(E) Since the start of the industrial revolution in the 1820s, human combustion of fossil fuels and destruction of forests have increased the concentration of carbon dioxide (CO2) into the atmosphere by 35% from 280 parts per million (ppm) to 380 ppm today. CO2 is an occurring gas emitted naturally by volcanoes in the Earth’s atmosphere. If you remember your high-school chemistry class, fossil fuels are mostly composed of carbon (C) and hydrogen (H) in varying (and some time complex) proportions. When burned, the carbon of the fossil fuel (C) combines with the air oxygen (O2) to produce the carbon dioxide (CO2) and its hydrogen (H) with the air oxygen (O2) to produce water (H2O). Similarly, when burned, trees and plants convert their carbon (absorbed from photosynthesis) with the air oxygen into CO2. And so by replacing forest lands by farmlands, deforestation has the same CO2 effects as burning gasoline when driving. Fossil fuels presently contribute to 80% while deforestation contributes to 20% of the total CO2 emissions.

The Greenhouse Effect

The greenhouse effect of carbon dioxide, methane (CH4), nitrous oxide (N2O), water vapor, and a few other gases  (fluorinated gases HFCs and PFCs) is to keep the heat energy from the Earth. Greenhouse gases are transparent to the sun ultraviolet radiations (that are short wavelengths) that warm the Earth. But as the surface of the Earth reflects those radiations back to space into infrared radiations (long wavelengths), a process called albedo, the energy of those infrared radiations are absorbed by the greenhouse gases keeping the heat in the atmosphere. While water vapor can disappear in days from the atmosphere, the lifetime of CO2 in the atmosphere can range from 50 to 200 years!

Before the first industrial revolution, half of the greenhouse gases produced by the Earth ecosystems were reabsorbed by the natural “sinks” of the oceans, the trees, and the plants. Life on earth could not have existed without natural greenhouse gases that kept the Earth warm enough. But human activity released around 36 billion tons of greenhouse gases in 2007, half went into the atmosphere and a half was absorbed by the sinks. There have been now a greater concentration of greenhouse gases into the atmosphere than there have been for up to 800,000 years. The rate of this change does not give any time to any species on Earth to change the path of its Darwinian evolution to adapt. We have altered the biosphere in a few decades in ways that would have naturally taken 1,000 years or more.

The Climate Sensitivity

Assuming that the current annual growth rate of carbon concentration stay at 2 ppm, by 2100, the concentration of CO2 will double to 560 ppm. But if you take into account the rapid economic growth of China, India and other developing countries, the present concentration of CO2 will not double in 2100 but in 2050 – and this could even come earlier if some positive feedbacks kick in (such as CO2 naturally sequestered by the oceans and the lands that could be released by warmer temperatures)! Since 1850, the Earth has already experienced an average near-surface temperature increase of 0.8 0C (or 1.4 0F). A doubling of CO2 will increase the average temperature from 2 to 4.5 0C (or from 3.6 to 8.1 0F). 2 0C or 3.6 0F is considered in the scientific community as the tipping point beyond which climate change becomes uncontrollable.

The Consequences of Climate Change

The consequences of climate change have been described in details in many publications and briefly include:

• Rising ocean levels due to the thermal expansion of seawater and the melting of the ice of the North and South Poles;
• Large-scale extension of the most vulnerable species, in particular, those with constrained habitat ranges or limited mobility to adapt to new lands;
• New types of diseases and increase of disease transmission due to higher temperatures and decline in rainfalls;
• Decrease in agricultural productivity due to altered seasons, rainfall patterns and biodiversity;
•  Decrease of water availability due to increase evaporation, changes in rainfall patterns and river flows;
• Increase destruction from natural hazards in particular flooding and droughts;
• Acidification of the oceans and waters due to rising CO2 that will change the ocean chemistry and alter marine biodiversity.

Can we Change the Course of Climate Change?

According to Jeffrey Sachs in 2007 fossil fuels contributed to 81% of the CO2 emissions and deforestation to 19%. More precisely, production of electricity generated 32%, industry 22%, transportation 18%, residential and commercial 9%.

So if we just start producing electricity with solar, nuclear and wind energy instead of coal and natural gas and if we stop deforestation, we could reduce the emissions by 51%. If half of our transport systems, in particular, our cars would be electric, we could reduce the emissions by 60%.  And through the use of renewable energy and more efficient energy savings, we certainly could take care of the remaining 40%. The numbers do not lie: there is significant room, if not eliminating completely, at least significantly reducing CO2 emissions.

We need to modify our behaviors, stop changing the climate, and transitioning quickly to a global society where environmental sustainability is the first priority for everyone.

References
• Intergovernmental Panel on Climate Change,  Fourth Assessment Report, 2007
• Nicholas Stern, the Economics of Climate Change, Cambridge University Press
• Jeffrey Sachs, Common Wealth, The Penguin Press.

Note: The picture above is one of my paintings.

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