Climate Change, Global Warming and Alternative Energy Sources
In this show we look at the causes and effects of global warming. Lloyd Peck, Howard Griffiths and Harry Elderfield delve into the hot topics of climate change, rising carbon dioxide levels, the role of oceans and plants in removing carbon dioxide from the atmosphere, and how climate change affects the environment, while Chris Llewelyn Smith provides a possible solution by discussing nuclear fusion as alternative energy. In our series on how Einstein has contributed to science in the home, Philippa Law gets excited by the photoelectric effect.
In this episode
Researchers working for the US military are developing a laser stun gun capable of inflicting paralysis and excruciating pain on anyone unlucky enough to be within its 2 km range. The new weapon, known as a PEP or Pulsed Energy Projectile, is being touted as a crowd-control measure to 'neutralise' rioters, and could be in action by 2007. It emits a powerful laser beam which generates a charged plasma cloud whenever it hits someone. The expanding plasma over-excites the nervous system triggering severe pain sensations, and temporary paralysis. At the moment the researchers are working on ways to optimise the system so that it's even more effective at producing pain but without damaging healthy tissue. However, some pain experts around the world are horrified and have expressed concerns over the long-term effects of such a weapon which could include life-long pain syndromes triggered by the stun gun causing the nervous system to re-wire itself.
Moans For Phones
If you're looking to spice up your mobile text life, then adult film company New Frontier Media might have just the thing for you - not ring tones but ring 'moans'. Fruity users will be able to download a selection of naughty noises said to range from the "suggestive" to the "positively tantilising". The company are also planning to provide saucy pictures and videos to accompany the sounds, although in an ironic twist of fate it could end up proving that size is important as users go blind straining their eyes trying to see what's going on on an inch-wide mobile screen !
Peckish Pilferers Fingered By Snack-attack
House breakers seem to have more than just an appetite for crime - frequently they get tempted by more than just the contents of the jewelry box and tend to rifle through the fridge too, leaving the discarded remnants of their snack at the scene. Unfortunately for them, the remains of their last meal could be their undoing because minute traces of saliva left in the food often contains DNA which can be used to identify the culprit. A number of food-felons have been convicted in this way over the last 10 years or so, but exactly what foods produce the most reliable for DNA fingerprinting wasn't known. So US researcher Heather Zarsky held a dinner party for 13 colleagues and invited them to snack on a range of offerings including fruit, corn on the cob, pizza, chocolate and vegetables, and to leave behind the discarded remnants of their meals. She then analysed the leftovers and managed to produce complete DNA profiles of nearly half of her 'guests', and partial profiles from a further third. The most successful burglar-busting foods turned out to be cheese, carrots, apples and pizza, but would-be housebreakers would be advised to stick to chocolate, because it proved almost useless for DNA techniques, possibly due to the small size of the pieces left behind.
Migration of Monarch Butterflies Could Be Key To Species' Survival
Scientists in the USA think that the annual monarch butterfly migration marathon from Canada to Central America may be keeping the species in tip top shape by reducing parasite infestations. Using the butterfly equivalent of a treadmill, scientists have found that members of the flock highly infested with parasites flew slower and tired more quickly than those with less parasites. Because migrating butterflies are known to have a lower number of parasites compared with those that don't migrate, it seems that butterflies with lots of parasites can't stand the pace and drop out of the race. By picking off the parasite-infested flyers, the gruelling migration leaves a flock of healthy front-runners that reduce the spread of infection and aid species survival.
- The Photoelectric Effect
The Photoelectric Effect
with Philippa Law interviews Dr Julian Allwood & Dr Lucy Green
Philippa - This week I've been finding out how my do-dah works. Maybe you call it a flicker, but maybe for simplicity I should call it a remote control. Here's Dr Julian Allwood from the Institute for Manufacturing at Cambridge University.
