Tag Archives: climate change

Science Week 2017: geoengineering, climate change and evolution

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This blog was written by Giulia Magnarini, Birkbeck graduate in Planetary Sciences with Astronomy and PhD candidate in Earth Sciences at UCL.geoengineeringmethods-climatecentral1-2To our knowledge, Earth is the only planet where life has developed. Life appeared very soon after the formation of our planet about 4.5 billion years ago, and continues to survive.

Dr. Philippe Pogge Von Strandmann examined the mechanisms that keep the Earth habitable in a recent talk. He noted that despite large oscillations between cold periods (ice ages) and warmer intervals (interglacial stages), our planet has managed to avoid the fates of Mars and Venus. Both of these planets have lost their oceans, while Earth has retained liquid water at its surface.

Meteorite impacts, glaciations and volcanic eruptions are some of the processes that mark the very dynamic history of the Earth. Atmospheric composition has also changed dramatically over time, formerly being composed of mainly CO2, to the increase of nitrogen and oxygen. These events across Earth’s history have caused extinction of some species, but life has survived nevertheless, and continues to adapt and evolve.

Dr. Von Strandmann illustrated some of the theories that aim to explain the endurance of life on our planet – for instance, Gaia Theory, the Medea Hypothesis, the Daisyworld Experiment – and explored the influence of geological processes on climate mitigation. Carbon dioxide, a greenhouse gas, dictates atmospheric and surface temperature; therefore its atmospheric abundance is critical in long-term climate change. Plate tectonics play an important role by removing gases through subduction (where oceanic plates sink under continental plates) and re-emitting them through eruptions. But this process is slow, acting on a time scale of hundreds of millions of years. The weathering of rocks is a more effective process. Dissolved material is washed away by rivers into oceans to form rocks, which lock crucial amounts of carbon dioxide inside.

Dr. Von Strandmann concluded his talk with considerations about consequences of human actions in the face of the current climatic stage. Atmospheric CO2 has surpassed the barrier of 400 ppm (parts per million) and over the last decade, every year has been hotter than the one prior. This is evidence we can neither deny nor ignore. Climate change is going to exert challenging environmental pressures, for instance in a reduction of land available for agriculture. Geoengineers are committed to finding ways to actively remove carbon dioxide from the atmosphere. However, the effects of carbon sequestration are still unknown and more research is needed.scienceweekgeoengineeringoriginalThe second speaker, PhD candidate Tianchen Hen, illustrated the emergence of animals that occurred as oxygen levels began to rise. About 540 million years ago, the Cambrian fauna started diversifying from the Ediacaran fauna, introducing several biological innovations. This event is known as the ‘Cambrian Explosion’, and is characterised by an accelerated rate of diversification. Cambrian rocks preserve amazing fossil records, dominated by Trilobites – the first representation of animals that we can call our ancestors.

What seems to be a sudden change in the fossil record has caused significant debate. Charles Darwin noted it to be the main counter-argument to his evolutionary theory of natural selection. However, although all Ediacaran fauna became extinct and were replaced by Cambrian fauna, there is not a distinct separation. Both faunae share a certain degree of diversification and show symmetrical structures. Indeed, molecular biology suggests that a co-occurrence is rooted in the Ediacaran fauna.

The rise of oxygen levels is vital for animal metabolism. It influences body size and allows more intense activities. However, it is unlikely that just one mechanism can explain the triggering of early animal radiation. Tianchen Hen explained other possible factors that may have contributed. Hox genes are responsible for biological innovations, such as appearance of limbs and eyes that could induce behavioural changes. These changes may have refined the relationship between predators and prey, bringing diversification in the battle to survive. Warmer temperatures following the period of extensive glaciations, known as the ‘Snowball Earth’, may have also played a part. The consequent rise of sea-levels expanded habitable shallow sea zones. Moreover, the post ‘Snowball’ stage caused an increased availability of minerals and nutrients.

The interaction between abiotic and biotic processes is extremely fascinating and deserves a better understanding – life as we know it depends on it.

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Climate Change and the River Thames

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This post was contributed by Colin Cafferty, an alumnus of the MSc Climate Change Management at Birkbeck.

Lifeblood of London

London is defined by its relationship to the physical landscape although it can sometimes be hard to see the wood for the trees in this urban jungle. Tower Bridge, the Houses of Parliament, the skyscrapers of Canary Wharf – none of these would form an iconic backdrop to the city without the mighty Thames flowing timelessly by. And so it was entirely fitting that Dr Becky Briant, Programme Director for the MSc in Climate Change Management at Birkbeck, decided to devote an entire lecture to the challenges to the future of the river and her citizens under future climate change.

Effects of climate change on the river

“We are living in what some analysts describe as a carbon military industrial complex”, she says rather ominously. Dr Briant makes liberal use of graphs to support her case including various emissions scenarios that model the predicted outcome in terms of changes to weather patterns. “The evidence is pretty strong that we are causing the changes we’re seeing”. We’re currently on track for a 4°C rise in global temperatures by the end of the century. “There’s a certain amount of climate change that’s going to happen no matter what we do”, Dr. Briant adds.

