Just why are we trying to reduce carbon “pollution”?

7 December 2009, By: David Walker, Executive Officer

There is now a strong agreement from scientists around the world that ‘normal’ rates of climate change are being accelerated by man’s activities. In particular they are referring to the emission of ever-increasing amounts of CO₂ (carbon dioxide) from power generation and industry around the world. Governments around the world are wrestling with how to respond to these changes, and how to mitigate them, so that catastrophic changes to natural systems can be avoided.

There is no argument that of course, carbon is a perfectly natural substance, a part of nature, and, through the Carbon Cycle, the basis for life on Earth.

The Carbon Cycle comprises the natural processes whereby Carbon changes form. I found a website at the University Corporation for Atmospheric Research that explains it all quite well (http://www.ucar.edu).

• Carbon moves from the atmosphere to plants. Through the process of photosynthesis, carbon dioxide is pulled from the air to produce food made from carbon for plant growth.
• Carbon moves from plants to animals. Through food chains, the carbon that is in plants moves to the animals that eat them. Herbivores include thousands of species, from elephants to termites. Animals that eat other animals get the carbon from their food too.
• Carbon moves from plants and animals to soils. When plants and animals die, their bodies, wood and leaves decay (food for another suite of organisms) taking the carbon into the ground. Some is buried and will become fossil fuels in millions and millions of years.
• Carbon moves from living things to the atmosphere. Each time you exhale (breathe out), you are releasing CO₂ into the atmosphere. Animals and plants need to get rid of carbon dioxide gas through a process called respiration. It’s how we get our energy
• Carbon moves from fossil fuels to the atmosphere when fuels are burned. When humans burn fossil fuels to power factories, power plants, cars and trucks, most of the carbon quickly enters the atmosphere as carbon dioxide gas. Each year, five and a half billion tons of carbon is released by burning fossil fuels. Of this massive amount, 3.3 billion tons stays in the atmosphere. Most of the remainder becomes dissolved in seawater.
• Carbon moves from the atmosphere to the oceans. The oceans, and other bodies of water, absorb some carbon from the atmosphere. The carbon is dissolved into the water, and the aqueous form of carbon is carbonic acid. Increased levels of dissolved carbon make the oceans more acidic.
• The problem is then, not that Carbon is a ‘bad’ thing, just that our natural systems are having trouble ‘digesting’ the extra amounts of CO₂ that we are producing.

According to Australia’s Chief Scientist, Professor Penny Sackett, there is a large body of scientific evidence to indicate that nearly all of the long-term increase of more than 35% (107 ppm, from 280 to 387 ppm) in atmospheric CO₂ concentrations since 1800 is due to anthropogenic (human) causes. Natural causes over this period contribute short-term variability on time scales of several months to a few years with transient amplitudes of about 10 ppm or less. According to Professor Sackett, these conclusions rest on data arising from ice core analysis, direct atmospheric CO2 measurements, careful accounting of the net amount of CO₂ released into the air by humans, and isotopic ``fingerprint’’ analysis of atmospheric and marine CO₂,

In sum, at any given moment in the present, about 90-99% of the industrial era change of 107 ppm in the atmospheric CO₂ concentration is due to human activity. The variability of this percentage is due to short-term, oscillatory natural causes. The much larger, steady long-term increasing trend is due to human activities.

The Carbon Cycle

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