A storm is gathering.
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storm → gather → ?
El Nino is a natural climate phenomenon occurring every two to seven years, towards the end of the year, but it comes in various different strengths, depending on the prevailing conditions.
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it → occur → conditions
El Ninos are considered strong if the surface temperature of the water off the west coast of South America is more than 1.5 degrees Celsius above average.
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temperature → consider → average
In July this year, the US National Oceanic and Atmospheric Administration (NOAA) was already observing temperature increases of greater than three degrees Celsius in the eastern and central Pacific.
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Oceanic → observe → Pacific
The German Meteorological Service believes this "could in all likelihood develop into one of the strongest El Nino events since records began."
uncertain
records → believe → events
But a recent article by the Max Planck Institute for Meteorology states that whether or not strong El Nino events will intensify as a result of climate change "remains the subject of ongoing research."
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intensify → state → research
The data gap: What corals can tell us about El Nino
The problem is that the data on ocean surface temperatures is only truly reliable from the 1980s onward, with the start of satellite observation.
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data → tell → observation
And this data doesn't tell us how El Nino behaved before industrialization and the burning of fossil fuels.
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Nino → tell → fuels
US researchers say corals can help to close this knowledge gap.
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corals → say → gap
Julia Cole, a climate scientist and paleoclimatologist at the University of Michigan, and her team recently published a study on this subject in the journal Science.
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Cole → publish → journal
"We've known for a long time that the last 40 or 50 years has really strong El Nino events," says Cole.
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Cole → know → events
"It's been hard to say whether the recent strong El Nino that we've had is part of a natural cycle, or if it's something a little bit unusual related to being in a warmer than normal world."
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it → say → world
The coral analysis points firmly in one direction: Unusual.
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analysis → point → direction
A repository of 1,000 years of climate history
Cole and her team examined fossilized and living corals around the Galapagos Islands off Ecuador in the eastern Pacific.
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Cole → examine → Pacific
Corals grow between one and two centimeters per year, and in doing so form a structure similar to growth rings on trees.
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Corals → grow → trees
"We made use of the fact that corals record ocean temperatures as they grow, in the chemical composition of their skeleton," Cole explains.
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Cole → make → skeleton
Corals are living creatures that construct external skeletons through calcification, adding a band of new growth each year with calcium carbonate precipitated from the surrounding water.
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that → live → water
In this way, over decades and centuries, corals have formed entire reef systems.
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corals → form → systems
Other chemical elements are also incorporated into the skeleton during the calcification process — strontium, for example.
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elements → incorporate → example
Sometimes more is deposited, sometimes less, depending on the temperature of the water.
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more → deposit → water
"In colder temperatures, it [the skeleton] absorbs more strontium, in warmer temperatures less," says Cole.
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Cole → absorb → temperatures
The ratio of strontium to calcium in the skeleton provides information about changes in temperature.
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ratio → provide → temperature
Specific isotopes of oxygen in coral skeletons provide clues, as well.
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isotopes → provide → clues
"The rare oxygen-18 and the common oxygen-16 are also taken up in a ratio that reflects temperature," says Cole.
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Cole → take → temperature
In colder conditions, more oxygen-18 is absorbed than in warmer temperatures.
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oxygen-18 → absorb → temperatures
In this way, researchers were able to reconstruct the changes in ocean temperatures over the past 1,000 years, according to the age of the corals.
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researchers → reconstruct → corals
Their conclusion was that El Nino events have become markedly stronger compared to the pre-industrial period.
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events → become → period
Corals give indications, not conclusive answers
Cole's study has confirmed a long-held suspicion.
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study → give → suspicion
"These developments correspond to the predictions of the best climate models.
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developments → correspond → models
They predict a quantifiably higher likelihood of extreme eastern Pacific El Nino events in the 2030s," says Jens Zinke, professor of paleobiology at the University of Leicester in England.
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Zinke → predict → England
However, other scientists are more circumspect in assessing the study's significance.
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scientists → assess → significance
"Coral data does achieve a high temporal resolution — monthly to seasonal — but its accuracy is dependent on local conditions, meaning that direct comparisons with modern measurement data are fraught with uncertainty," says Andreas Fink, professor of meteorology at the Institute for Meteorology and Climate Research in Karlsruhe.
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Fink → achieve → Karlsruhe
According to Fink, the significance of the study is undermined by its regional limitation to the eastern Pacific.
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significance → accord → Pacific
"Our data does fill a gap, but I want to be clear that our record isn't continuous," she says.
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she → fill → gap
"We don't have every single year over the last millennium.
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We → have → millennium
We have a little bit under half of the years covered.
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We → have → years
Although the epicenter of the El Nino phenomenon is the Pacific, it changes the weather across the globe.
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it → change → globe
In countries like Ecuador and Peru it can cause heavy rains and flooding, while Australia and Indonesia may experience a lack of rain, leading to drought and wildfires.
uncertain
Australia → cause → drought
El Niño also causes global temperatures to rise for a while.
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temperatures → cause → while
If the predictions prove right and this El Nino does in fact become a Super El Nino, the coming year, 2027, will probably be another of record heatwaves, according to Thomas Felis.
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year → prove → Felis
…and 11 more, not listed.
