Trying to understand Climate Change (I)

There is no doubt that climate change is becoming one of the most important issues on the news agenda, and rightly so: if there's one thing we can be sure about, it's that this is an issue that needs to be addressed. But, beyond that, I find it very hard to understand what's going on. What exactly is causing climate change? How exactly is our climate changing? And what should we, as individuals and as a global society, do about it?

There are a few reasons I think that make this such a complex topic. Firstly, there are numerous components to our climate system, and the components are notoriously 'chaotic' (i.e. if the model used to make predictions is just slightly inaccurate, the resulting predictions may be wildly inaccurate). As such, the exact details of the issue at hand tend to be vague and uncertain. Secondly, because the issue is not exactly clear, it's hard to know how to address it: should we attempt to resolve it, or is mitigation the most we can hope for? How much do we need to reduce our CO2 emissions by to be safe? And some questions are made even more complex by the political agendas surrounding them: Should we invest in renewables or is nuclear a better alternative? How much responsibility should lie with developing nations compared to developed nations?

What I'd like to do is start looking into these issues more, to gain a better understanding of what our best science tells us is going on. So I've started by looking at the papers from the IPCC (Intergovernmental Panel on Climate Change), who aim to provide a rigorous and balanced scientific view on climate change and its impacts. In particular, I've taken a look at their most up-to-date report, the Fifth Assessment report, in order to help me get a better understanding of the scientific consensus.

I've picked out a few claims from the report that I think set the landscape for how our best science views climate change. You'll see that claims have been usefully qualified by confidence and probabilistic measures:

• "Warning of the climate system is unequivocal...The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentration of greenhouse gases have increased."

• "It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century."

• "Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions."

• As a result of the changes in climate in the recent decades, with high confidence: a large fraction of terrestrial and freshwater species face increased extinction; and low-lying areas will increasingly experience adverse impacts such as submergence, coastal flooding, and coastal erosion. 

• In addition, also with high confidence, all aspects of food security are potentially affected by climate change; and climate change is expected to lead to increases in ill-health in many regions and especially in developing countries with low income, as compared to a baseline without climate change.

I'm sure none of this is a surprise to you, and it wasn't much of a surprise to me either. But, for me, seeing these claims in a well-reputed scientific report, rather than as second-hand claims in an article (or blog-post!) certainly helped give these claims more grounding.

And that comment, I think, touches upon another reason that makes climate change such a complex topic: it's so hard to know whether what you read and hear is true, or whether it has in some way been corrupted, either intentionally or inadvertently. Indeed, as suggested by George Monbiot's recent criticism of James Lovelock's latest book, even the most highly-respected sources may get their facts wrong.

So on that note, here are the links to the original documents of the IPCC's Fifth Assessment Report - or at least their Summary for Policy Makers - for you to take a look at yourself:

Part 1: The Physical Science Basis
Part 2: Impacts, Adaptation and Vulnerability
Part 3: Mitigation of Climate Change

And here is the link to the website: https://www.ipcc.ch/report/ar5/.

Next time, I'll be looking at the ideas of the fascinating and sparky James Lovelock so keep a look out.

A Look At Our World: Tree Bark

The bark of a tree has some wonderful textures to it: smooth, scaled, cracked, ridged, or some combination of these. There are generally two layers of bark, the outer layer and inner layer. Inside of these are the notable rings of wood that increase in number each season as the trunk grows to expand its girth. It is this growth that tends to cause the outer layer of bark to crack and peel away, giving it some of its distinct textures. Interestingly, it is not uncommon for the inner layer of bark to have the ability to photosynthesise, and if you scratch at the surface of a twig with your nail, you may expose a surface with a greenish tinge, indicative of the presence of chlorophyll, a requisite for photosynthesis.

In this very close-up photo of tree bark, you can see the top layer of outer bark peeling away to expose the inner bark. You can also see a greenish tinge, though whether this is the chlorophyll in the tree or perhaps some common tree lichen, I am not quite sure!

