Painting the floor white...

It is time to move on to the ultimate solar radiation management technique! How time flies... (particularly in the race against climate change!)

This next geoengineering scheme which we are going to consider is increasing land albedo, which like all solar radiation management techniques, is aimed to boost the reflectivity of Earth's surface to incoming solar rays but through increasing the albedo intensity on Earth's land surfaces. A 1.5% change in albedo would be needed in order to counteract climate change (Keith, 1998) - can this be achieved?

Irvine et al. (2011) present a thorough analysis of albedo enhancement schemes by categorising attempts into:

1. Urban Albedo Geoengineering-  This has been a strategy of response to impacts created by the urban heat island effect, and entails implementing new roofing and paving materials with more reflective materials, as these materials make up 60% of urban surfaces (Akbari et al. 2009). These usually include materials of lighter colours as they absorb a greater reduction of sunlight than dark coloured materials.This is being widely researched as it is highly feasible and despite initial high costs for materials and equipment, these are displaced by the amount of energy that the scheme saves. Bracmort et al. (2011) stated that the US Department of Energy (USDOE) National Nuclear Security Administration (NNSA) buildings saved 70% on their energy bills due to the installation of cooling roofs.

Source: Bits of Science

2. Crop Albedo Geoengineering- This requires a calibre of crops with higher albedos than currently planted. Crop land area covers 3.1% of  the Earth's surface (Irvine et al. 2011) and they have increased albedos in comparison to natural vegetation (Irvine et al. 2011). Human proliferation of agricultural activities historically has already modified albedo strengths within crops which has cooled the globe by 0.17°C (Matthews et al. 2003).  In a modelled global scenario of doubled carbon dioxide emissions, crop albedo geoengineering enhances cooling in the northern hemisphere- particularly in Eurasia and North America (Irvine et al. 2011).

3. Desert Albedo Geoengineering- This has the highest albedo enhancement potential, due to the large expanses of 'useless' space (Gaskill, 2004), and the high levels of incoming solar radiation experienced in these regions. Approximately 4.5 million kilometres of desert are available for surface albedo enhancement (Gaskill, 2004)  with reflective, high albedo enhancing materials.

Source: Weird Twist

However, could these three sub-schemes ultimately work to enhance land surface albedo?

Yes, however there do appear to be many caveats associated with increasing land albedo. Firstly urban land albedo requires constant maintenance, and the bright reflectivity of the material surface could cause glare and be aesthetically displeasing (Bracmort et al. 2011). Crop albedo enhancement is limited by time as increasing the reflectivity will take at least a decade on a commercial scale (Bracmort et al. 2011 ), this means it cannot respond quickly enough to the implications of climate change! Desert albedo enhancement was popularised due to its high potential, however, it has been criticized for its impacts on local eco-systems due to the installation of sheets of reflective materials, and rows of mirrors (Cascio, 2009). The costs of installing such devices would be colossal!

Enhancement of land albedo also has great influence on precipitation patterns which imposes large environmental changes that can have socio-economic impacts on livelihoods due to agricultural patterns change and surface adaptation. Studies have similarly shown that enhanced land albedo proposals could result in a cooler northern hemisphere (Irvine et al. 2011) but a warmer southern hemisphere. This is because the majority of Earth's land mass is situated in the northern hemisphere, so increased albedo and reflectivity in the northern hemisphere will reduce incoming solar radiation absorption in that area alone. This will have dominating regional effects on climate and could have significant impacts on the ocean due to increased temperatures. In fact, a strong association of increased temperatures of surface waters enhances the formation of hurricanes and storm events. This could increase the magnitude and frequency of freak storm events, which can have significant detrimental impacts on demography and livelihoods worldwide.

Enhancing land albedo is often compared to increasing ocean albedo, which is achieved through cloud brightening (see previous post!). But which one works better? Can they achieve similar results?

In fact, enhancement of ocean and land albedos have been found in research to have opposite effects. Increased land albedo has global repercussions of reduced precipitation on a large scale (Bala & Nag, 2011) as in a world of doubled carbon dioxide concentrations, precipitation is reduced by 13.38% (plus or minus 0.28%) (Bala & Nag, 2011). A study by the same leading author: Bala et al. (2010) on cloud albedo enhancement illustrated a dominance of increased precipitation and overland runoff, this contrast between the two studies is because land albedo enhancement is only applicable over land surface areas (Bala & Nag, 2011). But do either of these climatic impacts really benefit the globe? Application of increasing land albedo could cause strife, as deployment of the scheme in the US (for arguments sake) could have detrimental effects in Australia, a southern hemisphere country which is hot enough already without the scheme! Compensation would be owed, conflicting priorities could arise, and all because of the consequences of a humanly induced geoengineering project which is perhaps beyond the scope of human control.

Is it worth it?


S xx