Monday, August 10, 2015

Are We Heading Into A Mega-El Nino?

El Nino is a complex interaction between the oceans and the atmosphere and results in changes in the weather patterns worldwide. They occur aperiodically and are characterized by warming equatorial oceans in the eastern and central Pacific. Take a look at this plot of the sea surface temperature anomaly.

Source: CCI

The qualifying definition of an El Nino is when the Oceanic Nino Index (ONI) is +.5 or higher for three consecutive months. This first occurred for the current El Nino during the October-November-December 2014 period when the index hit .6 - a weak El Nino. It then fluctuated over the next few months between .4 and .5. But, in March-April-May it increased to .7, followed by increases to .9 in April-May-June (a moderate El Nino), and now to 1.0 in the May-June-July period. This is still an unspectacular event, but it is also increasing. What I find disturbing is the models which predict it might strengthen to a 3.0 event this fall. That would be a mega-event.

Let's put a 3.0 event into perspective. The strongest El Nino event recorded in the last 60 years occurred in the 1997-98 year and grew to 2.3 (twice over the winter). That's the largest ever recorded. In fact, the only other times the ONI has reached 2.0 was in 1972-73 when it hit 2.0 (October-November-December) and 2.1 in 1982-83 (three times during the winter months). An ONI of 3.0 would be massive.

How likely is it that will happen? Not very likely at all. That is the extreme level of the modeling forecasts so I would be surprised it if gets anywhere near that high. However, something in excess of 2.3 is very feasible. While less severe than 3.0, it would still be the most severe El Nino ever measured. And, that 1997-98 event had an ONI of 1.0 at this time of year, the same as what we have currently.

Why is this such a big deal? Recall that the only way to heat the planet is via sunlight. Greenhouse gases do not heat the planet, they merely keep it from cooling down after the Sun heats it. Much of that heat (about 93%) is stored in the oceans. When an El Nino occurs, it releases some of that stored heat back into the atmosphere, resulting in an increase in the surface temperature. (A La Nina is the opposite effect, taking heat out of the air and resulting in cooling). I have to wonder - are we about to experience a huge release of stored energy?

What can we expect? Let's take a look at the 1997-98 event for guidance. This is from the CARE report on the worldwide effects:
The El Niño phenomenon that affected weather conditions around the globe and contributed to massive flooding along the coast of Latin America and in parts of the Horn of Africa and drought in Southeast Asia has gradually weakened since April. The impact of El Niño has been particularly severe among the impoverished and vulnerable populations where natural disasters can easily upset their tenuous livelihood security. Heavy rains and flooding has lead to thousands of deaths, loss of household assets and crops and caused extensive damage to vital infrastructure in Ecuador, Peru, Bolivia, Somalia and Kenya. In addition, water related diseases, such as cholera and malaria, increased dramatically in drought and flood affected areas in East Africa, Latin America and Asia. In Papua New Guinea, drought affected mountain populations moved to lowland areas where they contracted malaria at higher rates since they'd previously had limited exposure to malaria.

In Indonesia, El Niño related drought has caused a cereal shortfall of over 3.5 million metric tons and large scale environmental degradation from uncontrolled fires in October 1997. Food commodity prices sky rocketed and became prohibitively expensive to the majority of people in the fourth most populous country in the world. In a complex web of cause and effect, natural disasters are often the contributing spark needed to light the tinderbox, or in this case push an already fragile society over the edge into social crisis. The El Niño drought in Indonesia was one of many contributing factors in fomenting the economic and political unrest that now exists in the country.

There's more, but the point is made. On a worldwide basis, a strong El Nino is a bad thing. But, the record shows it was not bad for the U.S. Here is the report from the National Climatic Data Center on the effects on the U.S. This report here indicates the U.S. damages were about $4 billion, while there were $19 billion in benefits. An estimated 189 people died because of the weather, but an estimated 850 were saved because of it.

If the pattern repeats itself, and taking into account a stronger event, the results could be really devastating for the world, but we might be spared the worst of it here.

Personally, I'd rather not find out if that is true.

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