"See the trees and the wood"

The common room in my Geography department is a little bit like a dentist's waiting area. However, instead of well-worn editions of Grazia and Trout Fisherman Magazine , you'll find lying around some slightly more academic — and considerably less read — publications, such as Scientific American and National Geographic. Today I was leafing through a copy of Nature when the phrase 'Treat forests as natural habitats' popped out at me. The line summarised a short correspondence from Bruun et al (2015) titled Forests: see the trees and the wood , a criticism of an earlier submission to the same journal for failing to recognise the natural value in forest ecosystems. This seemed right up my street, so I had to have a read of the article in question.


The comment piece (Fares et al, 2015), argues that European forest management policies should be reconsidered and centered more towards sustainability. At first, this doesn't seem at all seem unreasonable — I can't imagine many scientists supporting the practice of unsustainable forestry. However I think one has to question what exactly the authors really mean by 'sustainability'. In the hope that you get my point, I'll do my best to summarise the steps for managing Europe's forests that they suggest:

• Plant stronger, more productive tree species that are more resilient to climate change.
• Gear forest management strategies towards minimisation of disturbances (by removing dead or "excess" biomass to combat fires, and cultivation of more pest-resistant genetic lines) and maximisation of carbon storage (e.g.  more frequent harvests and greater practice of thinning).
• Focus on quantifying and expanding forest's potential economic value: the use of tree biomass for renewable energy, as well the less tangible "ecosystem services" (such as their use for recreation and the protection offered to river catchments).

Notice a recurrent theme in this? Personally, I'm surprised by how commercially focused the notion of sustainability promoted in this article is. My expectation was that, given the threat posed by rapid anthropogenic climate change, it would have described various methods to protect forests and their biodiversity. It appears instead that Fares et al's argue for shaping European forestry policy so as to extract the maximum economic value from them, and the main criticism by Bruun et al. is that such strategies "overlook the implications for forests as natural ecosystems and run counter to biodiversity sustainability guidelines".



Fallen trees can provide a habitat for "a wealth of species that thrive on dead and decaying wood"( Bruun et al, 2015) . 

Is the economic valuation of forests, particularly for bioenergy production, necessarily at odds with protecting their wellbeing (from a conservationist perspective)? I don't know the answer, but it seems like it shouldn't be impossible to achieve both. At least I hope so, since this dilemma is central to the field of work I'm interested in. Then again, especially considering what I've learnt with regard to palm oil biodiesel , I probably shouldn't be too optimistic.

Creating energy from the earth

Plantations of the oil palm in Indonesia.

This isn't the first time I've mentioned  EURENSSA, nor will it be the last. Among the various presentations given at the environmental research camp, one of particular interest to me discussed the production of biodiesel from palm oil plantations in Indonesia. Today I had the opportunity to interview Noor Hossain, the Industrial Ecology student who delivered that presentation. I asked him to shed some light the topic of biofuel; his research in it, key issues involved, and how modellers can contribute. Have a listen to our discussion below, and if you're interested in Noor's research then you can check out his ResearchGate page here.

The silver bullet that twinkles green

I find that there's something incredibly brazen in naming a journal article Irrigated afforestation of the Sahara and the Australian Outback to end global warming. I think it's because, in my head, the word 'to' in the title reads as is going to, rather the likely intended sense of so as to. Ornstein, Aleinov & Rind's 2009 paper proposes a massive biogeoengineering scheme: the afforestation of currently desert land in order to sequester ~8 Pg C per year, enough to effectively halt anthropogenic climate change.

Ornstein et al suggest the use of Eucalyptus grandis, a fast growing species native to Australia that is commonly used in commercial forestry, such as this Kenyan timber plantation.

Initially, sea water desalination could supply the enormous irrigation necessary to support subtropical forests in an arid desert such as the Sahara. Eventually, however, the climatic feedback mechanisms that contributed to previous green Sahara states would come into effect (if you don't know about this then you clearly haven't been reading my blog), with the amplified monsoon rains sustaining these new plantations. Since forests tend towards CO₂ neutrality as they mature, sections could be felled and replanted periodically, with the harvested trees being used for timber or to produce biofuel. Alternatively, this biomass could be pyrolysised to provide a renewable source of energy as well as produce biochar, a charcoal which can be buried to fertilise soil and store significant quantities of carbon in the ground.

To support these assertions, the study describes a GCM experiment in which the land surface of the Sahara and Australian Outback has been changed to represent a tropical forest, while soil moisture is artificially topped up at each time step so as to simulate irrigation.

Precipitation anomaly with an afforested Sahara and Outback. Image generated from supplementary video provided by authors.  

The resultant rainfall intensification shown above is very large, although it is not sufficient to completely supplant irrigation. Ornstein et al acknowledge that expense of this water supply, as well as those involved in the physical infrastructure necessary to establish a continent-spanning forest plantation, could be prohibitive. It is unlikely that the monetary value of the forest biomass (either as biofuel or more abstractly in the carbon trading market) would ever become economically competitive compared to fossil fuels, though even if this did happen it would still require a massive initial investment with a decades-long return period. With technological feasibility assumed, these costs, as well as the immense organisational difficulties involved, are identified by the authors as the most significant obstacles to such a desert afforestation scheme.

Like this, but in reverse. © John Holcroft

The Irrigated afforestation of the Sahara... paper provided the inspiration for this blog's name, so I'd really like to hear your opinions on the idea; whether from a modelling perspective and a more general one. Does the afforestation of the Sahara desert seem feasible to you? It amounts, essentially, to terraforming — are there any issues that you could see arising from this? If money wasn't an issue, would you support it?

The evolution of modelling

New year, new home.

Wait, that's not quite how it goes — not yet, anyway. Though humanity in 2016 is still stuck on the same planet that birthed it, our understanding of how the Earth works is improving year after year. In particular, the models that we use to emulate the climate system are becoming more and more powerful. The most advanced climate models are evolving to become Earth System Models, which are evolving in two main ways: increased resolution and more comprehensive incorporation of various physical processes.

To stress the importance of the former, have a listen to this short interview with Philip Rasch, the leader of the atmosphere group of the ACME project, a US government-funded collaborative effort to develop a next-generation ESM. While you listen, peruse this presentation on UKESM — the British answer to ACME — to gain an understanding of the challenges in the latter aspect of model complexity in ESMs. In particular, given that flexibility is very important if a model is to be usable for a wide array of applications, take note of the image on slide 18 (reproduced below) illustrating how modularity is incorporated into UKESM's design from the get go.

Organisation of the various components of UKESM

It's all exciting stuff, and I dream of being able to participate in the development of these kind of models someday (yes, my dreams are like this).