Human-Caused Global Climate Change
A major controversy regarding the atmosphere and climate is whether or not, and the degree to which human activity is changing climate. For instance, the surface temperatures of the earth have been increasing, although the high degree of variability of temperature may mask any changes and can make their measurements controversial. Many scientists believe that the burning of fossil fuels and emissions of carbon dioxide from land clearing have added to the greenhouse effect that we already know greatly increases relative temperatures of the Earth. For instance, it is a matter of simply measuring the levels of carbon dioxide in the atmosphere over time that carbon dioxide levels all are increasing at a rate of about 0.5% per year.
Carbon dioxide levels are increasing
This figure, for instance, shows the measurement of carbon dioxide at the Mauna Loa observatory in Hawaii. The amount of carbon dioxide has been increasing steadily. Note also the annual changes in carbon dioxide that give the curve a saw tooth appearance. These seasonal changes are due to the difference between respiration in the Spring and Summer in northern temperate areas, which has a much larger land surface area than the southern temperate areas. When Rob took Botany 101 at the University of Maryland in 1974, he was taught that carbon dioxide was 330 ppm, and it is now over 370 ppm on the average.
Greenhouse Gases (GHG
Increases in carbon dioxide are considered to be the major contributor to global warming potentially caused by human activity, accounting for nearly two-thirds of global warming. Methane, a much more potent but rarer component of the Earth's atmosphere, accounts for about 19%, with chlorofluorocarbons, nitrous oxides and Sulfur hexaflourides showing smaller relative impacts.
Ozone depletion
result of human activities
CFCs (chlorofluorocarbons)
used widely as refrigerants, sprays
catalyze the destruction of
OZONE O3, a chemical that
protects life on earth from harmful radiation.
10% loss of ozone
worldwide causes more
skin cancer and cataracts
In 1985: discovered a significant thinning of the ozone layer over the Antarctic in Southern Hemisphere:
“ozone hole.”
Ozone in stratosphere shields the Earth from harmful UV radiation.
Chlorofluorocarbons are strongly implicated in the ozone reduction in the upper atmosphere.
CFC production
The figure above shows the reduction in production of chlorofluorocarbons since the Helsinki convention, which largely banned their production, was passed in 1989. Notice that some developing countries continue to produce increasing levels of chlorofluorocarbons, though not nearly at the rate that the industrialized countries of the world produced 15 years ago.
Global warming facts
Potentially able to damage life on Earth
Natural fluctuations in weather/climate - ice ages
- warm periods
1. Thinning Ice
a. Antarctica
b. Mt. Kilimanjaro
c. Lake Baikal
d. Montana
e. Venezuela
2. Hotter times
90 yrs – hottest decade
3. Wild weather
a. Heavy Rains
b. Fires
c. Floods
d. Hurricanes
Global warming facts (2)
4. Nature’s pain
d. Massive Seal death in Caspian Sea
~10,000 seals
Pacific salmon death (West Canada)
sea lice = fish parasites
b. Polar bears – habitat loss
c. Coral reefs: cyanide & explosive fishing, global warming
5. Rising sea levels
a. Caspian Sea by ~2.25 m 1978 – 1996
b. Florida, Maryland
c. North Sea, Baltic Sea
d. Brazil
Environmental disaster: open net-cage salmon farming industry, and associated proliferation of billions of lethal sea lice, that blight the coast of British Columbia, west Canada.
Outlook
Little chance of halting global warming (even if every country in the world adheres to Kyoto protocol tomorrow).
How to ward off disaster
Storing Carbon (CO2)
a. Planting trees
b. No-till agriculture
c. Sequestration –
fixation of CO2
d. Silicate rocks
eating CO2 -> carbonates
2. Alternate energy
a. Wind power
b. Solar power
c. Nuclear power
d. Fuel cells
Sequestration – different methods to capture and store CO2:
Coal burning plants: flue gases are condensed, water separated and CO2 is stored.
Mixing ocean, Peat formation
No-till - нулевая обработка почвы, гербицидная обработка почвы (без вспашки)
In no-till agriculture, farmers plant seeds without using a plow to turn the soil. Soil loses most of it carbon content during plowing, which releases carbon dioxide gas into the atmosphere. Increased levels of CO2 in the atmosphere are associated with global climate change.