In the beginning, the atmosphere was all carbon dioxide and water vapor. The first life was bacteria that ate hot chemicals and the Earth was a cauldron. Then cyanobacteria came along and started splitting water, and producing the oxygen into the atmosphere. Later plants started forming the dirt; before that there was only rock. Only after there was enough oxygen, did we get animal life.
Life made the atmosphere and the Earth what it is. Without life, it would not be what it is today, and all along the way each and every life form has influenced the balance of the atmosphere and the water and the earth.
The carbon dioxide and temperatures are known for at least the last 65 million years, and probably before that. After Pangaea broke up and the various continents were drifting around, there was more volcanic activity. Carbon Dioxide was 1,000+ PPM, and there was no year round ice at all.
After India moved from south of the equator to where it is now, the volcanic activity dropped somewhat, and the weathering and plant growth increased in relation to the volcanic, so the carbon dioxide stopped increasing, and started decreasing.
Then Antarctica started freezing (when carbon dioxide dropped to around 450PPM and, then much later the Arctic froze, we had a series of ice ages. For quite a long time, the carbon dioxide was held in balance between ~180-280PPM. All the times it was on the low end, it was an ice age.
Now, in just ~150 years, it is up to ~389PPM; which is a huge and very rapid change. And it is getting warmer, on average. The Arctic ice is melting more in the summer -- around September 15th has been the date of the minimum, but lately, it has been September 20-21st.
The older ice is melting, and the average age of the used to be 5-6 years old, and now it is mostly 1-2 years old. Older ice is a lot thicker, younger ice is a lot thinner and is more fragile. Much of it is shards that just refreeze loosely.
Arctic ice data center is here:
http://nsidc.org/arcticseaicenews/
Here's the age of the ice graphic:
Quote:
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Researchers often look at ice age as a way to estimate ice thickness. Older ice tends to be thicker than younger, one- or two-year-old ice. Last winter, the wind patterns associated with the negative phase of the Arctic Oscillation transported a great deal of multiyear ice from the coast of the Canadian Arctic into the Beaufort and Chukchi seas. Scientists speculated that much of this ice, some five years or older, would survive the summer melt period. Instead, it mostly melted away. At the end of the summer 2010, under 15% of the ice remaining the Arctic was more than two years old, compared to 50 to 60% during the 1980s. There is virtually none of the oldest (at least five years old) ice remaining in the Arctic (less than 60,000 square kilometers [23,000 square miles] compared to 2 million square kilometers [722,000 square miles] during the 1980s).
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Taken from
here.
The phrase that sticks with me is that the "Arctic ice is in a death spiral".