Ecological issues

Lesson aims…  Have you ever wondered how human kind impact the environment?  How do we change our natural habitat ?  And what can we do to reverse damages in environment ?

What is global warming?  Global warming and climate change are terms for the observed century-scale rise in the average temperature of the Earth's climate system and its related effects.

Factors causing global warming?  Natural causes:  Greenhouse effect  Natural disasters  Slow tilting of Earth axis  Anthropogenic causes:  Respiration  Mining activities  Rapid industrialization  Increased automobile use

The greenhouse effect

The greenhouse effect - mechanism  Earth receives energy from the Sun in the form of ultraviolet, visible, and near-infrared radiation. Of the total amount of solar energy available at the top of the atmosphere, about 26% is reflected to space by the atmosphere and clouds and 19% is absorbed by the atmosphere and clouds.  Most of the remaining energy is absorbed at the surface of Earth. Because the Earth's surface is colder than the photosphere of the Sun, it radiates at wavelengths that are much longer than the wavelengths that were absorbed.  Most of this thermal radiation is absorbed by the atmosphere, thereby warming it. In addition to the absorption of solar and thermal radiation, the atmosphere further gains heat by sensible and latent heat fluxes from the surface.  The atmosphere radiates energy both upwards and downwards; the part radiated downwards is absorbed by the surface of Earth. This leads to a higher equilibrium temperature than if the atmosphere were absent.

The greenhouse effect gases By their percentage contribution to the greenhouse effect on Earth the four major gases are:  water vapor, 36–70%  carbon dioxide, 9–26%  methane, 4–9%  ozone, 3–7%

Effects of increased greenhouse gas emissions  Global Warming  Desertification  Increased melting of snow and ice  Sea level rise  Stronger storms and other extreme weather conditions  Ocean Acidification  Changes to plant growth and nutrition levels  Smog and ozone pollution  Ozone layer depletion

Ocean Acidification  Increases in carbon dioxide levels have made the world's oceans 30% more acidic since the Industrial Revolution. The ocean serves as a sink for this gas and absorbs about a quarter of human carbon dioxide emissions, which then goes on to react with seawater to form carbonic acid. So as the level of carbon dioxide in the atmosphere rises, the acidification of the oceans increases.

Changes to plant growth and nutrition levels  Since plants need carbon dioxide to grow, if there are higher amounts in the air, plant growth can increase. Experiments where carbon dioxide concentrations were raised by around 50% increased crop growth by around 15%. Higher levels of carbon dioxide makes carbon more available, but plants also need other nutrients (like nitrogen, phosphorus, etc.) to grow and survive. Without increases in those nutrients as well, the nutritional quality of many plants will decrease. In different experiments with elevated carbon dioxide levels, protein concentrations in wheat, rice, barley, and potato tubers, decreased by 5-14%.

Smog and ozone pollution  Over the last century, global background ozone concentrations have become 2 times larger due mainly to increases in methane and nitrogen oxides caused by human emissions. At ground level, ozone is an air pollutant that is a major component of smog which is dangerous for both humans and plants.  Long-term ozone exposure has also been shown to reduce life expectancy of annual premature cardiopulmonary deaths worldwide are attributable to ozone. Recent studies estimate that the global yields of key staple crops, like soybean, maize (corn), and wheat, are being reduced by 2- 15% due to present-day ozone exposure.

Ozone layer depletion  Nitrous oxide damages the ozone layer and is now the most important ozone depleting substance and the largest cause of ozone layer depletion. This is because CFCs and many other gases that are harmful for the ozone layer were banned by the Montreal Protocol (MP) which has reduced their atmospheric concentration. Nitrous oxide is not restricted by the MP, so while the levels of other ozone depleting substances are declining, nitrous oxide levels are continuing to grow.

Bibliography.  Charles J Krebs, „Ecology”  Ewa Symonides, „Ochrona przyrody”  Bożena Dobrzańska, Grzegorz Dobrzański, Dariusz Kiełczewski, „Ochrona Środowiska przyrodniczego”

Additional websites…   warming-overview/ 

Thank you for your attention The presentation prepared by Michał Ignatiuk, the teacher of Biology, I LO im. Tadeusza Kościuszki, Włodawa.