June 2, 2017

Yesterday, June 1, United States President Donald Trump announced that the United States would formally withdraw from the Paris Agreement, an international treaty designed to combat global warming. The decision to withdraw from the treaty represented a sharp break with leaders of nearly all nations and went against the wishes of thousands of corporate executives, economists, environmentalists, other U.S. politicians, scientists, and even members of the president’s own Cabinet. Trump’s decision to withdraw from the treaty met with immediate international and domestic scorn and spurred numerous protests.

On June 1, 2017, protesters gather outside the White House in Washington, D.C., moments after President Donald Trump announced that the United States would withdraw from the Paris Climate Agreement. Credit: Kellybdc (licensed under CC BY 2.0)

By joining the Paris Agreement in 2015 and ratifying it in 2016, the United States had voluntarily committed to cut back on the use of polluting fossil fuels, develop more green (environmentally friendly) technology, and raise funds to help poorer countries reduce their greenhouse gas emissions. Trump, who has previously called climate change a “hoax,” sees these commitments as an unfair economic burden on the United States. Most evidence, however, shows that climate change is real and that moving to green technology actually stimulates economic growth.

The goal of the Paris Agreement is to slow and eventually cease the rise in global temperatures that has sharply increased in the last few decades. Scientists predict that, if global warming continues unchecked, it will damage human society and the environment. For example, global warming could melt enough of the ice near Earth’s poles to raise sea levels, flooding many coastal cities. Global warming could lead to more widespread droughts. It could also raise the risk of extinction for many plant and animal species. Already, global warming has greatly reduced glaciers at the North and South poles, harmed the world’s coral reefs, and created ever more erratic and extreme weather patterns.

Withdrawing from the Paris Agreement is a lengthy process that will take until November 2020 to complete, leaving time for the United States to rejoin the treaty. A number of U.S. cities and states have already announced they will continue to comply with the provisions of the Paris Agreement whether the federal government does or not.

May 18, 2017

Glacier National Park in northwestern Montana may soon be without any of its trademark glaciers. Many of the park’s largest glaciers have lost much of their former size in the last 50 years, according to surveys published by the United States Geological Service (USGS) and Portland State University in Oregon. Steadily rising temperatures have dramatically reduced 37 of the park’s glaciers that are large enough to have individual names. Some have lost as much as 85 percent of their bulk.

Melt water from the Gem, Grinnell, and Salamander glaciers feeds the lakes of Grinnell Valley in Montana’s Glacier National Park. Credit: Tim Rains, National Park Service

A glacier is a large mass of ice that flows slowly under the influence of gravity. Glaciers consist of packed snow that has built up over many years. The snow’s weight eventually compresses its lower layers into ice. Glaciers scrape the ground as they move over it, eroding old landforms and creating new ones. They range in thickness from several feet or meters to 10,000 feet (3,000 meters) or more.

Click to view larger image
The retreat of a mountain glacier can provide visible evidence of global warming. These photographs show two late-summer views of Grinnell Glacier in Glacier National Park, Montana. In the photo taken around 1940, top, Upper Grinnell Lake had only begun to form at the glacier’s end. By 2006, bottom, melting ice had caused the lake to swell in size. Researchers predict that warming will melt all of the park’s glaciers by 2030. Credit: Glacier National Park Archives, top,U.S. Geological Survey, photograph by Karen Holtzer, bottom

Glacier National Park was named for the large number of glaciers found there. In 1850, the area had about 150 glaciers. Large glaciers in the park today include the Grinnell and Blackfoot glaciers. Over the past 50 years, scientists used digital maps from aerial photography and satellites to measure the glaciers in late summer when seasonal snow has melted to reveal the boundaries of the glacial ice. Surveys were conducted in 1966, 1998, 2005, and 2016. Since the first survey in 1966, the glaciers have shrunk by an average of 39 percent. Today, the park has just 26 ice masses large enough to qualify as glaciers.

Scientists blame this dramatic glacier melt on global warming, and they predict Glacier National Park will be without any glaciers at all by 2030. This is troubling news for the state of Montana, where more than 2 million tourists take in the scenic views at Glacier National Park each year. Experts worry that the glacier loss will also have serious damaging effects on the ecosystems of the park and surrounding Rocky Mountain habitats.

