One hundred and three years ago today, on September 5th, 1898, the Skibbereen Eagle ran its famous editorial: "We will keep our eye on the Emperor of Russia and on all such despotic enemies, whether at home or abroad, of human progression and man's natural rights." Weather Eye is similarly vigilant towards the tropical Pacific Ocean, where every now and then the first signs of an El Nino are detected - portents of unusual weather patterns to come.
The El Nino phenomenon is a general warming of the surface waters of large areas of the Pacific in the low latitudes. It occurs at irregular intervals of between two and seven years, and the anomalous warmth injects a great deal of extra energy into the atmosphere in contact with it.
This periodic heartbeat of El Nino causes palpitations in the world's climate. At its peak, the normally arid areas of western South America are drenched with rain; Indonesia and the Philippines experience droughts at times when abundant rain might otherwise be expected; abnormally dry weather facilitates forest fires in northern Australia; and hurricane activity off the western coast of Mexico is much enhanced, often bringing storms and floods to southern California. While the more extreme effects of an El Nino episode are experienced only in the low latitudes, there is convincing evidence also that it has some impact on rainfall patterns over North America and Europe.
The last El Nino was in 1997/98. It was exceptionally strong, with sea surface temperatures in parts of the Pacific rising to five degrees or more. And since February this year, there have been signs that the cycle is beginning once again. Sea temperatures over large areas of the tropical Pacific are currently one or two degrees above normal, and they are expected to continue rising for the remainder of this year, allowing El Nino to reach its peak in the early months of 2002.
It is only in the last 15 years or so that we have gained a satisfactory understanding of how an El Nino forms and is maintained. And it is only quite recently that computer models have been developed capable of simulating the complex oceanic and atmospheric interactions involved and capable of processing the vast amounts of data required to arrive at a prediction.
The models currently indicate that the emerging El Nino will be relatively mild. But such predictions are still tentative, so we must keep our Weather Eye, not on Russia, but on the distant equatorial waters of the Pacific Ocean.