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## An ecosystem under strain

A few weeks ago, as I metioned in a previous blog, I was on a panel discussing the science fiction film Silent Running. Also on the panel was Dr. Rob Thomas of Cardiff University’s School of Biosciences. Rob has kindly given me permission to reproduce here his comments on some of the issues raised in the film.

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### Silent Running: an ecologist’s perspective

The world is changing, and has already changed. Global temperatures are rising, weather patterns are altering and evidence for these changes being driven by human changes to the composition of the Earth’s atmosphere has (in the view of most mainstream scientists) become compelling.

It is now also becoming clear that the rapid changes to the climate over recent decades have been associated with major changes to the Earth’s ecosystems, species and individual organisms. For example, research at Cardiff School of Biosciences is mapping many of these changes, including case studies as diverse as the impacts of climate change on long-distance migratory birds, disease transmission, interspecific interactions and the structure of ecological communities in rivers, soil and tropical forests. Of course, climate change is not the only ecological issue; the combination of climate change with other human impacts on the environment, such as habitat destruction, pollution and unsustainable harvesting of wildlife (e.g. overfishing) has been described as a “deadly anthropogenic cocktail” which threatens the long-term viability of Earth’s ecosystems.

The film “Silent Running” is based on the premise that the Earth has already suffered an extreme environmental catastrophe, leading to Earth’s few remaining fragments of forest vegetation being evacuated to a spaceship for safekeeping. This apocalyptic scenario is of course deliberately extreme for cinematic effect, to get us thinking how we would behave in such an unprecedented situation. Yet there is a sense in which we can see Planet Earth itself as a relatively small and vulnerable “spaceship” travelling through the universe, whose fragile and precious ecosystems are the only ones we have left. Indeed, this is one of the great insights obtained by the first astronauts looking down on our home planet from space, seeing Earth for the first time as a tiny yet precious habitable outpost in the vastness of space. The question is; what on Earth can we do to protect it and ensure the survival of its biodiversity, including humanity?

Environmental protection is not straightforward -it is clear that human societies, governments and nation-states consistently fail to act for the good of the planet. Examples of ecologically harmful political and economic structures are innumerable; the Common Fisheries Policy, the Common Agricultural Policy, the abortive Copenhagan climate summit are just a few recent examples, but major human impacts on the environment can be traced back into deep pre-history. These much older examples include the extinctions of native megafauna that coincided with the arrival and spread of humans in Australia and the Americas; the complete deforestation of Polynesian Islands, and the unwitting or deliberate introduction of rats, pigs, goats and rabbits to fragile island ecosystems across the globe.

Case studies of this deadly anthropogenic cocktail of climate change and other human impacts should alarm us; not just because they show us that the biological word is indeed changing rapidly, but because they also highlight how little we currently know about the underlying mechanisms by which climate influences ecosystems, or what we could do to minimise -or even just predict- these ecological impacts. For example, we can describe how ecosystems have responded to climate variability within the historic range, but this does not necessarily let us predict how ecosystems would respond to more substantial climate change in the future. This is because responses of individual species may be non-linear, or community composition and ecosystem function may alter as individual species become extinct. Any or all of these are possibilities, or other, as yet unknown, effects may become apparent; so much is unknown that ecological prediction beyond the recent range of climate conditions remains largely guesswork.

Climate models indicate that even if emissions of greenhouse gases stabilised immediately, the increases in the insulating properties of the atmosphere that have already occurred have committed us to a substantial amount of future warming. Since it is clear that climate change leads to ecological change, substantial ecological changes appear inevitable too. It seems that rather than hoping to prevent climate change, we can only hope to minimise warming as far as reductions in emissions can allow. This means that we need to be pragmatic and focus on how to manage ecological change, for the inherent value of the ecosystems themselves, as well as for the long-term benefit of humanity.