January 27, 2017

Last week, the United States National Aeronautics and Space Administration (NASA) and the U.S. National Oceanic and Atmospheric Administration (NOAA) announced that 2016 was the hottest year on record, setting a new record for the third consecutive year. The average land and ocean surface temperature was 58.69 ˚F (14.83 ˚C), 1.69 Fahrenheit (0.94 Celsius) degrees warmer than the global average during the 1900’s. Sixteen out of the 17 warmest years on record have occurred since 2001, one of many clear indicators that the planet is warming.

This global heat map covering 2012 through 2016 shows areas with the sharpest temperature increases in red. White areas indicate Earth’s few remaining “cool” spots.  Credit: NASA

Global warming is an increase in the average temperature at Earth’s surface. People often use the term global warming to refer specifically to the warming observed since the mid-1800’s. Scientists estimate that Earth’s average surface temperature has risen by about 1.4 Fahrenheit (0.78 Celsius) degrees since 1880. Researchers have also found that most of the temperature increase occurred from the mid-1900’s to the 2000’s.

This chart clearly shows the sharp rise in global temperatures since 1980. Note the temperature spike coinciding with World War II (1939-1945). Credit: NOAA/NESDIS/NCEI

The record heat of 2014 topped the previous high by just 0.07 Fahrenheit (0.4 Celsius) degrees. Since then, however, record temperatures jumped by 0.29 Fahrenheit (0.16 Celsius) degrees in 2015 and 0.36 Fahrenheit (0.20 Celsius) degrees in 2016. The recent strong El Niño event, which began in mid-2014, contributed to the record-shattering heat. An El Niño is a part of the interaction between Earth’s atmosphere and the tropical waters of the Pacific Ocean. An El Niño occurs about every two to seven years, and it can affect the climate throughout the world.

El Niño was not the primary cause for the record heat, however. Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, estimated that the El Niño effect contributed just 0.09 Fahrenheit (0.05 Celsius) degrees to 2015′s record 1.62 Fahrenheit (0.90 Celsius) degrees increase and only 0.22 Fahrenheit (0.12 Celsius) degrees of 2016′s 1.69 Fahrenheit (0.94 Celsius) degrees record. Climate scientists agree that human activities, such as the release of carbon dioxide and other gases into the atmosphere, are responsible for the warming trend seen over the last several decades.

The recent El Niño ended in in the spring of 2016, and a La Niña cooling event emerged at the end of the year. Because of this development, almost all climate scientists agree that 2017 will not be as hot as 2016. But La Niña conditions are already declining, and some models predict another El Niño could begin as early as the middle of 2017.

The 2016 election of Donald Trump as president of the United States created new problems for climate scientists and environmentalists trying to slow global warming. Much of the momentum gained by last year’s Paris Climate Agreement has been halted by Trump, who has claimed that climate change is a hoax and has vowed to back out of the agreement. Working with Trump, the Republican-controlled U.S. Congress is preparing to dismantle many of the environmental regulations put in place or strengthened by former President Barack Obama. China and the other signatories of the Paris Agreement may have to act without the United States to try to prevent the direst effects of global warming. Trump’s administration has already removed climate change websites from numerous government agencies, and on Jan. 24, 2017, Trump banned government agencies from mentioning climate change on press releases and social media posts and from discussing the issue with other public officials.

November 8, 2016

Yesterday, November 7, officials from around the world gathered in Marrakech, Morocco, for the 2016 United Nations (UN) Climate Change Conference, or COP22. COP22 is an acronym for the 22nd annual session of the Conference of the Parties. The meetings come on the heels of the Friday, November 4, entry into force of COP21’s Paris Climate Agreement. One hundred countries—including the two considered to be the greatest polluters, China and the United States—have ratified the agreement for nations to report their greenhouse gas emissions.

