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| Credit: Alice Fitch. South Cardamoms |
We left our ancestors in the last post just getting involved in agriculture - but let's fast forward to today. One of the major side effects of agricultural expansion is deforestation (Chaplin-Kramer et al., 2014). The global impacts of this deforestation relate to:
- Carbon Storage
- Loss of biodiversity
- Hydrological changes
- Habitat fragmentation
In today's world with all our intensification methods, we
could question is agricultural expansion still occurring, namely, will we see
more deforestation for agriculture?
This is where modelling can help us; Schmitz et al., (2006) compared the results of
10 agro-economic models —MAgPIE, GLOBIOM, GCAM, IMPACT, AIM, FARM, GTEM, ENVISAGE,
MAGNET, EPPA — under a number of scenarios considering
socioeconomic developments and climate change to assess how much land will be
used for crops in 2050. Modelling inter-comparison is really important for attempting
to 'predict' the future as each model reaches its conclusion in a different
way; this happens as models differ in the number of land-use types they employ, what
assumptions they apply, and what they consider the most important for
determining crop allocation and expansion (Schmitz et al., 2006). Additionally, scenario modelling allowed us to handle uncertainty in changing climatic and economic conditions.
Their findings: a global rise in the amount of land devoted
to agriculture — possibly 200-300 million more hectares— with the greatest regional increases in sub-Saharan Africa and South America, and a general decrease in Europe (Schmitz et al., 2006).
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| Figure 1. The graph shows the development of cropland from 2005 to 2050, all data is normalized to HYDE model data for 2005. The boxplot shows the change in cropland under S1: no climate change, medium economic growth and population development. S2: no climate change, lower population growth in developed countries, higher in developing countries. S4 and S6: medium economic growth and population development with pessimistic climate change scenarios (Schmitz et al., 2006). |
However, it is important not to rely too much on the results as these land use models are all relying on
data from the other models the authors used to model climate, hydrology, vegetation,
crop growth, population growth etc. These models in themselves hold their own assumptions and difficulties, for instance with vegetation you have
to take into account phenology, water requirements, amount of photosynthetic radiation,
CO2, nutrient limitation etc. to be able to model growth. Scale this up globally and you can see where errors could creep in!
BUT, after we have taken all this into account, what is
interesting with the study is that across the extreme scenarios there is a trend
towards global increases in cropland by some degree. SO I think we will see more agricultural
expansion globally, occurring more in developing countries due to
socioeconomic factors, and therefore more deforestation occurring as a result of
land use change.
So, what will this
do for our environment?
Let's find out in the next post! Forests of Carbon or Fields of Food......
Good to see you tackle the modelling component here. Do you have a feel for what the factors are which cause most uncertainty in the models?
ReplyDeleteHi Anson - if we take out the uncertainty associated with the data that's inputted, with these agro-economic models I think what causes the uncertainty is the criteria they use for allocating land to the different land use types. Although it’s occurring it’s difficult to capture the exact combination of social and economic factors that cause an expansion of agricultural land, and each of these models employs a slightly different combination of factors. Added into this is the lack of knowledge on the cost of converting one land type to another, and what assumptions the models have concerning this, as well as how agriculture will respond to changes in price and cost. The model FARM predicted a continual decrease in agricultural land (the only model to do so) and appears to have done this because of rising energy prices in the simulation which meant it deemed forestry as the more competitive industry and so land was assigned to forestry.
DeleteI find the agro-economic models very complex! and definitely need to investigate them more.
Having visited the Amazon myself, witnessed the beauty and tranquility of it, it is shocking to read millions of hectares of it will be lost in such a short period of time. I wonder how the decrease of devoted land in Europe effects the increase in Africa & South America? Are we going to be 'doing our bit' whilst importing more food from further afield? Or is there no correlation between the two?
ReplyDeleteHi Alana –really intriguing question. I think there is a correlation between the two, but that the increase of devoted land elsewhere leads/is leading to the decrease of devoted land in Europe. In the models agricultural land in Europe decreases as it loses out to regions with low costs of cropland conversion and crop production. In the climate change scenario the authors ran – the models did show an increase use of agricultural land in Europe. I didn’t mention it initially because the future climate that was used the authors themselves said it was ‘unreal’. With climate change and increased population we may see a drive in European production but I don’t think it will halt or ameliorate the expansion of devoted land in Africa or South America.
DeleteThe best we could do is to focus on buying European/local and seasonal produce now, reducing the international demand which could decrease the profit for supermarkets and potentially slow down expansion. I also think ‘greener’ and more sustainable farming practices in Europe would make farming more cost-effective and productive. I will certainly explore this in later posts!