## Monday, May 03, 2010

### El Nino is transitioning to ENSO-neutral conditions

The latest weekly ENSO report shows on page 5/34 that the SST (sea surface temperature) departure in the defining Nino 3.4 region has dropped to +0.5 °C during the most recent one-week period which is just the boundary between the El Nino conditions and ENSO-neutral conditions.

The number +0.5 °C is well below +1.9 °C, the maximum that the recent El Nino episode reached before Christmas 2009 (which wasn't extremely far from the peaks around +2.5 °C in the 1997-98 El Nino of the century). Because the El Nino and La Nina episodes are computed from three-month averages, the El Nino episode will almost certainly continue at least through March-April-May 2010.

By the end of the year 2010, we may see the first hints of an ENSO-related cooling: the typical delay is about 6 months. I remain completely undecided whether 2010 will turn out to be warmer or cooler than 1998: the ENSO departures in the 2009/10 El Nino episodes seem to have an almost identical strength and timing as those during the 1997/98 El Nino of the century and because ENSO is a key driver of the interannual variability which is still the key at a decadal scale, it is a neck and neck race.

Bonus: tripled CO2 and plant growth

Olda K. has sent me a nice video showing two cowpea plants - how their growth differs at 450 ppm and 1270 ppm of CO2:

Indeed, CO2 is not a pollutant. Quite on the contrary. Because the total biomass increased 1.44 times when the CO2 concentration jumped 2.80 times, we may guess that the total biomass scales like the concentration^{0.35}, roughly a third root.

Because the CO2 concentrations will go from 390 ppm today to 560 ppm in 2100, which is an increase by the factor of 1.44, we may expect the biomass per plant to increase by the factor of 1.44^{0.35} = 1.14 i.e. by 14 percent. The CO2 growth itself may allow us to feed 8 billion people instead of 7 billion people. A hypothetical temperature increase by one or two degrees would make another positive contribution, possibly a more substantial one.

But technological progress is likely to be much more important than these two pretty much natural factors.

Via CO2 Science.

1. The Southern Oscillation and the El Niño are not connected, despite their frequent reference together.

There hasn't been anything out of the ordinary related to any oscillation or periodic event seen in years and this has been a pretty lukewarm El Niño.

Nobody would care much about any of this I don't think, if AGW had not become an invented and unnecessary subject of "concern"

2. Brian,

I agree that AGW is an invented and unnecessary subject, but I think ENSO events will always be newsworthy, simply because of the impact they have on local weather. For example, ski conditions were particularly good this year in Northern New Mexico, thanks to the El Nino.

I would also characterize this latest El Nino as 'strong'. While it fell short of 1997-98, I believe it takes second place in some categories when compared to El Nino's of the last several decades.

3. Dear Jim,

I think that you're clearly right that the recent El Nino was the second strongest in decades.

The tables on page 25 etc. of this document (click) show that the 1.8 three-month departure has only been reached/surpassed since 1982 in 1997-98 and 2009-2010 El Ninos.

Best wishes
Lubos

4. Hi Lubos,

I have a question regarding SST's and lags.

Given an external forcing that will ultimately warm STT's by C, can the unrecognized SST heat gain ("heat in the pipeline"), be modeled as per Newton's Law of Cooling: Ce^-rt

I suspect this isn't the case, otherwise we should be able to estimate r and calculate the unrecognized heat easily. Is there a simple formula or is a computer model needed?

Thanks, AJ