
Ask HN: Now that CO2 levels are down, can we see if CO2 causes global warming? - nkkollaw
The Chinese virus caused an almost complete stop of all activities, at a level that would be impossible to achieve in a normal situation.<p>It&#x27;s already been noticed that CO2 levels have decreased significantly.<p>Will we be able to observe temps and see if there is definitely a relation between CO2 and global warming, or will this not be possible?<p>I would think that this is a one-time opportunity.
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Someone
CO2 stays in the atmosphere for centuries
([https://www.researchgate.net/publication/38136820_Atmospheri...](https://www.researchgate.net/publication/38136820_Atmospheric_Lifetime_of_Fossil_Fuel_Carbon_Dioxide),
[https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_at...](https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere#Anthropogenic_CO2_emissions)),
so a temporary decrease or even a temporary stop will not make much of a dent.

I’m sure we will see papers on this, though, just as we saw them after 9/11.

Also “if CO2 causes global warming”? I thought that has been established; even
the starkest deniers only debate whether human contributions to CO2 emissions
make much of an impact.

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chewz
> It's already been noticed that CO2 levels have decreased significantly

I think CO emissions decreased not CO levels.. So we wont see decreassing
temperatures right away..

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nkkollaw
Is it known how long it takes for CO2 levels to decrease?

For instance, if we're supposed to reduce by 50% before 2030, after how many
months or years would we notice a difference?

