A Pro and Con of More CO2 in the Atmosphere

Rising levels of CO2 from fossil fuel emissions contribute to a rise in earth’s temperature, and is often demonized because of this effect.  What usually go unmentioned are the subtle effects that greater CO2 levels have on living organisms.

Plants require CO2 to perform photosynthesis.  Photosynthesis is the process by which plants take light energy, water, and CO2, and convert it into sugars and oxygen – providing both the food we need to survive and the oxygen we need to breathe.  In order for plants to perform photosynthesis, they need to get CO2 into their leaves.  CO2 enters the leaves of plants through tiny holes called stomata.  When CO2 enters, water is lost.  In today’s atmosphere plants are usually limited by CO2 in their ability to grow.  Thus we come to the first positive effect of increasing CO2 in our atmosphere: plants tend to grow better at higher CO2.  This comes with a caveat however – this increased growth requires more nutrients, and plant growth is usually limited by the nutrients available in the soil (this is why farmers need to fertilize their crops).  Next I will give an example of this effect.

Some scientists study the effects of elevated CO2 by using an equipment setup called a free-air CO2 enrichment (or FACE, for short).  Without going into too much detail, the scientists take an experimental forest, and construct a series of pipes to deliver CO2 to the trees.  To view and example of how these look when their setup, go to http://face.ornl.gov/expdes.html to view the Oak Ridge FACE site.  Many of these experiments run for up to ten years, and one of the studies from the Oak Ridge FACE site found that, after 11 years of CO2 enrichment, the growth-enhancing effects of increased CO2 wore off (Norby, Warren, Iversen, Medlyn, and McMurtrie, 2010, Proceedings of the National Academy of Sciences 107:19368-19373).  This study found that nutrients became limiting – essentially the plants that grew faster from having more CO2 depleted the soil of nutrients faster than they could be replenished.  Without extra nutrients to support extra growth, the growth rate of the plants declined to a normal level without extra CO2.

From my example we learn that increasing CO can be a good thing, but its benefits might only be temporary, depending on whether the plants can meet the nutritional requirements needed for increased growth.  On the other hand, if we look at plants that we fertilize for agriculture, increased CO2 will support greater yields and a greater food supply in the future.  However, we need to remember that higher growth also requires more water, and weather patterns could change dramatically in the future.  My take home message is that while a single study on a given environmental factor might show a positive effect (e.g. CO2 in the above study), other aspects of the environment can complicate the effect (as nutrient availability did in the study), making it difficult to predict how plants will respond.  Our world is vastly more diverse and complex than we could ever imagine, and we are only just beginning to get an idea of how little we know and understand.  So give scientists a break when they take back something they used to claim as true – often times it is because new evidence told them they were wrong, so they stepped up and changed their view of the world like a true scientist should.

Stay safe and stay informed,

-Joe

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Critique of a Climate Skeptic’s Skepticism

In an editorial published in the London Free Press titled, “Predictions on climate a big hoax,” (Sept. 17, 2013) Ezra Levant shows a riveting combination of ignorance, conspiracy theory, and irrationality. The article discusses a recent paper in Nature Climate Change (see Fyfe, Gillett & Zwiers, 2013, Nature Climate Change 3:767-769), which found that nearly all of the 117 simulations of a set of models (note: 117 simulations not models) predicted higher rates of warming than those observed, rightly suggesting an “inherent bias” as Mr. Levant points out. This inherent bias, which he goes on to attack, is not a conspiracy by environmentalists or scientists as is implied in the LFP article, but it is simply due to a lack of scientific knowledge.

                A major influence on climate that is still poorly understood is the world’s oceans. The oceans are vast, encompassing about two thirds of the earth’s surface. Water can absorb a lot of heat before it changes temperature: that is why it takes so long to boil a pot of water. As well, water has a strange property where it is most dense at 4°C (39.2°F). This means that the deepest parts of the world’s oceans are probably 4°C (I say probably because the deep ocean is still largely unexplored and uncharacterized – we know very little about it). Heat energy from the surface of the ocean can be conducted to the deep ocean, reducing the warming that we might expect in the ocean from warmer air temperatures. Since the ocean can absorb so much heat, the oceans have a stabilizing effect on our climate. So when climate scientists included just a small part (only 8%) of the world’s oceans in their climate models (see Kosaka & Xie, 2013, Nature 501:403-407), they found that it is the ocean temperature and heat absorption that has made the climate warming since 1998 “almost unmeasurable” as Mr. Levant retorts. The overestimate of warming produced by the first article I mentioned is likely due to neglecting the effect that the oceans can have on climate.

                Climatic changes typically take place on the order of hundreds to thousands of years. Given how rapidly we have changed our climate in the past 150 years or so, a ten year pause in warming shouldn’t herald hoorays and huzzahs that climate warming has stopped – instead we should be very disturbed, because clearly there is something that is absorbing all the extra energy trapped in the atmosphere from the CO2 we have been pumping into the atmosphere, and when whatever that reservoir is becomes saturated, it is possible that warming will accelerate beyond our worst-case scenarios. However, the Intergovernmental Panel on Climate Change’s Fifth Assessment Report on the Physical Basis of Climate Change is due out this week, so we shall see what the outlook is for climate this century.

                Just remember to read between the lines when you read articles from writers who are skeptical of scientific evidence: it can be very easy to misinterpret scientific information that comes directly from a scientific article, and many of these skeptics latch onto words that agree with their worldview, while ignoring all the other evidence.

Stay safe and stay informed,
– Joe

Motivation for Life, the Universe, and a Goldfish Bowl

This little project of mine has been a long time coming.  It is mainly the result of a growing cohort of science skeptics in this ‘information age’.  Sure, information may be accumulating at a more rapid rate than ever before, and most (and if you are clever and have a disregard for the law, all) information on the internet is freely available.  More and more people are self-educating themselves with this freely available information, most of the time unaware of the quality of the information itself, and the source of the information as well.  Sometimes this information is false, sometimes it is gilded in flowery and complex language to hide that the source of the information either: a) does not know what they are writing/talking about, or b) is purposely miscommunicating the information.  But this isn’t always the case.  My biggest issue is with science skeptics.  The skeptics who think vaccines don’t work, climate change isn’t driven by human influences on the environment, evolution isn’t real, etc. (think of anything with a huge burden of scientific evidence supporting that claim and you will find someone who thinks that the claim is ridiculous and wrong).  As a scientist, I am taught to let the evidence speak for itself, not to be emotionally or politically involved, simply show the evidence and let the people decide.  But nowhere in my training have I been informed on the proper response to people who simply do not accept evidence.  This project of mine is what I believe to be the appropriate response: proper education, freely available.