Prehistoric Planet: TV show asked us to explore what weather the dinosaurs lived through

Apple TV+, CC BY-NC-SA

When conjuring up images of when dinosaurs ruled the planet we often think of hot and humid landscapes in a world very different from our own. However, the new TV series Prehistoric Planet, narrated by Sir David Attenborough, shows dinosaurs living and indeed thriving in many types of environments, including colder regions where snowstorms, freezing fog and sea-ice were commonplace.

When the show’s producers first approached us to help understand the kinds of weather and environment that dinosaurs lived in before being wiped out around 66 million years ago, it prompted us to tackle a problem that has existed in palaeoclimate modelling for decades. That was, when scientists like us used computers to simulate, or “model”, the climate of prehistoric Earth, the models tended to make the poles much colder than evidence from fossils and rocks suggested they had actually been.

For the TV series, not only have we improved our models, but we have run the computer programmes for longer than anybody else has ever done to get the models as close to ancient “reality” as possible.

Prehistoric Planet depicts CGI dinosaurs based on the latest research.

The producers, the BBC’s Natural History Unit, needed to know about the weather so they could film “real world” locations similar to those that existed in the past where dinosaurs lived. But most of what we know about the climate that long ago comes from indirect “proxy” evidence, such as leaf fossils and traces of certain chemicals in rocks, which can only reconstruct the average climate over decades or centuries. This is where the narrative of a much hotter and more humid Cretaceous world comes from.

This narrative isn’t exactly wrong, but it doesn’t tell the whole story since weather and climate behave differently. For instance, even in today’s warming world a place like Texas, largely hot and humid, recently experienced widespread snowfall. Geologists a million years from now will spot the sudden global warming – but not the freak snowstorm. Nonetheless, modelling the the prehistoric equivalent of these snowstorms is important since we know warmer worlds will experience greater weather extremes. And these extremes will have largely determined which regions were completely inhospitable to dinosaurs.

Surface wind speed and precipitation through a typical year 69m years ago. An index of 1 means no visibility beyond 10 metres.

How do we know what the weather was like?

Unfortunately, although fossils give us many clues as to past climate, most cannot directly tell us what the weather was on a day to day basis.

So, for a given place on Earth, how do we know what the weather was on, say, May 27 some 66 million years ago? To do this we need to employ a computer simulation of the climate, similar to the ones used to look at future climate change today. These models are based on fundamental physical and biological processes which remain constant with time. It is therefore possible to adjust them for ancient worlds, even if we don’t know precise details like where or how high the mountains were, or exactly how much carbon dioxide was in the atmosphere.

We can then check these models using some of the ancient climate proxies, such as fossilised leaves, coral or rocks which contain traces of what conditions were like at the time. If our model matches up with the proxies – and it did – then we can be confident it is simulating typical weather at the time.

So what did we learn from modelling the climate of 66m years ago?

Our model found there would have been intense blizzards in Antarctica, for instance, “category six” hurricanes (something we are likely to see in our lifetimes) buffeting the mid and low latitudes and extensive, ever present, fog banks creating murky winters under polar cloud caps.

In a warmer world the water cycle is intensified over the poles. This meant more water in the air, and large parts of the planet would have been very foggy almost all the time (Source: modelling work by the authors)

This doesn’t immediately sound like a dinosaur-friendly environment. However, the old misconception that dinosaurs were cold blooded, thus requiring a warm climate for survival has for the most part already been dismissed. The new paradigm is that dinosaurs were warm blooded, and could to some extent regulate their internal temperature, like mammals do today.

This would be essential to survive large swings in temperature, driven by varied weather patterns, particularly in the polar regions. Our modelling therefore backs up recent fossil discoveries which show that some dinosaur species were cold-adapted, could see in low light conditions (useful in those huge fog banks), and thrived year-round near the poles.

Dinosaur in snow
Pachyrhinosaurus surviving and thriving.

The Prehistoric Planet scenes with the chilly Pachyrhinosaurus were set in Alaska, and demonstrate why the show wanted check its accuracy with climate models. We have an idea what the conditions would have been like there 66m years ago thanks to detailed fossils of plants, dinosaurs and other animals, yet the old models would have predicted intensely-cold and lifeless tundra.

