A ‘Revenue Neutral’ Carbon Tax Is a Costly Myth

Townhall.com ^ | January 20, 2019 | James Taylor

[TigersEye]

There are many science papers with statements like "Plants enriched with CO2 showed a significant increase in fresh and dry weight and yield of tomatoes.

I wasn't questioning that in the slightest. If you had read my post more carefully you would have realized I was questioning the significance to plant growth of a scant rise in CO2 per your example of 130 ppm.

More recently we have instruments that show an increase in CO2 worldwide of about 2.5 ppm per year. Those measurements were replicated worldwide with a wide variety of measurement methods starting in the 1950's. ... Then we have to ask where the 2.5 ppm per year increase comes from. Was there .25C of warming in the ocean per year in the past centuries to cause the rise now? No. The rise is simply due to fossil.

Since the rise in CO2 lags behind temperature rise by about 800 years it would be a little dubious to attribute any recent CO2 rise to the warming following the Little Ice Age which ended about 150 years ago and only began approx. 800 years ago. With that in mind, it would be ludicrous to attribute CO2 rise in the last 100 years to anthropogenic contributions and then correlate that to temperatures. (or the other way around for that matter)

[palmer]

I was questioning the significance to plant growth of a scant rise in CO2 per your example of 130 ppm.

A 40% rise is not scant. There are plenty more papers showing that the levels we have already reached enhance growth in some C3 and C4 crops and enhance drought tolerance.

I agree that the current rise is not attributable to past temperature changes. The main reason is that there are well founded estimates that the oceans today are a net sink. Therefore the oceans are not a source, therefore it is not the case that past temperature rises causing outgassing today (net)

However, were mankind not around, CO2 levels would be rising today. There would be outgassing from the oceans both from the warming centuries ago. First because 800 years is not a constant, nor is 800 years applicable to warm climates and high concentrations. As shown in the graphs you linked to, 800 is a crude average and mainly applicable at the trough of CO2 and temperature. That is, when both temperature and CO2 are very low, an initial rise in temperature from weather changes or solar changes) causes a rise in CO2 about 800 years later. In our current natural climate a rise in ocean temperature might produce CO2 rises in as little as 100 year later. A reasonable estimate for the current overturning circulations is a few hundred years or less.

Suffice to say that any natural rise in CO2 would be quite small. Henry's law suggests about 5-10 ppm rise in CO2 for 1 degree in ocean warming. We've had about 1 or 2 degrees of natural ocean warming in the past few hundred years. The rest of the rise of CO2 is manmade.