UN Secretary General Ban Ki-moon (second left); Christiana Figueres (left), executive secretary of the UN Framework Convention on Climate Change; Laurent Fabius (second right), minister for foreign affairs of France and president of the UN Climate Change Conference in Paris (COP21); and French President François Hollande (right) celebrate the signing of the historic Paris Climate Agreement in April 2016. The agreement went into effect on Nov. 4, 2016. Credit: © Mark Garten, UN Photo

Most scientists believe that greenhouse gas emissions contribute to global warming. Global warming is an increase in the average temperature at Earth’s surface, specifically the warming observed since the mid-1800’s. If it continues unchecked, it may melt ice on land near Earth’s poles, raising sea levels; lead to widespread droughts; and cause certain plant and animal species to become extinct. Natural processes have caused Earth’s climate to change in the distant past. But scientists have found strong evidence that human activities have caused most of the warming since the mid-1900’s. These activities include the release of such greenhouse gases as carbon dioxide into the atmosphere, where the gases trap heat like a blanket around Earth.

Countries that have ratified the Paris Climate Agreement must assess and report their emissions levels every five years. However, they are not obligated to lower emission levels. Officials hope that such “name and shame” practices will encourage countries to do their best to reduce emissions. Now that the agreement has entered into force, the Marrakech conference is being called the “COP of Action.” Talk has shifted from finger-pointing and negotiation to working out action plans to slash greenhouse gas emissions.

In some cases, action plans have already been developed. A few weeks ago, in the African country of Rwanda, officials agreed to phase out the production of hydrofluorocarbons (HFC’s). HFC’s are a type of molecule used as a refrigerant in air conditioning and refrigeration systems. They were originally designed as a replacement for chlorofluorocarbons (CFC’s), which were found to damage the Earth’s protective ozone layer. Unfortunately, HFC’s were later discovered to be incredibly potent greenhouse gases, up to 12,000 times more powerful than carbon dioxide. Scientists estimate that the phase-out will prevent 0.9 °F (0.5 °C) of warming during the next century alone. Also last month, aviation industry officials met in Montreal, Canada, and agreed to cap the emissions of greenhouse gases on international flights.  The pact is not as strict as many scientists had hoped, and will only take effect in 2021. Nevertheless, it serves as a first step in controlling the greenhouse gas output of an industry that has largely resisted regulation.

November 7, 2016

Under water, the box jellyfish is practically invisible. It is one of the most venomous animals on Earth. It kills more people each year than sharks do. At most, however, it weighs only about 4½ pounds (2 kilograms). This Monster Monday critter packs a lot of pain into a small package.

The sting of a box jellyfish can kill a person within minutes. Credit: © Visual&Written SL/Alamy Images

Chironex fleckeri, called the box jellyfish or sea wasp, is a dangerous stinging jellyfish found in the waters of northern Australia and Oceania. Similar species are also known as box jellyfish and have painful stings, but few are as painful as that of C. fleckeri. The creature has a box-shaped body that reaches about 15 inches (38 centimeters) across. The sea wasp has clusters of tentacles, with up to 15 tentacles in each cluster. The tentacles may reach about 10 feet (3 meters) in length. The tentacles contain billions of tiny capsules, many of which hold a poisoned barb.

Box jellyfish have sophisticated adaptations for active hunting that other jellyfish lack. Unlike other jellyfish, which usually float passively around in the current, the sea wasp swims at speeds of about 4 ½ miles (7 kilometers) per hour. The sea wasp has a whopping 24 eyes. Most of these are very simple sight organs called eyespots that detect light and shadow. But four are complex sight organs that possess corneas, lenses, and retinas. Researchers think sea wasps use these adaptations to spot and track down their prey, which includes shrimp and small fish.

Box jellyfish do not hunt large animals, but they do occasionally run into humans. Because box jellfish are translucent, it is practically impossible for people to see them and avoid them. People are usually stung without warning—an incredibly painful experience—while swimming or wading in the shallows. If the person is in poor health or suffers a bad sting with a large affected area, he or she may experience cardiac arrest and drown before reaching shore. Antivenin can counteract some the effects of stings. But because box jellyfish venom works so quickly, the antivenin must be administered within minutes for it to be of any use. Vinegar can be poured over the site of the sting to neutralize stinging cells that have not yet been activated. If the sting victim survives, the person may experience pain for weeks or even months after the initial contact.

Like other jellyfish, box jellyfish have increased in number and expanded their range in recent years. Scientists link their success to global warming and human damage to ocean environments. Most jellyfish live in warm water, so as climate change warms the oceans, jellyfish territory will slowly expand toward the poles. Overharvesting of the larger animals that usually eat box jellyfish (such as sea turtles) or compete with them for food are allowing jellyfish to spread unchecked. This could be bad news for beach goers everywhere.

