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| Carbon dioxide scepticism! | | | Dr. Pragya Khanna | 6/14/2018 10:17:46 PM |
| Carbon dioxide is considered a greenhouse gas, but it's not essentially bad for the planet. We all know without it there would be no plant life and no animal and human life on earth. However, it is toxic at high concentrations. Carbon dioxide exists naturally in the Earth's atmosphere and as a greenhouse gas, it contributes to the Greenhouse Effect, the process by which thermal radiation from the planetary surface is absorbed by some atmospheric gases and re-radiated in all directions, thereby preventing the Earth from over-cooling. Without this biosphere, life on earth as we know it would not be possible.
We also know that animals breathe in oxygen and breathe out carbon dioxide. Plants, meanwhile, breathe in carbon dioxide and breathe out oxygen. So long as this cycle remains balanced, the system works. Unfortunately, however, the balance is progressively threatened. The concentration of carbon dioxide in the atmosphere has risen considerably since the dawn of industrialization.
The result is global warming. One causative factor is the burning of fossil fuels such as coal, oil and gas. Another is the ongoing destruction of natural areas such as forests, which creates a disproportion and inequity in the carbon cycle by preventing their continued function as carbon sinks and laying waste to entire ecosystems.
Conversely, in recent decades, select groups of scientists and politicians have blamed carbon dioxide (CO2), a greenhouse gas, for increasing the global temperatures to dangerous levels. In order to understand whether CO2 is destroying our planet, let's delve deeper. Carbon dioxide is an odorless, invisible, trace gas in the atmosphere that acts as an important source of life for everything that lives on earth. Being an integral part of the photosynthesis process, it is used by the plants along with water and sunlight to produce chemical energy that sustains the plant and is also the elixir of life for the animal kingdom.
Carbon dioxide is not the only naturally occurring factor that has the greenhouse effect, others include water vapor, methane and nitrous oxide. These gases help keep the Earth warm by absorbing the sun's energy and by redirecting energy back to the Earth's surface. Apart from photosynthesis, plants also help to remove excess carbon dioxide from the atmosphere in a process called carbon sequestration. The carbon dioxide is stored in biomass then released by the plant. In most cases, the amount released is less than the amount consumed by the plant. Farms, grasslands and forests are considered sources or sinks of carbon dioxide, depending on the practices on these lands. For example, cows produce methane, but grass on the farm sequesters the gas.
Carbon dioxide is essential for the survival of animals. Oxygen is carried to body tissue during breathing and carbon dioxide is released. The gas protects the pH level of blood. Too much carbon dioxide, however, can kill animals. If carbon dioxide is confined, it can decrease the amount of oxygen reaching the body. Any increase or decrease to the amount of carbon dioxide reaching the body can lead to kidney failure or coma.
An increase in the amount of carbon dioxide creates an overabundance of greenhouse gases that trap additional heat. This trapped heat leads to melting ice caps and rising ocean levels, which cause flooding.
Combustible fossil fuels such as coal, power plant gas, oil, vehicles and big industry are the largest source of carbon dioxide. The production is from various items such as iron, steel, cement, natural gas, solid waste combustion, lime, ammonia, limestone, cropland, soda ash, aluminum, petrochemical, titanium and phosphoric acid. Carbon dioxide accounts for nearly 85 percent of all emissions and is produced when natural gas, petroleum and coal are used. The major areas where these fuels are used include electricity generation, transportation, industry and in residential and commercial buildings.
Since scientists know which wavelengths of energy each greenhouse gas absorbs, and the concentration of the gases in the atmosphere, they can calculate how much each gas contributes to warming the planet. Carbon dioxide causes about 20 percent of Earth's greenhouse effect; water vapor accounts for about 50 percent; and clouds account for 25 percent. The rest is caused by small particles (aerosols) and minor greenhouse gases like methane.
Water vapor concentrations in the air are controlled by Earth's temperature. Warmer temperatures evaporate more water from the oceans, expand air masses, and lead to higher humidity. Cooling causes water vapor to condense and fall out as rain, sleet, or snow.
