Our CO2 problem is BIG
Measured in Billions of Tons a Year
Here is a graph of the CO2 missions per year over the past 200 years. Notice the units are BILLIONS of metric tons (also called a gigaton) of CO2. A metric ton is 1000 KG, and a typical small car weighs 1.5 to 2 metric tons. World-wide in 2017 the graph shows we emitted 35 gigatons of C02. The earth's population in 2017 was approximately 7.5 billion people, so we emitted about 4.6 metric tons (or the weight of about 2 or 3 cars) of CO2 for every person on Earth in that single year. That is an average, if we focus on just the US, each person is responsible for over 16 metric tons (5 or 6 cars) each year).
CO2 is ACCUMULATING in the Atmosphere/Ocean
The scale of the graph is important but just as important is that it shows the ANNUAL emissions of CO2. Thus to get the total amount of extra CO2 in the atmosphere, you have add up all previous years (cumulative CO2 emissions is the area under this curve).
1100 Gigatons of CO2 has Accumulated so far
As of Jan 2019, mankind has emitted over 1100 gigatons of CO2 into atmosphere. This is the area under the graph of emissions. This is our carbon debt, and we have accumulated most of that debt in the lasts 50 years.
At Least 500 Gigatons More will be Emitted
The graph shows that in 2017 we emitted 35 gigatons of carbon per year. That will not go to zero instantly. Indeed carbon emissions are currently INCREASING RAPIDLY year over year. We need it to DECREASE RAPIDLY. Even under very optimistic assumptions, it will take 10-20 YEARS to get our per-year carbon emissions to zero. During that time we will have emitted at least 500 Gigatons more CO2 (probably significantly more).
1600 Gigatons Needs BIG Negative Carbon
So we have a 1600 Gigaton carbon 'debt' to pay off. Whatever we don't pay off we will 'pay' for in terms of more climate change (sea level rise, more hurricanes, change in rainfall, higher temperatures ...). We probably won't pay it all off, but we need to pay off a substantial fraction of it to avoid the worst effects. So we need at the very least many 100s of Gigatons of negative carbon, and we need to do it at a rate of at least many 10s of Gigatons of negative carbon PER YEAR to do it in a few decades. We need Negative Carbon at this scale.
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