Foraminifera fossils
With so much of Earth history occurring before creationism's little god allegedly created a small flat planet with a dome over it in the Middle East, it's useful to be able to recover data on global events such as climate change and sea temperature changes that can be projected into the future to predict what changes we can expect.
The 'El Niño' is a climate phenomenon that has a profound effect on world climate. It occurs every 2-7 years and is characterized by a warming of the sea surface in the central and eastern Pacific Ocean. It changes ocean currents, atmospheric humidity and rainfall, and jet streams that drive weather patterns, so understanding when these events occurred in the past and mapping them onto known climate patterns can help us predict future weather patterns.
Now scientist at the University of Arizona have developed a model for predicting how El Niño affects global weather patterns which needs to be validated against actual data, so they have analyzed the record of sea temperature change recorded in deposits of tiny foraminifera shells in ocean sediment, going back to the last Ice Age, 10,000 years before creationists think Earth existed.
Of course, the reason was not to refute creationism - it does that incidentally - but to provide a longer history on which to base future predictions than are currently available.
How can ancient foraminifera shells reveal a record of sea temperature change? Ancient foraminifera shells provide a valuable record of past sea temperature changes through the composition of their calcium carbonate shells. Here’s how they work as climate proxies:Their findings are the subject of an open access paper in Nature and are explained in a University of Arizona news release:
Through these methods, ancient foraminifera shells have become crucial tools for studying paleoclimates and understanding how Earth’s oceans have responded to temperature shifts over geologic timescales.
- Oxygen Isotope Ratios
Foraminifera incorporate oxygen from seawater into their shells, and the ratio of oxygen isotopes (18O and 16O) in the shells depends on both the temperature of the water and the volume of ice on Earth. The key processes are:By measuring the oxygen isotope ratio in fossilized foraminifera shells, scientists can infer past sea surface temperatures. This method is particularly effective over long timescales.
- Colder water leads to more 18O being incorporated into the shells, since colder temperatures favor 18O retention in the oceans (due to greater ice storage of 16O).
- Warmer water results in more 16O in the shells, as warmer conditions allow for more 16O in seawater.
- Mg/Ca Ratio
The magnesium-to-calcium (Mg/Ca) ratio in foraminifera shells is another important indicator. Foraminifera take in both calcium and magnesium from seawater while forming their shells. The incorporation of magnesium increases with water temperature, meaning:This relationship allows scientists to use Mg/Ca ratios as a proxy for past sea temperatures.
- Higher temperatures result in more magnesium in the shells.
- Lower temperatures lead to less magnesium.
- Carbon Isotope Ratios
Foraminifera also record carbon isotopes (e.g., 13C/12C) in their shells, which provide information about ocean productivity, carbon cycling, and even ocean circulation patterns. While carbon isotopes are more closely tied to biological and carbon cycle processes, they can indirectly suggest climate conditions.- Sediment Layering
Foraminifera shells accumulate in ocean sediments over time, creating layered deposits that provide a chronological record. By analyzing foraminifera from different sediment layers, scientists can reconstruct sea temperature changes over millions of years, correlating them with periods of glaciation, interglacial warming, and other climatic events.
Ice age clues point to more extreme weather patterns in our future
The last ice age peaked around 20,000 years ago and was marked by extensive glaciation and dramatic climate shifts that reshaped Earth's oceans, landscapes and ecosystems. A new study led by the University of Arizona suggests that Earth's last ice age may provide crucial insights into future El Niño weather events. El Niño is one of the most influential climate patterns affecting global weather.
The study, published in Nature, combines data from ancient shells of marine organisms with advanced climate modeling to shed light on how El Niño patterns might change in a warming world.
El Niño is a climate phenomenon characterized by the irregular but periodic warming of sea surface temperatures in the central and eastern Pacific Ocean. This leads to disruption of global weather patterns and causes extreme events like droughts, floods and heat waves.
"El Niño is a formidable force of nature – it induces droughts, floods and wildfires, disrupting marine and terrestrial ecosystems across the planet, with pervasive societal impacts across numerous sectors, from agriculture to the aviation industry," said Kaustubh Thirumalai, the study's co-lead author and an assistant professor in the U of A Department of Geosciences.