October 20, 2016

With a full quarter of the year left to record, climate scientists are already willing to bet their bottom dollar that 2016 will be the hottest year on record. Some of the unusual heat seen this year has probably been driven by short-term climactic cycles, but 2016 has been an exceptionally hot year in a streak of abnormally hot years. Most scientists attribute this worldwide trend to human-induced global warming.

Global warming has contributed to drought conditions in California, where rainfall totals in recent years are the lowest in the state’s recorded history. Dry lake beds, like this one in the Coyote Hills of northern California, are becoming an all-too familiar sight in the state. Credit: © Sheila Fitzgerald, Shutterstock

Global warming is an increase in the average temperature at Earth’s surface. People often use the term global warming to refer specifically to the warming observed since the mid-1800′s. Scientists estimate that Earth’s average surface temperature has risen by about 1.4 Fahrenheit degrees (0.78 Celsius degrees) since 1880. Researchers have also found that most of the temperature increase occurred from the mid-1900′s to the 2000′s.

The recent strong El Niño probably contributed to the record-shattering heat. An El Niño is a part of the interaction between Earth’s atmosphere and the tropical waters of the Pacific Ocean. An El Niño occurs about every two to seven years, and it can affect the climate throughout the world. The most recent El Niño ended in the spring of 2016. The event caused temperatures to surge. Eleven of the past 12 months have been the hottest months on record. July and August 2016 tied for the hottest months ever recorded.

Earth has continued to warm even in years without a strong El Niño effect. Every year of the 2010’s has been within the top 15 hottest years on record. 2015 ranked as the hottest ever, while 2014 came in second and 2013 was fourth. Of those years, only 2010 experienced a mild El Niño effect. Scientists think these record temperatures are the result of humans releasing massive amounts of gases such as carbon dioxide into the atmosphere.

Despite the end of the El Niño, Gavin Schmidt, the director of NASA’s Goddard Institute for Space Studies, stated that 2016 “seems locked in” to break 2015’s record temperatures. That year was 1.62 °F (0.90 °C) above the average annual temperature since 1900. Even if the rest of 2016 is unexpectedly cool, it should not be enough to counteract the heat of the first nine months. It would take an unprecedented climate anomaly to prevent 2016 from becoming the hottest year on record.

September 19, 2016

A sea spider is a terrifying beast. It has frighteningly long legs connected to a tiny body. It possesses no teeth or gaping jaws. Instead, it has a long tube called a proboscis, which it uses to suck the fluids out of its prey. Fortunately, sea spiders are too small to threaten humans. Furthermore, the largest ones live at the bottom of the ocean near the North and South poles, far away from people.

Sea spider.
Credit: © Dray van Beeck, Shutterstock

Sea spiders are ocean animals and most of them have eight legs. But they are not true spiders. Instead, sea spiders belong to a unique group of arthropods. Arthropods are animals with jointed legs and no backbones. Many sea spiders are slender and delicate. Others are chunky and robust. Most sea spiders are small, especially those found in shallow waters. They can be less than 1/10 inch (3 millimeters) across, including the legs. Sea spiders live in all the oceans, from the shallows to depths greater than 20,000 feet (6,000 meters).

Sea spiders feed by grabbing prey with their mouthparts. They then pierce the prey and suck out the fluids with their proboscis. Sea spiders feed on invertebrates (animals without backbones), especially those that are slow or fixed in place. Many sea spiders have colors and patterns that help them blend in with algae or other life on the ocean floor. Some are brightly colored, possibly to warn away predators (hunting animals).

The body of a sea spider is so small that there is little room available for its internal organs. As a result, some of the organs extend into the creature’s long limbs. Furthermore, sea spiders lack respiratory systems. Instead, the oxygen they need simply diffuses (flows) from the ocean water into their bodies.

Most sea spiders are quite small, but those near Antarctica and the North Pole can grow to more than 30 inches (75 centimeters) in diameter. In those areas, there are fewer critters that hunt sea spiders, and there are greater concentrations of what sea spiders like to eat. The frigid waters may also play a role in their giant proportions near the poles. Cold water holds more oxygen, so more of the gas can diffuse into a sea spider’s body, allowing it to grow larger.

