Ancient Humans Altered Climate

[Madame Butterfly 0]

Ancient humans 'altered' climate

By Helen Briggs

BBC News science reporter

 

 

 

Law Dome, Antarctica, where the ice cores came from. (Image: Science)

Humans were influencing the climate long before the Industrial Revolution, new research suggests.

 

Levels of methane rose steadily in the atmosphere in the first millennium, according to an analysis of gases trapped in ice beneath Antarctica.

 

Much of the greenhouse gas came from huge fires lit by humans as they cleared land for settlements and farming, researchers report in Science.

 

But natural climate change would have contributed to the emissions, they say.

 

Wetter, warmer

 

Greenhouse gas emissions have risen to record levels over recent centuries but little is known about the atmosphere in pre-industrial times.

 

 

Dr Ferretti with the ice core evidence. (Image: Science)

Now, using a new technique, scientists have been able to analyse traces of methane trapped in air bubbles within cores of 2,000-year-old Antarctic ice.

 

The chemical fingerprint of stable types, or isotopes, of carbon atoms gives a record of methane in the atmosphere over the course of history, and where it came from.

 

It appears that much of the gas came from the burning of biomass - the likes of wood and grass - rather than other known sources of methane, such as the burning of fossil fuels, or natural emissions of methane from swamps and wetlands.

 

"Fire has been known to mankind for hundreds of thousands of years - even though the human population was very small, they set off large fires on a regular basis," lead researcher Dominic Ferretti, of the National Institute of Water and Atmospheric Research Limited in Wellington, New Zealand, told the BBC News website.

 

"It shows that in pre-industrial times there were much higher levels of methane from wood and grassland fires than we ever thought before.

 

"The end result is that in the future, with climate change and inevitably warming, we are likely to experience more wild fires in the bush in many areas of the planet as it becomes warmer and drier."

 

Amazon fires

 

The research adds to a body of evidence that human settlers torched vast areas of jungle and grassland to clear land for farming and settlements.

 

In the Americas, large swathes of grassland appear to have been burnt every year, for farming or to drive animals into the path of hunters.

 

 

Early settlers cleared large swathes of grass and shrubland

Large-scale fires were also lit in the Amazon jungle, to produce charcoal for improving the fertility of the soil.

 

The data suggests that methane emissions from burning tailed off by about 1700.

 

The researchers say this may have been due to a natural trend toward cooler and wetter conditions, as well as the decline in the indigenous population in the Americas because of the introduction of diseases by European explorers.

 

With the advent of industry, however, emissions started to rise once again, far exceeding the levels seen between AD 1 and 1000.

[Beware of BAKKE 0]

Ah, but Cow farts contain Dangerous amounts of greenhouse gases.. should be get rid of all cows?

Anyway. on a more serious note. did anyone catch "little Ice Ages" Being into Paleontology and a general pain in the rump when it comes to general information most people would find useless.. did any other scientist note that just before an Ice age... it became rather hot? really?? anyone?? ::the climate in prehistoric times kept getting warmer and drier:: ICE age... ::prehistoric man tries to survive in an ever changing climate:: ICEAGE ::French revolution!!:: ICE AGE ::scrat tries to finally catch that nut and eat it:: ICEAGE... wait that last one is a movie....

 

anyway! I don't think the most danagerous part will be the heat... I think it will come when the Earth wants to recover and goes into a freeze again!! Bundle up everyone!!

[Alexander32 0]

My theory is that maybe after the polar caps melt it will cause the water levels to rise and therefore cool down differnt parts of the world.

Hence ice age

[ARMS 0]

My theory is that maybe after the polar caps melt it will cause the water levels to rise and therefore cool down differnt parts of the world.

Hence ice age

Sounds reasonable..

[fooligan 0]

Last weekend watching Sci-channel....studies on Ice cores going back 100,000 yrs.....warm up occurs,icecap melts.fresh water dilutes and shuts down warm currents from southern Atlantic....planet freezes......said has happened in ten yrs....They say a piece of ice the size of New Hampshire breaks off every year.....The ice cap used to be 10 ft thick...is now 6 ft.....I think I need some ice skates....