What is the Greenhouse Effect?
The exchange of incoming and outgoing radiation that warms the earth is known as the greenhouse effect. The gases that take part in this process are called greenhouse gases.
Earth is continuously bombarded with a large amount of radiation from the sun. We receive these radiations in the form of heat and light energy.
This radiations in the form of visible, UV, and infrared have to first pass the earth’s atmosphere before reaching the surface.
The ozone layer present in the earth’s atmosphere blocks some amount of UV rays from reaching the surface. Of the remaining rays reaching the surface, partly absorption takes place by the earth.
The infrared rays are reflected back into space. But some gases in the atmosphere trap this heat radiation and emits it to the surface. This leads to heating up of the environment. This exchange of incoming and outgoing radiation that warms the earth is known as the greenhouse effect.
And the gases involved in this entire process are known as greenhouse gases. They mainly include carbon dioxide, methane, water vapor, and CFC.
Greenhouse Effect, necessary for Life.
You may be wondering why it is known as the greenhouse effect. Does it have something to do with the greenhouse? If you said yes, you are thinking in the right direction.
A greenhouse is a glass building where plantation takes place in controlled environmental conditions. Now, consider the planet. The atmosphere acts as glass and traps the heat.
The greenhouse effect is very necessary to keep our planet alive and warm. In the absence of this effect, the temperature of the earth’s surface would have been between 20 to 40-degree centigrade.
But too much of something is bad. If plants in the greenhouse receive an excess of heat, they would burn. And if we consider planet earth, over the last two centuries human actions have changed the atmosphere of the earth in a dramatic way.
The number of greenhouse gases has increased and is still increasing. They trap too much heat. And this excess of greenhouse effect results in global warming. Which results in an overall increase in the average temperature of the earth.
Global Warming Effects are Enormous.
The effects of global warming are not limited to one country. It would affect the entire planet. Knowing the fact that global warming exists and human carbon dioxide emissions have caused it.
Following are the effects of global warming
• Change in animal migration and life cycle.
• Less snow and ice.
• Thawing Permafrost.
• Change in the plant life cycle.
• More droughts and wildfire, warmer oceans.
• Higher temperature and heatwaves, rising sea levels.
• Changing rain and snow patterns.
• Stronger storms.
• Damaged corals.
Climate Change is Happening and Why We are Causing it.
The sun is the source of warmth on earth. Ice and clouds reflect some of the light. But the rest is absorbed by land and water and emitted in the form of heat.
Some of this heat escapes earth and rest is trapped by the greenhouse effect of earth. It is because of the greenhouse effect that life exists on earth as we know it.
But human activities have increased the concentration of greenhouse gases on earth causing climate change.
Carbon dioxide concentration has increased by 40 percent since the industrial revolution. Since 1970 the temperature has increased fastest and solar activity have moved in the opposite direction.
If it were the sun to blame, the upper and lower layer of the atmosphere had to heat up together. But we see only the lower layer heating where the human-generated greenhouse gases are piling up.
Since 1870, increased fossil fuel consumption, cement production, and land used combined have put up 200 gigatons of carbon dioxide in the atmosphere. And about 40 percent has stayed there.
Studying gases trapped in the ice cores has let us see how the atmosphere of the earth was in the past.
At 400 ppm, today’s carbon dioxide levels are almost highest for the past million years. 800,000 years ago they were 190 ppm. More carbon dioxide in the atmosphere means average temperature across the globe is increasing fast.
Right now the earth is warming at a rate 10 times faster than that at the end of the ice age.
So Carbon Dioxide is Increasing. How do we Know it is Our Fault?
The best evidence comes from looking at what different kinds of carbon isotopes are there in the atmosphere. Fossil fuel comes mainly from all plants.
Plants prefer to use lighter carbon isotopes such as carbon-12 over the heavier carbon-13 so they contain a higher ratio of carbon-12 to carbon-13 in the atmosphere.
When more fossil fuel gets to burn the percentage of carbon-12 in the atmosphere should go up and that’s what exactly we see. And that is not because of volcanic activities.
Volcanoes only generate as one percent of carbon dioxide as we do. normally that carbon dioxide is balanced in the exchange between atmosphere, plants, and animals.
But continuous deforestation has released centuries worth of carbon dioxide just in few years. Other greenhouse gases are also increasing. like methane from farming and natural gas processing and nitrous oxide from fertilizers.