Our model instead matches up with the fossil evidence, and predicts forests right up to the margins of the Arctic Ocean at 82°N – much further north than any trees today. In the summer, dinosaur food would have been abundant, but in the long dark winters it would have been more difficult to find, particularly as both fossils and modelling suggests it was so foggy.

Dinosaurs survived for a remarkable 165 million years. Tyrannosaurus Rex lived much closer to present day humans than it did to Stegosauruses, for instance. They managed to survive so long because they were resilient and adaptable to changeable environmental conditions, much like mammals are today. Our work for Prehistoric Planet shows that they were able to survive through greater extremes in temperature, stormier weather, and more extreme droughts than humans have experienced – so far.The Conversation


This blog is written by Cabot Institute for the Environment members Dr Alex Farnsworth, Senior Research Associate in Meteorology, and Paul Valdes, Professor of Physical Geography, University of Bristol; and Robert Spicer, Emeritus Professor of Earth Sciences, The Open University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Dune: we simulated the desert planet of Arrakis to see if humans could survive there

Dune, the epic series of sci-fi books by Frank Herbert, now turned into a movie of the same name, is set in the far future on the desert planet of Arrakis. Herbert outlined a richly-detailed world that, at first glance, seems so real we could imagine ourselves within it.

However, if such a world did exist, what would it actually be like?

We are scientists with specific expertise in climate modelling, so we simulated the climate of Arrakis to find out. We wanted to know if the physics and environment of such a world would stack up against a real climate model.

Here’s a visualisation of our climate model of Arrakis:

You can zoom in on particular features and highlight things like temperature or wind speed at our website Climate Archive.

When we were done, we were very pleased to discover that Herbert had envisioned an environment that for the most part meets expectations. We might need to occasionally suspend disbelief, but much of Arrakis itself would indeed be habitable, albeit inhospitable.

How do you build a fantasy world like Arrakis?

We started with a climate model commonly used to predict weather and climate here on Earth. To use these sorts of models you have to decide on the physical laws (well-known in the case of planet Earth) and then input data on everything from the shape of mountains to the strength of the sun or the makeup of the atmosphere. The model can then simulate the climate and tell you roughly what the weather might be like.

We decided to keep the same fundamental physical laws that govern weather and climate here on Earth. If our model presented something completely strange and exotic, this could suggest those laws were different on Arrakis, or Frank Herbert’s fantastical vision of Arrakis was just that, fantasy.

Height map (in metres) of Arrakis.
Farnsworth et al, Author provided

We then needed to tell the climate model certain things about Arrakis, based on the detailed information found in the main novels and the accompanying Dune Encyclopedia. These included the planet’s topography and its orbit, which was was essentially circular, akin to the Earth today. The shape of an orbit can really impact the climate: see the long and irregular winters in Game of Thrones.

Finally, we told the model what the atmosphere was made of. For the most part it is quite similar to that of the Earth today, although with less carbon dioxide (350 parts per million as opposed to our 417 ppm). The biggest difference is the ozone concentration. On Earth, there is very little ozone in the lower atmosphere, only around 0.000001%. On Arrakis it is 0.5%. Ozone is important as it is around 65 times more effective at warming the atmosphere than CO₂ over a 20-year period.

Having fed in all the necessary data, we then sat back and waited. Complex models like this take time to run, in this case more than three weeks. We needed a huge supercomputer to be able to crunch the hundreds of thousands of calculations required to simulate Arrakis. However, what we found was worth the wait.

Arrakis’s climate is basically plausible

The books and film describe a planet with unforgiving sun and desolate wastelands of sand and rock. However, as you move closer to the polar regions towards the cities of Arrakeen and Carthag, the climate in the book begins to change into something that might be inferred as more hospitable.

Yet our model tells a different story. In our model of Arrakis, the warmest months in the tropics hit around 45°C, whereas in the coldest months they do not drop below 15°C. Similar to that of Earth. The most extreme temperatures would actually occur in the mid-latitudes and polar regions. Here summer can be as hot as 70°C on the sand (also suggested in the book). Winters are just as extreme, as low as -40°C in the mid-latitudes and down to -75°C in the poles.

