Beyond Land Use Change

There is a growing need to address climate forced changes to the land cover, as well as looking at land use change.

Our paper comparing Climate Induced Land Cover Change (CILCC) to LULCC (Land Use Land Cover Change) in the Land Use special issue in Global Biogeochemical Cycles compares the changes in land cover from the changing climate (as carbon dioxide increases) and from land use change (human land requirements). We found that despite LULCC being a main research topic for terrestrial climate scientists, actually the neglected topic of CILCC was much more important in terms of land area affected and carbon emitted. We suggested that if how much research is done on a topic is influenced by how much affect it has on the climate, that we should look at CILCC more than we do LULCC. At present, LULCC is a much more popular topic than CILCC, so this is a call to arms.

That’s just one paper, but there is a gathering zeitgeist about this subject. In the same special issue, Schneck et al. look at how anthropogenic LCC (LULCC) can be offset by natural land cover change (aka CILCC) on the millennial scale. Again, they show that climate forced changes to vegetation are important.

Earlier in the year, Ahlstrom et al published a paper in Environmental Research Letters showing that dynamic vegetation (aka CILCC) is a significant part of the terrestrial carbon cycle.

Then a couple of weeks ago, Almut Arneth had an opinion piece in Nature highlighting the complexities of the patterns of land use that emerge from human and climate drivers and calling for better accounting for land cover change in modelling.

The terminology for discussing this isn’t quite ‘set’, so it’s more challenging to see how these papers are connected. The use of the term ‘natural’ and ‘anthropogenic’ for CILCC and LULCC is problematic since it infers that the climate forced changes are natural, when in fact they are forced by anthropogenic climate change. I got argued down on anthropogenic too, as it infers that the other isn’t anthropogenic. I like the simplicity of natural vs anthropogenic and completely understand why others have used it. But in the end, I created the term CILCC because it fitted so nicely with LULCC (which has become a standard term).

Whatever you’re going to call it (obviously I’m in favour of CILCC), this is topic that we can’t afford to ignore any longer.

CO2 removal – feasibility questions

Does BECCS really cut it when you’re aiming to limit climate change to 2 degrees, or even just 1.5 degrees? In Nature, Phil Williamson argues the answer is “no”, and uses work by Andy Wiltshire and myself on the Planetary limits to BECCS Negative Emissions to show why.

The future is unknown for the effect of BECCS

BECCS is BioEnergy with Carbon Capture and Storage, and is included in many projections of future climate change that stay relatively low, not just those which aim to remain under 2 degrees warming.

Williamson highlights work Andy and I did, which is freely available to download from the AVOID project website, which shows that when you include the CO2 released by the land-use change, the net CO2 impact of BECCS begins to look rather different. In fact, in its worst case scenario, it can even result in more carbon being released into the atmosphere than is sequestered.

It all depends on the details of when and where the deforestation for cropland occurs, and how long the land is used for bioenergy crops. In essence, the longer land is used for bioenergy crops, the more likely it is the ‘carbon debt’ from the deforestation can be ‘paid back’. In the case of ‘abandoned agricultural land’, there is no debt to be paid – it was already cropland. But in a scenario where forest is removed to make way for BECCS, there is a considerable carbon debt to be paid back, before the BECCS actually makes a positive contribution to mitigating climate change.

However, recent work published in Science shows the real-world effect of what models have always shown: the non-carbon effects also matter. So where the figure above shows carbon emissions from large areas of forest converted to cropland and no agricultural productivity growth, adding in the non-carbon effects changes the story slightly. Because of more than half a degree of cooling from albedo effects, that scenario actually gives a small net cooling, if you’re only considering those land conversions as food crops. If they were BECCS, then probably the cooling would be even larger.

Now, I’m certainly not advocating chopping all the trees in the world down to grow BECCS and limit climate change. The biodiversity impacts would, in my opinion, be utterly unacceptable. But neither am I keen on ignoring biogeophysical effects, just because they don’t fit neatly into our carbon accounting.

Partly though, this is a failing of our science. We need clear metrics that can be used in climate change scenarios. There are ways that the biogeophysics could be fully enough represented that it could go into these sorts of policy decisions. Hopefully it won’t be long before I will be able to update you on how that aim is progressing.

Equality, Democracy or Wealth?

Rememberance Day seems like an appropriate time to think about changing the world.

If you gained a superpower to help a poor, undemocratic, unequal country to either equality, wealth or democracy, what would you do?

The problem is, although all those things are potentially beneficial, there are two problems lurking. One is the King Midas problem – that things don’t always turn out the way you expect them to. The second is that because of the unpredictability, heterogenity and specific circumstances of different countries, there is a potential of doing harm rather than good.

Essential tech and web tools for Geography Undergrads and Postgrads

Ladies and Gentlemen embarking on a degree, masters or PhD course.

Use a citation manager.

The benefits of using a citation manager have been proven by academics the world over. The rest of my advice about what are useful tools is somewhat subjective and possibly sub-discipline specific. But trust me about the citation manager. For academia, it’s more essential than sunscreen.

Home composting – the economic, social and legislative drivers

With a total about-turn of topic, I’d like to share with you some thoughts about home composting. Now hang with me, because really, it’s more interesting and complicated than you might initially think.

There are three main legislative drivers for home composting in the UK. The first is, indirectly, the Kyoto protocol. Targets for reducing green house gases have meant that methane (a green house gas 23 times stronger than carbon dioxide) from anaerobic decomposition of food waste and other organic substances in landfill sites is a significant area of potential improvement (Defra, 2007b, p.22.). By comparison the carbon dioxide that is given off in aerobic decomposition in home composting is favourable (Recycle Now, 2009b). This gain in terms of green house gases is the main reason in favour of home composting stated by Recycle Now (2009c).

