̽��ֱ�� of Cambridge - Climate

Extreme drought contributed to barbarian invasion of late Roman Britain, tree-ring study reveals

ta385 — Thu, 17 Apr 2025 06:00:00 +0000

̽��ֱ��‘Barbarian Conspiracy’ of 367 CE was one of the most severe threats to Rome’s hold on Britain since the Boudiccan revolt three centuries earlier. Contemporary sources indicate that components of the garrison on Hadrian’s wall rebelled and allowed the Picts to attack the Roman province by land and sea. Simultaneously, the Scotti from modern-day Ireland invaded broadly in the west, and Saxons from the continent landed in the south.

Senior Roman commanders were captured or killed, and some soldiers reportedly deserted and joined the invaders. Throughout the spring and summer, small groups roamed and plundered the countryside. Britain’s descent into anarchy was disastrous for Rome and it took two years for generals dispatched by Valentian I, Emperor of the Western Roman Empire, to restore order. ̽��ֱ��final remnants of official Roman administration left Britain some 40 years later around 410 CE.

̽��ֱ�� ̽��ֱ�� of Cambridge-led study, published today in Climatic Change, used oak tree-ring records to reconstruct temperature and precipitation levels in southern Britain during and after the ‘Barbarian Conspiracy’ in 367 CE. Combining this data with surviving Roman accounts, the researchers argue that severe summer droughts in 364, 365 and 366 CE were a driving force in these pivotal events.

First author Charles Norman, from Cambridge’s Department of Geography, said: “We don’t have much archaeological evidence for the ‘Barbarian Conspiracy’. Written accounts from the period give some background, but our findings provide an explanation for the catalyst of this major event.”

̽��ֱ��researchers found that southern Britain experienced an exceptional sequence of remarkably dry summers from 364 to 366 CE. In the period 350 to 500 CE, average monthly reconstructed rainfall in the main growing season (April–July) was 51 mm. But in 364 CE, it fell to just 29mm. 365 CE was even worse with 28mm, and 37mm the following year kept the area in crisis.

Professor Ulf Büntgen, from Cambridge’s Department of Geography, said: “Three consecutive droughts would have had a devastating impact on the productivity of Roman Britain’s most important agricultural region. As Roman writers tell us, this resulted in food shortages with all of the destabilising societal effects this brings.”

Between 1836 and 2024 CE, southern Britain only experienced droughts of a similar magnitude seven times – mostly in recent decades, and none of these were consecutive, emphasising how exceptional these droughts were in Roman times. ̽��ֱ��researchers identified no other major droughts in southern Britain in the period 350–500 CE and found that other parts of northwestern Europe escaped these conditions.

Roman Britain’s main produce were crops like spelt wheat and six-row barley. Because the province had a wet climate, sowing these crops in spring was more viable than in winter, but this made them vulnerable to late spring and early summer moisture deficits, and early summer droughts could lead to total crop failure.

̽��ֱ��researchers point to surviving accounts written by Roman chroniclers to corroborate these drought-driven grain deficits. By 367 CE, Ammianus Marcellinus described the population of Britain as in the ‘utmost conditions of famine’.

“Drought from 364 to 366 CE would have impacted spring-sown crop growth substantially, triggering poor harvests,” Charles Norman said. “This would have reduced the grain supply to Hadrian’s Wall, providing a plausible motive for the rebellion there which allowed the Picts into northern Britain.”

̽��ֱ��study suggests that given the crucial role of grain in the contract between soldiers and the army, grain deficits may have contributed to other desertions in this period, and therefore a general weakening of the Roman army in Britain. In addition, the geographic isolation of Roman Britain likely combined with the severity of the prolonged drought to reduce the ability of Rome to alleviate the deficits.

Ultimately the researchers argue that military and societal breakdown in Roman Britain provided an ideal opportunity for peripheral tribes, including the Picts, Scotti and Saxons, to invade the province en masse with the intention of raiding rather than conquest. Their finding that the most severe conditions were restricted to southern Britain undermines the idea that famines in other provinces might have forced these tribes to invade.

Andreas Rzepecki, from the Generaldirektion Kulturelles Erbe Rheinland-Pfalz, said: “Our findings align with the accounts of Roman chroniclers and the seemingly coordinated nature of the ‘Conspiracy’ suggests an organised movement of strong onto weak, rather than a more chaotic assault had the invaders been in a state of desperation.”

“ ̽��ֱ��prolonged and extreme drought seems to have occurred during a particularly poor period for Roman Britain, in which food and military resources were being stripped for the Rhine frontier, while immigratory pressures increased.”

“These factors limited resilience, and meant a drought induced, partial-military rebellion and subsequent external invasion were able to overwhelm the weakened defences.”

