It has become so obvious that the increases in greenhouse gases in our atmosphere are causing world temperatures to increase, that even the far right anti-science types can no longer deny it. They have now retreated to a position of claiming what we are observing is the variation of a natural cycle in carbon dioxide, methane and other greenhouse gases. Lucky for us, a new report, just published in science, blows that argument completely out of the water.
The analysis involves ice cores. So lets understand this process a bit. When show falls and compacts, it traps tiny gas bubbles with it. These tiny bubble are remarkably stable and represent a sampling of the atmosphere at the time that the snow fell. As more snow falls later, it covers previous snow. In very cold regions, like Antarctica, the snow never melts and just keeps building up. This process has been going on for thousands of years and the ice packs of Antarctica are kilometers thick. By drilling a core that goes for many kilometers and sampling the gas trapped in these bubbles, scientists get a record of what gases were present at various depths. The depth down the core can be correlated with the age of the snow through various analysis, thus giving a record of gas levels over time.
Siegenthaler et al. and Spahni et al. took a recent ice core samples from Dome C, in Antarctica. Dome C is an area that gets very little snow fall, thus each cm in the core represents more time. By drilling a very deep core, the scientists were able to analyze back 650,000 years. An important finding here for refuting the global warming is a natural phenomenon argument is at no point in the past 650,000 years has carbon dioxide or methane levels been as high as they are now. The maximum was between 260 to 300 ppm for carbon dioxide. We are currently at 370 ppm for carbon dioxide and 1720 ppb for methane. Clearly, this is caused by human activity and not a natural phenomenon. Another thing to note. Examine the graph that comes with the science perspective by Edward Brook. Notice the sharp increase in greenhouse gases with the advent of the industrial revolution and the burning of fossil fuel. Clearly this is anomalous and not a natural process.
Next time anyone trys that line on you, refer them to this data. We are performing a global experiment with the planet and the results of this are completely unpredictable. Global warming must be stopped.