The Power of Nuclear Fusion

Our world is in something of a environmental crisis. It seems that our unquestioning use of the Earth's resources, combined with an exploding population, has resulted in changes that could be detrimental to our civilisation: water levels are increasing, natural food resources are running out and our main energy sources won't last a great deal longer.

Because of this, green, sustainable energy is imperative: green, so as to minimise our production of atmospheric carbon-dioxide levels, which is already well above 'safe' levels, according to climatologist Dr James Hansen; and sustainable so that it can meet the demands of an increasing population and their rising standards of living.

For me, all this makes the ITER project of immense interest. Involving 35 nations and costing 13 billion Euros, this large scale experiment aims to demonstrate the potential of nuclear fusion as a source for future commercial energy.

Nuclear fusion is the process that powers our Sun, enabling it to emit the light and heat energy that lights and warms our Earth. Current commercial nuclear power plants generate energy by a process called nuclear fission, which works by splitting a heavy atomic nucleus into two lighter ones. Nuclear fusion, on the other hand, combines two light atomic nuclei into a heavier one. If these processes are carried out with the right types of atoms, they can generate a huge amount of energy.

The fusion process can be carried out by fusing hydrogen nuclei into a helium nucleus. Hydrogen, found in seawater, is abundant on Earth, and, as such, we'd have enough fusion fuel to last millions of years. Furthermore, it produces no carbon dioxide during operation and no radioactive waste that puts so many off nuclear fission.

So why aren't we currently using fusion to generate commercial energy? Unlike fission, fusion requires extremely high temperatures. Creating these conditions and managing them safely is a challenge. Furthermore, producing these high temperatures requires a lot of energy, and although experimental groups have generated energy using fusion before, no experiment has been able to generate an overall surplus of energy.

The ITER machine, currently being built in France, aims to be the first experiment to achieve this. Designed to fuse hydrogen atoms in conditions ten times hotter than the core of the Sun, ITER hopes to generate ten times as much energy as is put in. The construction, which began in 2010, is scheduled to be completed in 2020, with fusion operation beginning in 2027. But, the technological challenges presented by this ambitious project are already resulting in delays, and even if ITER does achieve its goal, there is much more testing to be done before fusion energy can be generated for commercial use. Experts think it unlikely to be available for another 40, 50 or even 60 years.

There is a long way to go before this solution to our energy needs can become a reality, but the ITER project is paving the way.

Green Goodness. And a lot of sugar

Whilst deciding what to have for lunch in a local Pret a Manger a few weeks ago, I came across their 'Green Goodness Juice'. Packed with with Goodness, its only ingredients are Apple, Cucumber, Celery, Spinach, Lime, Ginger.

It definitely sounds good, but eyeing up the nutritional breakdown on the back gave me a bit of a shock. Each bottle contains an impressive 42.8 grams of sugar. To put this in perspective, this is the equivalent of more than ten teaspoons of sugar, between 50%-80% of an adult's guideline daily amount (depending on what recommendations you look at); and even their carrot cake slice, the item with the highest sugar content I could find on the menu, has less sugar at 36.2 grams.

I should point out a few caveats: clearly, the Green Goodness Juice has additional nutritional content that the Carrot Cake Slice does not; and the Carrot Cake Slice is a reasonably small portion (112g), whereas the Juice is reasonably large (400g). Nevertheless, these statistics do make me wonder how 'good' the 'Goodness Juice' really is, and whether the 'naturalness' of the sugars make its high sugar content admissible.

There are different types of sugars, the main categories being 'glucose', 'fructose' and 'sucrose'. Sucrose is commonly known as table sugar, and is made up of both glucose and fructose in equal parts. Since sucrose is immediately broken down into its component parts on ingestion, the body only really distinguishes between glucose and fructose.

Glucose can be used for energy by all the cells in our bodies, and is circulated around the body to this end. Any glucose that is not needed by the body is stored for later use, eventually as fat. However, fructose can only be used for energy by a few types of cells, liver cells being the most significant. Fructose is also stored as fat, if not used. There are numerous ongoing debates as to which of these sugars is better or worse. Many arguments point towards fructose as being the worse of the two, due to the by-products created in liver upon metabolism, and its inability to dull our feeling of hunger. However, these accusations have not been shown conclusively, and there are various other arguments in favour of fructose.

