Pre AP Geo History of Earth's Climate

 

The History of Earth's Climate

What has Earth's climate been like over its four-and-a-half billion year history? This page provides a basic, broad overview of some of the major events in the history of Earth's climate. Far too much has gone on climate-wise in the history of our planet for this description to be comprehensive. The goal here is to make you aware of some of the major events and trends that make up Earth's climatic history.

We'll start with the present day and journey backward through time to Earth's origin more than four billion years ago. At first we'll discuss events and timeframes that span decades or centuries, then we'll move on to trends in climates that span millions of years or longer as we move further back in time.

Climate highlights during the past few centuries

What & When? Description of Earth's Climate

Dust Bowl

1930s

The "Dust Bowl" is the name given to a series of massive dust storms that ocurred across the Great Plains region of the United States during a severe drought in the 1930s. Much of the region's topsoil was blown away in a series of tremendous dust storms. Roughly 300,000 to 400,000 people were displaced as farmers lost their livlihoods.

Global warming

1800s to present day

Most scientists agree that the average global temperature has risen 0.6 ± 0.2 °C since the late 19th century, and that most of the warming observed over the last 50 years is attributable to human activities, in particular, the emission of greenhouse gases due to burning of fossil fuels. For example, the amount of the greenhouse gas CO2 in the atmosphere has risen more than 31% since 1750.

Little Ice Age

14th to mid-19th centuries

A period of relative cold, with numerous brutal winters and cool summers that caused widespread crop failures. This was not a true "Ice Age"; it wasn't cold enough and didn't last long enough. The Little Ice Age (LIA) had a major impact on Europe and North America; there is ongoing debate as to whether this event was truly global in extent. Major volcanic eruptions were the main cause of the cooling. A peculiar lack of solar activity (called the "Maunder Minimum") around the same time may have also played a role, though the precise link is also a subject of ongoing debate.

More info on Windows to the Universe

Medieval Warm Period

10th to 14th centuries

The Medieval Warm Period (MWP) was a spell of relatively warm climates before the Little Ice Age. The MWP may have only had an effect on Europe (and possible North America) or was a worldwide phenomenon. During this time farmers took advantage of the warm climate and grew wine grapes throughout Europe (including southern Britain), and the Vikings were able to colonize Greenland due to ice-free seas.

More info on Windows to the Universe

Climate highlights from a few millenia to a few milion years ago

What & When? Description of Earth's Climate

Younger Dryas

12,900 to 11,500 years ago

The Younger Dryas event was the last extremely cold period at the end of the last glaciation. Temperatures dropped rapidly within about a decade and the cooling lasted about 1,400 years. Scientists believe a sudden influx to the Atlantic of fresh water from melting glaciers may have triggered the cooling by disrupting the ocean currents in the Atlantic.

Pleistocene Ice Ages, 1.8 million years ago to ~10,000 years ago

The entire Pleistocene Epoch is characterized by climatic oscillations and cycles of glaciation (Ice Ages) and melting.

Climate highlights from many millions to billions of years ago

What & When? Description of Earth's Climate
Mesozoic Era, 251 to 65 million years ago Throughout most of the Mesozoic, the age of the dinosaurs, conditions were warm worldwide. Temperatures were especially warm during the end of the Mesozoic. This allowed the dinosaurs, which were mostly cold-blooded (probably), to thrive.

Carboniferous Period, 359 to 299 million years ago

The early part of the Carboniferous Period was warm and very wet. Swamps covered large swaths of the land, leaving behind organic deposits which later became the coal from which this period's name is derived. The atmosphere had unusually high levels of oxygen, allowing peculiar creatures (such as gigantic dragonflies with 3-foot wingspans) to evolve and thrive, and making wildfires more common.

Neoproterozoic Era, 750 million to 580 million years ago

The somewhat controversial "Snowball Earth" theory suggests that Earth may have frozen over completely at least twice and possibly as many as six times during a 170 million year span at the end of the Neoproterozoic Era. Average surface temperatures were likely as low as - 50° C (- 58° F) and there is evidence from many locations that a thick layer of ice covered Earth's surface, even at the equator. Extensive volcanic eruptions that spewed carbon dioxide into the atmosphere may have ended the cooling via increased greenhouse heating.

Around 2 billion years ago Earth's early atmosphere had almost no free oxygen. As photosynthetic microbes evolved and began to flourish, oxygen from photosynthesis became a major atmospheric constituent. This increase in atmospheric oxygen led to the formation of the ozone layer in the stratosphere, which absorbs solar ultraviolet radiation far above the planet's surface.
Shortly after Earth's formation, about 4 billion years ago Earth was scorchingly hot in the aftermath of its formation. Initially a molten ball, our planet eventually cooled enough to form a solid outer crust. The early atmosphere remained hot for millions of years as continued volcanic outgassing maintained a chemical composition far different from that of our modern atmosphere. Eventually Earth cooled enough that water vapor in the atmosphere could condense; the first rains fell, and eventually oceans of liquid water accumulated.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This Web Page Created with PageBreeze Free HTML Editor