History of climate change

During the last five billion years the Earth's climate has alternated between a frigid "Ice House", like the present world, and a steaming "Hot House", like the world of the dinosaurs. Though each of the changes may seem extreme, they usually occurred slowly over many thousands of years.

Tackling climate change is one of the biggest challenges being faced by the world today, and the first step is to understand exactly what it is. This is where knowing and understanding the history of climate change can be of help.

Why should I be aware of this?

• Life has always played a pivotal role in earth's climate. It has been forced to evolve by climate change and has actually led to climate change.
• Organism that suck up the greenhouse gases such as carbon dioxide from air and deposit the carbon into the ground and release oxygen into the atmosphere are one of the key climate change players.
• The tendency of climate to change very suddenly (often in just a few decades) and then reverse has been one of the most surprising lessons of recent study of the last 130,000 years.
• The history of climate change indicates that the present condition of global warming is a disturbing scenario.
• The Earth has warmed about 1ºF in the last 100 years.
• The eight warmest years on record (since 1850) have all occurred since 1998, with the warmest year being 2005.
• Severe climate change was the primary driver in the development and the decline of civilisation, according to new research by the University of East Anglia.

All about the history of climate change

The past climate of the Earth can be determined by mapping the distribution of ancient coal, desert deposits, tropical soils, salt deposits, glacial material, as well as the distribution of plants and animals that are sensitive to climate, such as alligators, palm trees and mangrove swamps.

Studies show that the earth's climate has changed many times in response to natural causes since its existence. It also shows that various life forms have played a key role in climate change. These include plants, algae and other photosynthesisers, which consume the [greenhouse gases]] such as carbon dioxide from air and deposit the carbon into the ground and release oxygen into the atmosphere are one of the key climate change players. They enriched the atmosphere with the oxygen they released, making animal life possible.

Scientists opine that the global warming that took place about 11,000 years ago took several decades in the Arctic, but was marked by a series of sudden steps in warming, each taking less than 5 years. About half of the warming was concentrated into a single period of less than 15 years.

This sudden stepwise instability is also a disturbing scenario to be borne in mind when considering the effects that humans might have on the climate system through adding greenhouse gases. Judging by what we see from the past, conditions might gradually be building up to a 'break point' at which a sudden dramatic change in the climate system will occur over just a decade or two.

Climate change over the years

• 15,000 and 30,000 years ago -- During that time, most of North America was covered by great ice sheets. Some 14,000 years ago, the last ice sheet began to melt very quickly. By 7,000 years ago, the ice was gone. This end to the ice ages caused big changes on the Earth. The changes caused many kinds of plants and animals to die. For example, mastodons – elephant-like animals – and other large mammals that preferred cold climates may not have been able to live in the warmer, drier conditions.
• The Little Ice Age -- Starting in the 14th century, Europeans lived through what is known as the "Little Ice Age." The Little Ice Age lasted for several hundred years. During the Little Ice Age, the advance of glaciers along with hard winters and famines caused some people to starve and others to leave their homes.

Civilisations affected by climate change

• Indus Valley Civilisation -- The prosperous villages and towns of the Indus Valley civilisation show that it was fertile in ancient times. At present it has only rainfall of about 15 cm. Research to understand the decline of the civilisation indicates great changes in the environmental conditions and climate in the beginning of the second millennium BC.
• Maya Civilization -- Some scientists theorize that the paleoclimate of the region was not only different than the present day climate, but the natural climate variability of the past could have included a period of intense drought that occurred in conjunction with the Classic Maya Collapse.

90 degrees - what we do not know yet

• According to recent research, special clay minerals (made by soil microbes on land and washed into the sea), acted like "kitty litter" in the seas and absorbed vast quantities of oxygen consuming organic carbon compounds. The mineral sank to the sea floor with their carbon loads and were buried.
• A rapid global rise in methane production 11,000 years ago suggests that the warming and moistening of climate (causing more methane output from swamps and other biotic sources) was a globally synchronized change, with the water vapor content of the atmosphere as the most ikely 'messenger' in this transition, by virtue of its effect as a greenhouse gas
• The early civilisations of Egypt, Mesopotamia, South Asia, China and northern South America were founded between 6000 and 4000 years ago when global climate changes, driven by natural fluctuations in the Earth's orbit, caused a weakening of monsoon systems resulting in increasingly arid conditions. These first large urban, state-level societies emerged because diminishing resources forced previously transient people into close proximity in areas where water, pasture and productive land was still available.

References

• Paleomap Project: Climate History
• The History of Climate Change Science
• Constant Climate Change: 4,000,000,000 years ago:Discovery Channel
• A brief history of climate change
• Climate Change:USEPA
• Sudden Climate Change Through Human history; Jonathan Adams and Randy Foote
• Rapid Climate Change