So back to the natural sugars in out Green Goodness Juice. Natural sugars are made of both glucose and fructose, though proportions vary depending on the product. Apples and pears have a particularly high fructose content, but many other fruit and vegetables, for example, pineapple, peaches and carrots have an approximately equal ratio. As mentioned, table sugar is also made up of glucose and fructose in equal ratio. So, it seems, there is often little difference between natural and added sugars.

It should be emphasised that this is not to say that there is little difference between eating fruit and eating cake. Not only does fruit offer nutrients that the cake will not, but whole fruit will most likely have a lot less sugar per serving, and the fibre in whole fruit will slow the body's absorption of the sugar, reducing the negative impact it might have on you. Fruit juice, on the other hand, may be packed full of nutrients, but will contain more sugar per serving and less fibre.

So where does all this leave our Green Goodness Juice? Well, it certainly has nutrients aplenty, unlike the Carrot Cake slice. But it also has a whole lot of sugar, which is not redeemed in virtue of it being natural, and nor does it boast the fibre that absolves whole fruit. I guess whether it is 'good' or not really depends on how much other sugar you'll be eating throughout your day: as my grandmother quips, 'Everything in moderation'.

How I'll be spending New Year's Day

New Year's Eve is here, and for many of us, that means a night of heavy alcohol consumption, leaving behind a torturous headache by which to make the most of the first day of the new year. So, in festive spirit, I'm taking a quick look at why we get some of the symptoms that constitute a hangover at all.

Like many ailments, the hangover certainly has its own set of characteristic symptoms: headaches, dizziness, nausea, fatigue and thirst are amongst the most common. Whereas the causes for the first three are less clear, the last two of these symptoms have the fairly straightforward explanations.

We feel thirsty simply because we are dehydrated. Alcohol is a diuretic, making us need the toilet more. In fact, for every standard unit (UK) of alcohol drunk, urine excretion increases by around 80ml. Note that this means that if I drink a pint of beer, I will not only lose the amount of liquid that I would if I were to drink the equivalent of water, but I would lose more, thanks to the alcohol - so the water content in the beer does not replace the water that is lost due to the alcohol content in the beer.

Similarly, we feel fatigue simply because we lack proper sleep. Though alcohol can put us quickly into a deep sleep once we hit the pillow, it significantly disrupts sleep later in the night. Moreover, it cuts the amount of time we spend in REM sleep, important for the proper functioning of our brains. Also, heavy drinking is likely to mean you'll need to wake up a couple of times in the night needing the loo, which certainly doesn't facilitate effective sleep. All this leaves us rather tired.

So what about the headaches, dizziness and nausea? These symptoms are in part due to dehydration and lack of sleep, but beyond this, explanations become much more hazy. These other symptoms may also be due the side effects our bodies experience in clearing up the mess we've made: our bodies break alcohol down into acetate, so that it can be removed from the body; but it is thought that the alcohol may be broken down into the chemical 'acetaldehyde' first, a chemical that is much more toxic than alcohol, thus worsening hangover symptoms. More commonly quoted hangover culprits are 'congeners', since they tend to be found in those darker alcoholic drinks that reportedly lead to worse hangovers. These are just a few of the speculations amongst researchers and the media, but, overall, there seem to be no conclusive explanations here.

So we have some clear answers and some other vague speculations. What we do know is that I, along with many others around the world, shall be facing a splitting headache, a nauseous disposition and the acrid taste of wine at the back of my throat on New Year's Day. Lovely.

Happy New Year!

The lives of honey bees

Ever since a bee-enthusiast told me a few facts about the lives of honey bees, I've wanted to write about them. If it made sense to describe the behaviour of the honey bee using terms from human sociology, I think something along the lines of 'fascist matriarchy' might be suitable: the queen bee seems to yield a rather authoritarian power, and the males seem to get a rather rough deal.