Suggested solutions to the environmental crisis includes “technological fixes” for specific problems, such as “carbon-free” energy from technologies such as nuclear fusion, or by seeding the oceans with iron filings to induce phytoplankton blooms that would act as carbon “sinks”. However, our pragmatism needs to encompass the distinct possibility that humans will accidentally fail to develop workable technologies to achieve these “fixes”, or develop them too late to prevent ecosystem collapse.
This pragmatism also requires a frank appreciation of how human societies, as well as individual humans, behave; our motives as well as our constraints and limitations. For example, we humans are not good at evaluating long-term risk, and we tend to favour our own self-interest, especially over the interests of people we do not know. Similarly, our political structures influence the means by which change is –or is not- possible; governments take a short-term view because they need to be re-elected every 4-5 years, politicians are answerable to their local constituents, or at least to their own nation-state, rather than the global community. Ecologists and conservationists need to acknowledge these human realities (frailties?!) if we are to see meaningful protection of the environment.

It is not enough to sigh and wish that humans would be more altruistic –we need to examine the circumstances in which humans have incentives to behave altruistically. The type of incentive may vary; money certainly motivates governments, so our arguments need to be economic as well as moral. Family ties certainly motivate individuals, so our arguments need to encompass our environmental legacy to our own children and grandchildren as well as to the human family as a whole.

The future for Spaceship Earth is uncertain. It does have a future of course, but whether that future includes a healthy environment for humans and for the current diversity of other species, is now largely up to our own generation –in other words, you and me. The responsibility is mind-boggling, and tempting to deny, but there seems no more important issue that the scientific community can address. And despite everything that I have written above, I believe there is room for optimism. Nature is, by very definition, adaptable. And in that sense, nature is resilient. So too is humanity, whose human frailties go hand in hand with traits such as intelligence, morality, and the ability to plan strategically for the future. Climate change may well precipitate the greatest ecological, societal and moral challenges that our species has faced, yet the scientific challenges that lie ahead are exciting, vital and I for one want to be involved!

Dr. Rob Thomas

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## The ups and downs

On Saturday (19th) I, and several other Penarth & Dinas Runners club members, drove a couple of hours up to the Elan Valley in mid-Wales to compete in the Elan Valley 10 mile race. The previous Sunday (13th), I had run a 10k race in Bute Park in Cardiff, and had got (back) under 45 minutes, my target for 2011. The Elan Valley race was a different story.

Elan Valley is home to a series of reservoirs which were built in the 1893-1904 period. The reservoirs are Craig Goch, Pen-y-Garreg, Garreg Ddu and Caban Coch. Claerwen reservoir was added in 1946-1952.

Elan Valley reservoirs

The start of the race was next to Caban Coch reservoir, about 10 minutes walk from the visitor centre. This is a photograph my 13-year old daughter took with my iPhone near the start of the race. As you can see, the autumn colours were beautiful, making this one of the most scenic races I have done.

Caban Coch reservoir, Elan Valley

There were about 120 or so runners doing the race, and as I looked around at the start I could see there were very few younger (under 30) runners. This is usually a sign that the course is going to be tough, and in fact our Club captain Clem and his wife Janice had warned us of a nasty hill at 2 miles. We had a good turnout from Penarth & Dinas, in addition to myself there was Paul W, Paul F, Malcolm, Yvonne, Sara, Clem and Michelle. Steve H and Janice came up too to support us (shout at us).

The race started at 1pm, with the mayor of Rhayader setting us off on our way. The first mile was downhill, and when I checked my time at the first mile marker and saw it reading 6 minutes 45 seconds, I told myself to slow down! The course was then flat for the best part of a mile, but just approaching the two mile marker a local (who looked like a farmer) told those of us bothering to listen that a “short, sharp hill” was approaching. He was right about it being a hill, and it was sharp in places, but there was nothing short about it. It carried on for a good mile, with numerous false “peaks” where one thought one had reached the end of it. From the top of that (never-ending) hill through to the end the course was undulating, with hardly any flat stretches.