̽��ֱ��researchers expanded their climate-conflict analysis to the entire Roman Empire for the period 350–476 CE. They reconstructed the climate conditions immediately before and after 106 battles and found that a statistically significant number of battles were fought following dry years.

Tatiana Bebchuk, from Cambridge’s Department of Geography, said: “ ̽��ֱ��relationship between climate and conflict is becoming increasingly clear in our own time so these findings aren’t just important for historians. Extreme climate conditions lead to hunger, which can lead to societal challenges, which eventually lead to outright conflict.”

Charles Norman, Ulf Büntgen, Paul Krusic and Tatiana Bebchuk are based at the Department of Geography, ̽��ֱ�� of Cambridge; Lothar Schwinden and Andreas Rzepecki are from the Generaldirektion Kulturelles Erbe Rheinland-Pfalz in Trier. Ulf Büntgen is also affiliated with the Global Change Research Institute, Czech Academy of Sciences and the Department of Geography, Masaryk ̽��ֱ�� in Brno.

Reference

C Norman, L Schwinden, P Krusic, A Rzepecki, T Bebchuk, U Büntgen, ‘Droughts and conflicts during the late Roman period’, Climatic Change (2025). DOI: 10.1007/s10584-025-03925-4

Funding

Charles Norman was supported by Wolfson College, ̽��ֱ�� of Cambridge (John Hughes PhD Studentship). Ulf Büntgen received funding from the Czech Science Foundation (# 23-08049S; Hydro8), the ERC Advanced Grant (# 882727; Monostar), and the ERC Synergy Grant (# 101118880; Synergy-Plague).

Three consecutive years of drought contributed to the ‘Barbarian Conspiracy’, a pivotal moment in the history of Roman Britain, a new Cambridge-led study reveals. Researchers argue that Picts, Scotti and Saxons took advantage of famine and societal breakdown caused by an extreme period of drought to inflict crushing blows on weakened Roman defences in 367 CE. While Rome eventually restored order, some historians argue that the province never fully recovered.

Our findings provide an explanation for the catalyst of this major event.

Charles Norman

Adam Cuerden

Milecastle 39 on Hadrian's Wall

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Licence type:

Public Domain

Cambridge is shaping AI for everyone

lw355 — Mon, 07 Apr 2025 08:15:22 +0000

Explore how Cambridge is using AI for better healthcare, smarter public services and new ways of tackling climate change. Meet our community and discover how ai@cam is supporting the development of AI that works for science, citizens and society.

Turbocharging the race to protect nature and climate with AI

lw355 — Sun, 06 Apr 2025 17:00:51 +0000

Rebalancing the planet must happen faster. Cambridge researchers are using AI to help.

Opinion: AI can help us heal the planet

lw355 — Fri, 04 Apr 2025 16:23:55 +0000

AI can do in seconds what might take a team of experts a year. This is why we must harness it to reverse the damage we’ve done to the planet. Anil Madhavapeddy explains.

Emissions-free flying takes off at Cambridge Climate Challenge

plc32 — Thu, 03 Apr 2025 09:11:42 +0000

A biology PhD candidate and an early career aerospace engineer researcher won the 2025 Cambridge Zero Climate Challenge for turning waste into sustainable jet fuel

Opinion: AI can democratise weather forecasting

lw355 — Tue, 01 Apr 2025 14:12:44 +0000

AI will give us the next leap forward in forecasting the weather, says Richard Turner, and make it available to all countries, not just those with access to high-quality data and computing resources.

Thriving Antarctic ecosystems found following iceberg calving

Anonymous — Tue, 25 Mar 2025 10:22:45 +0000

An international team of scientists have uncovered a thriving underwater ecosystem off the coast of Antarctica that had never before been accessible to humans.

̽��ֱ��team, including researchers from the ̽��ֱ�� of Cambridge, were working in the Bellingshausen Sea off the coast of Antarctica when a massive iceberg broke away from the George VI Ice Shelf in January of this year.

̽��ֱ��team, on board Schmidt Ocean Institute’s R/V Falkor (too), changed their plans and reached the newly exposed seafloor 12 days later, becoming the first to investigate the area.

Their expedition was the first detailed study of the geology, physical oceanography, and biology beneath such a large area once covered by a floating ice shelf. ̽��ֱ��A-84 iceberg was approximately 510 square kilometres (209 square miles) in size, and revealed an equivalent area of seafloor when it broke away from the ice shelf.

"We seized upon the moment, changed our expedition plan, and went for it so we could look at what was happening in the depths below," said expedition co-chief scientist Dr Patricia Esquete from the ̽��ֱ�� of Aveiro, Portugal. "We didn't expect to find such a beautiful, thriving ecosystem. Based on the size of the animals, the communities we observed have been there for decades, maybe even hundreds of years.”