El Niño events occur approximately every two to seven years, and anticipating how these events might change in the future is a major challenge for climate scientists.
There are several state-of-the-art climate models out there, and they suggest different El Niño responses to ongoing and future human-caused warming Some say El Niño variations will increase, others say it will decrease – it is a complex, multifaceted phenomenon. So, addressing what might happen to El Niño is a key priority for climate science.
Kaustubh Thirumalai, lead author.
To address this uncertainty, the research team – which included collaborators from the U of A, University of Colorado Boulder, University of Texas at Austin, Middlebury College and Woods Hole Oceanographic Institution – turned to the past. They focused on the Last Glacial Maximum – a period about 20,000 years ago when there were ice sheets over much of North America and Europe.
The researchers used the Community Earth System Model – developed to simulate the Earth's climate system and predict future climate scenarios – to simulate climate conditions from the Last Glacial Maximum to the present day. This model is a collaborative project primarily led by the National Center for Atmospheric Research, with contributions from numerous institutions. The modeling portion of the study was conducted by co-lead author Pedro DiNezo at the University of Colorado Boulder.
To validate this model, Thirumalai and his team compared the model's results with data from the remains of tiny marine organisms called foraminifera. They are found in ocean samples extracted from the seabed that contain layers of sediments deposited over thousands to millions of years.
An 8x-zoomed microscopic image of washed, tropical marine sediments showing a vast number of individual foraminiferal shells.Kaustubh Thirumalai
These beautiful, microscopic creatures, which float in the upper ocean, build shells that lock in the ocean temperature when they were alive.
Kaustubh Thirumala
As foraminifera grow, they secrete shells using materials from the surrounding seawater. The chemical composition of these shells changes based on the water temperature. This enables the preservation of a snapshot of ocean conditions at the time the shell formed.
When foraminifera die after a few weeks of life, their shells sink to the ocean floor and become part of the sediment. By analyzing shells from different layers of sediment, scientists can reconstruct ocean temperatures from thousands of years ago and compare them to the model simulations of past climates.
The team analyzed individual foraminiferal shells, allowing them to capture seasonal temperature variations that would otherwise be impossible to detect.
We zoom in to a tiny section of the sediment core and analyze multiple individual shells from the same layer. This gives us a range of Pacific Ocean temperatures within a short time period, which we can compare between the ice age and today.
Kaustubh Thirumala
The study found that El Niño variability was significantly lower during the Last Glacial Maximum compared to the present day, and that future extreme El Niño events could become more prevalent as the planet warms. This could lead to more intense and frequent weather disruptions worldwide. Importantly, these findings suggest a common mechanism of extreme El Niño variations under both ice age and future conditions, allowing the researchers to validate the climate model's prediction.This gives us more confidence in the model's projections for the future. If it can accurately simulate past climate changes, it's more likely to give us reliable predictions about future changes in the El Niño system.
Kaustubh Thirumala
AbstractTiny organisms were making their shells, dying and building up deposits of the fossilised remains since the Cambrian and so leaving a record of changes that occurred in the 99.9975% of Earth long history that preceded creationism's 'Creation Week'.
El Niño events, the warm phase of the El Niño–Southern Oscillation (ENSO) phenomenon, amplify climate variability throughout the world1. Uncertain climate model predictions limit our ability to assess whether these climatic events could become more extreme under anthropogenic greenhouse warming2. Palaeoclimate records provide estimates of past changes, but it is unclear if they can constrain mechanisms underlying future predictions3,4,5. Here we uncover a mechanism using numerical simulations that drives consistent changes in response to past and future forcings, allowing model validation against palaeoclimate data. The simulated mechanism is consistent with the dynamics of observed extreme El Niño events, which develop when western Pacific warm pool waters expand rapidly eastwards because of strongly coupled ocean currents and winds6,7. These coupled interactions weaken under glacial conditions because of a deeper mixed layer driven by a stronger Walker circulation. The resulting decrease in ENSO variability and extreme El Niño occurrence is supported by a series of tropical Pacific palaeoceanographic records showing reduced glacial temperature variability within key ENSO-sensitive oceanic regions, including new data from the central equatorial Pacific. The model–data agreement on past variability, together with the consistent mechanism across climatic states, supports the prediction of a shallower mixed layer and weaker Walker circulation driving more frequent extreme El Niño genesis under greenhouse warming.