Like most organisms, sea spiders are vulnerable to the effects of global warming, but the polar habitats of giant sea spiders increase their risk. As polar ice melts, giant sea spiders lose their protection from such predators as birds and marine mammals. Also, because warm water holds less dissolved oxygen, warming seas reduce the range of giant sea spiders. Scientists have identified more than 1,000 species (kinds) of sea spiders, but many more probably remain undiscovered. Because of the effects of global warming, scientists fear a large number of those unknown species will disappear before they can be identified.

April 28, 2016

Last Friday, April 22—Earth Day—representatives from 175 countries signed the Paris Agreement at the United Nations headquarters in New York City. The agreement stated that each country would voluntarily monitor and reduce greenhouse gas emissions. This agreement, which was developed in Paris, France, at the end of 2015, will be the most comprehensive climate change treaty ever—should it enter into force.

People gather for a climate change protest in front of the U.S. Capitol in Washington, D.C.
Credit: © Hyungwon Kang, Reuters/Landov

Global warming is an increase in the average temperature at Earth’s surface, usually used to refer specifically to the warming observed since the mid-1800’s. Much of the warming that has occurred is due to a process called the greenhouse effect. In the greenhouse effect, certain gases in the atmosphere, such as carbon dioxide, trap heat from the sun. They act much like the glass roof and walls of a greenhouse. Since the mid-1800’s humans have been releasing more carbon dioxide and other greenhouse gases into the atmosphere, mainly though the burning of fossil fuels. Scientists think these extra greenhouse gases are strengthening the greenhouse effect and causing the climate to warm. If it continues, global warming could cause extreme weather, flooding of coastal regions, and massive environmental changes.

The signing ceremony set a record for most signatures on a UN treaty on a single day. Signing the treaty is only the first step toward it becoming binding, however. State governments must now ratify the treaty, a processes that could take years. The treaty will go into effect once at least 55 countries that together produce at least 55% of global carbon emissions ratify it.

Even if the treaty is ratified, it will be up to individual nations to lower their greenhouse gas emissions. The treaty will require countries to assess and report their emissions levels every five years, but what they do with that information will be up to them. Climate change activists are hoping that the process encourages the countries to significantly curb their emissions. They hope the Paris Agreement will help keep global temperatures below 3.6 °F (2 °C) higher than their averages in the 1800’s. Scientists think that some of the most harmful effects of climate change can be prevented this way.

April 27, 2016

In this illustration, a group of dinosaurs and flying reptiles flee a vast fire. Such an event, connected to the eruption of a volcano, could have caused the extinction of the dinosaurs at the end of the Cretaceous, some 65 million years ago. Credit: © Mark Garlick, Photo Researchers

Dinosaurs reigned supreme on Earth for tens of millions of years. Other animals, such as mammals, lived in the shadows, eking out an existence among giant plant-eaters and ferocious predators. Dinosaurs were so dominant that, if it hadn’t been for some extremely bad luck 65 million years ago in the form of a giant asteroid, they might still populate Earth today. Right? Maybe, maybe not.

A recent study published in the journal Proceedings of the National Academy of Sciences casts doubt on this picture of dinosaur supremacy. Paleontologists Manabu Sakamoto and Chris Venditti of the University of Reading and Michael Benton of the University of Bristol analyzed parts of the dinosaur family tree over time. They compared speciation (spee see AYE shun) events to extinction events. Speciation is when one species evolves from another—for example, human beings, chimpanzees, and gorillas evolved from a common ancestor that lived between 4 million and 10 million years ago. That split that occurred was a speciation event. Sakamoto, Venditti, and Benton made comparisons of speciation and extinction events within five groups of dinosaurs: meat-eating theropods, long-necked sauropods, horned ceratopsians, duck-billed hadrosaurs, and other plant-eating dinosaurs.

The scientists found that the rate of extinction began to exceed the rate of speciation for theropods, sauropods, and other plant-eating dinosaurs 50 million years before the asteroid hit. This means that dinosaur species in these groups were going extinct faster than new species evolved to take their place as much as 115 million years ago, in the middle of the Cretaceous Period.