Using Schmidt Ocean Institute’s remotely operated vehicle, ROV SuBastian, the team observed the deep seafloor for eight days and found flourishing ecosystems at depths as great as 1300 meters.

Their observations include large corals and sponges supporting an array of animal life, including icefish, giant sea spiders, and octopus. ̽��ֱ��discovery offers new insights into how ecosystems function beneath floating sections of the Antarctic ice sheet.

Little is known about what lies beneath Antarctica’s floating ice shelves. In 2021, British Antarctic Survey researchers first reported signs of bottom-dwelling life beneath the Filchner-Ronne ice shelf in the Southern Weddell Sea. ̽��ֱ��current expedition was the first to use an ROV to explore this remote environment.

̽��ֱ��team was surprised by the significant biomass and biodiversity of the ecosystems and suspect they have discovered several new species.

Deep-sea ecosystems typically rely on nutrients from the surface slowly raining down to the seafloor. For centuries, the ecosystems under the ice shelf have been covered by ice almost 150 metres thick, completely cutting them off from surface nutrients. " ̽��ֱ��fact that we found long-living species suggests that the lateral transport, which mostly consists of glacial meltwater from the ice shelf, could be the source of the nutrients to sustain the life we found," said team member Dr Laura Cimoli, from Cambridge’s Department of Applied Mathematics and Theoretical Physics.

̽��ֱ��newly exposed Antarctic seafloor also allowed the team, with scientists from Portugal, the United Kingdom, Chile, Germany, Norway, New Zealand, and the United States, to gather critical data on the past behaviour of the larger Antarctic ice sheet. ̽��ֱ��ice sheet has been shrinking and losing mass over the last few decades due to climate change.

“ ̽��ֱ��ice loss from the Antarctic Ice Sheet is a major contributor to sea level rise worldwide,” said expedition co-chief scientist Sasha Montelli of ̽��ֱ�� College London (UCL). “Our work is critical for providing longer-term context of these recent changes, improving our ability to make projections of future change — projections that can inform actionable policies. We will undoubtedly make new discoveries as we continue to analyse this data.”

“We were thrilled by the opportunity to explore the newly exposed seafloor,” said team member Dr Svetlana Radionovskaya from Cambridge’s Department of Earth Sciences. “ ̽��ֱ��research will provide key insights into ice sheet dynamics, oceanography and sub-ice shelf ecosystems. At a time when the West Antarctic Ice Sheet is melting at an alarming rate, understanding these dynamics and their impacts is crucial.”

photo1_fkt250110-20250117-gliderdeploymentzodiac-ingle-2717.jpg

̽��ֱ��oceanography team, led by Cimoli in collaboration with the ̽��ֱ�� of East Anglia and the British Antarctic Survey, used autonomous underwater vehicles to characterise the ocean circulation of the region and study the impacts of glacial meltwater on the physical and chemical seawater properties. "Antarctica and the Southern Ocean are a nexus point for ocean circulation, so changes that happen around Antarctica can affect global ocean circulation and global climate," said Cimoli.

̽��ֱ��researchers are also investigating how the iceberg calving event has contributed to mix the upper ocean, not just in the recently exposed area, but also further downstream as the iceberg floats away. As the giant iceberg drifts, it can generate turbulence that mixes water properties and could potentially mix the deep nutrient-rich water with the surface waters, fuelling biological productivity.

̽��ֱ��expedition was part of Challenger 150, a global cooperative focused on deep-sea biological research and endorsed by the Intergovernmental Oceanographic Commission of UNESCO (IOC/UNESCO) as an Ocean Decade Action.

“ ̽��ֱ��science team was originally in this remote region to study the seafloor and ecosystem at the interface between ice and sea,” said Schmidt Ocean Institute Executive Director, Dr Jyotika Virmani. “Being right there when this iceberg calved from the ice shelf presented a rare scientific opportunity. Serendipitous moments are part of the excitement of research at sea – they offer the chance to be the first to witness the untouched beauty of our world.”

Svetlana Radionovskaya is a Junior Research Fellow at Queens’ College, Cambridge. Laura Cimoli is a Research Fellow at the Institute of Computing for Climate Science, Department of Applied Mathematics and Theoretical Physics at the ̽��ֱ�� of Cambridge.

Adapted from a media release by the Schmidt Ocean Institute.

Inset image: Dr Cimoli (right) and Dr Meyer (UEA, left) prepare an underwater glider for deployment. Credit: Alex Ingle/Schmidt Ocean Institute.

Scientists explore a seafloor area newly exposed by iceberg A-84; discover vibrant communities of ancient sponges and corals.

