Reference to the above titled letter by Vijdan Saeed in the Nation of Apr 01, I would like to add that ‘Earth Hour’ is not only about saving electricity, which we are already doing for many hours every day, it is also about how we are generating electricity. Earth Hour is meant to create awareness about the electricity we use which is being generated by burning fossil fuel like oil, gas and coal which emits green house gases like carbon dioxide, which forms an envelope around the earth. Much like a green house in a garden, these gases prevent solar radiation from escaping to the atmosphere and reflects it back to the earth. This is what causes global warming and climate change and brings about floods and droughts.

Another aspect of global warming is that 70 percent of solar radiation is reflected back to the atmosphere, from the polar ice caps, and only 30 percent is absorbed by the ice. On the other hand 70 percent is absorbed by the seas and only 30 percent is reflected back. As the polar caps shrink, because of global warming and the seas expand, the amount being reflected back gets less and less. However, most of what is reflected is reflected back by the green house gases, setting up a vicious cycle. The rapid melting of the ice caps is also causing the sea levels to rise which is a danger signal for coastal cities like Karachi.

We urgently need to move away from fossil fuels to the alternate sources of energy, of which hydel energy, is the only one that can give us clean energy in the desired quantities and also give us water, which none of the other alternate sources will give.

ENGR KHURSHID ANWER,

Lahore, April 1.