Climate Change

We know that Earth's continents move around because the speed and direction of the movement is measurable. Plate tectonics is the theory that explains how and why this movement occurs. Basically, Earth's crust is broken up into large chunks of rock, called plates. The plates slowly drift across the surface of the globe, floating atop the Earth's mantle. The mantle is made up of hot, partially liquified rock, called magma. It's this slippery layer that allows the plates to slide around, getting pulled into different areas by uneven heating. As the plates move, they may separate or collide with one another. This activity can spread seafloors and form mountains, plateaus, valleys, volcanoes, or other geologic formations. 

By monitoring the rate of seafloor spreading, scientists have determined that plate movement tends to happen very slowly, at about the rate human fingernails grow. Still, with enough time, the drifting plates and their geologic features can alter air and ocean currents. This impacts global climate.
 

Because the Earth is a globe, its surface is unevenly heated by the Sun's warmth. This makes the Equator warmer than the poles. Different temperature zones effect the kinds of ecosystems that continents can support. For example, you tend to find tropical rainforests closer to the Equator, while snowy tundras are closer to the poles.The color of Earth's surface influences how and where heat from the Sun is absorbed and/or reflected back out into space. Snow and ice are brightly colored, so they're more reflective than dark-colored features, like oceans and forests. In these ways, the color and reflectivity of Earth's surface features have a big impact on climate.

Aerosols (fine solid or liquid particles suspended in the air) also contribute to Earth's reflectivity. Aerosols can be natural or manmade. Dust, volcanic ash, organic compounds, and wildfire smoke are some examples of natural aerosols. Manmade aerosols are typically a byproduct of pollution or deforestation. Aerosols can contrubute to Earth's cooling or warming, depending on location, particle size, and other factors. 
 

Earth's atmosphere is made up of many gases. Nitrogen, oxygen, and argon are the main ones, but a small amount of the air we breathe is also made up of greenhouse gases. These include methane, carbon dioxide, nitrous oxide, water vapor, and ozone. They're called "greenhouse gases" because they trap heat from the Sun, like the walls of a greenhouse. Because of this, greenhouse gases have a big role to play our planet's climate, despite making up less than 1% of the atmosphere. Geologic and biologic activity can also emit gases in amounts large enough to influence air composition.
 

Biological activity (the activities of living things) can also affect climate by influencing the gaseous makeup of our atmosphere. As Earth's many lifeforms experience natural processes such as growth, death, decay, and renewal, gases are consumed, released, recycled, and exchanged on a grand scale. For example, plants inhale the carbon dioxide (a greenhouse gas) that animal organisms breath out. Plants also exhale the oxygen that animal organisms breathe in. In this way, large forests and other plant-saturated areas play a big role in keeping Earth from overheating. Just like our planet's geology, the rate of biologic change isn't always constant or easily predictable, but it can be observed and studied.

Living organisms have the power to influence climate and have done so throughout time: 

• About 2.5 billion years ago, ocean cyanobacteria developed the ability to photosynthesize. This produced a ton of oxygen, causing rapid global cooling. Some scientists think it may have been enough cooling to cause global glaciations. This sequence of events is sometimes called the Great Oxydizaton Event.
• The Late Devonian Extinction (374-359 million years ago) may have been caused by the proliferation of land plants, which eroded soils that were swept into the ocean, causing acidification.
• In the 1970s, humans discovered that a huge hole in the ozone layer opening annually above Antarctica was increasing in size as a result of industrial chemicals called CFCs. By the 1980s, it was having wide-ranging impacts on the climate and jet streams of the Southern Hemisphere. In 1987, nations around the world ratified the Montreal Protocol to curb the release of CFCs. Since then, the hole in the ozone layer has been healing.

Yes, many times. One of the most dramatic warming events happened at the end of the Permian period (about 252 million years ago), well before dinosaurs ever existed. This rapid warming resulted in the largest extinction event in Earth's history. About 90% of all plant and animal species went extinct.