Julian - What happens when you press a button on your remote control is that a light flashes, sending a code in the direction you're pointing. The receiver in the object you are trying to control is waiting and looking for light of one particular frequency, which is the frequency given out by your remote control. Once it sees that frequency, it watches to see a series of 'ons' and 'offs' and works out what that signal was meant to communicate.
Philippa - I've never seen light coming out of my remote control.
Julian - Good comment. The light is usually in the infra-red frequency, which is outside the range of your eyes.
Philippa - How on earth can there be light you can't see? Let's ask Dr Lucy Green from the physics and astronomy department at Cardiff University.
Lucy - Normally when we talk about light, we use it to describe light that our eyes can pick up, including all the colours in the rainbow. In reality, there is a much wider spectrum that we can't pick up with our eyes. This extends from very energetic sources like gamma rays, x - rays and UV light, and then through visible light. After that you move in a region of lower energy waves like the infra-red and radio waves.
Philippa - So infra-red light is just one part of the electromagnetic spectrum.
Julian - You could prove to yourself that it was light because when you use a TV remote you have to point it in the general direction of the TV. If you wanted to check that it was light, you could put a mirror facing the television and fire the remote away from the television. You could then use the mirror to reflect the signal back towards your TV.
Philippa - So we've got a code coming out of the remote control made from pulses of invisible light. If we can't see it, how does the TV see it?
Lucy - The TV picks up the signal by using something that's sensitive to light, or in other words, it uses the photoelectric effect. The light falls on the sensitive detector and electrons are knocked out of a piece of material, which causes a current to flow.
Philippa - Is this the same as in the solar panels of a calculator?
Lucy - Yes, it's exactly the same thing. It's a way of turning light into electricity.
Julian - That's rather a difficult thing to understand because it depends on the behaviour of a semiconductor. Pieces of metal are very good at conducting electricity and heat, while glass does not conduct heat or electricity at all. So a semiconductor is a material that will conduct electricity under some circumstances. They are used as the basic material for transistors, and they are also the basis of light sensors, which are called photodiodes. Some semiconductors exposed to certain frequencies of light will transmit a small current.
Philippa - How does that work?
Lucy - In the classical sense, people thought of light as a wave propagating along through space. They thought that the more light you shone onto a plate, the higher the kinetic energy the electrons should have. This isn't what we see. To change the energy of the electrons being knocked off, you need to change the colour (or frequency) of the light. The more blue the light is, the more energy the light has. In order to be able to understand the photoelectric effect, you can't think of light as a wave. You have to think about it as tiny packets of energy called photons. Blue light has photons of higher energy than the red light, so blue light would knock electrons off with more kinetic energy than a red light would. Einstein worked out how to use this effect, and it helped us to be able to apply the effect in the everyday world.
Philippa - The TV has received the light. What next?
Julian - What the TV does is to amplify this small current and creates enough of a signal so that it can tell whether it is a one or a zero. From that it can build up a series of instructions which it can respond to.
Philippa - How do those all-in-one remote controls work? How does it know when it should be working the TV, the hi-fi or the garage doors?
Julian - In that case, the devices have all agreed an international code. For example, the video has a special code that identifies itself, and therefore if the remote is talking to the video, it starts by saying that code so the video knows to listen and the garage door knows to take no notice.
Philippa - Thanks to Einstein's understanding of photons, I can spend the entire evening sitting on the sofa.
Lucy - Without Einstein you would have to get out of your chair and change the channel yourself!
- Giant Sea Spiders and How Antarctic Animals Cope With The Big Freeze
Giant Sea Spiders and How Antarctic Animals Cope With The Big Freeze
with Prof. Lloyd Peck, British Antarctic Survey
Lloyd - I'm a scientist who's interested in animals that live in extremely cold conditions. I work in Antarctica and look at some of the more unusual animals that live there in the sea, such as giant sea spiders that are larger than a dinner plate! I'm interested in their tolerance to the environment, and what the prospects are for these animals when the climate changes. I also like scuba diving under sea ice!
