Sunday, September 17, 2017

A History of Earth's Climate and the Greenhouse Effect (reposting)

NOTE: I'm having to repost this blog entry, because I'd originally reversed the two numbers 30% and 70% in the initial posting. It should have said:
"In Earth's early history, the sun was 30% dimmer than it is today, which is to say that the sun was only 70% as bright then as it is now."

"Earth had a climate long before we showed up and started noticing it, and it's influenced by a whole series of cycles that have been churning along for hundreds of millions of years. In most cases those cycles will continue long after we're gone. A look at the history of climate change on Earth can give us some much needed perspective on our current climate dilemma because the surprising truth is, what we're experiencing now is different than anything this planet has encountered before....."

A History of Earth's Climate (11 min.)

Demonstration of Greenhouse Effect: In Earth's early history, the sun was 30% dimmer than it is today, which is to say that the sun was only 70% as bright then as it is now. But, because the atmosphere was laden with methane, a potent greenhouse gas, the temperature on Earth was very hot, nonetheless. Much later, the methane and carbon dioxide were so sufficiently removed from the biosphere by Cyanobacteria that the Earth became completely frozen over. After that, an oxygen CO2 balance became established and then roughly maintained -- until we artificially unsequestered massive amounts of CO2 in a very short time. Eventually, the balance will be reestablished; but, not before the aftermath of the 'amplified greenhouse effect' aka 'global warming' reeks havoc on our biosphere.

Hottest and Coldest Earth Has Ever Been:


World's Fish Decreasing In Size and In Numbers

Overfishing has caused population collapses of certain fish species, and ocean acidification is already causing difficulties in the oceanic micro-species based food web. Now, it appears that "warming temperatures and loss of oxygen in the sea is shrinking hundreds of fish species—from tunas and groupers to salmon, thresher sharks, haddock and cod—even more than previously thought."

"Because warmer seas speed up their metabolisms, fish, squid and other water-breathing creatures will need to draw more oxyen from the ocean. At the same time, warming seas are already reducing the availability of oxygen in many parts of the sea.... and since the bodies of fish grow faster than their gills, these animals eventually will reach a point where they can't get enough oxygen to sustain normal growth... the body size of fish decreases by 20 to 30 perent for every 1 degree Celsius increase in water temperature."

"These changes will have a further profound impact on many marine food webs, upending predator-prey relationships in ways that are hard to predict. Lab experiments have shown that it's always the large species that will become stressed first. Small species have an advantage, respiration-wise."

As water warms, it is less able to retain gases such as CO2. Thus, as Milankovitch cycles (orbital variations around the sun) cause the Earth to become warmer, the oceans are less able to absorb atmospheric carbon dioxide. 
Note: Oxygen is, also, a gas.

Related reading:
Mountain Goats Shrinking In Size

Question: Will becoming smaller become beneficial for humans in the future?