Is deforestation a necessary evil? Part 1

Welcome to the last post within this blog (although it has been split into two parts because it is of considerable length). Way back in the realms of early October this blog set out an assortment of slightly related aims: explore the consequences of deforestation; examine whether the effects of deforestation are always bad; explore solutions; look at past patterns of deforestation and examine how complicated the discourse on deforestation is. They have all been examined in one blog post or more and now it is time to draw conclusions and thought from what this blog has researched. The overarching question of this blog, and the title of this post - is deforestation a necessary evil? - shall be finally answered.
This blog post will examine four key areas of interest that have been discussed throughout the blog:

1. The relationship between global environmental change and deforestation. 
2. The relationship between humans and deforestation.
3. Why deforestation is a bad process.
4. Sustainable Deforestation and Is a tree apocalypse inevitable?

Drawing upon references and ideas discussed in other blog posts will bring in an element of repetition but it is ultimately a post to explore my personal opinions towards the topics being discussed, in conjunction with academic research. 

The Relationship between Global Environmental Change and Deforestation

Trees, and vegetation generally, are an integral part of the Earth system involved in various cycles including the hydrological cycle, carbon cycle, nitrogen cycle and countless ecological cycles/systems. 

The importance of trees in the global nitrogen cycle (source)

In terms of carbon, trees act as a major carbon sink taking up carbon dioxide during the process of photosynthesis (Malhi et al. 2008). 150-200 Pg of carbon is stored in the Amazon within biomass and soils (Brienen et al. 2015). This study demonstrated the importance of trees as well as other vegetation and biomass that stores carbon and questioned the future of carbon sinks within the Amazon. 

Deforestation removes this store of carbon and releases it into the atmosphere. It is estimated that 1.8ppm of atmospheric carbon can from deforestation of the Amazon (Exbrayat and Williams 2015). Fueling climate change will have a positive feedback mechanism in which a warmer world causes increased drought (and wildfires) in the tropics leading to the destruction of more forests which in turn release their stored carbon (Haog 2009). 

The effect of deforestation on regional climate is also severe with increased surface temperature (due to reduced albedo) leading to a decrease in evapotranspiration and precipitation. A reduction in cloudiness and increases in insolation creates an increase in high pressure systems and frequent droughts. Furthermore, the alteration of the land surface increases wind speeds and therefore desertification and soil erosion (IPCC 2007; Malhi et al. 2008; Shukla et al. 1990). 

Trees impact on climate and vice versa and are an important factor in influencing global climate - the Amazon is the engine for global atmospheric circulation - and an alteration to this precious system would change our climate. 

The Relationship between Humans and Deforestation

Like the mighty oak, human beings have become an integral part of the Earth system (see their influence in the nitrogen cycle diagram) and have an impact on the climate and landscape more so than any other species. 

The causes of deforestation have been discussed extensively whilst the relationship between urbanization and deforestation in Africa has also been explored. 

The reality is that like oil, food and water, the human population needs trees as a source of fuel (e.g. firewood), shelter and for basic necessities (paper, furniture etc.). It has been at the core of our civilization for thousands of years and the relationship between humans and the threes is as delicate as their relationship with climate. 

I won't drone on about this in much detail with two blog posts already exploring societal collapse on Easter Island and in Mayan Central America but a brief recap won't hurt. There are numerous studies that contribute the collapse of Mayan society to deforestation (Haug et al. 2003; Ogelsby et al. 2010; Shaw 2011). The studies illustrate how important trees are in local climate - influencing drought. However, archaeological evidence and paleoenvironmental evidence is not always complementary and their are disputes as to whether deforestation alone contributed to the collapse of Mayan society (MacNeil et al. 2009). In reality it was probably a combination of socio-economic and political factors exaggerated by detrimental environmental effects such as drought that was caused by over-deforestation. 

I have already suggested that the attitude past societies (such as the Mayans and the Polynesians) had towards deforestation is much the same as our own and that there is potential for us to eventually cut down all the trees. 

A quirky diagram to illustrate MacDonald's arguement (Cool Geography)

Humans need trees (as I have mentioned already) and an article by MacDonald (2012) offers a concise synthesis of the relationship between humans and climate change. He notes that the humble tree is a hindrance to human societal expansion (in terms of space) as well as food production but that without trees mankind could not survive. Trees create an idyllic and comfortable in which human beings can frolic and grow by taking in heat during photosynthesis. He interestingly draws upon the dated works of Thomas Malthus to explore how human populations grow and survive. MacDonald further offers a controversial (yet logical) view point to combating deforestation and climate change saying it is the responsibility of world leaders to keep the world's population in decline in order to ensure a good quality of life for the current population. I think for MacDonald, the root cause of the world's problems is overpopulation (draining resources, taking up space, degrading the landscape and producing pollution). To some extent he is correct but there are definitely alternatives to controlling population and implementing anti-natalist policies. 

It is true that we need trees for survival but I think (and this will be discussed later) we can do more to manage the way in which we use trees. What I want everyone to take from this post (is not the doom and gloom population comments) but that trees are vital in the Earth System and that everything is interlinked. 