This is counter intuitive as the equatorial region receives more energy from the sun. However, in the model the polar regions of Arrakis have significantly more atmospheric moisture and high cloud cover which acts to warm the climate since water vapour is a greenhouse gas.

gif of temperatures
Monthly temperatures on Arrakis, according to the model. Both poles have very cold winters and very hot summers.
Author provided

The book says that there is no rain on Arrakis. However, our model does suggest that very small amounts of rainfall would occur, confined to just the higher latitudes in the summer and autumn, and only on mountains and plateaus. There would be some clouds in the tropics as well as polar latitudes, varying from season to season.

The book also mentions that polar ice caps exist, at least in the northern hemisphere, and have for a long time. But this is where the books perhaps differ the most from our model, which suggests summer temperatures would melt any polar ice, and there would be no snowfall to replenish the ice caps in winter.

Hot but habitable

Could humans survive on such a desert planet? First, we must make an assumption that the human-like people in the book and film share similar thermal tolerances to humans today. If that’s the case then, contrary to the book and film, it seems the tropics would be the most habitable area. As there is so little humidity there, survivable wet-bulb temperatures – a measure of “habitability” that combines temperature and humidity – are never exceeded.

The mid-latitudes, where most people on Arrakis live, are actually the most dangerous in terms of heat. In the lowlands, monthly average temperatures are often above 50-60°C, with maximum daily temperatures even higher. Such temperatures are deadly for humans.

Four people in black rubbery suits in desert
Stillsuit models, autumn 10191 collection.
Chiabella James / Warner Bros

We do know that all humanoid life on Arrakis outside of habitable places must wear “stillsuits”, designed to keep the wearer cool and reclaim body moisture from sweating, urination and breathing to provide drinkable water. This is important as stated in the book that there is no rainfall on Arrakis, no standing bodies of open water and little atmospheric moisture that can be reclaimed.

The planet also gets very cold outside of the tropics, with winter temperatures that would also be uninhabitable without technology. Cities like Arrakeen and Carthag would suffer from both heat and cold stress, like a more extreme version of parts of Siberia on Earth which can have both uncomfortably hot summers and brutally cold winters.

It’s important to remember that Herbert wrote the first Dune novel way back in 1965. This was two years before recent Nobel-winner Syukuro Manabe published his seminal first climate model, and Herbert did not have the advantage of modern supercomputers, or indeed any computer. Given that, the world he created looks remarkably consistent six decades on.

The authors modified a well-used climate model for exoplanet research and applied it to the planet in Dune. The work was carried out in their spare time and is intended as an appropriate outreach piece to demonstrate how climate scientists use mathematical models to better understand our world and exoplanets. It will feed into future academic outputs on desert worlds and exoplanets.The Conversation

This blog is written by Cabot Institute for the Environment members, Dr Alex Farnsworth, Senior Research Associate in Meteorology and Dr Sebastian Steinig, Research Associate in Paleoclimate Modelling, University of Bristol; and Michael Farnsworth, Research Lead Future Electrical Machines Manufacturing Hub, University of Sheffield.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Warming up the poles: how past climates assist our understanding of future climate

Eocene, by Natural History Museum London

The early Eocene epoch (56 to 48 million years ago), is thought to be the warmest period on Earth in the past 65 million years. Geological evidence from this epoch indicates that the polar regions were very warm, with mean annual sea surface temperatures of > 25°C measured from geological proxies and evidence of a wide variety of vegetation including palm trees and insect pollinated plants found on land. Unfortunately, geological data from the tropics is limited for the early Eocene, although the data that does exist indicates temperatures only slightly warmer than the modern tropics, which are ~28°C.  The reduced temperature difference between the tropics and the poles in the early Eocene and the implied global warmth has resulted in the label of an ‘equable’ climate.

Simulating the early Eocene equable climate with climate models, however, has not been straightforward. There have been remarkable model-data differences with simulated polar temperatures are too cool and / or tropical temperatures that are too hot; or the CO2 concentrations used for a reasonable model-data match being outside the range of those measured for the early Eocene.

