(Volcano Watch is a weekly article written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)

In this age of the Internet, anyone’s opinion on any subject, whether thoroughly researched or derived from an Ouija board, can be broadcast to the world.

For example, in recent weeks, while Climate Summit delegates argued curbs on the emission of climate-changing gases, several blogs and letters to the editors of various newspapers have been blaming volcanoes for two critical parts of the climate debate: the abundance of greenhouse gases, and the rising indicators of those gases at the world’s network of monitoring sites.

The fundamental attack is that many, if not most, climate monitoring stations are located downwind of active volcanoes. The inference is that these stations are measuring volcanic emissions rather than atmospheric carbon dioxide (CO2).

On the surface, this may seem plausible, because, for example, the oldest climate CO2 monitoring record comes from the upper slopes of the active volcano Mauna Loa.

Named the Keeling Curve, after the scientist who started the measurements, this record has shown a steady increase in the concentration of atmospheric CO2 since the 1950s.

Is the Keeling Curve contaminated by CO2 emissions from Mauna Loa? Absolutely not. Researchers at this location painstakingly sift through their data to weed out any possible influence from local volcano sources. Steve Ryan, a climate monitoring scientist at the Mauna Loa Observatory, has actually extracted from the discarded CO2 monitoring data a good record of Mauna Loa’s CO2 degassing.

These volcanic emissions are easily recognizable and have been removed from the atmospheric monitoring record to produce a solid record of global atmospheric gas concentrations that are uncontaminated by local sources of any kind.

What about the other charge that world volcanoes produce more CO2 than all humankind and their many industrial endeavors?

As we have reported in previous Volcano Watch columns, since people started burning fossil fuels, human civilization has produced more CO2 than volcanoes.

Volcano observatories and researchers have measured volcanic CO2 emissions for many years as way to understand how volcanoes work and what makes them erupt.

All of these data have been gathered in a few studies to estimate how much CO2 is produced, on average, by Earth’s volcanoes. The answer is about 200 million tonnes annually.

This may seem like a huge amount of CO2, but a visit to the U.S. Department of Energy’s Carbon Dioxide Information Analysis Center (CDIAC) Web site (cdiac.ornl.gov/) helps anyone armed with a handheld calculator and a high school chemistry text put volcanic CO2 emissions into perspective. Compared to global fossil fuel CO2 emissions, which tipped the scales at 30,000 million (30 billion) tones in 2006, volcanic CO2 is less than 1 percent of the amount produced by human activity.

Volcanoes have been erupting throughout Earth’s history, which encompasses human development from chipping stone tools to landing men on the moon. While the number of volcanic eruptions on Earth has not increased significantly, atmospheric concentrations of greenhouse gases noticeably increased when humans began producing energy by burning fossil fuels.

Science involves thorough research, both on what is already known and what can be further tested or investigated. Opinions and questions are part of the scientific process, but we hope that those who opine and question can also acknowledge the answers available in documented data.