Earth's Hottest Periods

Key Definitions

• Collision: When one object strikes with force against another.
• Sediment: Solid material that settles at the bottom of a liquid or body of water.
• Thaw: To melt or become liquid due to warming.
• Swamp: A wetland area with stagnant water, dominated by trees and vegetation.
• Interglacial: A period of warmer climate between ice ages.
• Ancient: Something belonging to a time long ago
• Glacier: A large mass of ice moving slowly down a mountain or valley
• Evidence: Facts or information used to support a statement or claim
• Oxygen: Gas essential for living things to survive and breathe
• Volcano: A mountain with a lava vent, rocks fragments, hot vapour and gas erupt from the Earth's crust

Earth's Hottest Periods

• Earth is 4.54 billion years old and has experienced hot and cold periods
• Early Earth was bombarded by space rocks, leading to the planet melting and reaching 3,600 degrees Fahrenheit
• Scientists can estimate past temperatures using rocks, fossils, ocean sediments, tree rings, and ice cores
• After the Moon formed, the Earth reached 3,680 degrees Fahrenheit
• After the collisions stopped, the Earth remained over 400 degrees Fahrenheit.
• Between 600 and 800 million years ago, the Neoproterozoic ice age occurred, with ice sheets possibly reaching the equator
• Volcanic activity released carbon dioxide, causing the temperature to rise and end the ice age
• "Cap carbonates" on ice age deposits and rocks in Namibia suggest a temperature increase
• Earth has generally been warm for the past 500 million years, preventing ice sheets
• Around 250 million years ago, it was too hot for peat swamps to survive
• 92 million years ago, temperatures were so high that palm trees and crocodiles inhabited the Arctic Circle
• During the Paleocene-Eocene Thermal Maximum 65 million years ago, the US had a sub-tropical environment, with temperatures 9-14 degrees Fahrenheit higher than today
• High carbon dioxide levels contributed to the heat.
• The spike in temperature 56 million years ago is a mystery, with volcanic eruptions and methane release as possible causes
• Humans have enjoyed a cool, stable climate for the past 10,000 years.
• The present climate is cold relative to most of Earth's history and is currently in an interglacial period

Earth's Coldest Periods

• One of the coldest periods occurred over 2 billion years ago, after oxygen increased in the atmosphere
• There were more freezing times 750 to 600 million years ago
• The Pleistocene ice ages covered much of the Northern Hemisphere with glaciers in the past few million years
• Geologists find marks on rocks and erratic boulders as evidence of past ice ages
• Around 3.5 to 2.5 billion years ago, cyanobacteria produced oxygen via photosynthesis, turning methane into carbon dioxide and water causing the planet to cool and promoting ice formation
• The rise of oxygen enabled oxygen-breathing life forms to evolve and created the ozone layer
• Between 750 and 600 million years ago, the Cryogenian Period occurred
• Volcanoes may have influenced both freezing and thawing during the Cryogenian Period
• The Sturtian ice age occurred about 720 to 660 million years ago
• The Marinoan ice age occurred about 640 to 635 million years ago
• Volcanoes released carbon dioxide, warming the Earth between these ice ages.
• The Pleistocene Epoch started 2.6 million years ago and ended 11,000 years ago
• There were cycles of glacier growth and melting during this time with present time being a warmer interglacial
• 34 million years ago, the Antarctic Ice Sheet started to form
• 4.5 million years ago, the Isthmus of Panama formed, leading to the most recent ice age
• The Last Glacial Maximum was 20,000 years ago during the Pleistocene Ice Age
• The Great Lakes, Niagara Falls, and the Channeled Scablands formed due to ice sheets and melting from the Last Glacial Maximum
• Milankovitch Cycles can affect climate and ice sheet growth
• Increased carbon dioxide in the atmosphere is currently warming the Earth

Cretaceous Kansas

• Many states designate a "State Fossil" based on discoveries within their borders
• Kansas designated the Tylosaurus and Pteranodon as state fossils in 2014
• These organisms lived during the late Cretaceous period and existed when Kansas looked very different

Paleocene-Eocene Thermal Maximum (PETM)

• Earth experiences climate fluctuations, including ice ages and warm periods
• During ice ages, glaciers extend from the poles, causing sea levels to drop
• Melting ice results in rising sea levels.
• The fossil record shows climate events
• Scientists use physical, chemical, and biological materials from the fossil record as proxies to correlate with historical and modern events.
• Fossilized alligators and giant turtles in the Arctic Ellesmere Island suggest a tropical climate 56 million years ago
• The Paleocene-Eocene Thermal Maximum (PETM) was 9-14 degrees Fahrenheit hotter than today and the warmest period since the dinosaur extinction.
• Scientists investigated the PETM looking for proxies and found that the carbon cycle was disrupted by increased carbon dioxide in the atmosphere over 20,000 to 50,000 years.
• Large-scale wildfires, seafloor spreading in the North Atlantic, and extraterrestrial impacts and volcanic activity could have increased carbon dioxide levels.
• Scientists studied marine sediment cores and used mercury as a proxy for volcanic activity
• 20-40% of atmospheric mercury comes from volcanoes; increased mercury levels indicate increased volcanic activity
• During the PETM, marine sediments showed decreased sequestered carbon and increased mercury, linking volcanic activity to warming
• All volcanoes release carbon dioxide, especially less effusive volcanoes associated with warming events like the PETM.
• During the breakup of Greenland from Eurasia, the approximate amount of lava released could have covered Montana in a 10 km thick lava pile
• This volcanic event created the North Atlantic Igneous Province
• The province released 3,000-10,000 PgC into the atmosphere over 20,000-50,000 years.
• Global temperatures rose and ice melted including the sea levels rising during the PETM, lasting about 200,000 years.