The remainder of this posts (questions 3+4) will be explored in "Part 2" but please feel free to comment and vote on the poll in the top left of the screen - it will be interesting to see what everyone thinks. 

Amazon Deforestation and Climate Change

In last week's post we explored the relationship between humans and deforestation in the African continent. Now we are flying a few thousand miles across the Atlantic to explore the relationship between deforestation and global (and local) climate change in the Amazon.

The Amazon Rainforest is one of the most beautiful and captivating locations on our planet and hosts roughly half of the world's species and covers an area of 5.4 million km2 (62% of Brazil).

Outstanding Natural Beauty - the Amazon is at risk (source)

How does deforestation alter the landscape and effect local climate?
The removal of lowland tropical rainforests in the southern and eastern parts of the Amazon jungle for cattle ranches and soybean production means that trees are being replaced by grass.
Shukla et al. (1990) undertook numerical modelling to evaluate the effects of deforestation on local and global climate. They found that there would be an rise in surface temperature and a reduction in evapotranspiration and precipitation would cause an increase the duration of the dry season (supported by Malhi et al. 2008). This was also modeled in the 2007 IPCC report which showed a decrease in dry season rainfall but an increase in rainfall in the western Amazon during the wet season. Shukla et al's work is convincing yet dated and the recent work by Malhi et al. (2008) explores the climatic effects of deforestation one step further.

Evaporation and condensation over the Amazon  are the locomotives driving global atmospheric circulation. Furthermore, 25-50% of rainfall is recycled from forests which is important in places, such as the Amazon, where precipitation is a consequence of regional convection (Shukla et al. 1990). Removing the trees reduces rainfall, decreases cloudiness and increases insolation. It also alters the surface roughness increasing wind speed and therefore desertification and soil erosion. The changes to local scale climate are extensive.

% Change in Rainfall due to deforestation. Red shows the areas that will experience large decreases in rainfall. This are often the areas where the greatest deforestation occurs (NOAA)

How does deforestation alter global climate?
An incredibly recent study by Exbrayat and Williams (2015) showed that Amazon deforestation had a net contribution of 1.8ppm of atmospheric CO2 or 1.5% of historical growth which reflects the significance of the Amazon in the global system. It reinforces the argument that deforestation directly contributes to climate change (much in the same way as burning fossil fuels).
Malhi et al's (2008) work also touched upon the global carbon cycle and climate change talking about the release of stored carbon from trees and within the soil following deforestation. Soil carbon is released when the tree roots that hold rainforest detritus together are no longer present and the soil is eroded through aeolian and fluvial processes.

Significance and Future
As these articles and pieces of research demonstrate, the Amazon rainforest is an important component in the Earth system. It is vital for so many species including our own (Feeley and Rehm 2012). However, if nothing is done the Amazon rainforest could be completely gone within 50-100 years (Shukla et al. 1990). An increased rate of deforestation is chronicled in an interesting article by the Guardian written last year.Huge amounts of research continues to be conducted in the Amazon because it is a site of outstanding scientific interest.

Picking up the pace - rates of deforestation in the Amazon are increasing (The Guardian)

Global Deforestation Trends

The first post on this blog will probably be the most cringe-worthy but its purpose is simple - to set the scene for future blog posts.


Deforestation is defined as the clearing of forest into cleared land. It is a heavily discussed topic since it is embroiled in the global carbon cycle and hence global climate change. This blog will not offer descriptions of global processes but facts, opinions and up-to-date academic research into the various issues surrounding global environmental change.

It is estimated that 11.5 million hectares of forest, an area the size of Portugal, is removed through cutting or burning and questions arise from this:

• Is deforestation always bad? Perhaps it is a necessary evil?
• What are the consequences of current deforestation patterns?
• Is reforestation an option for this generation?
• How have past patterns of deforestation influenced global environmental change?
• What about the plants and animals?

A blog about controversies summaries logging debates nicely, although it lacks scientific depth. It can be found here.

The removal of ancient trees that have stood for longer than some human civilizations appears to be wrong. How could humans destroy a carefully constructed piece of nature in just minutes?  The truth is that deforestation is not a pointless evil. It has a purpose and it is to supply wood to the planet's burgeoning population and to create space for the rapidly urbanizing metropolises of the 21st century. If we want to stop deforestation surely we should look at the uncontrollable population booms in the developing world and the unplanned expansion of our mega-cities.

Logging in Brazil (National Geographic)

Deforestation and Climate Change

The main debate and smaller arguments surrounding deforestation have now been put forward and these shall be discussed in future blog posts. The link between deforestation and climate change is relatively simple.
Plants and trees remove carbon dioxide from the atmosphere. If trees are cut down then less carbon dioxide is removed from the atmosphere and therefore the planet gets warmer. Furthermore, the burning of sections of forest releases stored carbon dioxide into the atmosphere, accounting for the second largest contribution of CO2 to the atmosphere, after fossil fuel combustion (Van de Werf et al. 2009).


This blog will also examine the future of deforestation? Can it be stopped? Is there an alternative?