There are uncertainties in both geological evidence and climate models, and whilst trying to resolve the early Eocene equable climate problem has resulted in an improved understanding of geological data, there are uncertain aspects of climate models that still need to be examined.  Climate processes for which knowledge is limited or measurements are difficult, such as clouds, or which have a small spatial and temporal range are often simplified in climate models or parameterised. These uncertain model parameters are then tuned to best-match the modern observational climate record. This approach is not ideal, but it is sometimes necessary and it has been shown that the modern values of some parameters, such as atmospheric aerosols, may not be representative of past climates such as the early Eocene, with their removal improved the model-data match.

However, a climate model that can simulate both the present day climate and past more extreme climates without significant modification potentially offers a more robust method of understanding modern and future climate processes in a warming world. We have conducted research in which uncertain climate parameters are varied within their modern upper and lower boundaries in order to examine whether any of these combinations is capable of the above. And we have found one simulation, E17, from a total of 115, which simulates the early Eocene equable climate and improves the model-data match whilst also simulating the modern climate and a past cold climate, the last Glacial Maximum reasonably well.

This work hopefully highlights how paleoclimate modelling is a valuable tool in understanding natural climate variability and how paleoclimates can provide a test bed for climate models, which are used to predict future climate change.

This blog has been written by Nav Sagoo, Geographical Sciences, University of Bristol.

Why the Pliocene period is important in the upcoming IPCC report

Critical to our understanding of the Earth system, especially in order to predict future anthropogenic climate change, is a full comprehension of how the Earth reacts to higher atmospheric CO2 conditions. One of the best ways to look at what the Earth was like under higher CO2 is to look at times in Earth history when atmospheric CO2 was naturally higher than it is today. The perfect period of geological history is the Pliocene, which spans from 5.3 – 2.6 million years ago. During this time we have good evidence that the Earth was 2-3 degrees warmer than today, but other things, such as the position of the continents and the distribution of plants over the surface, was very similar to today.

There is therefore a significant community of oceanographers and climate modellers studying the Pliocene, many of whom were in Bristol last week for the 2nd Workshop on Pliocene climate, and one of the main points of discussion was the exact value of CO2 for the Pliocene.

80 top scientists from 12 countries gathered for the 2nd Workshop on Pliocene climate on 9-10 September 2013 at the University of Bristol

The imminent release of the first volume of the 5th assessments of the IPCC is also expected to include sections on Pliocene climate.

Today we published a paper in Philosophical Transactions of the Royal Society A which therefore represents an important contribution to the debate. Several records of Pliocene CO2 do exist, but their low temporal resolution makes interpretation difficult. There has also been some controversy about what these records mean, as some show surprisingly high variability, given what we understand about Pliocene climate.

We sampled a deep ocean core taken by the Ocean Drilling Program in the Carribean Sea. Cores such as this record the ancient envrionment as sediment collects over time like the progressive pages in a book, and by analysing the chemical composition of the layers a history of the Earth System can be discovered. The approach that Badger et al take is to use the carbon isotopic fractionation of photosynthetic algae, which has been shown to vary with atmospheric CO2.

What this study revealed is that atmospheric CO2 was actually quite low, at around 300 ppm for much of the warm period. What was also revealed was that CO2 was relatively stable, in contrast to previous work. This implies that in the Pliocene the Earth must have been quite sensitive to CO2, as small changes in atmospheric CO2 drove changes in climate. The study of Badger et al doesn’t explicitly reconstruct climate sensitivity but it does have important implications for future change.

The paper is published in a special volume of Philosophical Transactions of the Royal Society A, edited by Bristol scientists Dan Lunt, Rich Pancost, Andy Ridgewell and Harry Elderfield of Cambridge University. The volume is the result of the Warm Climates of the Past – A lesson for the Future? meeting which took place at the Royal Society in October 2011. The volume can be accessed here:

Marcus Badger

Chasing Ice with the All Party Parliamentary Climate Change Group

Watching the film of a self-confessed reformed climate skeptic with members of parliament and Lords isn’t how I usually spend my Tuesday morning, but it was what I found myself doing last Tuesday. The occasion for this unlikely meeting was a special screening of photographer James Balog’s film Chasing Ice for the All Party Parliamentary Climate Change Group (APPCCG), of which the Cabot Institute is a member. The film, which documents the work of the photographer’s Extreme Ice Survey, follows James and his team on a journey to record the retreat of 13 glaciers across the globe continuously over a two year period. 