The route of the Elan Valley 10 mile race

This was the 3rd ten mile race I have done this year, with my previous best being the 2nd one at Brecon, where I did 1 hour 21 minutes 13 seconds. I was aiming for a time of 1 hour 20 minutes, and went through halfway in 38 minutes 40 seconds feeling fine. But, after mile 6, my lack of distance runs of late took their toll. I have concentrated my training since the Swansea Bay 10k on speed work to get my 10k time down, and have not done many runs longer than 6-7 miles. From 6 miles onwards my legs turned to lead, and it seemed everyone who was behind me started going past, including Paul F from our Club.

I ran with Paul for about half a mile, but could not keep up with him as my legs tired more and more. By 8 miles I knew I was going to miss my target time, and in the last mile (which was slightly downhill), I could only muster a time of 8 minutes 3 seconds, pretty pathetic for the last mile of a race, and a sure sign of how tired my legs were. I finished in 1 hour 21 minutes 53 seconds, nearly 2 minutes outside my target time, and a terrible second half to the race after going through the first 5 miles well under my target time.

I was very disappointed to miss my target time, but did feel a little better when other members of the Club who had done the Brecon 10 mile race told me how much slower they were in this race. I was only 40 seconds slower, several who had done the Brecon 10 were 2 or 3 minutes slower. Also, it was good to cheer in the (few) Club members who came in after me.

After the race, we all retired to the visitor centre for the prize giving. I’m delighted to say that our Club chairman Clem won the male 50-60 category, with an amazing time of just over 1 hour 5 minutes. Here he is receiving his prize.

Clem receiving his 50-60 category prize

So, the previous weekend I do my season’s best for 10k, this weekend I was disappointed to not beat 1 hour 20 minutes for a 10 mile race. The ups and downs of running. But I, and all the other Club members who ran this race, need to remind ourselves just how tough a course it was. We should be pleased with ourselves we actually competed in it and completed it!

Our next Club championshp race is this Sunday, the Drovers run, an “off road odyssey” which I am sure will be equally as challenging at the Elan Valley 10.

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## Song for whoever

I have a very busy day today, so I thought I would just do a quick post with this video of one of my favourite songs by The Beautiful South. This song, “Song For Whoever” was a hit for them in 1989, and features many of their trademarks; clever lyrics and beautiful harmonies. Enjoy!

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## Galilean Relativity

Relativity has been in the news quite a bit recently with the detection of neutrinos apparently travelling faster than the speed of light. Although most people don’t know the details of Einstein’s theory of Relativity, many are aware of the “cosmic speed limit” predicted in it, and also the most famous equation in physics which came from his theory – $E=mc^{2}$.

Many people, however, are unaware that the idea of relativity had been around long before Einstein. In fact, we can trace the idea of relativity back to Galileo. Galileo was one of the first scientists to do experiments on the motions of bodies (what we would now call mechanics), and was also one of the first scientists to use “thought experiments” to make scientific arguments.

Galileo

Galileo started thinking about whether mechanical experiments would behave differently if one were in motion or at rest. For example, if a ship is anchored in the port and one were to drop a stone from the top of the mast, we all know that it would strike the deck at the bottom of the mast, i.e. vertically below the place from where it was dropped (as long as we were careful not to give it any sideways motion). This is, of course, a pretty obvious statement.

But, what would happen if the ship were in motion? Let us suppose the ship is sailing at 5 metres per second $(5m/s)$ in some direction on a perfectly smooth lake. If someone were now to drop a stone from the mast, surely it would fall behind the mast because the ship has moved forwards whilst the stone was dropping. If the stone were to take 1 second to drop to the deck, surely the stone would land 5 metres behind the bottom of the mast, rather than at the bottom, because the ship has moved 5 metres forwards in that 1 second.

