Disabled cooling mechanism don’t just cease to cool

from my book 97%

There is another point to all this, however, which it is even more important to grasp.  When these cooling factors are disabled they don’t just cease to cool.  They go into reverse and start actually warming the planet more than ever.  Every tree that catches fire not only ceases to store carbon.  It releases into the atmosphere the carbon it has already stored, thus making the planet that much warmer so that next year even more trees will catch fire.  When phytoplankton die they poison the ocean so even more plankton die from carbon poisoning, thus toxifying the ocean even more.  Larger creatures lose their food source and so they too die and they too release carbon into the already saturated ocean.   Ice that melts does not simply cease to reflect heat back into space, it turns into water that absorbs it.  It is this feedback mechanism that the public has understood so little and the scientists fear so much.   We are taking the brakes off.  We could reach a point where runaway global warming takes place because nature itself would now  be heating the planet on a far vaster scale than anything we could ever achieve.   Every degree of global temperature increase would not only mean that the planet was that much warmer, it would also, because of the feedback mechanism,  make a rise to the next degree inevitable. Once the feedback process reached that point it would have totally escaped our ability to control it.

How close are we to reaching that point, the tipping point as the scientists call it?  The answer is very close.   For hundreds of thousands of years the carbon in the atmosphere had stayed at a steady 282 parts per million.  By 1990 it had reached 390 ppm.  For a long time the scientists have calculated that  the iconic 2 degrees of increased warming  could be reached when  the ppm count reached 450, but to be on the safe side, because even now the feedback mechanism is beginning to take hold,  it needs to be restricted to 400.  It was thought that the earliest that 400 point could be reached was 2015.  In fact we passed it in May 2013.  It was one of the most important dates in the history of the world but went largely unregarded in the newspapers.    There is an even more serious factor to be taken into consideration.   If the planet got hot enough, at round about 4 degrees perhaps, the Arctic tundras would begin to melt.   These huge frost-bound  landscapes  lock up billions of tons of methane, and methane is generally reckoned to be  72 times more dangerous  than CO2 over a twenty year period – and it is during the next twenty years that the fate of the earth will be decided – and 25 times over a hundred year period.  Once that happened climate change really would begin to gallop, leading on to a yet more terrifying scenario.

 

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