I won’t spoil the film too much (and strongly encourage you to see it if you can) but suffice to say placing 28 cameras at locations across the globe in some of the most difficult terrains and extremes of temperature is a challenge for both the men and technology involved. The aim to take one photo every hour of daylight for two years solid was massively ambitious, but worth the effort and the pain, as the result is a spectacular demonstration of how our hydrocarbon based economy is changing the face of the planet.

“What the public need […] is something spectacular that grabs people in the gut”
James Balog

James’s desire was to capture what is perhaps the most visually compelling effect of climate change. Retreating glaciers are a clear indication of the effects of rising global temperatures and one (despite the attempts by some to highlight the minority which are advancing) which is hard to ignore. Of course the glaciers highlighted in the film are only a small proportion of global land ice (which has the power to raise sea level) but can be seen as an important “canary in the coal mine” demonstrating the processes which are happening in the really large ice sheets too. Over the last twenty years, mass loss of ice sheets on Greenland and Antarctica are estimated to have contributed 0.59 ±0.20 mm yr -1 to global sea level rise (Shepard et al., 2012). While that may seem like a small number, the effects over the next century could be dramatic, especially as, if last year’s unprecedented Greenland melt are anything to go by (
Tedesco et al., 2012), this rate could be accelerating.

“If you had an abscess in your tooth, would you go to dentist after dentist until one told you not to pull it out?”
James Balog

Before the screening there was an introduction to the film by Chris Shearlock, Sustainable Development Manager at The Co-operative Group who explained the Co-op’s involvement in the film, and their outlook on sustainable and ethical investment. The Co-op has invested £1billion in renewable energy, and he estimated that they have refused £300 million of investment opportunities in hydrocarbon extraction, and so when following the film, the questioning turned to exploitation of the soon-to-be summer sea ice free arctic the voice of the Co-operative was clear – that they will not be investing in hydrocarbon extraction. That question was dealt with very differently by Chris Barton, Head of International & Domestic Energy Security at the DECC who put forward the UK government’s current position that whilst we should reduce demand, in order to maintain cheap oil and gas for UK consumers “sensible” and regulated extraction in the arctic should be a priority for UK plc. What to do with the resulting CO2 emissions in order to hit the < 2 °C target? Well in Chris Barton’s mind carbon capture and storage will come to the rescue.

The debate moved to whether, as we are not an Arctic state, we can do anything about the regulation of commercial activity in a basin which is a combination of the territorial water of eight nation states, and open ocean controlled under the international law of the sea. The DECC view seemed to be that it is largely none of our business and out of our control, but interestingly Jane Rumble, Head of Polar Regions Unit at the FCO, had a different perspective. She suggested that we should be (and can be) working constructively through the Arctic Council, towards a similar regulatory framework to that which controls the other end of the Earth via the Antarctic Treaty, and by influencing Canada (one of the eight bordering nation states) through the commonwealth. Colin Manson, Director of Manson Oceanographic Consultancy and member of the IMO Polar Code working group spoke of the frustration of many in the shipping industry that talks on the Polar Code had stalled and encouraged UK intervention as a broker. He also pointed that one little talked about impacts of the opening up of the Northern Passage would be dramatic reductions in the time and fuel needed for bulk cargo shipping from the far east to Europe. With the representative routing of Shanghai – Rotterdam dropping to 5 weeks, vs the current 8 week route via the Indian Ocean. Colin, along I think with many in the audience, hoped thoughtful regulation and consideration of the impacts of this increased shipping through the arctic would come before it was too late.

Julia Slingo OBE, Chief Scientist at the Met Office closed proceedings with an impassioned plea to take care with the interpretation of our current generation of climate models following questions from the audience, and highlighted the importance of sustained development of what are our best hopes for accurate and precise predictions of future climate change.

All in all it was a fascinating day, and I was grateful to be exposed to a beautiful film, as well as an insight into the minds of those at the policy end of climate change science.

“We think we need new oil and gas production whether people like it or not”
Chris Barton, Head of International & Domestic Energy Security, DECC

This blog is by Dr Marcus Badger (Chemistry) at the University of Bristol
. He writes about the APPCCG meeting held on 5 March 2013.
Marcus Badger