<story><title>Guy Callendar, the engineer who discovered human-caused global warming</title><url>https://nautil.us/the-part-time-climate-scientist-542351/</url></story><parent_chain><item><author>andrewla</author><text>Just to nitpick, while commonly accepted, the idea that CO2 increase is anthropogenic is routinely disputed by climate skeptics [1].&lt;p&gt;The argument generally is that warming temperatures cause rising CO2. This in turn is a fact not disputed by climate scientists, only that it is not sufficient to explain the current rise in CO2.&lt;p&gt;[1] A pro-AGW debunking of the common argument &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;skepticalscience.com&amp;#x2F;co2-lags-temperature.htm&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;skepticalscience.com&amp;#x2F;co2-lags-temperature.htm&lt;/a&gt;</text></item><item><author>hn_throwaway_99</author><text>This is why I am completely, totally baffled that anyone tries to still deny the anthropogenic source of climate change.&lt;p&gt;I &lt;i&gt;fully&lt;/i&gt; understand that climate models are mind boggingly complex, and that it&amp;#x27;s incredibly difficult to predict how all the different intertwined factors will play out in real time. But at a very fundamental level, we&amp;#x27;ve drastically increased one of the primary greenhouse gas concentrations at a rate unseen in Earth&amp;#x27;s history (not to mention many of the other major greenhouse gases like methane and nitrous oxide). Literally no sane person disputes that fact. How could we think that making this major change to Earth&amp;#x27;s climate system &lt;i&gt;wouldn&amp;#x27;t&lt;/i&gt; have huge effects?</text></item><item><author>zug_zug</author><text>&amp;gt; he showed [atmospheric CO2] at 315 parts per million in 1958; today it is 421 ppm; in the pre-industrial 19th century, it had rested around 280 ppm)&lt;p&gt;Wow, somehow I was unaware that we had raised atmospheric CO2 by 50% -- that&amp;#x27;s impressive in sense.</text></item></parent_chain><comment><author>biotinker</author><text>Ya know, I saw this a year ago, and was curious if it actually held up. After all, the amount of CO2 released by humans is only about 4% of all CO2 released, on an annual basis (730 gigatons all sources, ~30 gigatons by humans).&lt;p&gt;But it&amp;#x27;s a pretty simple equation. We know the approximate mass of the atmosphere, and the number of molecules per weight. We know how many molecules are in a unit mass of CO2.&lt;p&gt;Thus we should be able to calculate out &amp;quot;how many gigatons of CO2 are necessary to increase atmospheric CO2 by 1ppm&amp;quot;, and then given measurements of actual CO2 increases, how much CO2 is necessary to increase atmospheric levels by the amounts seen.&lt;p&gt;If the amount of CO2 required to yield the observed increase is greater than annual human emissions, then that&amp;#x27;s a strong signal that CO2 increase is &lt;i&gt;NOT&lt;/i&gt; anthropogenic and something else is going on. If it&amp;#x27;s less, then that is a strong signal that humans are the primary culprit.&lt;p&gt;Anyway, I did out all the math and it takes about 8.8 gigatons to increase atmospheric levels by 1ppm, and we&amp;#x27;re netting an increase of about 17gt into the atmosphere per year, for an increase of ~2ppm annually. So it&amp;#x27;s pretty clear that this is anthropogenic.&lt;p&gt;If anyone wants to check my math I wrote it all up here [0]. Numbers are a couple years old at this point but the conclusion still stands.&lt;p&gt;[0] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;biotinker.dev&amp;#x2F;posts&amp;#x2F;climate1.html&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;biotinker.dev&amp;#x2F;posts&amp;#x2F;climate1.html&lt;/a&gt;</text></comment>
<story><title>Guy Callendar, the engineer who discovered human-caused global warming</title><url>https://nautil.us/the-part-time-climate-scientist-542351/</url></story><parent_chain><item><author>andrewla</author><text>Just to nitpick, while commonly accepted, the idea that CO2 increase is anthropogenic is routinely disputed by climate skeptics [1].&lt;p&gt;The argument generally is that warming temperatures cause rising CO2. This in turn is a fact not disputed by climate scientists, only that it is not sufficient to explain the current rise in CO2.