NO, Galileo argued, this would not be the case. He argued that it would hit the deck at the bottom of the mast, just as in the case when the ship is not moving. If you think about it carefully you can see why.

When the person drops the stone from the mast, they are moving forwards with the ship. So the stone is actually given a forwards motion as it is dropped, and it is this forwards motion which leads it to land at the bottom of the mast, not behind it. As the ship moves forwards at $5 m/s$, so does the stone. By performing this simple mechanical experiment one would not be able to tell whether the ship were anchored in the port, or moving on a smooth lake.

If the person at the port were able to see the motion of the stone against some sort of background, he would see the stone move in a parabola, which is exactly the motion a falling object which is also given some sideways velocity has. But, at every point of its travel down towards the deck, it will be next to the mast, as this is moving forwards as the stone falls.

Galileo then went on to generalise this specific thought experiment to say that there was no mechanical experiment that one could perform which would be able to tell the difference between being at rest or moving with a constant velocity (that is, with no acceleration). This principle is know as Galilean relativity, and we define a set of equations known as the Galilean transforms which allow us to switch between what we would see in two frames of reference, for example what someone standing on the shore would measure and what someone on a moving ship would measure.

If the ship is moving with a constant velocity $v$ then in time $t$ it will move a distance $v t$ (distance = velocity x time). To make it easier for ourselves we will set up the $x,y,z$ axes so that the ship is moving only along our $x-axis$. If we refer to the position and time of any event in the person on the shore’s frame of reference as $(x,y,z,t)$ and those in the frame of reference of someone on the ship as $(x^{\prime},y^{\prime},z^{\prime},t^{\prime})$ then the equations which relate the two (known as the Galilean transforms) are:

$\begin{array}{lcl} x^{\prime} & = & x + vt \\ y^{\prime} & = & y \\ z^{\prime} & = & z \\ t^{\prime} & = & t \end{array}$

What these equations mean is that the only variable which is different in the two frames of reference is the x-displacement. The y and z-displacements are unaltered (as the ship is only moving in the x-direction), and time is the same for the two frames of reference. Let us look at how the x-displacement is transformed in going from one frame of reference to the other.

Suppose the ship is moving in the positive x-direction at $5 m/s$. We want to measure the position of an object which is on the deck of the ship, let’s say the mast, as time goes by. For the person on the ship, it’s position is say, $15m$ in front of the stern of the ship. This is clearly not going to change with time, the mast does not move relative to the ship! So, we shall call this $x$.

For the person on the shore, the position of the mast is going to change as the ship sails away from him. So if the ship is sailing away at $5 m/s$ and the mast is initially $15m$ away from the person on the shore, then after $1 second$ it will be $15+(5 \times 1)=15+5=20m$ away. This is the x-position $x^{\prime}$, the x-position for the person in the other frame of reference, as given by the Galilean transformation equations above.

You can get this straight from using the equation $x^{\prime} = x + v t = 15 + (5)(1) = 20m$

The Galilean transforms are mathematically very simple, and conceptually simple too. As I will discuss in a future blog, the idea of performing experiments to determine between a state of rest or uniform motion, which Galileo argued could not be done, haunted scientists for centuries. In the 19th Century, with the development of electrodynamics (the study of the electricity and magnetism of moving bodies), physicists thought they could devise experiments to distinguish one’s state of uniform motion. They were wrong in thinking this, and it led to Einstein overthrowing the whole ideas of absolute time and absolute space in his Special Theory of Relativity.

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## The state of the Union

The state of the Rugby Football Union, the governing body of English rugby, is not good. Thankfully for the Welsh, the state of the Welsh Rugby Union is very good, so I am not going to lose too much sleep over the state of the game in England. In fact, I look forward to, hopefully, Wales giving England a good hammering at Twickenham in the 2012 Six Nations game on the 25th of February.

The RFU and WRU

Yesterday (Wednesday 16/11/2011), Martin Johnson resigned as coach of the England national rugby team.

