Global temperatures, volcanoes and El Niño
I have now added some extra functionality to my Global Temperature application to overlay (or should that be underlay) ENSO and volcanic events on it. As you can see there must be a strong correlation between increases in global warming and El Niño events, having said that the El Niño event of 1991-92 does seem to stand out as having the opposite effect, curiously global temperatures fell rather drastically during the rest of 1991 and 1992. It might be difficult to see but there are a couple of vertical grey bands plotted on the graph around then, these represent the Mount Pinatubo eruption that occurred on the 15th of June 1991. This is what caused the crash of 0.5°C in global temperatures and the cooling that followed the eruption, but the El Niño event that started the same year must have had a been a big mitigating effect and holding temperatures up, who knows how much the world would have cooled without it.