ROV SuBastian / Schmidt Ocean Institute

Deep-sea coral at a depth of 1200 metres

Yes

Licence type:

Attribution-Noncommercial-ShareAlike

Fully AI driven weather prediction system could start revolution in forecasting

sc604 — Thu, 20 Mar 2025 15:56:54 +0000

̽��ֱ��system, Aardvark Weather, has been supported by the Alan Turing Institute, Microsoft Research and the European Centre for Medium Range Weather Forecasts. It provides a blueprint for a new approach to weather forecasting with the potential to transform current practices. The results are reported in the journal Nature.

“Aardvark reimagines current weather prediction methods offering the potential to make weather forecasts faster, cheaper, more flexible and more accurate than ever before, helping to transform weather prediction in both developed and developing countries,” said Professor Richard Turner from Cambridge’s Department of Engineering, who led the research. “Aardvark is thousands of times faster than all previous weather forecasting methods.”

Current weather forecasts are generated through a complex set of stages, each taking several hours to run on powerful supercomputers. Aside from daily usage, the development, maintenance and use of these systems require significant time and large teams of experts.

More recently, research by Huawei, Google, and Microsoft has shown that one component of the weather forecasting pipeline, the numerical solver (which calculates how weather evolves over time), can be replaced with AI, resulting in faster and more accurate predictions. This combination of AI and traditional approaches is now being used by the European Centre for Medium Range Weather Forecasts (ECMWF).

But with Aardvark, researchers have replaced the entire weather prediction pipeline with a single, simple machine learning model. ̽��ֱ��new model takes in observations from satellites, weather stations and other sensors and outputs both global and local forecasts.

This fully AI driven approach means predictions that were once produced using many models – each requiring a supercomputer and a large support team to run – can now be produced in minutes on a desktop computer.

When using just 10% of the input data of existing systems, Aardvark already outperforms the United States national GFS forecasting system on many variables. It is also competitive with United States Weather Service forecasts that use input from dozens of weather models and analysis by expert human forecasters.

“These results are just the beginning of what Aardvark can achieve,” said first author Anna Allen, from Cambridge’s Department of Computer Science and Technology. “This end-to-end learning approach can be easily applied to other weather forecasting problems, for example hurricanes, wildfires, and tornadoes. Beyond weather, its applications extend to broader Earth system forecasting, including air quality, ocean dynamics, and sea ice prediction.”

̽��ֱ��researchers say that one of the most exciting aspects of Aardvark is its flexibility and simple design. Because it learns directly from data it can be quickly adapted to produce bespoke forecasts for specific industries or locations, whether that's predicting temperatures for African agriculture or wind speeds for a renewable energy company in Europe.

This contrasts to traditional weather prediction systems where creating a customised system takes years of work by large teams of researchers.

“ ̽��ֱ��weather forecasting systems we all rely on have been developed over decades, but in just 18 months, we’ve been able to build something that’s competitive with the best of these systems, using just a tenth of the data on a desktop computer,” said Turner, who is also Lead Researcher for Weather Prediction at the Alan Turing Institute.

This capability has the potential to transform weather prediction in developing countries where access to the expertise and computational resources required to develop conventional systems is not typically available.

“Unleashing AI’s potential will transform decision-making for everyone from policymakers and emergency planners to industries that rely on accurate weather forecasts,” said Dr Scott Hosking from ̽��ֱ��Alan Turing Institute. “Aardvark’s breakthrough is not just about speed, it’s about access. By shifting weather prediction from supercomputers to desktop computers, we can democratise forecasting, making these powerful technologies available to developing nations and data-sparse regions around the world.”

“Aardvark would not have been possible without decades of physical-model development by the community, and we are particularly indebted to ECMWF for their ERA5 dataset which is essential for training Aardvark,” said Turner.

“It is essential that academia and industry work together to address technological challenges and leverage new opportunities that AI offers,” said Matthew Chantry from ECMWF. “Aardvark’s approach combines both modularity with end-to-end forecasting optimisation, ensuring effective use of the available datasets."

“Aardvark represents not only an important achievement in AI weather prediction but it also reflects the power of collaboration and bringing the research community together to improve and apply AI technology in meaningful ways,” said Dr Chris Bishop, from Microsoft Research.

̽��ֱ��next steps for Aardvark include developing a new team within the Alan Turing Institute led by Turner, who will explore the potential to deploy Aardvark in the global south and integrate the technology into the Institute’s wider work to develop high-precision environmental forecasting for weather, oceans and sea ice.

Reference:
Anna Allen, Stratis Markou et al. ‘End-to-end data-driven weather prediction.’ Nature (2025). DOI: 10.1038/s41586-025-08897-0

Adapted from a media release by ̽��ֱ��Alan Turing Institute

A new AI weather prediction system, developed by researchers from the ̽��ֱ�� of Cambridge, can deliver accurate forecasts tens of times faster and using thousands of times less computing power than current AI and physics-based forecasting systems.

̽��ֱ��Alan Turing Institute

Professor Richard Turner using Aardvark Weather

Yes