Martin Johnson resigns as England coach

Earlier in the week, Shaun Edwards committed to another 4 years as defence coach for Wales.

Shaun Edwards commits to another 4 years with Wales

Shaun Edwards is, ironically, a very proud Englishman, but he clearly feels he will be better treated by the WRU than the RFU. Apparently, four years ago, just before he signed with the WRU to be Wales’ defence coach, the RFU tried to sign him. But, according to what I heard on BBC Radio 5 this week, the RFU wanted him to agree to all kinds of conditions, including giving up working with London Wasps. The WRU, very wisely, were far more flexible, and allowed him to continue coaching Wasps these past 4 years. Edwards has now left Wasps, but the WRU are arranging for him to work with various clubs and regions in Wales in addition to his duties with the National team.

The difference in the state of the two rugby unions could not be greater. The Rugby Football Union seems to be in a state of turmoil, with a story emerging yesterday that Graham Rowntree is set to leave the RFU and, maybe, join either the WRU or the Scottish Rugby Union.

A few of the stories in today's Telegraph about the RFU

Meanwhile, the Welsh Rugby Union are benefiting from a strong Chief Executive in Roger Lewis, and a coach with over a decade of experience at the top level in Warren Gatland. Maybe the RFU can learn a thing or two from the WRU about how to get the management of the game right.

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## A moveable feast

Last week, the 9th of November 2011, marked the end of Eid al-Adha, the Muslim festival to commemorate Abraham’s willingness to sacrifice his only son Isaac to God. Eid al-Adha started on Sunday the 6th of November (or Monday the 7th, depending on where you are) and ended on the 9th (or 10th) of November in 2011. But, next year it will start on Friday the 26th of October, and last year (2010) it started on the 16th of November. Why does it move?

It all has to do with the Moon. For the Muslim calendar, which is based on the Moon, Eid al-Adha is celebrated on the 10th day of the 12th month, so on the 10th day of the month of Dhu al-Hijja. There are 12 months in the Muslim calendar, and each month lasts from one new Moon to the next new Moon.

A waning gibbous Moon

I got this quote from here

Regional customs or moon sightings may cause a variation of the date for Islamic holidays, which begin at sundown the day before the date specified for the holiday. The Islamic calendar is lunar and the days begin at sunset, so there may be one-day error depending on when the New Moon is first seen.

Most societies initially created calendars based on the Moon. If you think about it, there are only three natural cycles, apart from the daily one of day and night. These are

• the waxing and waning of the Moon
• the time it takes for the stars to appear in the same part of the sky at e.g. sunrise.
• the solar cycle, e.g. the time between successive longest days of the year.

Of these 3, the cycle of the Moon is by far the most obvious and easiest to observe, and it is why most early civilisations based their calendars on the Moon. Today, most calendars are either Solar (based on what the Sun is doing), or Lunisolar, a combination of Lunar and Solar calendars. Examples of lunisolar calendars are the Jewish calendar, the Chinese calendar, the Hindu calendar and even parts of the Christian calendar, such as the date of Easter [which is determined by a combination of what the Sun and the Moon are doing]. Any festivals which are based on a Lunisolar calendar will move from year to year, but back and forth rather than just getting earlier each year.

The Moon actually takes 27.32 days to complete a $360 ^{\circ}$ passage around the Earth. This is known as the sidereal period of the Moon, the word sidereal deriving from the Latin word “sidus” meaning “star“. So the sidereal month is the completion of an orbit with relation to the “fixed” stars [so, if you were in a space ship looking down on the Moon moving around the Earth, with the distant stars in the background to provide a reference, you would see the Moon move $360^{\circ}$ in a sidereal month].

However, this is not the time between one new Moon and the next, or one full Moon and the next. For a second new Moon to occur, the Moon has to travel a little further than $360^{\circ}$ in its orbit. This is because, in the time between the previous new Moon and this one, the Earth has moved around the Sun, and so the Moon has to travel a little further than $360^{\circ}$ to produce a 2nd new Moon.

