I get so angry when reading climate change denial blogs on the internet. They love to present all sorts of graphs and bamboozle a gullible public with arguments that sound like science, but are actually right-wing spin and often purposeful deception. Climate change is a subject where it is easy to fool people who don’t know much about the subject. I have read enough at this point, that I can generally figure out many of the deceptive interpretations and the use of partial data, nonetheless, I always learn more when reading skepticalscience.com which is a web site dedicated to debunking the climate change debunkers. For example, I just ran across this specious article “The big picture: 65 million years of temperature swings“.
After I wasted my time writing a comment to point out the flaws in the arguments, I looked through the previous comments and realized that the owner of the blog was probably deleting comments like mine which are critical of his “interpretation” of the data. Since my comment is likely to be deleted, I will post it here:
Warming is not a killer, but global cooling is. It would only take a few years of global crop failures from cold weather to put populations at serious risk. Both the Antarctic and Greenland ice sheets are thickening: Leave anything on the ice, and it gets buried pretty fast
Actually thickening icesheets are a sign that global warming is occuring. The atmosphere currently has 4% more humidity in it compared to the 1970s because warmer air holds more water. Due to the higher humidity, more snow is falling on Antartica and Greenland compared to the past. In Greenland, the icesheets 1500m above sea level are currently thickening, due to the extra snow, but the icesheets under 1500m above sea level are melting. Measurements of the entire Greenland icesheet show that on a whole, the icesheet is loosing ice. Despite the fact that the icesheet is thickening above 1500m, Greenland temperatures are rising significantly and Greenland as a whole is loosing ice. In the case of Antarctica, part of the continent is getting colder and the icesheets are thickening due to extra humidity which cases more snow, and but as a whole the continent is warming and it is loosing ice.
As for the general argument that the earth is cooling, your graphs conveniently stop at the year 1905, before the vast majority of recent warming has occurred. If your graph included temperature date for the last century, it would have a very different shape. Yes, the snow from the last century hasn’t completely converted into ice, but there is plenty of data from other sources to show the dramatic rise in temperatures over the last century. Also your type of trendlines can be misleading, which is why scientists generally use running averages for their trendlines.
People who decide that they can interpret data better than the professional scientists often make thses sort of mistakes, which is why it is best to read what scientists are saying rather than amateur bloggers on the internet.