So what lies in store for us? We can expect wetter winters where peak flow in the river could increase by 40% by 2080. Between 3-24 billion litres of freshwater already flows over Teddington Weir, the upper limit of the tidal Thames. London is particularly vulnerable to flooding due to impermeable surfaces, whether that be concrete or the clay-rich impermeable soil beneath our feet. We can also expect drier summers and more intense rainfall events, which will in turn affect water quality in the river. And then there is the whole issue of surface water on our many paved streets that the Drain London Forum is seeking to address in a sustainable way.

So what does the future hold in store for the Thames?

Thames Barrier at night with Canary Wharf and O2 arena in the background

London is fortunate to have a vital piece of infrastructure in place that can protect the city from tidal flooding, the Thames Barrier. The lifetime of this key flood defence is predicted to expire in the 2070s due to sea-level rise at which point a new barrier further downstream at Long Reach (or Tilbury) has been proposed. But already the barrier is having to be closed more frequently due to tidal surges. Lest we forget, 307 people died in the UK due to the floods in 1953, which prompted the construction of the barrier in the first place.

Professor Gerald Roberts, Head of the Department of Earth and Planetary Sciences, remarked at the lecture’s end that he was “particularly struck by the image of London with so many rivers running through it”. So next time, you’re out and about, keep an eye open for all those small creeks, tributaries and hidden rivers that feed the mighty Thames and remember that they could yet rise up in response to climate change. And so, hopefully, will we, the citizens of this great city, to take action before the cost is too great.

Useful links:

UK Climate Projections from DEFRA
Thames Estuary 2100 Plan
London Draft Climate Change Adaptation Strategy

This post was contributed by Colin Cafferty. Colin is a documentary photographer who focuses on sustainability, energy and environmental themes. He graduated with distinction as part of the first MSc in Climate Change Management class at Birkbeck. Since then, he has set-up a website called Climate Change Café which features photo stories and blogs on a number of ongoing projects. He has shown five exhibitions of his work in the last year including one entitled, “Urban sustainability in London” which showed at an international conference at University College London (UCL) in November 2012. More info and images available at www.climatechangecafe.com and www.colincafferty.com

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Science Week: Piecing together the jigsaw of climate change and human evolution

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This post was contributed by Guy Collender, of Birkbeck’s Department of External Relations.

Dr Phil Hopley, of Birkbeck's Department of Earth and Planetary Sciences

Dr Phil Hopley exhibited replica skulls of our ancestors during Science Week. Photo: Harish Patel

I knew an unusual presentation was in store as soon as I saw six skulls menacingly positioned at the front of the lecture theatre. The exhibits – all different shapes and sizes – immediately caught the audience’s attention, and our questions about their origins were answered in the fascinating hour that followed.

Dr Phil Hopley began Birkbeck’s series of Science Week lectures with a talk on 16 April about the links between climate change and human evolution. He used the skulls – five replicas of our ancestors and one gorilla skull – to illustrate how evolution is all about the changing dimensions of the head as it has become rounder and larger to accommodate a bigger brain over millions of years. In comparison, the gorilla’s skull includes ferocious canines and space for huge powerful jaws – it certainly sent a shiver up my spine being only a few feet away from my seat.

A family tree dating back millions of years
Dr Hopley, of Birkbeck’s Department of Earth and Planetary Sciences, explained how the last common ancestor of chimpanzees and modern humans was on this planet about six of seven million years ago. Both branches of the family tree then developed separately, with chimpanzees on the one hand, and about 20 species of hominins – the ancestors of modern humans – walking on two legs on the other. As the hominins evolved, they became characterised by their tool use, larger brains, language and art, eventually developing into Homo sapiens – our own species. But our ancestral line has not been straightforward, and Dr Hopley highlighted the complexity. He said: “Homo sapiens is the only human species alive today, but for most of human evolution there have been a number of co-existing human species.”

As Dr Hopley explained, hominin fossils have mainly been found in two areas – the Rift Valley in East Africa (dating back five million years), and caves in Southern Africa (dating back 2.5 million years). Yet, hardly surprising, given the awesome amount of time involved, it is very rare to find a whole hominin specimen. What is clear is that the human fossil record is very incomplete, both geographically and temporally, and solving the mystery is a bit like piecing together a jigsaw.

Climate change: from forest to grassland
The question of why our ancestors evolved to become bipedal was then addressed, and this was where Dr Hopley referred to his work studying fossils from caves in South Africa. The study of carbon and oxygen isotypes and climate modelling has shown that the savannah in Africa developed eight million years ago due to the reduction in carbon dioxide and reduction in rainfall. As the grasslands replaced the forests, our ancestors evolved to walk on two feet as they needed to cover large distances to search for food, which wasn’t necessary when they were still living in the forest. Although it’s difficult to build up a comprehensive understanding of how climate change drives evolution, Dr Hopley did present a general conclusion. He said: “Human evolution did occur because of climate change in the broad sense as forests were replaced by savannah.”

I’ve never been to a lecture with skulls on display before and I’ll certainly never forget this one. It was a powerful way to remind us that our common ancestors adapted to the African bush and started walking when the forests began to recede.

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