Another thing we have to notice is that each of these gases works a little bit differently. Some gases trap more heat than others like methane and nitrosoxide and those fluorinated gases trap way more heat molecule for molecule than CO2 does. Some gases have different lifetimes in the atmosphere too and we have to take that into account. Such as Methane, in particular that we admit today will be gone in 10=20 years. Carbon dioxide we emit today will be in the air for centuries and centuries. So we have to look at the strength and lifetime of these different gases. If you look at the impact on today’s climate for the next 100 years, Methane will cause about 16% warming over the next 100 years. But if we look at the next 20 years the role of Methane doubles and becomes 32 percent. So in the near term CH4 is crucial but in the long-term, CO2 dominates. So which gases we focus on depends on what time period of climate change you are most concerned about. We have to look at all of them. So now that we understand what greenhouse gases are and how they work we are going to look at what controls the level of those gases. What makes them go up and what makes them go down.
To do this it helps us think of a bathtub in which we can fill and empty with water. We do that every day, right! We add water to the bathtub, scientist call that a source. We can also remove water by opening up the drain and scientist call that a sink.The diffence between the sources and sinks depends if the water goes up or water goes down. So if the source > sink, the water goes up but is the sink > source, the water level goes down. So let’s take that and apply it to earth’s atmosphere. Earth’s atmosphere is basically a big bathtub in the sky. We can fill it with pollution and greenhouse gases, which is largely due to us and then we have sinks of greenhouse gases, that pollution out of the sky and put it someplace else. We have sinks of greenhouse gases mainly in plants on land and in the ocean. We put pollution in the atmosphere; nature pulls it out in forest and in the oceans. Now right now our sources in the atmosphere in our pollutions is much bigger than nature can take it out and that’s why the levels are going up. But what if we reduced our pollution by half? Well then, maybe nature could keep up with it. If that were to happen, we would hit that level of drawdown and it would stabilize CO2 levels and it would stay flat. But if we could go farther and reduce our pollution down to 0, and pull more carbon and stuff out of the atmosphere and actually have greenhouse gases decline and begin to reverse the damage we’ve done. So this balance of sources and sinks will be what will determine the future of our planet and our climate. So let’s look at the numbers in today’s atmosphere we see that we have about 6 major sources of greenhouse gases and pollution. We’ll go into the later we’ll see that we have electricity, food, industry, transportation, buildings and other stuff. Then we’ll go into nature on land and oceans pull out a total of about 41 percent total of those greenhouse gases, primarily the carbon dioxide part. And that leaves behind 59 percent of those greenhouse gases building up year over year over year. To achieve Drawdown, we got to work on both sides of this equation. To achieve Drawdown we have to work on 3 basic principles. Principle 1, we have to reduce sources bringing emissions to zero; Principle 2 we have to support sinks uplifting nature’s carbon cycle; Principle 3, we have to improve society.
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