Does this mean that dinosaurs were already on their way out, and a huge rock from space only hastened their demise? Absolutely not! While the dinosaurs may have been experiencing a downturn in diversity, this study does not indicate that they were at death’s door. Whether dinosaurs gradually declined before their extinction has been a hotly-debated topic in paleontology for many years. In fact, long before the Chicxulub impact crater (created by an asteroid that struck Earth 65 million years ago) was discovered, most paleontologists thought the dinosaurs had slowly died out and that there was no mass extinction. The question of dinosaur decline is very complicated and touches on such paleontology issues as the completeness of the fossil record. Because of many differences in the layers of Earth, some animals in some periods have nearly complete fossil records, while others from other periods may have few or no fossils. This study will not be the last word on the matter.

The study does, however, highlight a few important things about dinosaur diversity and extinction. First, the extinction of the dinosaurs was a complex event. The environment of the Late Cretaceous was challenging. Enormous volcanoes called the Deccan Traps raged in what is now India. The climate was getting colder. Drifting continents and changing sea levels were fragmenting land habitats, making it more difficult for land-dwelling dinosaurs to move from place to place. These factors may have affected the group’s species diversity.

Second, the study highlights how diverse dinosaurs were. There are about 600 named dinosaur species, and scientists estimate that another 600 or more remain to be discovered. Some of these species may have lived in regions where fossilization rarely occurs (such as mountain environments) and thus will never be found. Some paleontologists involved in assessing dinosaur diversity point out that the astonishing diversification that occurred in the Jurassic Period could never have lasted forever, particularly in the challenging environment of the Late Cretaceous.

Finally, the study holds great relevance for us today. If the results are borne out by future analyses, it would suggest that a modest loss of species diversity may have made the dinosaurs more susceptible to random cataclysmic events such as the Chicxulub asteroid. Today, many species are going extinct, and the planet is warming rapidly. The loss of diversity might make today’s ecosystems more susceptible to collapse from random events such as volcanic eruptions or asteroid impacts. Like the dinosaurs, humans might have built their global dominance on an unstable foundation. Unlike the dinosaurs, however, we have the ability to make changes to strengthen ecosystems and reduce global warming, giving us more of a fighting chance against extinction.

Other World Book articles

• Drilling for Answers (March 9, 2016) – Behind the Headlines article
• Geology (2007) – A Back in Time Article
• Global warming

March 29, 2016

The Great Barrier Reef, off Australia’s northeastern coast, is the largest coral reef system on Earth.
Credit: © Gary Bell, Getty Images

Recent studies reveal that the Great Barrier Reef, the world’s largest system of coral reefs, is suffering from severe and record-setting bleaching. Bleaching, as the term suggests, is a whitening coral disease caused by the loss of colorful single-celled algae called zooxanthellae. Most coral depend on zooxanthellae for food and the creation of their limestone skeletons. Coral cannot survive for long without zooxanthellae. The main cause of bleaching is heat stress caused by rising water temperatures produced by global warming. This year’s El Nino, a periodic warming current in the Pacific Ocean, has added to the heat stress. The Great Barrier Reef is made up of more than 3,000 individual reefs that extend about 1,400 miles (2,300 kilometers) along the northeast coast of Australia.

Great Barrier Reef
Credit: WORLD BOOK map

Australia’s Coral Reef Studies group filmed the northern half of the Great Barrier Reef over a period of six days. The group—based at James Cook University in northeast Australia—found that 95 percent of 500 reefs studied showed evidence of severe bleaching, a drastic and record-setting percentage. Professor Terry Hughes, who led the film survey, fears the current bleaching event could kill up to 50 percent of the system’s reefs. The group will soon have results on the lower half of the reef, and the Great Barrier Reef Marine Park Authority will conduct in-water surveys to more exactly determine the extent of the bleaching. This year’s bleaching is the third such event since 1998, when the disease killed 16 percent of the world’s coral reefs. A 2005 bleaching wiped out half the coral reefs in American waters of the Caribbean Sea.

If water temperatures cool, zooxanthellae will return and corals will survive and resume their normal colors. This process can take decades, however, and bleaching stress decreases coral’s future ability to grow and reproduce. It also increases the likelihood of later—and increasingly worse—bleaching events.