Global Warming, Carbon Dioxide, and Plants

There was an article published recently that traced the melting of glaciers in the US over the last 50 years.  This study showed, pretty convincingly, that the glaciers are, indeed, melting, and melting rapidly.  Meanwhile, in our atmosphere, levels of carbon dioxide from humans burning fossil fuel are increasing in a manner roughly correlated to the increase in temperature that’s melting the glaciers.  But is the carbon dioxide actually causing the warming?  Believe it or not this is still an area of discussion among scientist, and the answer isn’t as simple as many newspapers make it out to be.  Almost all of the scientists that you care to talk to, even those skeptical of the role of carbon dioxide in global warming, admit that increasing carbon dioxide is going to cause a net increase in global temperature.  But there is a decent amount of research out there showing that solar and geothermal activity (in other words things that we can’t control) may cause anywhere from 15 to 75% of the warming that we’re seeing.  To be honest, based on what I’ve read (and I’m no climate scientist), I tend to side with those who believe that global warming is mostly caused by human releases of carbon dioxide, but I also think that to accept that theory as proven is a mistake.

In my humble opinion we’re missing the more compelling reason to reduce our emissions of carbon dioxide (besides the fact that we’re running out of fossil fuels of course).  Plants.  Most people simply assume that, temperature increases aside, increasing carbon dioxide in the atmosphere is going to be good for plants, and that’s just not the case. True, some plants, like Canadian thistle and many other weeds, love the increase in carbon dioxide, but other plants, such as many grasses, just don’t respond to it that well.  The ironic thing is that, for those plants that respond strongly to CO₂, nutrients like nitrogen and potassium are taken up quickly from the soil (as you’d expect with a rapidly growing plant) and then, as the nutrients in the soil run out, the growth of the plant is drastically reduced.  In other words, CO₂ causes unfertilized soils to become more rapidly depleted.  So what does this all mean?  It means that as we increase CO₂ levels in the atmosphere we’re changing the world’s ecosystem, including the fields that grow our crops.  Indeed, we’re actually adjusting the atmosphere to alter which plants are most appropriate for certain situations.  There are even those who argue that, because of our CO₂ emissions, we’re encouraging invasive plants to take over our native forests because these plants tend to be able to handle high CO₂ (and high temperatures) better than the plants that are already there.

To me this is the more important reason to reduce our carbon footprint.