Chris - Have you got any evidence that things are already on the move?
Lloyd - There is a lot of evidence. The Antarctic Peninsula, which accounts for about 5% of the Antarctic continent, is possibly the fastest changing place on earth. The temperature has gone up by three degrees in 50 years. Most of Antarctica isn't changing, but on the peninsula we are seeing glaciers receding, ice shelves collapsing, plants growing where they never grew before, and the general ecology is changing. Fifty years is just a blink of an eye in geological time.
Chris - And is man causing this?
Lloyd - I think a lot of it is down to man. You can't discount some contribution from natural cycles and natural effects, but you just can't get away from the fact that man is changing the environment on earth.
Chris - Why is Antarctica such a special place?
Lloyd - Antarctica is different from most of the continents on earth as it's been isolated for 35 million years. This mean that the life in the seas has been isolated too. On top of that, Antarctica is one of the most seasonal places on the planet and has a very short summer season. In addition, the oceans are very stable between minus two and plus one degrees. It has been like this for millions of years, so you would expect the animals and plants that live there to be very very special. That's one of the reasons that I'm so interested in Antarctica because it's a special environment with special animals in it.
Chris - You'd think that the animals would be quite small because it's so cold.
Lloyd - If you look on the land, the animals are small. The biggest animals are 2 millimetre long mites! The reason life on land is so small is because the Antarctic terrestrial environment has only been about for a very short time and things have been pushed off by glaciations. In the sea, the environment has been around for a long time and the temperatures have been very stable. This has allowed animals to evolve to the environment very finely. What we find is that the environment puts limits on the size animals can grow. The limits are set by the amount of energy an animal can get in to use, and by the amount of oxygen in the water. As you can get more oxygen in the water the colder the water gets, the animals in Antarctica can get bigger. That's why we can get woodlice 5 inches long and sea gooseberries over half a metre long. We also have very large sea spiders.
Chris - What actually is a sea spider.
Lloyd - Scientifically, they're in the same major group of animals as terrestrial spiders and scorpions, but they live in the sea. In most places in the world, they are eight-legged like spiders on land. In Europe, the biggest ones are about 5 or 6 millimetres across. In Antarctica they have spread and formed many different sizes, including having 10 or 12 legs! However, they move very slowly and won't climb out of the ocean to attack you.
Chris - What do these animals do to stop themselves from freezing?
Lloyd - If you look at invertebrates such as sea spiders, anemones and starfish, they don't freeze because their body composition is the same salt concentration as the sea water around. So, they won't freeze as long as they stay away from the parts of the water that do freeze. Fish that live in the sea have slightly more dilute body concentration than the sea water around them. If their body temperature drops below about 0.6 degrees, they will freeze. In Antarctica, these fish have to have anti-freezes. In the early 1960s, the natural anti-freezes in fishes were discovered. Since then, companies have been trying to exploit them.
Chris - If you take these animals that are adapted to cold conditions and put them I warm water in a lab, do they die pretty quickly? For example, if sea temperatures are rising, is it pushing the margins for these guys?
Lloyd - One of the things concerning me most at the moment is if you warm up these Antarctic animals to plus 5 degrees, they will die in experiments. If you warm them up to 2 or 3 degrees, they lose the ability to do the things they need to live. Currently the top summer temperatures are about zero and plus one, so it doesn't need much of an increase to make it hard or impossible for these animals to feed properly or defend themselves against predators. They are therefore not very tolerant.
- Carbon Dioxide, Climate Change and The Role of Plants
Carbon Dioxide, Climate Change and The Role of Plants
with Howard Griffiths, Plant Sciences, Cambridge University
Howard - I'm interested in photosynthesis and the driving force for life on earth, which is how plants acquire carbon and potentially sequester carbon. This may be part of the system that might help maintain the balance of carbon going into the atmosphere.
Chris - Why is carbon so important?
