AN INCONVIENT TRUTH
The Earth�s atmosphere is pathetically thin when compared to the size of the earth�almost nothing.� That is why humanity can have such a devastating impact on it.���
What is global warming (aka �greenhouse effect,� �climate change�)?� Sunlight arrives here on earth, giving us light.� Some of the light hits the ground, readily penetrating it, and then gets converted into heat radiation.� Now, the air has just a little bit of CO2 in it. That CO2 acts a bit like the glass in a greenhouse, or a sweater: it traps the heat, thus keeping the earth warm and comfortable.� But now we�re increasing the amount of CO2 and other greenhouse gases such as methane (natural gas), and the earth is getting warmer.�
We go back to another educational experience Al Gore had, this one with a great teacher.� The teacher�s name was Roger Ravelle, the first scientist to measure CO2 in Earth�s atmosphere.� And even then, almost 40 years ago, Ravelle already presented evidence to Al�s college class that the levels of CO2 in the entire atmosphere were rising.� He projected all that into the future.� These projections really got the teacher, and Al, worried.
When we look at the graph, at how CO2 �levels rise, we see that that they go up, overall, but also that every year they perform a mini-cycle of going up and down.� Why is that?� Well, we have a much greater landmass and hence vegetation in the Northern hemisphere than in the Southern.� So, overall, in the northern summer, much more CO2 is captured by trees and vegetation than in winter, when trees are often dormant and do not use CO2 (in a process of photosynthesis).� This can be almost viewed as if the earth �breathes� in a yearly cycle, a beautiful expression that the biosphere is alive.� For instance, glaciers are melting, and this could cause all kinds of problems.� Thus, 40% of the world�s people depend on glaciers of the Himalayas whose expected melting might cause serious water shortages.� The same...
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