Modern Australian
Men's Weekly

.

how a new carbon dating timeline is changing our view of history

  • Written by Chris Turney, Professor, Earth Science and Climate Change, UNSW

Geological and archaeological records offer important insights into what seems to be an increasingly uncertain future.

The better we understand what conditions Earth has already experienced, the better we can predict (and potentially prevent) future threats.

But to do this effectively, we need an accurate way to date what happened in the past.

Our research, published today in the journal Radiocarbon, offers a way to do just that, through an updated method of calibrating the radiocarbon timescale.

An amazing tool for perusing the past

Radiocarbon dating has revolutionised our understanding of the past. It is nearly 80 years since Nobel Prize-winning US chemist Willard Libby first suggested minute amounts of a radioactive form of carbon are created in the upper atmosphere.

Libby correctly argued this newly formed radiocarbon (or C-14) rapidly converts to carbon dioxide, is taken up by plants during photosynthesis, and from there travels up through the food chain.

When organisms interact with their environment while alive, they have the same proportion of C-14 as their environment. Once they die they stop taking in new carbon.

Their level of C-14 then halves every 5,730 years due to radioactive decay. An organism that died yesterday will still have a high level of C-14, whereas one that died tens of thousands of years ago will not.

By measuring the level of C-14 in a specimen, we can deduce how long ago that organism died. Currently, with this method, we can date remains up to 60,000 years old.

Read more: Explainer: what is radiocarbon dating and how does it work?

A seven-year effort

If the level of C-14 in the atmosphere had always been constant, radiocarbon dating would be straightforward. But it hasn’t.

Changes in the carbon cycle, impinging cosmic radiation, the use of fossil fuels and 20th century nuclear testing have all caused large variations over time. Thus, all radiocarbon dates need to be adjusted (or calibrated) to be turned into accurate calendar ages.

Without this adjustment, dates could be out by up to 10-15%. This week we report a seven-year international effort to recalculate three radiocarbon calibration curves:

  • IntCal20 (“20” to signify this year) for objects from the northern hemisphere
  • SHCal20 for samples from the ocean-dominated southern hemisphere
  • Marine20 for samples from the world’s oceans.
Close-up of bristlecone pine tree rings. We dated bristlecone pine tree rings from the second millennium BC. P. Brewer/Uni of Arizona

We constructed these updated curves by measuring a plethora of materials that record past radiocarbon levels, but which can also be dated by other methods.

Included in the archives are tree rings from ancient logs preserved in wetlands, cave stalagmites, corals from the continental shelf and sediments drilled from lake and ocean beds.

An ancient New Zealand kauri tree log. Ancient New Zealand kauri (Agathis australis) logs like this example were used to help construct the calibration curves. This tree is about 40,000 years old and was found buried underground. Nelson Parker

In total, the new curves are based on almost 15,000 radiocarbon measurements taken from objects up to 60,000 years old.

Advances in radiocarbon measurement using accelerator mass spectrometry mean the updated curves can use very small samples, such as single tree rings from just one year’s growth.

Close-up of an ancient stalagmite. Stalagmites from inside the Hulu Cave in China were key to estimating the amount of radiocarbon present in objects between 14,000 and 55,000 years old. Hai Cheng, Author provided

Reassessing old beliefs

The new radiocarbon calibration curves provide previously impossible precision and detail. As a result, they greatly improve our understanding of how Earth has evolved and how these changes impacted its inhabitants.

One example is the rate of environmental change at the end of the most recent ice age. As the world started to warm some 18,000 years ago, vast ice sheets covering Antarctica, North America (including Greenland) and Europe melted – returning huge volumes of fresh water to the oceans.

But the sea level didn’t rise at a consistent rate like the global temperature. Sometimes it was gradual and other times extremely rapid.

A prime location to detect past sea levels is the Sunda Shelf, a large platform of land that was once part of continental Southeast Asia.

One study published in 2000 showed mangrove plant remains found on the seabed recorded a catastrophic 16-metre sea level rise over several hundred years (about half a metre each decade). This event, known as Meltwater Pulse-1A, flooded the Sunda Shelf.

Our latest work has modified this story considerably. The new calibration curves reveal this extreme phase of sea level rise actually began 14,640 years ago and lasted just 160 years.

This equates to a staggering one-metre rise each decade – a sobering lesson for the future, considering the current much lower projected changes for the end of this century.

An extra half a millennium of art

Going further back in time, we also looked at some of the world’s oldest cave art in France’s Chauvet Cave, first discovered in 1994.