&lt;p&gt;[1] A pro-AGW debunking of the common argument &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;skepticalscience.com&amp;#x2F;co2-lags-temperature.htm&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;skepticalscience.com&amp;#x2F;co2-lags-temperature.htm&lt;/a&gt;</text></item><item><author>hn_throwaway_99</author><text>This is why I am completely, totally baffled that anyone tries to still deny the anthropogenic source of climate change.&lt;p&gt;I &lt;i&gt;fully&lt;/i&gt; understand that climate models are mind boggingly complex, and that it&amp;#x27;s incredibly difficult to predict how all the different intertwined factors will play out in real time. But at a very fundamental level, we&amp;#x27;ve drastically increased one of the primary greenhouse gas concentrations at a rate unseen in Earth&amp;#x27;s history (not to mention many of the other major greenhouse gases like methane and nitrous oxide). Literally no sane person disputes that fact. How could we think that making this major change to Earth&amp;#x27;s climate system &lt;i&gt;wouldn&amp;#x27;t&lt;/i&gt; have huge effects?</text></item><item><author>zug_zug</author><text>&amp;gt; he showed [atmospheric CO2] at 315 parts per million in 1958; today it is 421 ppm; in the pre-industrial 19th century, it had rested around 280 ppm)&lt;p&gt;Wow, somehow I was unaware that we had raised atmospheric CO2 by 50% -- that&amp;#x27;s impressive in sense.</text></item></parent_chain><comment><author>throw0101c</author><text>&amp;gt; &lt;i&gt;The argument generally is that warming temperatures cause rising CO2. This in turn is a fact not disputed by climate scientists, only that it is not sufficient to explain the current rise in CO2.&lt;/i&gt;&lt;p&gt;It should also be noted that the type of C in CO2 matters:&lt;p&gt;&amp;gt; &lt;i&gt;In addition, only fossil fuels are consistent with the isotopic fingerprint of the carbon in today’s atmosphere. Different kinds of carbon-containing material have different relative amounts of “light” carbon-12, “heavy” carbon-13, and radioactive carbon-14. Plant matter is enriched in carbon-12, because its lighter weight is more readily used by plants during photosynthesis. Volcanic emissions are enriched in carbon-13. The ratio of carbon-13 to carbon-12 in the atmosphere and the ocean are roughly the same. Since carbon-14 is radioactive, it decays predictably over time. Young organic matter has more carbon-14 than older organic matter, and fossil fuels have no measurable carbon-14 at all.&lt;/i&gt;&lt;p&gt;&amp;gt; &lt;i&gt;As carbon dioxide concentrations in the atmosphere have risen over the past century or more, the ratio of carbon-13 to carbon-12 has fallen, which means that the source of the extra carbon dioxide must be enriched in &amp;quot;light&amp;quot; carbon-12. Meanwhile, the relative amount of carbon-14—radioactive carbon—has declined. The record of carbon-14 in the atmosphere is complicated by nuclear bomb testing after 1950, which doubled the amount of radioactive carbon in the atmosphere. After the nuclear test ban treaty in 1963, the excess atmospheric carbon-14 began to decline as it dispersed into the oceans and the land biosphere.&lt;/i&gt;&lt;p&gt;* &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.climate.gov&amp;#x2F;news-features&amp;#x2F;climate-qa&amp;#x2F;how-do-we-know-build-carbon-dioxide-atmosphere-caused-humans&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.climate.gov&amp;#x2F;news-features&amp;#x2F;climate-qa&amp;#x2F;how-do-we-k...&lt;/a&gt;&lt;p&gt;&amp;gt; &lt;i&gt;In this “Grand Challenges” paper, we review how the carbon isotopic composition of atmospheric CO2 has changed since the Industrial Revolution due to human activities and their influence on the natural carbon cycle, and we provide new estimates of possible future changes for a range of scenarios. Emissions of CO2 from fossil fuel combustion and land use change reduce the ratio of 13C&amp;#x2F;12C in atmospheric CO2 (δ13CO2). This is because 12C is preferentially assimilated during photosynthesis and δ13C in plant-derived carbon in terrestrial ecosystems and fossil fuels is lower than atmospheric δ13CO2. Emissions of CO2 from fossil fuel combustion also reduce the ratio of 14C&amp;#x2F;C in atmospheric CO2 (Δ14CO2) because 14C is absent in million-year-old fossil fuels, which have been stored for much longer than the radioactive decay time of 14C.&lt;/i&gt;&lt;p&gt;* &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;agupubs.onlinelibrary.wiley.com&amp;#x2F;doi&amp;#x2F;full&amp;#x2F;10.1029&amp;#x2F;2019GB006170&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;agupubs.onlinelibrary.wiley.com&amp;#x2F;doi&amp;#x2F;full&amp;#x2F;10.1029&amp;#x2F;201...&lt;/a&gt;</text></comment>