Corals as Climate Archive: Are El Ninos Intensifying?<\/p>\n
Reporter<\/p>\n
September 13, 2026 | 12:59 pm<\/p>\n
TEMPO.CO, Jakarta - A storm is gathering. Most likely a very big one.\nEl Nino is a natural climate phenomenon occurring every two to seven\nyears, towards the end of the year, but it comes in various different\nstrengths, depending on the prevailing conditions.<\/p>\n
El Ninos are considered strong if the surface temperature of the\nwater off the west coast of South America is more than 1.5 degrees\nCelsius above average. In July this year, the US National Oceanic and\nAtmospheric Administration (NOAA) was already observing temperature\nincreases of greater than three degrees Celsius in the eastern and\ncentral Pacific.<\/p>\n
The German Meteorological Service believes this \u201ccould in all\nlikelihood develop into one of the strongest El Nino events since\nrecords began.\u201d<\/p>\n
But a recent article by the Max Planck Institute for Meteorology\nstates that whether or not strong El Nino events will intensify as a\nresult of climate change \u201cremains the subject of ongoing research.\u201d<\/p>\n
The data gap: What corals can tell us about El Nino<\/p>\n
The problem is that the data on ocean surface temperatures is only\ntruly reliable from the 1980s onward, with the start of satellite\nobservation. And this data doesn\u2019t tell us how El Nino behaved before\nindustrialization and the burning of fossil fuels.<\/p>\n
US researchers say corals can help to close this knowledge gap. Julia\nCole, a climate scientist and paleoclimatologist at the University of\nMichigan, and her team recently published a study on this subject in the\njournal Science.<\/p>\n
\u201cWe\u2019ve known for a long time that the last 40 or 50 years has really\nstrong El Nino events,\u201d says Cole. \u201cIt\u2019s been hard to say whether the\nrecent strong El Nino that we\u2019ve had is part of a natural cycle, or if\nit\u2019s something a little bit unusual related to being in a warmer than\nnormal world.\u201d The coral analysis points firmly in one direction:\nUnusual. Not normal.<\/p>\n
Corals: A repository of 1,000 years of climate history<\/p>\n
Cole and her team examined fossilized and living corals around the\nGalapagos Islands off Ecuador in the eastern Pacific. Corals grow\nbetween one and two centimeters per year, and in doing so form a\nstructure similar to growth rings on trees. \u201cWe made use of the fact\nthat corals record ocean temperatures as they grow, in the chemical\ncomposition of their skeleton,\u201d Cole explains.<\/p>\n
Corals are living creatures that construct external skeletons through\ncalcification, adding a band of new growth each year with calcium\ncarbonate precipitated from the surrounding water. In this way, over\ndecades and centuries, corals have formed entire reef systems. Other\nchemical elements are also incorporated into the skeleton during the\ncalcification process \u2014 strontium, for example. Sometimes more is\ndeposited, sometimes less, depending on the temperature of the\nwater.<\/p>\n
\u201cIn colder temperatures, it [the skeleton] absorbs more strontium, in\nwarmer temperatures less,\u201d says Cole. The ratio of strontium to calcium\nin the skeleton provides information about changes in temperature.<\/p>\n
Specific isotopes of oxygen in coral skeletons provide clues, as\nwell. \u201cThe rare oxygen-18 and the common oxygen-16 are also taken up in\na ratio that reflects temperature,\u201d says Cole. In colder conditions,\nmore oxygen-18 is absorbed than in warmer temperatures.<\/p>\n
In this way, researchers were able to reconstruct the changes in\nocean temperatures over the past 1,000 years, according to the age of\nthe corals. Their conclusion was that El Nino events have become\nmarkedly stronger compared to the pre-industrial period.<\/p>\n
Corals give indications, not conclusive answers<\/p>\n
Cole\u2019s study has confirmed a long-held suspicion. \u201cThese developments\ncorrespond to the predictions of the best climate models. They predict a\nquantifiably higher likelihood of extreme eastern Pacific El Nino events\nin the 2030s,\u201d says Jens Zinke, professor of paleobiology at the\nUniversity of Leicester in England.<\/p>\n
However, other scientists are more circumspect in assessing the\nstudy\u2019s significance. \u201cCoral data does achieve a high temporal\nresolution \u2014 monthly to seasonal \u2014 but its accuracy is dependent on\nlocal conditions, meaning that direct comparisons with modern\nmeasurement data are fraught with uncertainty,\u201d says Andreas Fink,\nprofessor of meteorology at the Institute for Meteorology and Climate\nResearch in Karlsruhe. According to Fink, the significance of the study\nis undermined by its regional limitation to the eastern Pacific.<\/p>\n
Cole is also aware of her study\u2019s limitations. \u201cOur data does fill a\ngap, but I want to be clear that our record isn\u2019t continuous,\u201d she says.\n\u201cWe don\u2019t have every single year over the last millennium. We have a\nlittle bit under half of the years covered.\u201d<\/p>\n
Floods, droughts, record heat \u2014 the consequences of stronger El\nNinos<\/p>\n
Although the epicenter of the El Nino phenomenon is the Pacific, it\nchanges the weather across the globe. In countries like Ecuador and Peru\nit can cause heavy rains and flooding, while Australia and Indonesia may\nexperience a lack of rain, leading to drought and wildfires. El Ni\u00f1o\nalso causes global temperatures to rise for a while.<\/p>\n
If the predictions prove right and this El Nino does in fact become a\nSuper El Nino, the coming year, 2027, will probably be another of record\nheatwaves, according to Thomas Felis. Felis leads the research group on\ncoral paleoclimatology at the MARUM Center for Marine Environmental\nSciences at the University of Bremen, and has conducted a similar study\nto Cole\u2019s.<\/p>\n
Heat-stressed oceans: El Nino is a threat for corals<\/p>\n
A year of record heat \u201cwill very probably lead to another global\ncoral bleaching,\u201d says Felis. This has happened before, in the years\n2023\u201324 and 2015\u201316, which were also El Nino years.<\/p>\n
Corals get their characteristic colors from certain algae with which\nthey live in symbiosis. Through photosynthesis, the algae provide the\nenergy the corals need to live. If the temperature of the ocean is too\nhigh, the algae start to pr<\/p>", "url": "https:\/\/jawawa.id\/newsitem\/corals-as-climate-archive-are-el-ninos-intensifying-1789282248", "image": "" }, "sponsor": "Okusi Associates", "sponsor_url": "https:\/\/okusiassociates.com" }