Is geoengineering the most probable solution now?

This is a very good video on geoengineering and its varying solutions to the hotly debated topic, climate change. One of the methods mentioned in the video is the imitation of volcanic eruptions that releases sulphur dioxide particles so as to reflect incoming sunlight. In the long term, this may cool Earth’s surface temperature and produce the global dimming effect. An example would be the famous eruption of Mount Pinabuto on Luzon in the Philippines erupted in 1991, releasing 20 million tonnes of sulphur dioxide cloud into the stratosphere and resulted in a cooling of Earth’s surface for 3 years by about 1.3 degrees.

‘The scariest thing is that there is no backup plan at all’ and I support this statement. Even though there are many uncertainties with this method, but looking at the relatively unchanging behaviour and actions of the wider public, geoengineering may just be the solution to climate change in the near future.

Aerosols over Cheshire

Here is a video showing the visual effects of the sky in Cheshire after a plane flew over the area, releasing aerosols as part of geoengineering attempt.

Two Harvard engineers and a balloon

Two Harvard engineers, David Keith James Anderson, have engaged in a field experiment in solar geoengineering, aimed to create a technology that replicates the observed effects of erupting volcanoes spewing sulphates into the stratosphere. This natural spewing of sulphates cools the Earth by bouncing sunlight back to space. Therefore, by analysing such natural events and mimicking, they planned to spray sun-reflecting chemical particles into the atmosphere to artificially cool the planet. The chemicals are transported using a balloon flying 80,000 feet over Fort Sumner, New Mexico.

geoengineering balloom

(click for a larger and clearer image)

The experiment involves the release of tens or hundreds of kilograms of particles to measure the impacts on ozone chemistry as well as to test ways to make sulphate aerosols the appropriate size (Lukacs, 2012). Keith hopes his experiment can help improve models of how the ozone layer could be altered by much larger-scale sulphate spraying.

However, environmental groups fear the ‘geoengineering solution’ may undermine efforts to reduce carbon emissions. Other concerned parties include scientists who warn that such methods could result in unpredictable and disastrous consequences for the Earth’s weather systems and food supplies.

“Impacts include the potential for further damage to the ozone layer, and disruption of rainfall, particularly in tropical and subtropical regions – potentially threatening the food supplies of billions of people,” said Pat Mooney, executive director of the Canadian-based technology watchdog ETC Group (Lukacs, 2012).

Furthermore, a scientific study showed that solar radiation management could cause rainfall to decrease by 15% in areas of North America and northern Eurasia and by more than 20% in central South America (Schmidt et al., 2012).

The use of geoengineering to attempt to alter Earth’s atmosphere is a highly contested issue, just as global warming is. The multiple factors and stakeholders involved make the issue even more complex than it already is but time is ticking and Earth continues to suffer as seemingly never-ending arguments seem to go on. More concrete solutions should be enforced as soon as possible and existing alternatives like reducing carbon emissions should be capitalized on.


Lukacs, M. (2012). US geoengineers to spray sun-reflecting chemicals from balloonThe Guardian. Retrieved 11 February 2015, from

Schmidt, H., Alterskjær, K., Karam, D., Boucher, O., Jones, A., & Kristjansson, J. et al. (2012). Solar irradiance reduction to counteract radiative forcing from a quadrupling of CO2: climate responses simulated by four earth system models. Earth System Dynamics3, 63-78.

“Let’s spray fancy particles in the sky to save our atmosphere!”

geoengineering cartoon


It looks like a very cool term and sounds like it has the potential to save us all from the effects of global warming. The concept is simple. It functions by creating a global dimming (i.e. cooling) effect to counter global warming, thereby mitigating climate change. This is done with the effect of sulfate aerosols as they reduce the amount of incoming solar radiation.

Another method to fight global warming would be to remove carbon dioxide from the atmosphere by seeding oceans with iron particles which stimulate phytoplankton growth, which in turn suck up carbon dioxide (Horton, 2015). However, because this blog is on global dimming and its main cause – aerosols, I will thus further focus on the former geoengineering approach of using aerosols in future posts.

Geoengineering map

(click for a larger and clearer image)

The above image shows a map of the various kinds of geoengineering projects around the world. This documentation demonstrates the expanding scope of research and experimentation in the large-scale manipulation of climate systems and hints about its increasing popularity among governments who are unable or unwilling to dramatically reduce their carbon emissions.


Horton, J. (2015). How can adding iron to the oceans slow global warming?HowStuffWorks. Retrieved 9 February 2015, from

Have Your Head in the Clouds

I mentioned clouds being formed by aerosols in the previous blog post so here is a video on how aerosols are actually important key players in our atmosphere!