The difference between a sidereal Month and a synodic Month

This takes 29.53 days, and is called the Synodic period of the Moon. [Note: due to variations in the Earth-Moon system, and the fact that the Earth varies its speed of orbit about the Sun during the course of the year, the synodic period varies between 29.18 and 29.93 days. 29.53 is the average.]

There are nearly exactly 365.25 days in a year [I will come back to discuss the measurement of what a “year” is in a future blog], so if you divide $\frac{365.25}{29.53}$ you get $12.37$, which is not exactly 12, so a 12-month calendar based on the Moon will not fit into a year without some days being left over. The civil calendar in all(?) countries is the Gregorian calendar, which keeps the Sun doing the same thing on the same day each year (i.e. it is a solar calendar). The number of extra days between a 12-month Lunar calendar and a year is $0.37 \times 29.53 = 10.89$, so nearly 11 days. In a 12-month Lunar calendar, the same day in the same month will be approximately 10-11 days earlier each year.

This is why Eid al-Adha started 10 days later in 2010 than it did this year, 2011, and why Easter will not be on the same day in 2012 and it was in 2011, and why the Chinese new year will not be on the same date in 2012 as it was in 2011, or Diwali, or Hanukkah.

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## The birthplace of modern astrophysics

Last Thursday (10th of November) I gave a talk to Swansea Astronomical Society. This is the 3rd or 4th time I have talked to them, and I was asked by Dr. Steve Wainwright to talk about the early history of the Universty of Chicago‘s Yerkes Observatory.

The great 40-inch refractor at Yerkes Observatory

I worked at Yerkes from 1995 to 2001, during my time there as a post-doctoral researcher I worked with Professor Al Harper on Airborne astronomy, initially on the Kuiper Airborne Observatory. In 1997 I started working on the HAWC far-infrared instrument for the Stratospheric Observatory For Infrared Astronomy (SOFIA). I feel very privileged to have worked at such an amazing place, so steeped in the history and development of 20th Century astrophysics.

Yerkes Observatory, which was founded by the University of Chicago, was home to the World’s largest telescope when it opened in 1897. This is the famous 40-inch refractor, which is still today the largest refracting (lens) telescope in the World. The Observatory gets its name from Charles Tyson Yerkes, the man who paid for the Observatory and the telescope. Its first Director was George Ellery Hale, a remarkable man who went on to establish Mount Wilson Observatory. I am giving a talk about Hale in a few months, so will write a longer blog about him then.

George Ellery Hale as a young man

Hale left Yerkes in 1903 to try to set up Mount Wilson Observatory. Initially he wanted the University of Chicago to establish it as a remote observing station, but they refused. So, he resigned his position and struck out on his own. Mount Wilson became the premier observing site in the World for the best part of 50 years, being home to the 60-inch and then the 100-inch telescopes. It was the 100-inch which Edwin Hubble (who did his PhD at Yerkes in 1919) used to show in 1923 that the Andromeda Nebula was external to our Milky Way galaxy, and in 1929 that the Universe was expanding.

My talk was on the early history of Yerkes, from 1891 to 1903. I stopped at 1903 as this is when Hale left to establish Mount Wilson. I chart the appointment of Hale as Associate Professor of Astro-physics at the University of Chicago by its first President William Rainey Harper, the meetings they had with Yerkes to persuade him to fund the building of the Observatory and its massive telescope, and the trials and tribulations in bringing the dream to fruition.

Here is the first few minutes of my talk – filmed by my daughter Esyllt.

Here is a link to a PDF file of the slides I presented. There are 46 slides in the presentation, but many of them are just photographs from the Observatory’s early days.

I will also try and put them up as a slideshow, but so far I have not had much success in getting this to work on my blog.

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