Biologist Nathan Mineo

Did You Know...?

Carbon Dioxide and Earth's Temperature

Written by Nathan Mineo 
Reprinted from the 2012 Cape Ann Vernal Pond Team Newsletter
Photograph by Cheryl Briscoe

Did you know that driving your SUV for one hour consumes up to 390,000 liters of air? That’s about as much air as one person consumes in 40 days! And during that hour, about 40 pounds of carbon dioxide (CO2) are produced and released into the atmosphere. By now we should all be very well aware of the “greenhouse effect,” “global warming,” and what role CO2 plays in all of it. Back in 1998, paleoclimatologist Michael Mann used tree rings to compile temperature data for the past 1000 years. The now famous “Hockey Stick” graph produced by that data shows a relatively stable global temperature until around 1900 (just after the industrial revolution), when the average global temperature starts a sharp and dramatic continuous increase. Since the “Hockey Stick,” mountains of global climate studies have been done, not only confirming the validity of the original study, but also clearly linking the increase in temperature to the increase in atmospheric CO2 concentrations caused by humans.

So how does CO2 increase temperature? That’s the infamous “greenhouse effect.” Essentially what happens is that short wavelengths of sunlight pass through the atmosphere and are absorbed by Earth. The resulting heat is released back toward space as longer wavelengths of infrared radiation. Some of that infrared radiation is deflected back to Earth, mostly by water vapor, but also by other gases in the atmosphere, such as CO2. This isn’t a bad thing. The greenhouse effect is, after all, why Earth is habitable. The problem that has been building since the turn of the 19th century is the accumulation of other greenhouse gases, predominantly CO2, which are amplifying the greenhouse effect by reflecting more infrared radiation back to Earth; literally, trapping more heat.

So what, doesn’t everyone like warmer weather? Well it’s not that simple. In fact, climate modelers trying to predict the repercussions of global warming are finding the task to be immensely complex. Global warming doesn’t mean everyone will experience warmer weather. For example, the Gulf Stream current brings warm tropical water from the Caribbean, up the east coast of the US, and then over to England. That warm water moderates England’s climate, which would otherwise be much harsher and colder. Adding more heat to the oceans could disrupt ocean currents like the Gulf Stream. If the Gulf Stream stops, England’s climate will become colder and harsher, even while the planet gets warmer. But even that scenario is grossly oversimplified. Climatologists are uncovering new layers of complexity with every new discovery. In particular, carbon sinks (systems that absorb CO2), and feedback loops (systems caused by warming that reduce absorption of CO2, produce more CO2, or absorb CO2) make predicting the repercussions of global warming a daunting task. Even with all the uncertainties, however, models seem to agree that if we don’t reduce our CO2 production the global average temperature will continue to increase.

There are things we can do to reduce our own CO2 production. Simple things like unplugging appliances while not in use can cut your electrical use by as much as 40% and cut as much as 1200 lbs of CO2 production a year! You can even purchase carbon offsets (see terrapass.com). The money you spend on the offsets goes to building green energy sources. Even just planting a tree can help. The forests are one of the largest carbon sinks on Earth. Protecting existing trees and planting more are crucial to offsetting our CO2 production. And don’t forget to support your local conservation organizations. If everyone does their small part at home and in their community, it will have a huge effect globally.

Multiple sources.