Howard - We are changing the atmosphere. In the last 200 years, carbon dioxide (CO2) in the atmosphere has gone up by one third, and it's quite possible that plants have absorbed the remaining two thirds of the remaining carbon that we have emitted into the atmosphere.
Chris - A 30% increase is a huge amount.
Howard - It certainly is, and this is why we know there is the so-called greenhouse effect. These gases help to trap the heat within the earth's atmosphere and that's led to a 0.6 degree warming in the last 50 years. This is at a global level rather than just a regional level.
Chris - What else do you work on?
Howard - I also work on what I think is the most important enzyme in the world: rubisco. It's the basis for life on earth and has been around for 3800 million years. It's products through photosynthesis ultimately led to the products that drove the industrial revolution. I'm interested in how the enzyme is regulated under a whole host of modern conditions. I look at how plants might respond to climate change in the future and whether trees will continue to sequester carbon and bury it below ground.
Chris - If you are growing tomatoes on your greenhouse, you can make them grow better if you pump in extra carbon dioxide. Don't our activities here on earth translate into better growth for plants?
Howard - That's the theory, but in fact for natural vegetation, they are nutrient limited. Although we are seeing plants responding and they are continuing to sequester carbon, we won't see this rampant growth that you might expect from your greenhouse plants.
Chris - You said at the start that CO2 concentrations have gone up by 30%. What does this actually add up to, because if there isn't much out there to start with, you don't have to add much to get a 30% increase.
Howard - It's now going up at an exponential rate. At the moment, we have 0.038% of CO2 in the atmosphere. Back in 1800, it was somewhere in the region of 0.028%. It's projected to go on increasing to 0.05 or even 0.08% by the end of this century.
Chris - How much CO2 does the average person put out? How much do I account for as an average British citizen on an annual basis?
Howard - If you were to fly to the United States, each person on the flight would emit about half a tonne of carbon. Just heating your house every year, you're probably producing about 6 tonnes of carbon, and if you drive around in your car for about 12 000 miles per year, you're probably emitting about 3.5 tonnes of carbon.
Chris - So when people say 'let's plant a tree', that's not going to solve the problem.
Howard - Funnily enough, it could in principle. There's been lots of publicity about celebrity forests recently, including Joe Strummer having one on the Isle of Skye. About a hectare of oak woodland can sequester about 3.5 tonnes of carbon per year, which is what everyone on earth uses on average. However, there are 6 billion people on earth, so it's quite a tall order to sequester all that carbon. It is impracticable. We need to think about other ways of reducing carbon. The worse thing that could happen is the northern boreal region or peat lands start to release their carbon, making them sources instead of sinks. The World Bank has now set up a system of carbon credits so that countries such as Mozambique and Uganda can set aside areas of forest. Richer countries can then pay for them to retain those resources.
- How Carbon Dioxide Is Making The Ocean Acidic
How Carbon Dioxide Is Making The Ocean Acidic
with Prof. Harry Elderfield, Earth Sciences, Cambridge University
Harry - I'm also interested in carbon. I'm a chemist and work on what the climate was like in the past on different time scales. We can learn about what might happen in the future by understanding the natural variability in the past.
Chris - The oceans cover a massive amount of the earth's surface and apparently account for most of the carbon dioxide that is on the planet.
Harry - Not all of it. Some of it obviously stays in the atmosphere while a fair bit of it is on land. It is true that the oceans are a huge reservoir and about half of the carbon from fossil fuels ends up in the sea.
Chris - Carbon dioxide gives rise to an acid when you dissolve it in water. What are the consequences of essentially all this acid being dumped in the ocean?
Harry - This is the thing that people are beginning to think about. It makes the sea water slightly more acidic than normal and it is going to be a real problem. There is evidence from experiments that many of the marine organisms don't like it because their shells are calcified. This is when their shells are made from calcium carbonate, which is a mineral like a bone. Some of these organisms are going to be more at risk, especially corals, as the form of this mineral is more soluble than other organisms. This slightly acidic seawater will stop them calcifying. There is evidence in corals such as bleaching because they are moving to areas that are better for them to live in. We have to do something about it.
