AILSA CHANG, HOST:
And now for a longish-term (ph) weather report - for the last two months, the waters of the equatorial Pacific Ocean have been warmer than usual. And this can be problematic. Warmer ocean temperatures are the leading cause of coral bleaching, for example.
MARY LOUISE KELLY, HOST:
The real effects are yet to come. If conditions persist, that patch of warm water could throw weather systems across the world out of wack.
CLARE NULLIS: We do expect an El Nino to develop during the northern hemisphere winter until February 2019.
KELLY: That's Clare Nullis, spokesperson for the World Meteorological Organization in Geneva, which announced this week it is highly likely we're in for an El Nino winter.
CHANG: So what exactly does that mean? Well, first that warm Pacific water will start a bit of a dance with the atmosphere above it.
NULLIS: It takes two to tango. You can't have a full El Nino if one of the partners is not kicking in.
CHANG: Once that atmosphere dance partner kicks in, wind currents will shift. As we saw three years ago, this will redistribute moisture around the world in troubling ways.
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UNIDENTIFIED REPORTER #1: Precious little water in southern and eastern Africa where El Nino is scorching the Earth.
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UNIDENTIFIED REPORTER #2: The West Coast deals with rainstorms fuelled by El Nino.
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UNIDENTIFIED REPORTER #3: You're going to see the El Nino headlines - right? - the Godzilla El Nino, the Darth Vader - or Darth Nino.
KELLY: Thankfully this year's El Nino is expected to be weaker than the last one. But when it comes to droughts and floods...
EMILY BECKER: That doesn't necessarily mean that the impacts themselves will be weaker. But it means that the chance that it will happen is less.
KELLY: That's Emily Becker, a research scientist at the National Oceanic and Atmospheric Administration, NOAA. For those in her line of work, El Nino events also provide a chance to keep digging into a bigger looming question.
BECKER: We're quite sure that climate change will affect El Nino, but we don't quite know how it's going to be affected - whether we'll be seeing stronger El Ninos or more frequent or the opposite.
CHANG: So whatever happens this winter, it's another data point for climate scientists to chew on.
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