When did you see a sparrow last time? I remember when I was a child, herds of sparrows used to visit my terrace and my mother used to feed them each morning. I loved their chirping melodies. Their chirps brightened up my day. My mother used to whistle and there was always a sparrow whistling back to her. But gradually with time, the number of sparrows visiting us declined and I didn’t realize as the time went by they just stopped turning up. According to the latest data catalogue of the world bank, 4,393 bird species are being considered as threatened species. Something has gone wrong!
Is climate change real?
The average temperature of earth has increased about two degrees since 1880. This number might seem small, but it is quite high as an average for the entire earth.
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Our planet is changing for sure. I’ve seen three decades in my life so far and within this short span, I have seen the earth changing. I have seen villages changing to cities, lush-green farmlands changing to buildings of concrete. Alas! I have seen the sparrows disappearing! Alongside, there have been drastic changes in weather patterns and average temperatures of the world. Although the earth’s climate has changed throughout history due to various natural causes, experts believe that earth is currently under pressure as the climate is changing much more rapidly than at any time before. The average temperature of the earth has increased by about two degrees since 1880. This number might seem small, but it is quite high as an average for the entire earth.
The Arctic is warming up. The polar ice has started to melt and the ocean levels are rising at an incredible pace. And all this clearly seems to be having an impact on the lower latitudes. Our summers are getting hotter and winters are being clutched by extreme cold snaps. With the ever-increasing human population, unregulated urbanisation and rapid industrialization, the fate of our planet’s changing climate is difficult to predict. The Intergovernmental Panel on Climate Change (IPCC), an important scientific body set up by the World Meteorological Organization (WMO) and United Nations Environment Programme (UNEP) in 1988, releases a report on scientific evidence of climate change every five to six years’ time. Most scientists believe that the current state of the earth’s climate is a result of human activities that expand the ‘greenhouse effect’.
What is the greenhouse effect?
To understand what the ‘greenhouse effect’ is, let me give you an example from our day-to-day lives. You may have observed that during the summer months if you park your car under direct sunlight and return to the car after a few hours, the temperature inside the car becomes hotter than outside. This is because the windows of your car allow the sunlight to enter your car, the light gets converted into heat. The heat gets trapped by the window glass. The same concept is utilized in a greenhouse that is used to grow plants under controlled conditions. The walls of such a greenhouse are made of materials (usually glass) that allow the sunlight to enter freely but only allow a minimal amount of heat to escape. Earth’s atmosphere acts as a greenhouse. This property of the earth’s atmosphere is because of some of its special component gases including carbon dioxide, methane, water vapour, ozone, nitrous oxide amongst others. The sun’s rays infiltrate through the atmosphere. A part of this light energy is absorbed by the earth’s surface. In return, the earth’s surface radiates back the infrared radiations which we feel as heat. These radiations rise back to the upper layers of the atmosphere where a layer of the so-called ‘greenhouse gases’ acts as a thermal blanket to trap the heat radiations and a part of these radiations is re-emitted to upper atmospheric layers and back into space. For the temperature of the earth to remain constant over time, the solar energy absorbed by the earth’s surface must be in perfect balance with the rate at which infrared radiations are lost to outer space.
So, why is the climate changing?
The credit goes to the ‘Enhanced Greenhouse Effect’. If we had a very low greenhouse effect in operation, our earth would have been like Mars on which the average surface temperature is -63 degrees Celsius. On the contrary, if we had an excess of the greenhouse effect, our earth would have been very hot like Venus which has surface temperatures reaching up to 460 degrees Celsius. We got lucky that our planet has managed to maintain an optimum greenhouse effect so far, thereby sustaining life. However, in the post-industrial era, human activities have started to have an impact on the earth’s natural balance in unprecedented ways. Climate scientists have observed that the greenhouse gas emissions due to human activities have increased ‘significantly’ over the past century causing what is called the ‘Enhanced Greenhouse Effect’.
If we talk about the figures, according to the United States Environment Protection Agency, there has been an observed 35% increase in greenhouse gas emissions between 1990 and 2010. Such a massive increase in just 20 years! Isn’t this alarming? Climate change is not a concept that has come into being in these 20 years; the concentration of greenhouse gases in the earth’s atmosphere has certainly changed to some extent throughout history, thereby changing the earth’s climate several times. But this change has always been at an extremely slow pace.
But, what about the heat absorbed by the oceans?
We know that about 71% of the earth’s surface is covered by oceans. The heat capacity of water is about a thousand times greater than that of air. Hence, our oceans have been acting as huge heat buckets, thereby, playing a key role in cooling off the entire planet and affecting the weather patterns. Record increase in greenhouse gases means that the atmosphere is trapping a massive amount of heat and almost 80-90% of the extra heat from the earth’s surface is absorbed by the oceans. This has accelerated the rise in sea temperatures over the last few decades. Due to the thermal expansion of water, the sea levels are rising. The melting polar ice is further contributing to rising sea levels. Needless to say, rising sea levels could be a serious threat to life.
Read my next blogpost to know what’s contributing to climate change and what could be done to deal with it.
– Your ScienceBuddy Arohi
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Learning With Fun
Greenhouse Gas Attack– an interactive game by NASA; intended for making people aware of the greenhouse effect in a fun way
If you enjoyed reading this article, you might also like watching our ‘Climate Change Series’ on YouTube.
Image Credits (in order of occurrence in the post)
- Featured image for this article (climate change justice): Photo by Markus Spiske on Unsplash
- A sparrow: Photo by Sanjay Koranga on Unsplash
- Natural Greenhouse Effect: A snippet from a YouTube video by Sciency Soup
- Enhanced Greenhouse Effect: Another snippet from a YouTube video by Sciency Soup
- Ocean: Photo by Sithamshu Manoj on Unsplash