When we run simulations just using natural causes of climate change, they predict no change or even cooling in the 20th century and that is not happening.
It is getting colder in some places but since 2000 there were as many as twice places recording higher temperatures as against low-temperature places. The past three decades have been warmer than any other decade since we started measuring temperature.
Since 1900, the average temperature around the world has increased almost a full degree and most of that has happened since 1970. Looking from the tree rings and ice cores, the past 30 years are the warmest in the last 8 centuries.
Of course, not every place on planet warms equally. Oceans cover 70 percent of the earth’s surface and they absorb more than 90 percent of the heat added to the planet. That’s the place where we see the most extreme changes.
Effects of Rising Levels of Greenhouse Gases on Water Bodies
Around the world, water levels in the oceans are rising at one-tenth of an inch per year and they have risen by 8 inches since 1900.
Water expands as it warms. When ice sheets and glaciers melt in Greenland and Arctic, the water present in the form of ice gets into the ocean.
The oceans are the earth’s largest carbon heat sinks. As more carbon dioxide enters the atmosphere more of it enters the oceans. Making the water in the oceans more acidic, this doesn’t mean the oceans are made of acids.
But organisms with calcium shells are super sensitive to ph. The ph around the world could rise to 7.8 by the end of the century. This could wipe one-third of the ocean species.
We also know that the level of summer sea ice in the Arctic has decreased by 40 percent since 1978, they might be the lowest level since the past 1400 years.
That white sea ice reflects the solar energy back to the atmosphere. But, the oceans around the world trap the sun rays. If carbon dioxide emissions continue on their current course, the earth will become hotter by 2.6 to 4.8 degrees.
The oceans could be a meter higher by the end of the century. Is that a big deal? Yes, it is the biggest deal. It is by far the greatest issue that our species faces. The last time earth went few degrees colder, most of North America got covered in miles of thick ice. That many degrees warmer, we gonna have a bad time.
Climate Change, Causes and Effects
Industrialization and overpopulation are causing the global temperature to rise. And fundamentally changing the world around us leading to climate change. The main causes of the phenomenon known as the greenhouse effect.
Gases in the atmosphere such as water vapor, carbon dioxide, methane, nitrous oxide and CFCs let the sun lights in but keep some of the heat from escaping like the glass walls of a greenhouse.
The more greenhouse gases present in the atmosphere, the more heat gets trapped strengthening the greenhouse effect and increase the temperature of the earth.
Human activities such as the burning of fossil fuel have increased the amount of carbon dioxide in the atmosphere by more than 40 percent since the industrial revolution.
The continuous increase in the number of greenhouse gases is heating the planet. While earth climate has fluctuated in past, atmospheric carbon dioxide hasn’t reached today’s levels in hundreds of thousands of years.
Climate change has consequences for our oceans, weather, food resources, and our health. Ice sheets such as Greenland and arctic are melting.
The extra water once held in the glaciers causes the sea levels to rise and spills out of the oceans leading to flooding in coastal regions.
Warmer temperature also makes the weather more extreme. This means not only intense major storms, floods, and heavy snowfalls but also longer and more frequent droughts. These changes in weather pose challenges.
Effects of Climate Change
Growing crops becomes difficult. The area where plants and animals can live. Water supplies get into a diminishing state. In addition to creating new agricultural challenges, climate change directly affects the physical health of people.
In urban areas, the warmer atmosphere creates an environment that traps and increases the amount of smog.
Exposure to higher levels of smog can cause health problems such as asthma, heart disease, and lung cancer. While the rapid rate of climate change is due to humans, humans are also the ones who can combat it.
If we work to replace fossil fuels with renewable sources of energy sources such as solar and wind that do not cause greenhouse gas emissions, we still might be able to reverse the threats caused by climate change.
What can we do??
How can we contribute to reduce global warming and avoid its consequences?
Well planting More number of trees, reducing waste generation, reducing the use of products which generate greenhouse gases, using energy-efficient appliances, increasing the fuel efficiency of the vehicles, using more renewable energy sources.
All these practices lead to greener ways of life. these practices cause less harm to the environment. Many nations of the world came together to sign the Kyoto Protocol, an international treaty.
The major objective of this protocol is the commitment to reduce greenhouse gas emissions by about 5 percent by the 1990 levels. The 2nd phase of commitment is in the year 2008 to 2012 and the third phase in 2013 to 2020 which is the Doha amendment.