But CO2 concentrations were higher in the past…
[Merlin and Gaius are chatting about magic when suddenly…]
Gaius: Merlin! Don’t you ever think of the CO2 we breathe out?
Merlin: Yes, Gaius. These days, CO2 levels are skyrocketing as high as the stars…I worry –
Gaius: Really? But, they were higher before in the past…are you crazy, my boy? Don’t you trust me since I have taught you well about magic? My words are golden!
Merlin: Don’t you know that there’s evidence from paleoclimate records?
Gaius: Paleoclimate records? What the heck are they and what makes you think of them as mighty? I tell you this – you are making up such nonsense to act like you’re better than me.
Merlin: No! You must listen carefully…this is the truth. You of all people should learn to listen to the hard facts. Scientists have traveled all over the world and have collected such beautiful data from archives and proxies. Let me tell you this: Archives are the physical objects that store wonderful data that must be calibrated in our modern setting to be used as proxies. Proxies are valuable in that they tell us about temperature changes, ice levels, sea surface temperatures, and lots more!
Gaius: Enough with your science talk, Merlin. You know you’re just trying to act smart. This stuff does not exist! Are you in your right mind? Do you have a goblin inside of you?
Merlin: Not to worry, I have much more to say. You just can’t stand the truth. Anyway, there are wonderful ice cores…chunks of ice analyzed in the lab. It’s exciting you know – plus scientists can calculate the delta O-18 which essentially looks at Oxygen-16 and Oxygen-18 isotope compositions. As that delta O-18 increases, temperatures increase and then CO2 increases!
Gaius: See, I told you. Seems like you can’t prove me wrong. You just said CO2 increases and it sounds like those ice cores or whatever are old so haha – I win!
Merlin: Not quite…I am just warming up. Now, scientists separate time periods into glacial and inter-glacial. Glacial just means CO2 levels were low and it was a cold time along with low sea level. Inter-glacial is just the opposite. Moreover, yes, CO2 levels were higher in the past, but the reasons are what you skipped – and they are vital in understanding why you believe the myth! Studies show CO2 is increasing at unprecedented rates. Why is it so hard for you to understand?
Gaius: You just said CO2 levels were higher in the past – exactly my point! We know this is a natural cycle so why bring humans into this? We are tiny creatures on the face of this planet…don’t you see what I am trying to tell you? We humans are playing a little role in changing our climate and that’s all there is to this whole nonsense climate change phenomenon.
Merlin: Oh, Gaius! Please listen to me…I still haven’t finished yet. If only you would be patient with what I have to say. Well, let’s take a look at figure 1 taken from Royer 2006. This data looks at the time period known as the Phanerozoic eon which includes the last 540 million years. By using proxy records which I explained before, this amazing graph shows the incredible peaks of CO2. There’s a notable peak at around 5000 ppm around 415 million years ago but also a minimum value close to 200 ppm around 300 million years ago. So, what do you think of this?
Gaius: Isn’t CO2 around 400 ppm today? It was much higher in the past so what’s your point? If it reached levels much higher when there were no people around millions of years ago, then how can you say humans are contributing to climate change?
Merlin: I am saying CO2 is not the only driver of climate change. There are a ton of factors such as the albedo and sun levels. If there was more ice as in the glacial periods, then the albedo or reflectivity of radiation would be higher since white objects reflect greater amounts of light. Also, the sun was surprisingly weaker in the past – if the sun was weaker, then CO2 clearly had to play some role. Now, the sun is much stronger, but its strength on the “forcing” of the planet is low because greenhouse gases like CO2, CH4 and N2O play a much greater role. Just take a look at figure 2 from the IPCC AR4 report. Although people say the sun is powerful and warms up our planet, they are not paying attention to the relative amounts of forcing. Yes, the sun is a factor, but it is not a major contributor to climate change. That is why CO2 is such a big deal and for a valid reason.
Gaius: So, what controlled CO2 in the past? Isn’t it just a climate variation since I see in figure 1 that CO2 varies through time? What is the big deal? Maybe we are going through a normal time and another glacial period is sure to fix our problems. Why spend so much time on this?
Merlin: Remember the archive I mentioned before – ice cores? Consider another IPCC constructed graph – figure 3. Delta-D is a useful proxy that can be calculated from ice cores – in this case, the graph was constructed from Vostok and Epica Dome C cores from Antarctica. We also have delta O-18 from benthic foraminifera which are amoeboid protists that live in the deep ocean. Anyway, this graph shows several important pieces of information: It differentiates glacial periods from inter-glacial periods and shows correlations between greenhouse gas concentrations and delta values. Delta-D values are essentially temperature – increase in delta-D means an increase in temperature. Also, notice the lines match up almost exactly and in particular, the inter-glacial periods reach only a maximum of about 280 ppm of CO2…then, there is a sudden steadily increasing trend after 2000. Don’t you think this point is unusual?
Gaius: But previously you stated millions of years ago CO2 levels were much higher…then how does figure 3 make any difference?
Merlin: Remember, the world was much different before…continents were configured differently, ice sheet distribution varied and abrupt climate change was common. Think of the planet as a sensitive child – the more that changes, the greater the impact. Furthermore, according to Assistant Professor Tripati at UCLA: “The last time carbon dioxide levels were apparently as high as they are today and were sustained at those levels global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland” (https://thinkprogress.org). Why were global temperatures and sea level higher? Why was there barely any ice? One such time period was the Paleocene-Epicene-Thermal-Maximum hypothetically marked by the eruption of a large igneous province in the North Atlantic which increased CO2 levels and shortly after, temperature, thereby causing the destabilization of methane hydrates which resulted in high CH4 emissions corresponding to a very low (~60 o/oo) delta C-13 value as measured from marine sediments. The atmospheric-ocean interaction was powerful in that ocean circulation suddenly slowed down since deep ocean temperatures increased. The LIP triggered a chain of events that led to what scientists call “abrupt climate change.” Therefore, figure 3 is showing an equivalent time period marked by the astonishing rise of CO2. Humans are actively influencing the composition of greenhouse gases in the atmosphere; thus, the Arctic is proposed to become ice-free and sea levels are expected to rise dramatically by the end of the century. The continents have not changed positions in millions of years and volcanic eruptions would have to increase by more than 270 times the normal rate if they were the sole sources of carbon. Human impact is the primary driver of climate change – undoubtedly CO2 is the major constantly shifting factor that is contributing to all of the deadly consequences you hear about in the news – nothing more, nothing less.
Gaius (laughing hysterically): What a story…maybe you haven’t seen figure 4 from NASA. Look! It shows an area from South America where temperatures are actually decreasing…and this is in Brazil – an area that is normally hot? I should say global cooling is the real deal, not global warming!
Merlin: Oh, Gaius. You just can’t trust scientists, can you?
Gaius: I am all for calling out fake data. I must teach you more magic spells now!
Merlin: I guess we will have another long conversation on fake data…oh well, better get my spell book ready…
Cover Image Credit: jaymantri.com
Source: Royer 2006.
Source: IPCC AR4.
- Figure 3:
Source: From lecture slides; IPCC AR4.
- Figure 4: http://www.telegraph.co.uk/comment/11367272/Climategate-the-sequel-How-we-are-STILL-being-tricked-with-flawed-data-on-global-warming.html
Source: NASA Goddard Institute for Space Studies.