Main
El Niño events can reach extreme magnitude, as during the record-breaking events of 1982, 1997 and 2015, when extremely warm temperatures in the equatorial Pacific (≥2 K in the central Pacific7) drove highly disruptive environmental changes, including bleaching and widespread coral mortality8, tropical forest fires, heat waves9 and ice-shelf instability. Limited observations hinder our understanding of these extreme El Niño events because only three such events have been fully observed, to our knowledge, since the advent of satellite and moored observations2. Models predict increasing rainfall and sea-surface temperature (SST) variability under greenhouse warming10, potentially linked with stronger or more frequent extreme El Niño events. However, these predictions cannot be validated using historical records because of uncertainties in the forced response combined with high levels of unforced El Niño–Southern Oscillation (ENSO) variability2. This issue can be addressed by studying changes in ENSO during past geological intervals when the climate was substantially different from what it is today. However, contradictory palaeoclimatic evidence and uncertain mechanisms have complicated this approach5. Holocene records suggest a highly variable ENSO phenomenon, largely insensitive to external forcings3,11. Records from the last glacial period show large, potentially forced changes in ENSO variability, although a systematic, model-based attribution of these changes has not been carried out so far12,13,14,15. Furthermore, a lack of common mechanisms linking past and future changes has prevented the use of any reconstructions of past ENSO variability to directly validate the multiple mechanisms controlling ENSO changes under future warming.
We addressed this problem using climate model simulations of key intervals spanning the past 21,000 years (or 21 kilo-annum before present (ka BP))—a period in the history of Earth when global climate experienced substantial changes. We studied common mechanisms between past and future changes in ENSO using additional simulations of greenhouse warming under doubling and quadrupling CO2 concentrations. These simulations are comparable to medium-range and high-emission scenarios, respectively. All simulations were performed with Community Earth System Model v.1.2 (CESM1.2), a model that realistically simulates key ENSO dynamics, including asymmetric event evolution16 and drivers of extreme El Niño events (Methods). We focus on SST variability over the Niño–3.4 region in the central equatorial Pacific (170° W–120° W, 5° S–5° N), where strong ocean–atmosphere interactions give rise to El Niño and La Niña events. We quantify the strength of the different feedbacks involved in the growth of El Niño events to identify common mechanisms driving changes across climatic states. Our technique considers seasonality and asymmetries in the evolution of El Niño and La Niña, which is a marked improvement compared with the previous work4,17. Finally, we validate the simulations against existing and new reconstructions of past climate variability from multiple sites across the tropical Pacific that unambiguously capture changes in ENSO compared with other sources of variability. All reconstructions are based on the individual foraminiferal analyses (IFA) technique that can estimate past interannual ocean temperature and, thus, ENSO variability12,13,14,18,19. Our validation considers the site-specific influence of ENSO on surface and subsurface temperature variations, and rigorous statistical tests of the influence of externally forced changes in variability, including changes in the seasonal cycle (Methods).
Thirumalai, K., DiNezio, P.N., Partin, J.W. et al. Future increase in extreme El Niño supported by past glacial changes. Nature (2024). https://doi.org/10.1038/s41586-024-07984-y
Copyright: © 2024 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
But of course the parochial Bronze Age pastoralists who made up the creation myths in the Bible to fill the gaping gaps in their knowledge and understanding of the world would have known nothing whatever about them, nor about the ocean floor sediment they were depositing their evidence in, like the pages of a book recording the real history of Earth, not a figment of someone's imagination.
Now scientist have learned how to read those pages, it is becoming harder and harder to understand how people alive today could believe the authors of the Bible were writing real history, when it differs so completely from the record of real history scientists are now discovering.
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