Tag Archives: climate change

Science Saturdays: Coughing up a lung, pollutants in our air

In May, Birkbeck’s School of Science held ‘Science Saturdays’, a programme of free online talks every Saturday, open to a global audience. In this blog, Tina Wright, Birkbeck PhD student, gives an overview of the talk she attended about pollutants in the air and how they affect the physical wellbeing of humans.

The Science Saturdays talk, ‘Coughing up a lung: pollutants in our air’ delivered by Dr Katherine Thompson, Reader in Biophysical Chemistry, observed how the environment influences physical wellbeing, more specifically, how the atmosphere and its composition of gases and particulate matter, which includes pollutants, interacts with a monolayer of molecules (surfactant) at the air-water interface of the lung to cause respiratory problems.

The content of the talk was a boon to the global cause of tackling climate change and its subsequent effects on worldwide mortality and morbidity rates. It provided information on how to investigate exactly what is happening on a molecular level and systemically in our bodies.

Our atmosphere, pollution and photochemical smog

Our atmosphere predominantly consists of nitrogen (N) and oxygen (O2) along with trace amounts of unnatural and naturally sourced gases, the former being sourced from human processes, for example, car exhaust fumes. These may be from petrol or diesel motors. Petrol motors release some water combined with lots of carbon monoxide (CO), hydrocarbons from incomplete combustion of fuel and nitrogen oxides (NOx) which includes nitric oxide (NO) and nitrogen dioxide (NO2). Diesel motors burn fuel differently, therefore generate a different composition of exhaust gases, such as CO and hydrocarbons, but also release tiny particles that may be dangerous for human health, dependent on particle size.

As I’ve already mentioned, there are some natural sources of trace gases that add to our atmosphere and these include green plants that emit organic pollutants, called volatile organic compounds (VOCs).

Photochemical smog is pollution present on sunny days and has a distinct character. Nitrogen dioxide (NO2) features as a brown/orange gas, visible on the horizon on a clear day. A combination of this with volatile organic compounds (VOCs) and sunlight produces ozone (O3). It is vital for life to have O3 in the stratosphere as it absorbs short wavelengths of light that may damage our DNA, however, when present in the troposphere as a secondary pollutant, the VOC-NOx-O3 relationship keeps its concentration high during warmer months, therefore, adverse effects may occur, notably at the air-water interface of the lung.

Lung physiology, function and properties on a molecular level

The lung is composed of the trachea, bronchi, bronchioles and finally, millions of alveoli, which are tiny sacs that increase the surface area of the lung for gas-exchange of oxygen (O2) and carbon dioxide (CO2).

Our bodies are wet systems but if the alveoli were lined with pure water, the surface tension (cohesive forces between water molecules), would be too high for expansion of the lung after compression. This issue is resolved by the action of surfactants present as a film on the lung interface that are composed of lipids, proteins, and cholesterol. Its importance is reflected by premature, newborn babies that lack lung surfactant and consequentially, experience difficulties breathing.

Diagram of the human lung. Credit: Frontiersin.org.

What happens when pollutants reach the lung interface?

Dr Katherine Thompson’s research focuses on the interaction of pollutants with the lung. A single layer of molecules (monolayer) of lung surfactant, similar to when it is found on the surface of the lung, may be analysed by the reflection of light. For example, a technique known as Brewster Angle Microscopy, allows the observation of the organization of molecules at the surface or interface, a simile of the lung.

A monolayer is very thin, therefore, the wavelength of light chosen for the reflection experiments should be shorter than the thickness of the monolayer. The wavelength of x-rays (photons) are very short, therefore, it can be used to look at these reflections. Photons may hit a surface and ‘bounce off’ to a detector, comparable to a gymnast jumping and landing on a mat, then coming away. This will give information, in the case of the gymnast, on the thickness of the mat or in the experiment, the single layer of molecules.  These experiments may be undertaken whilst the lung surfactant is simultaneously exposed to ozone and a thinning of the monolayer can be observed from rearrangement, breaking and bending of molecules at the surface. Physiologically, this may lead to inflammation of the lung.

This research is of paramount importance in the modern world, where the extent of the damage to our environment, and the subsequent effect on human health, needs further investigation and awareness raised to all.

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Science Week 2017: understanding climate change

This blog was written by Giulia Magnarini, Birkbeck graduate in Planetary Sciences with Astronomy and PhD candidate in Earth Sciences at UCL.scienceweekclimatechange850x450To understand current climate changes, we need to understand past events. However, using our existing climate model is really difficult.’ This is how Professor Andrew Carter began his talk on Earth’s long-term climate. Professor Carter’s research focuses on studying Antarctica in terms of climate changes.

Despite some persistent denial, evidence for an increasingly warm climate is clear. To provide a visual idea of the impact that the total melt of ice in Antarctica could have, Professor Carter asked the audience to imagine Big Ben under water up to the clock. Thames barriers would be ineffective and it is increasingly obvious how important research on climate change to tackle its consequential threats is.

Geological evidence for the first appearance of the ice sheet in Antarctica resides in sediments that date from 33 million years ago. The question is: why did Antarctica freeze over? Two hypotheses are proposed. The first one involved plate tectonics; as Antarctica separated from Australia and South America (circa 50 million years ago), ocean circulation changed and the strong Antarctic Circumpolar Current emerged, causing thermal isolation of the continent.

The second one takes reduction of atmospheric carbon dioxide into account. Historic data collected for ice volume, deep sea temperature and sea level all follow the same trend of the reconstructed amount of carbon dioxide in the atmosphere.

However, there are problems with both hypotheses. For instance, at the moment of the break, Antarctica was in a northern position and, although carbon dioxide was lower, overall temperature was warmer.

There are many difficulties in modelling over geological time. Nowadays, different models running for Antarctica show completely different results. Improving the quality of data is crucial because uncertainties are very high. On this point, Professor Carter has been conducting what is called ‘provenance analysis.’ This involves studying sand grains to locate their sources to better constrain past tectonic events and past environmental conditions. The grains that Professor Carter studies have typical shape due to ice erosion. Detrital zircons (very resistant minerals) are used to conduct U-Pb geochronological assessments to reconstruct the age distribution of the sediments. These ages are then compared with rocks from different areas for which age is known.

Oceanic drilling programs have been conducted within the ‘Iceberg Alley’. This is an area where icebergs are transported by currents and during the journey they deposit sediments. Results from sediment cores have shown that the grains come from other areas, meaning that they had been transported by icebergs, therefore implying that ice was already present on the continent at that time.

This new set of information can help improving tectonic models related to the opening of oceanic passages. Sampling the ‘Shag Rocks’, which are the only exposed part of the continental block within the Iceberg Alley, would be of benefit for this. Unfortunately, due to strong currents, this can be very difficult and dangerous.

Professor Carter concluded by pointing out the importance of better understanding the geology of this area because it was here that the Antarctic Circumpolar Current originated. This in turn had a significant implication on the global cooling of the planet. In fact, its influence reaches up to the northern hemisphere.

Therefore, more geological data can greatly improve the quality of climatic models. Better and more reliable climatic models will be fundamental to help future governments make important decisions.

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Science Week 2017: geoengineering, climate change and evolution

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

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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