Clouds form as water vapour condenses on the surface of aerosols and become very large. When they are too big, they then fall as raindrops. Therefore, without aerosols, clouds and rain cannot possibly form in Earth’s atmosphere.

Cloud puns

The major role of many anthropogenic aerosols as cloud condensation nuclei strongly influences the size, longetivity and radiative properties of clouds (Stanhill & Cohen, 2001). In addition, solar activity is also linked to the amount of aerosol concentration present. Hence, research groups are willing to invest time, effort and resources in studying this issue and building sensitive, elaborate experiments which can reproduce the conditions in earth’s atmosphere in a bid to return it to a healthier state. This can be better seen in interesting geoengineering efforts to alter our atmosphere which I will talk about in the next few blog posts.


Stanhill, G., & Cohen, S. (2001). Global dimming: a review of the evidence for a widespread and significant reduction in global radiation with discussion of its probable causes and possible agricultural consequences. Agricultural And Forest Meteorology107(4), 255-278.

Food Security Issues

Stanhill ss

This post will discuss about a paper written by Stanhill and Cohen (2001). It talks about the possible causes and consequences of global dimming on agriculture. The paper is a very scientific one which focuses on the methods used in their research to determine the causes and effects.

Findings have shown that since global radiation provides the energy for the carbon assimilation of plant canopies and their water loss to the atmosphere, it can thus also determine the heat balance of agricultural surfaces. This means that global radiation, too, controls the temperatures of the major environmental factors controlling the development of crops and livestock and hence threatens food security.

This information is of particular importance because the ecosystem is temperature sensitive. A “10–20% decrease in solar radiation reaching the surface of the earth, if unaccompanied by other climatic changes, would probably have only a minor effect on crop yields and plant productivity” (Stanhill & Cohen, 2001). However, any further decrease by phenomenon like global dimming might be expected to decrease productivity of plants.

Since aerosols are linked to the formation of clouds and hence rain, it is vital in providing moisture. Crop productivity can be largely limited by water. This moisture limitation caused by decreases in solar radiation (i.e. global dimming) often occurs in in tropical latitudes and in the arid and semi-arid regions of other latitudes. However, in wet climates with low radiative heat load on the plants, any decrease in solar radiation is likely to be accompanied by a small decrease in productivity (Wang et al., 1994).

Such are the possible agricultural consequences of global dimming and we must keep in mind that everything in the ecosystem is linked one way or another. A small effect on the productivity of plants may not seem as a cause for concern but may generate a domino effect in future generations.


Stanhill, G., & Cohen, S. (2001). Global dimming: a review of the evidence for a widespread and significant reduction in global radiation with discussion of its probable causes and possible agricultural consequences. Agricultural And Forest Meteorology107(4), 255-278.

Wang, G.G., Qian, H., Klinka, K. (1994). Growth of Thuja plicata seedlings along a light gradient. Can. J. Bot. 72, 1749–1757.


Save our water and food supply!

Fast food

Solar dimming can be a double-edged sword. It is essential for life on Earth because it maintains the planet’s surface temperature, mitigates the initial effects of global warming, and provides plants with the appropriate amount of solar radiation for important processes like photosynthesis. However, too much of the phenomenon can bring unfortunate events like droughts.

In recent news at the Northern Hemisphere, air pollution caused by aerosols was believed to have resulted in an increase in river flow. The pollutants prevent proper sunlight form reaching the Earth and thus reduced evaporation and rise in river flow by as much as 25% (Passary, 2015). The study was led by Nicola Gedney from the British Met Office and it found that the impacts mostly occurred in Europe’s industrial regions. This corresponds with the previous blog post on urbanization and it being a main contributor of aerosol pollutants.

Going back to the effects of solar dimming, its reversal could result in a reduction in river water level due to the fall in river flows. This in turn produces a cause of concern for estimation of future water supplies. As mentioned by Gedney, “With water shortages likely to be one of the biggest impacts of climate change in the future, these findings are important in making projections for the future” (Passary, 2015).

From the above issue we can see that global dimming, albeit not a well-known issue, ties in with the security of our water supplies. This thus stresses on the importance of understanding it and its interactions with global warming so that adequate solutions can be proposed and carried out. Mitigation and adaptation measures to ensure food security need to be paid close attention to too (FAO, 2012) since weather ad climate are crucial determinants of the issue.


FAO (2012). Climate change adaptation and mitigation: Challenges and opportunities in the food sector. Food And Agriculture Organization Of The United Nations.