Carbon dioxide, on the other hand, remains a gas at a wider range of atmospheric temperatures than water. Carbon dioxide molecules provide the initial greenhouse heating needed to maintain water vapor concentrations. When carbon dioxide concentrations drop, Earth cools, some water vapor falls out of the atmosphere, and the greenhouse warming caused by water vapor drops. Likewise, when carbon dioxide concentrations rise, air temperatures go up, and more water vapor evaporates into the atmosphere which then amplifies greenhouse heating.
So while carbon dioxide contributes less to the overall greenhouse effect than water vapor, scientists have found that carbon dioxide is the gas that sets the temperature. Carbon dioxide controls the amount of water vapor in the atmosphere and thus the size of the greenhouse effect.
Rising carbon dioxide concentrations are already causing the planet to heat up. At the same time that greenhouse gases have been increasing, average global temperatures have risen 0.8 degrees Celsius (1.4 degrees Fahrenheit) since 1880.
The degree to which temperatures go up beyond that depends in part on how much more carbon humans release into the atmosphere in the future.
About 30 percent of the carbon dioxide that people have put into the atmosphere has diffused into the ocean through the direct chemical exchange. Dissolving carbon dioxide in the ocean creates carbonic acid, which increases the acidity of the water. Or rather, a slightly alkaline ocean becomes a little less alkaline. Since 1750, the pH of the ocean's surface has dropped by 0.1, a 30 percent change in acidity.
Ocean acidification affects marine organisms in two ways. First, carbonic acid reacts with carbonate ions in the water to form bicarbonate. However, those same carbonate ions are what shell-building animals like coral need to create calcium carbonate shells. With less carbonate available, the animals need to expend more energy to build their shells. As a result, the shells end up being thinner and more fragile.
Second, the more acidic water is, the better it dissolves calcium carbonate. In the long run, this reaction will allow the ocean to soak up excess carbon dioxide because more acidic water will dissolve more rock, release more carbonate ions, and increase the ocean's capacity to absorb carbon dioxide. In the meantime, though, more acidic water will dissolve the carbonate shells of marine organisms, making them pitted and weak.
Warmer oceans, a product of the greenhouse effect, could also decrease the abundance of phytoplankton, which grow better in cool, nutrient-rich waters. This could limit the ocean's ability to take carbon from the atmosphere through the fast carbon cycle.
Yet another interesting account suggests that plants on land have taken up approximately 25 percent of the carbon dioxide that humans have put into the atmosphere. The amount of carbon that plants take up varies greatly from year to year, but in general, the world's plants have increased the amount of carbon dioxide they absorb since 1960. With more atmospheric carbon dioxide available to convert to plant matter in photosynthesis, ideally plants are able to grow more. This increased growth is referred to as carbon fertilization.
Models predict that plants might grow anywhere from 12 to 76 percent more if atmospheric carbon dioxide is doubled, however, plants also need water, sunlight, and nutrients, especially nitrogen. If a plant doesn't have one of these things, it won't grow regardless of how abundant the other necessities are. Moreover, warmer temperatures also stress plants. With a longer, warmer growing season, plants need more water to survive, otherwise the plants become stressed.
Dry, water-stressed plants are also more susceptible to fire and insects when growing seasons become longer. In the far north, where an increase in temperature has the greatest impact, the forests have already started to burn more, releasing carbon from the plants and the soil into the atmosphere. Tropical forests may also be extremely susceptible to drying. With less water, tropical trees slow their growth and take up less carbon, or die and release their stored carbon to the atmosphere.
The warming caused by rising greenhouse gases may also "bake" the soil, accelerating the rate at which carbon seeps out in some places. This is of particular concern in the far north, where frozen soil, permafrost, is thawing. Permafrost contains rich deposits of carbon from plant matter that has accumulated for thousands of years because the cold slows decay. When the soil warms, the organic matter decays, and carbon in the form of methane and carbon dioxide seeps into the atmosphere.
Current research estimates that permafrost in the Northern Hemisphere holds 1,672 billion tons (Petagrams) of organic carbon. If just 10 percent of this permafrost were to thaw, it could release enough extra carbon dioxide to the atmosphere to raise temperatures an additional 0.7 degrees Celsius (1.3 degrees Fahrenheit) by 2100.
Hence, carbon dioxide has always been essential for our survival and also regulates the temperature of the earth. It is only human interference and activities that are manipulating the climate of the planet. |
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