Interview advice for postdocs


There seems to be a lack of advice on the web for postdoctoral posts – those jobs between a PhD and a permanent academic position. All the advice is about academic lectureship positions. There’s also advice about getting onto a PhD program. But the middle ground is forgotten about. Nearly all of us in science will go through a postdoc and are generally unprepared for how to interview for it.

In two years since finishing my PhD, I’ve done six interviews and got three jobs. So I’m going to share some of what I’ve learnt in those interviews and this process. All the usual provisos apply & YMMV.

General Principles, Harsh Realities

Many postdoc positions are already allocated and there is no point in applying or interviewing unless you are the person who the position is intended for.

Sorry. This is the truth. Most universities force professors to advertise jobs, even if they have a candidate they want for the job. This is great if you are that candidate, but a colossal waste of time if you are not (I have been in both positions).

Indentifying jobs that are a waste of your time is actually easy. Usually, the requirements are very specific and include things that seem a bit unrelated. This is done so it is easy to say that the preferred candidate is the right person for the job, because they are a perfect fit.

So it’s imperative to contact the PI before you apply for the job. There is always a contact on the job description. Phone them, or email and ask for a quick chat on the phone. Why phone? So they can be more candid with you. Don’t be afraid to ask questions like, “do you have a particular candidate in mind for this job?”. Or “what outcomes are key for this job?”

The other thing you definitely want is a copy of the grant proposal that the job is funded from, and which work package or similar the job is designed to fulfil. This will help you understand exactly what deliverables the job will actually have.

The application letter and CV

As PhD students we think often that a PI wants to employ a great researcher, and we try to show we are that. Actually, somewhat unreasonably, most PIs seem to want to employ an expert.

Trying to catch a postdoc job in an interview.

Trying to catch a postdoc job in an interview.

So what you need to do in the application (and interview) is draw direct links between the experience you have and what the project aims to do. E.g. “The project aims to do X, and I have experience doing X though blah.”

Don’t be afraid to talk about their project. In fact, showing that you’ve read about the topic, the project and them, will help you a lot. They want someone with enthusiasm, that they can trust to be engaged and get on with the work.


The interview itself

Most interviews I’ve done have had three components: a short talk, questions about the talk, then generic questions.


The talk

  • Read what the guidance says about this talk carefully. Does it say, ‘your work and your fit to the project’? Then give 50/50 to each aspect.
  • Don’t overrun. Really. They aren’t timing it usually, but everyone knows when you’ve overrun and is grumpy.
  • Don’t talk about yourself too much. Honestly, they’re not interested in you, they’re interested in what you can do for the project. Harsh but true.
  • Don’t be tempted to go into any detail. The job of this talk to convince them you’ve done some interesting work and you’ve published it (or will publish it). The talk I bombed the worst was when I tried to give a mini summary of several bits of work I did. It overran and was a disaster.
  • Do talk about the project, how you would do it, and what aspects you’re particularly interested in.
  • Do take questions and go on tangents. This is their opportunity to get to know you – show them that you’re flexible and can talk about what they are interested in.

Questions after the talk

This is their opportunity to ask for more details about you and your work. If you’ve done your job properly and intrigued them, this bit should be fun.

Generic questions

In the UK it seems that they have to ask the same questions to each candidate. So expect very generic questions about how you would do the project, and questions that check your basic knowledge of the subject area. Expect and prepare the following:

  • Generic questions you would ask to check basic and advanced knowledge of the subject area.
  • Conventional academic interview questions. They’re a chance to really shine. Things like:
    • What are your strengths/weaknesses
    • What work you are most proud of?
    • How would you manage if this critical thing failed?
  • What are the potential pitfalls of the project and how would you manage them?

At the end and after the interview

If things have gone very well, they might ask you something like, “Would you take the job if we offered it?” or “When could you start?”. It is absolutely fine to be evasive and put in provisos here. Things like, “I’d be really happy to take the job, subject to discussions about pay and conditions” or “If you were to formally offer me the job, in principle I’d be delighted to work with you.” You’ll note that what these phrases do is sound very enthusiastic and give no commitment at all.

Don’t read too much into how long they keep you hanging on the result. Academics are busy and aren’t always considerate.

If you interviewed, it’s always worth asking for some feedback. Even if you got the job – ask what they liked or didn’t like. You won’t always get a straight answer, but it might be something useful, you never know.

A final word

Good luck with your post-doc interviews! And please give me a shout on twitter if there are other things I should add to this.

Just published: already out of date.

As has been commented on many times, the publishing process for academic papers takes a long time. The consequence of this is that even when a paper has only just become available – only just been published – it is already frequently out of date. This is particularly problematic for review papers, which struggle to keep pace with research articles.

Let me show you what I mean.

Soil Erosion

I hope that I’ve convinced you by now that soil is important to the sustainable gardener/allotmenteer. Therefore I now turn to the process that would remove this precious substance from us: soil erosion. So why is soil erosion a problem? Well, in some cases it can be irreversable, meaning that agricultural land can be lost forever (and with a rising population is that sensible..). In less severe cases it degrades the soil quality, neccessitating more use of fertilisers and soil improvers. The soil washed away is deposited somewhere – fine on fields – but more normally deposited in rivers, causing eutrophication from high nutrient levels and clogging of important water ways. All in all, it’s bad news.

Soil improvement and composition

The worms have now settled down into their new home (with the aid of imported soil) and generally stopped committing suicide, which is excellent. As per instructions however, they aren’t getting too much to eat from my kitchen scraps just yet. But ultimately, the idea is that they create lovely rich compost for my plants. All this hassle just for some soil I hear you ask? Oh yes. “A true gardener does not tend the plants, he tends the soil.”