Passary, S. (2015). Air pollution increases river flow in Northern Hemisphere: StudyTech Times. Retrieved 30 January 2015, from

Urbanization’s Contribution to Global Dimming

NY Urban

Global dimming is said to be one of the most prominent examples indicative of athropogenic disturbances. This phenomenon is mostly dominant in large urban sites as studies have shown that large cities with a population greater than 0.1 million, when compared to sparsely populated sites, are in general steady sources of anthropogenic pollutants like fossil fuels, nitrates, sulfates, and soot (Alpert, 2005). The paper by Alpert (2005) aims to investigate if global dimming is a local or global phenomenon.

However, I feel that urban development produces other effects too that can contribute to the changes in solar radiation and it is not solely the fault of anthropogenic aerosols. Some examples include the urban heat island effect, deforestation, and changes in surface albedo. Moreover, people tend to settle near coastal areas which further contribute to the uncertainty of the study.

(3) rural vs urban pop

Figure 1. (World Urbanization Prospects, 2014)

The above figure demonstrates the varying levels of urbanization across regions. Nevertheless, they have one thing in common and that is that the urban population is increasing. Over the decades, the level of urbanization is expected to increase in all regions with Africa and Asia doing so at a faster rate than the rest.

Hence, in my opinion, it is not so much an issue of whether global dimming is a global or local phenomenon because with most parts of the world catching up with the trend on urbanization, it will soon be a global concern.


Alpert, P. (2005). Global dimming or local dimming?: Effect of urbanization on sunlight availability. Geophysical Research Letters32(17).

World Urbanization Prospects. (2014). World Urbanization Prospects, the 2014 revision. Retrieved 23 January 2015, from

New Aerosol Study

aerosol study

I came across this article that reveals a possibility of countering the natural aerosol emissions with man-made ones. The study, published in Proceedings of the National Academy of Sciences, was conducted by Professor Sally Ng from the School of Chemical and Biomolecular Engineering, her students, as well as researchers from institutions throughout the Southeast. The natural emissions from trees that undergo oxidation to form aerosols and they can then interact with the anthropogenic emissions, eventually releasing even more aerosols in the environment.

The study then suggests a solution to this problem by using the knowledge of a strong correlation between aerosols and carbon monoxide (a man-made emission) as well as the fact that most aerosols originate from organic sources rather than directly from vehicles and industries. In the paper, they explain “the chemical mechanisms by which man-made pollutants cause greater production of organic aerosols, effectively solving the paradox” (Marino, 2015).

Such studies on pollutants are particularly important for understanding the climate and human health at a greater depth. Aerosols can be beneficial in cooling our environment, especially with global warming today, but it is seen as harmful according to the World Health Organization because it is classified as carcinogenic. This demonstrates that there is a trade-off when using aerosols to counter the effects of global warming since it may cause more damage to human health.

Even though we should not be too complacent and must still recognize the fact that anthropogenic emissions of aerosols have greatly distorted the mechanisms of natural emissions today. This thus creates an imbalance that we should aim to remove, as mentioned in my first blog post. There is always a threshold for all things and I strongly feel that once that threshold is crossed, the ability to live comfortably as before would be compromised.

Marino, K. (2015). Professor Ng presents new aerosol study. Technique. Retrieved 22 January 2015, from

What is Global Dimming?

Global dimming is the opposite of global warming. It is defined as the reduced amounts of solar radiation reaching the surface of the Earth. When we put it that way, by right, global dimming should be seen as a good thing to us since it counters the warming effects. However, upon more research, this seemingly ‘helpful’ environmental phenomenon has actually caused devastating effects on both the living and the environment.

How is this so? Global dimming is caused mainly by the by-products of burning fossil fuels, and an example would be aerosols. They reflect sunlight away from the Earth’s surface and hence decreases the amount of solar radiation entering, producing a cooling effect. This effect has caused the water in the northern hemisphere to turn colder, leading to a slower evaporation rate and lesser water droplet generation. With that, there would thence be many fewer occasions of rainfall, resulting in droughts and famines. An example would be the situation in Sahel in sub-Saharan Africa during the 1970s where thousands of people suffered during the drought due to global dimming (Kukreja, 2015).

Today, the concern of this environmental issue falls more on Asian monsoons where half of the world’s annual rainfall derive from. The decrease in solar radiation can also have a huge impact on the productivity of plants.

Since global dimming counteracts the effects of global warming, actions that drastically impact any one of them such that there is an imbalance could distort global temperatures which would then spell disaster. Hence, attempts to maintain, or restore, the harmony between global dimming and warming should aim to reduce emissions of both greenhouse gases as well as particulate matter.

Kukreja, R. (2015). What is Global Dimming?. Conserve Energy Future. Retrieved 18 January 2015, from

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