Month: February 2015

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.


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