There are three 'castes' of honey bees in a hive: the queen bee, the worker bee and the drone.

The queen bee: there is only one queen bee in a hive. When she hatches, she will go and kill off all other unhatched or hatched queens, so assuming her right to the throne. Soon after birth, she goes on her one and only ever mating flight, mating with multiple male bees. Her primary purpose in the hive is the lay eggs.

The worker bee: worker bees are all female. They lack the ability to reproduce themselves, and devote their lives to foraging and storing nectar and pollen, cleaning the hive, feeding the male bees and the unhatched eggs, and servicing the queen with all her needs.

The drone: drone bees are the male bees. Their primary purpose is to mate with the queen bee. However, those that are successful unluckily die in the very act. Male bees are the first to be expelled from the hive when winters are harsh and honey reserves are low, left to starve without food.

So why have honey bees evolved to behave in this way that I rather ridiculously call 'fascist matriarchy'? Thanks to evolution, this behaviour must be to their benefit, but I found hard at first to see how.

In the animal kingdom, this type of behaviour is known as 'eusociality'. Eusociality is different to other social systems in the animal kingdom because, in eusocial animals, different castes of the animal perform functions that other castes of the animal cannot perform. Because of this, a single honey bee, whether it be a queen, worker or drone, cannot survive for very long by itself; it needs the rest of its hive to live. Because it is the hive rather than individual that is self-sufficient, such eusocial groups are often referred to as 'super-organisms'.

When considered as a super-organism, the behaviour of the honey bee makes much more sense. Just like organs in a self-sufficient organism, the bees each have different functions in the running of their self-sufficient hive; so, for example, only one female in the whole hive need have reproductive organs, because she reproduces on behalf of the whole hive. Furthermore, since bees do not mate in winter, the drones are of no use to the hive at this time, and are thus expelled in favour of the workers and the queen, needed to care for the hive and produce its next generation.

At the level of the individual, their lives seem starkly different to ours, but at the level of the super-organism, this difference is less stark. I think they're a great example of how varied the workings of the natural world can be, yet how life ultimately works in very similar ways.

How we might make physics lessons a bit more exciting

A lot of people are put off by physics - it can come across as dry and tedious, where the content is too abstract to be interesting and the calculations involve too many numbers. I am somewhat of a physics-lover, and even I found physics at school quite a chore.

From the little I know about what it is to teach, I have no doubt that the national curriculum is very stringent, allowing little space in which teachers might inject excitement. Even if there was the space, teachers tend to be so over-worked that it's hard to see where they could find the time. However, there is something I think that could make a difference; something that teachers could do that would attract students' interest, creating a foundation upon which learning physics could be more engaging.

Students listen when they see things they don't expect, whether it be their teachers put on a ridiculous Christmas pantomine or something less excusable such as their peers creating class mayhem. Physics has the advantage of lending itself to demonstrations with impressive, and often unexpected, results. So perhaps physics lessons could involve a few more things like that.

I was watching a QI repeat quite recently and Stephen Fry was describing a rather fantastic demonstration he was privy to in one of his school science lessons. His teacher brought into his class a single, red rose. Rather dramatically, the teacher whipped the rose into a bucket of liquid nitrogen and then flung it against the wooden desk, causing it to shatter, like glass, into a hundred pieces. Watching a rose shatter on impact is definitely something you wouldn't expect to see, and would have definitely got my attention in a lesson. After a short discussion on the exciting properties of liquid nitrogen (nitrogen - liquid? etc.), perhaps this demonstration could be an introduction to a GCSE lesson in cooling and heating.

I know that there are so many reasons why this, in general, couldn't be a solution to the lack of interest in physics lessons. Obstacles show up in their plenty, from the limits of technical support available to teachers to having a class disciplined enough to perform demonstrations of this kind. But the point here is that physics lends itself to eye-widening phenomena, and enabling students to realise this might make them a bit more excited about it.