may appear pale yellow and red in the midday heat.

Thorny devils are solitary animals. The thorny devil is active in the daytime. It feeds by positioning itself near an ant trail, using its sticky tongue to slurp up ants. The devil’s teeth are specialized for shearing tough ant exoskeletons (outer coverings).

The thorny devil has a unique way of getting water in dry environments. Its spines are surrounded by a network of microscopic grooves. The grooves draw in dew and other moisture from the lizard’s surroundings through an effect called capillary action. The grooves channel this water to the lizard’s mouth.

Thorny devils are preyed upon by larger lizards and birds. The devil’s spines may help to discourage predators. The animal can also puff itself up with air when threatened. The thorny devil walks with a slow, jerky movement that is thought to confuse predators. A large knob on the lizard’s neck may also confuse predators, appearing as a false head.

Thorny devils are active in the spring and fall. They take refuge in underground burrows during the hottest months of summer and the coldest months of winter. Thorny devils mate in the late winter and early spring. The female lays 3 to 10 eggs in a burrow 12 inches (30 centimeters) deep. The eggs hatch in three to four months. Thorny devils can live to about 20 years in the wild.

Periodical cicada
Credit: © Thinkstock

They’ve waited underground for 17 years. Now, they’re coming to the surface to burst out of their skins, give off earsplitting screeching sounds, bore into trees, and cover the ground with their carcasses. But—like many blockbusters over the past year and a half—you can’t view this spectacle in movie theaters. You can’t even stream it on Netflix. If you live in the eastern U.S. Midwest or Middle Atlantic, this summer’s invasion is coming to a backyard or forest preserve near you. It’s called Brood X.

Brood X is not a movie, but a group of cicadas emerging this month. A cicada is a large insect with four thin wings which it folds over its body like a peaked roof. It can measure 1 to 2 inches (2.5 to 5 centimeters) long. It has a wide head and short, bristlelike antennae (feelers).

Just as crickets serenade us on warm summer nights, cicadas make up the soundtrack of hot summer afternoons. The male cicada makes two drumlike membranes (thin sheaths of skin) on the abdomen vibrate rapidly. This produces a characteristic buzzing sound. The sound attracts females or calls large numbers of males together. Each species (kind) of cicada has its own song. Male cicadas often assemble in large groups and produce a loud chorus of sounds.

Many of us hear cicadas every summer. So why is this summer different? There are thousands of species of cicadas. They can be roughly divided into two types: annual cicadas and periodical cicadas. As their name suggests, annual cicadas can be heard every year. But periodical cicadas emerge on 13- or 17-year cycles. Brood X is a 17-year periodical cicada, having last emerged in 2004. Other brood numbers (X is the Roman numeral for 10) emerge in different years in different regions. But Brood X is one of the largest and most famous.

Why do periodical cicadas emerge this way? It has to do with evading predators. Cicadas are a hearty, protein-packed snack for birds, raccoons, foxes, opossums, fish, spiders, and practically any other animal. Humans eat them, too! Cicadas are vulnerable when they are emerging. They don’t bite or sting and are clumsy flyers. But when so many cicadas emerge at once, there are just too many for predators to eat. Even with every predator’s belly filled with cicadas, billions or trillions survive to reproduce.

Seventeen years is a long time. Potential predators can’t rely on a food source that appears so infrequently. So, although animals take advantage of the cicada smorgasbord, nothing has evolved to rely on them exclusively.

Where do periodical cicadas go for all those years? After the adults mate, the female bores into twigs of bushes and trees with a sawlike organ near the tip of her abdomen. She lays her eggs in the holes. The eggs hatch in a few weeks and the young cicadas, called nymphs, drop to the ground. They live in the soil and eat roots for years—17 years in the case of Brood X.

The periodical cicadas will spend the summer shedding their skins and making lots of noise. However you decide to spend your summer, have fun and keep an ear out for Brood X!

Swedish environmental activist Greta Thunberg
Credit: © Alexandros Michailidis, Shutterstock

April 22 is Earth Day, an annual observance to increase public awareness of environmental issues. Each year on Earth Day, millions of people throughout the world gather to clean up litter, protest threats to the environment, and celebrate progress in reducing pollution.

Earth Day began in the United States. In 1969, the U.S. Senator Gaylord A. Nelson suggested that a day of environmental education be held on college campuses. The following year, the lawyer and environmentalist Denis Hayes, then a recent graduate of Stanford University, led hundreds of students in planning and organizing the observance of Earth Day on April 22, 1970. About 20 million people participated in this celebration.

The observance of Earth Day in 1970 helped alert people to the dangers of pollution and stimulated a new environmental movement. That same year, Congress created the Environmental Protection Agency to set and enforce pollution standards. Congress also passed the Clean Air Act of 1970, which limited the amount of air pollution that cars, utilities, and industries could release. Other new environmental laws soon followed.

One modern champion for the environment is the Swedish activist Greta Thunberg. She has worked to convince politicians to take action against climate change due to global warming. Global warming is an observed increase in Earth’s average surface temperature. As a teenager, Thunberg became known for her boldness in confronting adult politicians for their inaction on climate change. She has called upon leaders to reduce emissions of greenhouse gases, mainly carbon dioxide. Such gases trap heat in the atmosphere, warming the planet’s surface.

Thunberg was born in Stockholm, Sweden, on Jan. 3, 2003. She was diagnosed with autism spectrum disorder at a young age. As a child, she showed an interest in environmental issues. She convinced her family to reduce their carbon footprint by becoming vegan and giving up air travel. Carbon footprint is a measure of the greenhouse gas emissions associated with human activities.

In 2018, at the age of 15, Thunberg protested for action on climate change outside the Swedish parliament, inspiring other student protesters. Together, they organized school strikes to demand action on climate change. In August 2019, Thunberg sailed across the Atlantic Ocean from Plymouth, in the United Kingdom, to New York City, in the United States, on a “carbon neutral” voyage. Thunberg sailed aboard a yacht that got its electric power from solar panels and underwater turbines. While in the United States, she addressed the United Nations as part of its Climate Action Summit. During her speech, she announced that she and a group of other children were filing a lawsuit against five nations not on track to meet their emission-reduction targets under the Paris Agreement. The Paris Agreement is a global treaty designed to fight global warming.