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In the last 140 years or so, humans have added almost 1,000,000,000,000 tonnes of CO2 to the air (equivalent), or 1,000 billion tonnes. It would have been more except for oceans and land absorbing around half of it.

We are adding a lot of CO2 to the air

This leads me to talk about one of the many misconceptions thrown around by climate disinformers. Some deniers wrongly claim our CO2 emissions add little to atmospheric CO2. How they could ever think that is a mystery. It’s not a secret that CO2 is a product of burning hydrocarbons. (Some are very confused, mixing up various numbers they’ve heard and tossing them back together in strange and wrong patchwork.)

If deniers don’t understand organic chemistry (which is not expected of anyone but a student of the subject), they can look at what’s happening to our air. Atmospheric CO2 was stable at around 280 ppm for around 10,000 years, which supported the development of civilisations. (
See xkcd’s infographic.) Then we started digging up and burning long-buried hydrocarbons, which had been tucked away beneath the ground and no longer part of the carbon cycle. This caused atmospheric CO2 to increase (now approaching 410 ppm), which is why the temperature is rising.

Our long-running greenhouse gas experiment

Another common denier trick is to ask for experimental evidence that increasing CO2 causes a rise in temperature. (Some weird people even question the fact temperatures are rising!)

We’re in the experiment. Earth is our laboratory. We’re adding CO2 to the air and temperature is increasing, just as expected with the science of the greenhouse effect.

The chart below shows how temperatures have risen as CO2 emissions have gone up.

Figure 1 | CO2 (red curve) and global surface temperature change (blue curve). Data sources: NASA GISS (temperature) and Scripps Oceanography (CO2).

CO2 stays in the air for a very long time

Then there are deniers who wrongly, if hopefully, think that CO2 only stays in the air for a few years. I can’t imagine how they reconcile that with the growth in atmospheric CO2. It’s not possible. As Professor David Archer says in his book, The Long Thaw: “The lifetime of fossil fuel CO2 in the atmosphere is a few centuries, plus 25% that lasts essentially forever.”

It may be too late to stop seas from rising, but it’s not too late to stop them rising as quickly as they might, or to stop other calamities. At present we’re not doing nearly enough.

It’s time to stop this experiment. If we don’t do that soon we’ll be in deep trouble. Many scientists are very concerned that the consequences will be a lot worse than most people imagine if we don’t.

References and further reading

Le Quéré, Corinne, Robbie M. Andrew, Pierre Friedlingstein, Stephen Sitch, Judith Hauck, Julia Pongratz, Penelope A. Pickers et al. “Global carbon budget 2018.” Earth System Science Data (Online) 10, no. 4 (2018). (available here)

Global Carbon Projecthttps://www.globalcarbonproject.org/carbonneutral/index.htm

Inman, M., 2008. “Carbon is forever”. Nat. Rep. Clim. Change. https://www.nature.com/articles/climate.2008.122

Matthews, H. Damon, and Susan Solomon. “Irreversible does not mean unavoidable.” Science 340, no. 6131 (2013): 438-439. (pdf here)

Archer, David. The long thaw: How humans are changing the next 100,000 years of earth’s climate. Vol. 44. Princeton University Press, 2016.

IPCC flags risks and response options for polar and ocean environments in latest report article by Simon Torok in CSIRO’s ECOS. September 26th, 2019





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