These three plots tell us why hydrocarbon substitution is so vital. Top left – the level in the atmosphere (red) going back 400,000 years. In blue, we see the temperature. Temperature and levels are clearly correlated. The last ice age occurred some 20,000 years ago and corresponded to a average temperature difference from today of about 5 degrees. Note: levels never go above 305 ppm…until in the last 100 years. The plot above shows the increase in over the last 60 years. The bottom plot shows the levels since 2009. The level exceeded 400ppm in May 2013. What temperature rise does that suggest?