Greenhouse effect

Greenhouse effect


When seen from space, our planet Earth is a marvelous blue and white ball. It is the third planet from the sun and is the largest of the inner planets. Earth is the only planet that we know has life and liquid water on its surface. Its atmosphere consists of a mix of gases and a magnetic field, both of which are essential for the existence of life on Earth.

Earth’s climate has changed many times over the course of its history. This variation is due to natural changes, which have produced equilibrium between the solar energy that reaches it and the energy reflected by the Earth into space. Among the natural causes of these variations are volcanic eruptions, changes in the Earth’s orbit, changes in the angle of the pole of the Earth’s rotation in relation to the plane on which it orbits and variations in the composition of the atmosphere.

Recently, in the second half of the 20th century, the number of studies of environmental issues increased. Observations showed that the global temperature of the planet rose in the last century between 0.3 °C and 0.7 °C (almost one degree Fahrenheit). Because of this rapid increase, most scientists believe that beginning in the 20th century humanity has witnessed a new kind of climate change. The abrupt increase in the global temperature of the planet has been linked mainly to the increased emissions of greenhouse gases into the atmosphere.

What is the atmosphere?

The atmosphere is a layer of gases that covers our planet and is divided into five sub-layers: the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere. The first layer of the atmosphere is called the troposphere, where the temperature drops with altitude. This layer can reach to 12 to 15 kilometers and is where most of the atmospheric phenomena, such as vertical and horizontal movement of air masses (wind), take place. This layer has abundant quantities of water. The troposphere is the zone where clouds and climactic phenomena such as rain, wind, and changes in temperature occur, and it is the layer of greatest interest for ecology and for human life. In this layer, the temperature drops at higher levels until it falls to -70 ºC at the upper limit. The atmosphere consists of gases: nitrogen is the most abundant, at 78%; oxygen is 21%; the other 1% consists of other gases such as helium and argon, among others. Additionally, at higher levels the atmosphere becomes less dense until it gradually becomes space.

Earth's average temperature, 1999-2008

Earth’s average temperature, 1999-2008

What causes the Greenhouse Effect?

This effect takes place mainly in the troposphere, which is the region that allows solar rays of various frequencies to enter and warm the Earth. While the Earth warms, it also reflects heat, which allows it to cool. But when the atmosphere prevents the radiation from escaping to space and returns it to the Earth’s surface, the planet warms up. This phenomenon is called the greenhouse effect. The main gases in the greenhouse effect are carbon dioxide (CO2), methane (CH4), nitrogen oxides (NOx), water vapor, ozone (O3) and chlorofluorocarbons (CFCs), among others.

The greenhouse effect is produced both naturally and artificially. Natural causes include gases emitted by sources such as volcanoes, evaporation, etc. Artificial or anthropogenic (human) causes are mainly industrial processes, the use of automobiles, and the use of electric energy or, in other words, the use of petroleum products, also called fossil fuels, which change the composition of our planet’s atmosphere.
If it was not for the natural greenhouse effect, the Earth’s temperature would be -15 °C (5 °F), which would make our life on the planet difficult, because such cold temperatures could not produce food for humans and animals. However, this natural greenhouse effect makes the average global temperature a more agreeable 15 °C (59 °F). As a result of both phenomena — both natural and anthropogenic — the current temperature of the planet is approximately 18 °C (64 °F). This represents an increase of 33 °C (91 °F) in comparison to the Earth’s temperature 4.5 billion years ago when the planet formed, which leads us to believe that the warming of the Earth is mainly due to the use of fossil fuels by human beings.
In general, climate changes occur over millions of years when they are caused by natural causes such as astronomical or geologic effects. During the past century, however, the average temperature of the Earth has increased almost 1 °C (approximately 1.8 °F), a greater increase than that of the last 2,000 years. If the current rate of pollution and use of petroleum-derived fossil fuels continues, scientists estimate that by 2050 the temperature could increase as much as 2 °C (approximately 3.5 °F) and that would be catastrophic for the planet.

The main sources of greenhouse gases

Human activity has increased the emission of greenhouse gases. Among the activities that generate the highest emissions of pollutants are:

1. energy use;
2. the use of fossil fuels such as petroleum and its derivatives;
3.-concrete construction (this type of construction enormously increases the emission of carbon dioxide);
4. the use of refrigeration systems that emit large quantities of chlorofluorocarbons (CFC);
5. deforestation;
6. agriculture and land use;
7. livestock;
8. changes in wetlands; and others.