This cave contains hundreds of beautifully preserved paintings. They depict a European menagerie with long-extinct mammoths, cave lions and woolly rhinoceroses, captured in real-life scenes that provide a window into a lost world.

The Chauvet Cave reveals the artistic sophistication of our early ancestors in phenomenal detail.

how a new carbon dating timeline is changing our view of history The Chauvet Cave contains hundreds of cave paintings created more than 30,000 years ago. Thomas T/flickr

With the new IntCal20 curve, our best estimate for the creation of the oldest radiocarbon-dated painting in the cave is now 36,500 years ago. This is almost 450 years older than previously thought.

These are just two of many more examples of the far-reaching impact our latest work will have.

As the new calibration curves are used to re-analyse ages of a host of archaeological and geological records, we can expect major shifts in our understanding of the planet’s past – and hopefully, a better forecast into its future.

Read more: Is that rock hashtag really the first evidence of Neanderthal art?

Authors: Chris Turney, Professor, Earth Science and Climate Change, UNSW

Read more https://theconversation.com/from-cave-art-to-climate-chaos-how-a-new-carbon-dating-timeline-is-changing-our-view-of-history-143620

Powering Shepparton’s Businesses: Expert Commercial Electrical Services You Can Count On

When it comes to running a successful business, having reliable, compliant, and efficient electrical systems is non-negotiable. From small retail ou...

Maximise Efficiency: Cleaner Solar Panels for Optimal Performance

Solar panels are a smart investment in energy efficiency, sustainability, and long-term savings—especially here in Cairns, where the tropical sun ...

7 Common Air Conditioner Issues in Melbourne – And How to Fix Them

Image by freepik Living in Melbourne, we all know how unpredictable the weather can be. One moment it’s cold and windy, the next it’s a scorchin...

Powering Palm QLD with Reliable Electrical Solutions

Image by pvproductions on Freepik When it comes to finding a trustworthy electrician Palm QLD locals can count on, the team at East Coast Sparkies s...

The Smart Way to Grow Online: SEO Management Sydney Businesses Can Rely On

If you’re a Sydney-based business owner, you already know the digital space is crowded. But with the right strategy, you don’t need to shout the...

What Your Car Says About You: The Personality Behind the Vehicle

You can tell a lot about someone by the car they drive—or at least, that’s what people think. True Blue Mobile Mechanics reckon the car says a l...

The Confidence Curve: Why Boudoir Photography Is the Empowerment Trend You Didn’t Know You Needed

Boudoir photography has been quietly taking over social feeds, Pinterest boards, and personal milestones—and for good reason. It’s not just abou...

Understanding Level 2 Electricians: Why Sydney Residents Need Licenced Experts for Complex Electrical Work

When it comes to electrical work around the home or business, not all electricians are created equal. In Sydney, particularly when you're dealing wi...

Retirement Anchored in Model Boat Building for Waterford’s Doug Unsold

WATERFORD — When Doug Unsold sees his ship come in, it’s usually one he’s crafted with his own hands. The 67-year-old retiree from Waterford ...

The Science Behind Alarm Clocks and Your Circadian Rhythm

Waking up on time isn’t just about setting an alarm—it’s about working with your body, not against it. At the heart of every restful night and...

How to Use Plants to Create a Calming Atmosphere in Your Home

In today’s fast-paced world, cultivating a calm, soothing environment at home has never been more important. Whether you live in a busy urban apar...

How Maths Tutoring Can Help Students Master Maths

Mathematics can be a daunting subject for many students, often causing stress and frustration. However, maths tutoring has proven to be an effective...

Refurbished iPads Are Better Than New Ones (Here's Why)

Image by rawpixel.com on Freepik Apple's refurbished iPad program has quietly become one of the best deals in tech. While everyone obsesses over the ...

Your Guide to Finding the Right GP: What Perth City Doctors Offer Today

Choosing a General Practitioner (GP) is one of the most important health decisions you’ll make. Luckily, Perth’s vibrant CBD now hosts a new ge...

Why Every Mining Operation Needs a Robust Safety Management System

Mining is one of the backbones of the Australian economy, particularly in Western Australia. Back in 2019-20, mining contributed 10.4% of Australia...

Australian Classic Literature Enjoys Resurgence

Welcome back to the good old days of storytelling! As the modern world becomes increasingly more demanding, returning to childhood favourites offers...

How to Choose the Right Lawyers in Sydney for Your Situation

When faced with a legal issue, selecting the right legal representation can make all the difference. Whether you're dealing with a personal injury, ...

Building a Governance Model for Headless Content Management at Scale

Image by pch.vector on Freepik There's never been a better time to implement a headless content management system (CMS) to gain the flexibility and ...