Dear Students,

Congratulations on finishing the class on climate change!

I enjoyed teaching you and learned a lot in the process.

After correcting the answer papers, there were two common errors, which I though I would address here.

What is the most water-friendly form of protein? (Which source of protein takes the least amount of water to grow) (1 point)

Most of you answered “Millets”. This is not correct and here’s why.

Millets contain about 4 grams of protein for every 100 grams (http://nutritiondata.self.com/facts/cereal-grains-and-pasta/5702/2) compared with Soya at a median value of 16-19 grams of protein for every 100 grams of cooked soya.

Dry Soya kernels contain 35 grams of protein for every 100 grams. (http://nutritiondata.self.com/facts/legumes-and-legume-products/4382/2)

Further Millets take anywhere between 3300 and 4300 m3 of water/ ton to grow while Soya takes between 1800 to 3400 m3 of water/ton to grow. (http://www.waterfootprint.org/Reports/Report-48-WaterFootprint-AnimalProducts-Vol1.pdf)

So, Soya on a per gram protein basis is superior to millets. Millets, however, tend to be hardier and can grow in a more varied and drought prone environment.

The other common error involved

Consider the Earth’s Energy Budget at the surface. What are the aspects of the planetary system reflect the sun’s light? (3 points)

Most of you put down clouds and snow – both correct.

The Earth’s surface (land and water) are not great reflectors of light, they absorb the light, heat up and emit their own heat in the form of infrared radiation, which is not what the question was about.

The other parts of the planetary system that reflect light are Aerosols (not all types) and Ozone – that reflects ultraviolet radiation.

Averages and other statistics will be up soon.

Best wishes,

Mridula