Thermohaline circulation

Thermohaline circulation

How do we know that the climate has changed?

Scientists have conducted studies of climate in the past. Paleo-climatology is the science of studying these climates of the past. Various branches of science are involved, including biology, oceanography, climatology, physics, chemistry and geology.

Paleo-climatology also includes study of the Earth’s crust, the landscape, fossil records, tree rings, pollen, coral and other elements in an effort to determine the history of the planet’s climactic variations. These studies also include historical research in order to better understand the effects of human activities on climactic processes. The best known examples of climactic changes have been the ice ages, the separation of the continents — better known as Pangea — the formation of islands, etc.

Today, the most recent climate predictions are made using powerful and sophisticated models of the climactic systems. Much of the research has centered on making the models capable of simulating the majority of the aspects of the current climate. It is also important to know how these models simulate climactic changes using data and observations from paleo-climatology and current observations. Paleo-climatology helps us improve the precision of the computer models used to simulate the climate of the future.

Effect of global warming on the planet

The increase in the average temperature of the planet’s surface has been such that the 15 hottest years occurred between 1990 and 2010. It is predicted that the impact of climate change will have three main effects:

1. an increase in the global temperature of the planet;
2. an increase in sea levels;
3. a reduction in the ice coverage of the continents.

Due to the melting of glaciers, sea levels will increase. Currently, some regions have seen an increase of between 4 to 8 inches since the middle of the past century and a resulting reduction in beach areas. Small islands will be greatly impacted by this effect. This will also affect the thermohaline circulation — the currents of warm water from the tropics to the poles and cold water from the poles to the tropics — which maintains the equilibrium of the planet’s ocean temperatures.

How will climate change affect Puerto Rico?

In the case of the island of Puerto Rico, global warming will increase the number of heat waves that last for a period of 24 to 72 hours. This will mainly affect people with respiratory ailments, especially children and the elderly. Another consequence of global warming is an increase in respiratory and infectious illnesses, such as dengue fever, the West Nile virus and others. Due to a proliferation of mosquitoes, other insects and rodents, diseases that were thought to be extinct will reappear. More frequent cold fronts will arrive from the north and cause cold temperatures in the winter, which means we would move toward climate extremes with hotter summers and colder winters.

The intensity and frequency of rain has also increased, due to increased evaporation from bodies of water (oceans, seas, rivers, lakes, etc.). This increased evaporation adds to the formation of cyclonic systems (hurricanes, storms, depressions, etc.) each year, producing greater floods and landslides that can cause great loss of life and property.

Other areas to be impacted are marine and coastal ecosystems, such as mangroves, coral reefs, etc. These are greatly affected by increased sea levels. Higher sea levels will also lead to salt intrusion in the wetlands and freshwater reserves (aquifers), and will affect mangroves and buildings (housing) close to the coasts.

As for the flora and fauna, they will also be affected by the increase in temperature, which could cause changes in their habitats. Among the species most sensitive are amphibians and reptiles, such as coquis, the Puerto Rican crested toad, sea turtles, etc.

What can we do to reduce the impact of global warming?

To reduce the effects of global warming will require efforts from various sectors, such as individuals, public and private businesses, as well as governments and institutions acting through various mechanisms such as the Kyoto Protocol, which has now been signed by 155 countries. This protocol is a mechanism designed by the United Nations (UN) to reduce emissions of pollutants into the atmosphere and, in turn, reduce the increase in the planet’s temperature. Institutions of all kinds and governments should make efforts to:

First, reduce the emission of pollutants. This is possible by reducing the amount of petroleum products consumed each day. We should commit ourselves to education aimed at:

a) Reducing the use of electricity; turning off appliances that are not being used and using appliances that save energy.

b) Trying to use renewable (green) energy by increasing energy generation through solar, wind, ocean thermal, etc.

c) Recycling, reusing and reducing the amount and the kinds of solid wastes.

d) Using water with awareness and not wasting it.

e) Using recycled paper.

f) Making appropriate use of cars and using public transportation or sharing rides when possible.

g) Reforesting cities and the countryside to help reduce carbon dioxide.

h) Using fluorescent lights.

i) Using solar water heaters.

j) Protecting aquatic and terrestrial ecosystems, which help absorb carbon dioxide.


Author: Rafael Méndez Tejada
Published: January 07, 2012.

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