We are now in the longest Nino-less period since NOAA record-keeping started:
The last three-month period classified as El Nino was March-April-May of 2010. 51 months have passed since then (with more likely in the pipeline, given a 0.0 anomaly now.) This chart only goes back to 2002, but the full record shows what an anomaly this is. Fifty month gaps occur in 1959-1963 and again in 1978-1982. The present 51 months is longer than either.
So, how is this significant? Most simply, recent temperature trends are likely to under-estimate the long-term trends, unless a suppressed El Nino is a long-term consequence of AGW. That's possible, but most climate models predict El Nino will become more frequent and strong in a warmer world, rather than the converse.
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So, how is this significant? Most simply, recent temperature trends are likely to under-estimate the long-term trends, unless a suppressed El Nino is a long-term consequence of AGW. That's possible, but most climate models predict El Nino will become more frequent and strong in a warmer world, rather than the converse.
Actually recent (I'm thinking the last decade or so) temperature trends will underestimate the long term trend even if El Nino suppression is the new normal. Such a transition would be expected to produce essentially a step change down followed by resumption of more or less the same rate of long term increase in temperature as we saw during the previous period of historically normal ENSO variation.
ReplyDeleteCorrect me if I'm wrong, but if El Nino suppression is the new normal, we may see more of the earth's heat imbalance convoyed into the deep ocean.
ReplyDeleteIn the link above, Mann points to research which hypothesizes that this could be a very modest negative feedback.
I certainly don't mean to imply that we should regard the short-term temperature trend as the new normal. Warming is going to accelerate, regardless of what happens with El Nino, and in point of fact, one slightly-longer-than-usual dearth of El Nino could simply reflect random variation.