impact of continued global warming

global changes

As greenhouse gases increase, changes will be more extreme. Oceans will become more acidic, making it more difficult for creatures with carbonate shells to grow, and that includes coral reefs. A study monitoring ocean acidity in the Pacific Northwest found ocean acidity increasing ten times faster than expected and 10% to 20% of shellfish (mussels) being replaced by acid-tolerant algae. Plant and animal species seeking cooler temperatures will need to move poleward 100 to 150 km (60 to 90 miles) or upward 150 m (500 feet) for each 1.0o C (8o F) rise in global temperature. There will be a tremendous loss of biodiversity because forest species cant migrate that rapidly. Biologists have already documented the extinction of high-altitude species that have nowhere higher to go. Decreased snow packs, shrinking glaciers, and the earlier arrival of spring will all lessen the amount of water available in some regions of the world, including the western United States and much of Asia. Ice will continue to melt and sea level is predicted to rise 18 to 97 cm (7 to 38 inches) by 2100 (Figure 1.3). An increase this large will gradually flood coastal regions, where about one-third of the worlds population lives, forcing billions of people to move inland. Sea ice thickness around the North Pole has been decreasing in recent decades and will continue to decrease in the com- ing decades. Weather will become more extreme, with more frequent and more intense heat waves and droughts. Some modelers predict that the midwestern United States will become too dry to support agriculture and that Canada will become the new breadbasket. In all, about 10% to 50% of current cropland worldwide may become unusable if CO2 doubles. You may notice that the numerical predictions above contain wide ranges. Sea level, for example, is expected to rise somewhere between 18 and 97 cm quite a wide range. What is the reason for this uncertainty? It is partly because scientists cannot predict exactly how the Earth will respond to increased levels of greenhouses gases. How quickly greenhouse gases continue to build up in the atmosphere depends in part on the choices we make. An important question people ask is this: Are the increases in global temperature natural? In other words, can natural variations in temperature account for the increase in temperature that we see? The answer is no. Changes in the Suns irradiance, El Nio and La Nia cycles, natural changes in greenhouse gas, and other atmospheric gases cannot account for the increase in temperature that has already happened in the past decades. Along with the rest of the worlds oceans, San Francisco Bay is rising. Changes are happening slowly in the coastal arena of the San Francisco Bay Area and even the most optimistic estimates about how high and how quickly this rise will occur indicate potentially huge problems for the region. Click image to the left or use the URL below. URL:

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temperature scenarios

Computer models are used to predict the effects of greenhouse gas increases on climate for the planet as a whole and also for specific regions. If nothing is done to control greenhouse gas emissions and they continue to increase at current rates, the surface temperature of the Earth can be expected to increase between 0.5o C and 2.0o C (0.9o F and 3.6o F) by 2050 and between 2o and 4.5o C (3.5o and 8o F) by 2100, with CO2 levels over 800 parts per million (ppm). Global CO2 emissions are rising rapidly. The industrial revolution began about 1850 and industrialization has been ac- celerating. On the other hand, if severe limits on CO2 emissions begin soon, temperatures could rise less than 1.1o C (2o F) by 2100. Click image to the left or use the URL below. URL: Whatever the temperature increase, it will not be uniform around the globe. A rise of 2.8o C (5o F) would result in 0.6o to 1.2o C (1o to 2o F) at the Equator, but up to 6.7o C (12o F) at the poles. So far, global warming has affected the North Pole more than the South Pole, but temperatures are still increasing at Antarctica (Figure 1.2).

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future warming

The amount CO2 levels will rise in the next decades is unknown. What will this number depend on in the developed nations? What will it depend on in the developing nations? In the developed nations it will depend on technological advances or lifestyle changes that decrease emissions. In the developing nations, it will depend on how much their lifestyles improve and how these improvements are made. If nothing is done to decrease the rate of CO2 emissions, by 2030, CO2 emissions are projected to be 63% greater than they were in 2002.

instructional diagrams

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questions

temperature increases are predicted to happen

a) uniformly around the globe.

-->  b) in the polar regions more than in the equatorial regions.

c) only in the polar regions.

d) only in the equatorial regions.

if nothing is done to shift society away from using fossil fuels,

-->  a) the rate of increase in emissions will continue to increase.

b) the rate of increase in emissions will slow down.

c) the emissions rate will remain the same.

d) the emissions rate will begin to decrease.

water shortages will become a problem in some areas because

a) drought will become more common and more severe.

b) groundwater resources will be reduced.

-->  c) reduced snowpack and earlier spring will reduce snowmelt as a summer water source.

d) all of these.

even an increase of global temperature of 1oc would make a difference to earths environment.

-->  a) true

b) false

global warming has affected the south pole more than the north pole.

a) true

-->  b) false

predictions for what will happen in the future with our climate

a) are well known and very accurate.

-->  b) are not well known, but the trends are clear.

c) are really unknown, no more than a guess.

d) will never be known.

temperatures are rising globally. how much they rise in the future depends on our actions in the next decades.

-->  a) true

b) false

the entire increase in global temperatures seen in the past two decades was caused by

a) an increase in the suns irradiance.

b) an increase in el nino and la nino cycles.

c) natural changes in greenhouse gas levels.

-->  d) none of these.

oceans are becoming more acidic, which means that

-->  a) organisms with carbonate shells will have a more difficult time growing.

b) marine organisms will move toward the poles.

c) temperatures will increase.

d) all of these.

a decrease in snow pack can cause a shortage of the summer water supply in many regions.

-->  a) true

b) false

diagram questions

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