If solar geoengineering using increased albedo or the presence of aerosols reflects solar radiation, then it will result in a lower temperature increase.

Question 1: What is climate change?

Climate change is the long-term shift in overall weather patterns. These shifts can be natural, because of things like big eruptions of volcanoes, but since the 1800s, most of them have been due to human activities such as burning coal, oil, and gas. This creates something a bit like an invisible blanket wrapped around the Earth. Continuing to burn fossil fuels will continue to heighten the effect of this invisible blanket.

Question 2: What is solar geoengineering?

Solar geoengineering is a way to slow climate change by reflecting the sun's light back into space. This can be done by things like whitening more land surfaces or injecting aerosols into the atmosphere using planes, which is called stratospheric aerosol injection, where they reflect more of the solar radiation that gets through to the Earth's atmosphere. However, it’s not a permanent solution, just one that will slow down global warming while humans find a more sustainable solution. It’s a dangerous fix, but not as dangerous as sitting around and doing nothing about climate change.

Question 3: What effect do unmitigated greenhouse gases have on the climate?

The higher the levels of greenhouse gases in the atmosphere, the hotter it is. Rising temperatures may produce changes in precipitation patterns, storm severity, and sea level. The Earth being hotter could also result in more polar ice melting. This lowers the albedo resulting in even less solar radiation being reflected back into space, making the ice melt even faster. This is called ice-albedo feedback.

Question 4: What is albedo and what effect does it have on the climate?

Albedo is the percentage of solar radiation that is reflected off of any object back into space. The darker an object is, the lower it’s albedo. The lower the planetary albedo is, the less solar radiation is reflected back into space, meaning that the Earth warms up more. (Planetary albedo is the average albedo of all of Earth’s surfaces). 

Question 5: What are aerosols and what effect do they have do the climate?

Aerosols are small particles suspended in the atmosphere. They are rarely visible to humans, yet they have a significant impact on climate and weather, among other things. But despite being a pollutant, aerosols actually cool down the atmosphere slightly. However, aerosols such as sulfur dioxide are not the best choice for slowing down climate change, due to their effect on human health.

Independent variable:  

What I put in each jar.

Dependent variable:

The temperature of each jar after twenty minutes.

Controlled variables:

-The distance between the jar and the lamp

-The amount of time each jar is exposed to light

-The temperature of each jar before it is exposed to light

-The brightness of the light

Base Procedure

1. Stack ice cream tubs on top of each other near outlet. Place jar on top of tubs.
2. Plug lamp with 90 watt bulb into outlet. Position lamp to be roughly 7.5cm away from top of jar.
3. Cut small piece of paper just big enough to block light from directly hitting bulb of thermometer. Tape to thermometer blocking light from hitting bulb.
4. Tape thermometer to lid of jar.
5. Put lid on jar.
6. Wait 20 mins. 
7. Check temperature.

CO2:

1. Place shot glass on scale. Measure 2 grams of baking soda into it.
2. Place mini-pitcher on scale. Measure 28 grams of vinegar into it.
3. Wrap an elastic band around shot glass. 
4. Wrap an elastic band around each prong of tongs and use them to put shot glass in jar.
5. Pour vinegar into shot glass without spilling any vinegar in jar. 
6. Wait until most of vinegar and baking soda has reacted. Test by lighting lighter and putting in jar. If it goes out, there is enough CO2 in the jar.
7. Take shot glass out of jar using tongs.
8. Continue with base procedure. 

Paper: 

1. Cut paper to fit in jar. Cut an extra window to see thermometer and a circle to go at bottom of jar. Make sure light can still shine into jar.
2. Put paper in jar without crushing it. Make sure window lines up with thermometer.
3. Proceed with base procedure.

Calcium carbonate: 

1. Ground chalk to fine dust.
2. Measure 3 grams of this dust into jar.
3. Now proceed with base procedure.

Note: During these experiments, jar must be shaken every 2 minutes.

Solar geoengineering by both aerosols and increasing albedo lower the increase in temperature. However, increasing the albedo is more effective than aerosols. It is a bit hard to tell how much of a cooling effect the aerosols had as they weren’t consistently floating in the jar. One thing that did surprise me was that the jar with white paper was hotter than the jar with nothing. It’s possible it was because the light was being reflected back into the jar with the white paper in it, whereas with nothing, a lot of the light could just pass right through the glass. The jar with CO2 and black paper seemed to represent most closely the current state of the Earth, and the jar with CO2 and white paper seems to model what the Earth would be like if we painted everyone’s roof white and had white asphalt. 

Solar geoengineering by both aerosols and increasing albedo lower the increase in temperature. However, increasing the albedo is more effective than aerosols. It is a bit hard to tell how much of a cooling effect the aerosols had as they weren’t consistently floating in the jar. One thing that did surprise me was that the jar with white paper was hotter than the jar with nothing. It’s possible it was because the light was being reflected back into the jar with the white paper in it, whereas with nothing, a lot of the light could just pass right through the glass. The jar with CO2 and black paper seemed to represent most closely the current state of the Earth, and the jar with CO2 and white paper seems to model what the Earth would be like if we painted everyone’s roof white and had white asphalt. 

We could increase planetary albedo by making everyone’s roof white, which would in turn reflect more solar radiation and cool down the planet. However, in colder climates like ours, this might not be the best idea as it could result in less snow melting off of roofs. We could also use stratospheric aerosol injection to reflect more solar radiation. If we do in fact decide to do this, however, we must use the right aerosol. Some of them are dangerous for human health.

-It’s hard to check the temperature of the jars at exactly 20 minutes, so it’s possible the temperature isn't always exact

-The paper can’t be put in exactly the same spot for each paper trial, again meaning it’s possible the temperature isn’t always exact

-The scale I used didn’t measure milligrams, so things like chalk dust and CO2 mixtures weren’t always accurate

-For many trials vinegar spilled while making CO2, fogging up the jar during trials, therefore I often had to take the thermometer out of the jar to read it

-While making CO2, some CO2 was removed from the jars by removing the shot glass, but it wasn’t necessarily the same amount every time

-The calcium carbonate isn’t always all floating in the jar, making it hard to know what the true effect of the aerosol is

https://www.un.org/en/climatechange/what-is-climate-change

https://www.technologyreview.com/2019/08/09/615/what-is-geoengineering-and-why-should-you-care-climate-change-harvard/

https://www.epa.gov/climate-indicators/greenhouse-gases

https://science.nasa.gov/climate-change/effects/

https://mynasadata.larc.nasa.gov/mini-lessonactivity/what-albedo

https://scied.ucar.edu/learning-zone/how-climate-works/albedo-and-climate#:~:text=Understanding%20how%20much%20energy%20from,the%20climate%20gets%20even%20cooler.

https://earth.gsfc.nasa.gov/climate/data/deep-blue/aerosols

https://science.nasa.gov/science-research/earth-science/climate-science/aerosols-small-particles-with-big-climate-effects/

https://www.chartgo.com/home.html

I would like to thank my parents for helping me edit my wording, print the papers for my trifold, cut and glue said papers, and buy the required materials for my project. I would also like to thank Mme Wafa Boussaha for pushing me to make my project one that would get an Advancing or a Mastering. Lastly, I would like to thank my sister, for encouraging me whenever I felt discouraged.