What happened? 
In what's now Siberia, huge amounts of a volcanic rock, called basalt, burbled up and flooded the surface with lava on a continent-wide scale. The area already held huge stores of coal, oil, and natural gas that had built up during the Paleozoic period. The lava ignited these, releasing huge amounts of carbon dioxide and other volcanic gases into the atmosphere. Even though these fiery "basalt floods" took about 60,000 years to cover the continent, the changes to global climate happened too quickly for most species to adapt. The fossil record reveals that about 90% of plant and animal species on Earth died out during the end-Permian extinction event. This is the largest extinction event identified in the fossil record. To paleontologists, it's known as, "The Great Dying."
 

The Quarry dinosaurs lived in the Late Jurassic Period, about 150 million years ago. This was still the middle age of the dinosaurs, about 84 million years before the asteroid strike. Back then, the ecosystem of northern Utah was very different than the dry, cold desert we find today. Instead, this area was a flat, warm floodplain full of lush plants, tall coniferous trees, and braided rivers cutting through the land.

What happened?
Locally, the climate of Late Jurassic Utah was warm and humid. Not only was Utah closer to the Equator back then, but a mountain building event called the Nevadan Orogeny had just begun along the west coast. The low elevation of these mountains allowed moisture from the Pacific Ocean to flow further inland and nourish the region's extensive plant life. Just like today, local climates were also influenced by the global climate. In the Jurassic, Earth as a whole was warm and humid, too. This was because the supercontinent Pangea had begun to break up about 50 million years prior. When this happened, volcanoes sprang up around the world. The ash and greenhouse gasses they produced warmed things up. Shallow seas formed at the seams where the continents were spreading and the planet humidified. While Pangea's breakup initially resulted in the end-Triassic Mass Extinction (about 201 million yeas ago), the global climate had more or less stabilized by the Late Jurassic Period.
 

Yes. Climate change happened throughout the Mesozoic Era (the Age of Dinosaurs). For most of the Mesozoic, climate change happened very slowly and didn't result in mass extinctions because Earth's lifeforms had time to adapt to the changes. But there were a few instances when the rate of change increased and mass extinctions occurred as a direct result. 

What Happened?
The National Park Service offers details about Mesozoic Era Extinctions on their Age of Dinosaurs subject page. There, you can read about the role climate played in various extinctions throughout the Triassic, Jurassic, and Cretaceous periods.
 

When the dinosaurs were here in the Late Jurassic period, this area experienced at least 3 severe droughts. When each drought ended, the river filled with water again, pushing the bones of any dinosaurs who died along the shore downstream. The bones were caught at a bend or sandbar, where they were quickly buried in the river sediments. 

What Happened?
The dinosaurs found in the Quarry Exhibit Hall lived about 150 million years ago — that's about 84 million years before the asteroid impact that rendered the big dinosaurs extinct. The droughts that killed the Quarry dinosaurs probably happened every few decades or so. We know the droughts happened because the bones are surrounded by unionid clams, whose death positions indicate drought. 
 

All non-avian dinosaurs were victims of the End-Cretaceous mass extinction event, which happened about 66 million years ago. A huge asteroid impact caused sudden, rapid climate change around the world.

What Happened? 
Most scientists attribute the extinction of the non-avian dinosaurs to a massive crater on the Yucatán Penninsula in Mexico. The presence of shocked quartz in ocean sediments beneath the crater indicate that it was formed by an asteroid impact. The age of this crater (66 million years old) perfectly matches the age of iridium-rich sediment deposits around the world, collectively known as the K-T boundary. Iridium is rare in the Earth's crust, but very common in asteroids. Today, the Chicxulub Crater is about 120 miles (200 km) wide. The asteroid that created it is estimated to have been about 6 miles (9.6 km) across.

Scientific evidence suggests that the impact released greenhouse gases from deep within the Earth causing global volcanism that quickly heated the planet. The presence of glass beads in the gills of fossilized fish at the Tanis Fossil Site suggests that debris thrown up by the impact became molten as it reentered the lower atmosphere. Because the K-T boundary line is also rich in fossilized charcoal, it's thought that the flaming debris caused global wildfires. This would've killed plants and animals on a grand scale. When the fires ended, lingering smoke blocked out sunlight, swiftly cooling the planet and causing even more ecological mayhem. The fossil record reveals that about 76% of Earth's species went extinct around this time. Large animals that required a lot of food, like the dinosaurs, died out when their ecosystems collapsed. The majority of creatures who survived were less than 50 lbs (22.6 kg).