- Fusion: Alternative Energy For The Future ?
Fusion: Alternative Energy For The Future ?
with Chief Executive of UKAEA, Prof. Chris Llewelyn-Smith Chris - Nuclear power has had a bad press in the past, but people like you think that fusion might hold the key to cleaning up its act.
Chris L-S - Fusion powers the sun so we know it works. If we could master this on earth, it would provide essentially limitless, environmentally responsible sources of energy. We're tantalisingly close to mastering it in the sense that we have managed to create 16 megawatts of fusion power. We had to put in more than that amount of energy to achieve this, but we are convinced that if we built a reactor twice as big, we would be able to produce far more energy than we had to put in to clean up the gas.
Chris - Why is it cleaner or superior to existing fuel?
Chris L-S - The products of the fusion reaction are not radioactive. The heat created is taken out to heat water and turn turbines. Any radioactivity produced in the walls is short-lived and decays away with a half life of about 10 years. There is no problem of long term storage and there is nothing left for our great grandchildren.
Chris - What does a fusion reactor burn as its fuel?
Chris L-S - It burns heavy hydrogen and super heavy hydrogen. This comes from water and lithium respectively. We have to give it a go.
Chris - How long until this is likely to be ready?
Chris L-S - We want to build one the size of a power station, which should be ready to start in the next 10 years. Therefore, it should be built by the early 2020s.
Chris - How much are the costs likely to be?
Chris L-S - The costs of fusion power look reasonable. It's hard to predict the future, but it looks to be in the same range as existing sources of power but with no carbon dioxide or sulphur dioxide.
- If you had a stem cell transplant, would your DNA change?
If you had a stem cell transplant, would your DNA change?
A fantastic question! It's not just stem cells you need to consider, but indeed any type of organ transplant or tissue donation. Another person, unless they are your identical twin, will have DNA different from your own. The reason lung transplants or bone marrow transplants actually work is because you are substituting dodgy tissue for healthy tissue. At the same time, you are replacing a gene that has gone wrong by putting in a healthy copy of the gene. That means the DNA in the tissue you've replaced will be different. The rest of your body won't change. If you do a bone marrow stem cell transplant for someone with leukaemia, the cells that you will have inside your bone marrow will come from your donor. Therefore, they will also be genetically identical to the donor. This means that a man who receives a bone marrow transplant from a lady will have bone marrow cells that have two X chromosomes. Sometimes people can even see a change in their blood group.
- Have scientists drilled into Lake Vostok?
Have scientists drilled into Lake Vostok?
Lake Vostok is a very large lake underneath the main 2km-thick ice sheet of eastern Antarctica and has been isolated from surface for a half a million years. There has been a project to drill through the ice sheet down to Lake Vostok that's been running for quite a few years. They started drilling and got to about 50 metres above the lake itself and decided to stop. They weren't sure if there would be any life in the lake, and there was also the problem of infecting the lake with modern microbial material. It could therefore contaminate an undisturbed environment. People have been trying to invent a sterile drill to get around these problems. I don't know the exact date of going into the Lake.
- Why the delay in responding to climate change?
Why the delay in responding to climate change?
Like everything else, it's really difficult to convince people that things are really happening. There's also the problem of making the economics of these large issues aware to the public and convincing them that we need to take action. Just as we took action over CFCs and the ozone hole, we now need to address the issues regarding elevated CO2.
- What effect have the atomic tests that were carried out in the 1960s had on the environment?
What effect have the atomic tests that were carried out in the 1960s had on the environment?
They probably didn't have a great direct effect on our climate. Such explosions are actually small in comparison to something such as a volcanic eruption, which releases so much debris that they end in global cooling rather than global warming. What the explosions have done is provided a radioactive marker in the land and in plants.