The Warming Planet Earth

Geog410 Applied Climatology

Dr Ye

Evidence for global warming

Temperature-dependent phenomena(1) earth’s mountain glaciers are melting(2) Antarctica’s ice sheets are breaking up(3) Sea level is rising(4) Temperature of the ocean is rising(5) Northern hemisphere permafrost is melting(6) Arctic pack ice is thinning and retreating(7) Tree line in mountain ranges is moving upward(8) Tropical diseases are spreading toward the

poles and to higher elevations in the tropics

1. Temperature recordsSince 1880 the instrumental records began. Average surface temperature increases 0.7-

1.4F (0.4-0.8C) during the past century.

Most occurred during 1920-1990s.

Most warming occurred at night time temperature.

Growing season has increased by 11 days since 1970 in northeastern US

The length of snow cover has shortened in NH

The frequency of El Nino has increased in the past 25 years

2. Changes in plant and animal life

1. Adelie penguins in Antarctic dropped 40% in last quarter of 20th century (warmer temperature is harder for penguins to find food and breed)

2. Zooplankton declined 80% due to higher sea surface temperature of the coast of CA.

3. Coral reef are dying due to warmer temperature caused bleaching (death of microscopic algae that both color and feed the coral)

4. Changes in migratory patterns of the caribou in Arctic Wildlife Refuge in Alaska due to melting of permanently frozen ground

5. Rising sea levels inundating Maryland’s Blackwater Natural Wildlife Refuge, driving away many species of birds

6. Plants normally found at low elevations are appearing in the alpine meadows in Mount Rainier and Olympic National Parks

7. Unusual growth of spruce trees in Rocky Mountain National Park8. Sea birds have disappeared off west coast as offshore waters

become warmer

3. Spread of Tropical Diseases

Extremes of heat, cold, wet and dry have been frequent in recent years. Such extremes have often followed by outbreaks of diseases, insect pests, bacteria, protozoa, and viruses that spread the diseases. (malaria, cholera, yellow fever, the plague, dengue fever, hantavirus).

Example: rise 4F, anopheles mosquito (malaria) spread from 42% to 60% area and increases biting rates (doubled metabolism rate lead to feed more frequently).

1991 outbreak of cholera in coast of Peru and 1993 in Bangladesh due to heavy monsoon rain

Dengue fever epidemics in south America and Australia in 1990s

Hantavirus pulmonary syndrome (HPS) occurred in southwest of US after a long drought followed by heavy rainfall. HPS is a deadly disease from rodents. Humans can contract the disease when they come into contact with infected rodents or their urine and droppings. HPS was first recognized in 1993 and has since been identified throughout the United States. Although rare, HPS is potentially deadly. Rodent control in and around the home remains the primary strategy for preventing hantavirus infection.

Deer mouse

Aedes mosquito

anopheles mosquito

4. Melting of Earth’s Glacial Ice

The second largest iceberg ever recorded broken free from the Ross Ice Shelf and floated into the Ross Sea in March 2002 although temperature has not shown increases in Ross Ice Shelf (the largest was 1956).

In western Antarctic Peninsular, ice shelve have either broken up completely or are rapidly melting due to increasing air temperatures (4.5F between 1950-2000). Concern is removing these ice shelves will result in more rapid advances and faster melting of the glaciers. If Western Antarctic ice sheet melt, sea level will rise by 6 meters; if both Western Antarctic ice sheet and the Ross ice sheet melt, sea level will rise by 70 meters. (Breaking up ice shelves will not affect significantly affect sea level since (ice is 9% lower density than water) they are already floating in the water.)

5. Changing temperatures and rising sea levelsThe world ocean warmed by 0.06C (1F) from surface to 3000m

during 1955-1995. Indian ocean warmed 0.3C (0.5F) down to 800 meters in 20 years period.

If this storage of heat in water is released to atmosphere, it will increase global air temperature another 0.5C (0.9F) over the next century.

The warming in ocean water will rise sea level 10-25cm (5-10 inch) in 20th century due to thermal expansion.

If sea level rise by 1m, it will flood 5000 mile2 of dry land and 4000 mile2 of wetland.

Lake Superior was 20C above normal in 1998, increased evaporation drops water level. In 1999 the water level was the lowest in 30 years. Lake Huron and Michigan dropped 2 feet between 1988 and 1989. This will affect shipping, power generation, and other economic activities.

High temperature causes lake ecosystem changes. For example, undesirable organisms such as zebra mussels moved into lake, destroying existing native plants and animals. Warm water kills plankton on which higher life form depends. (less fish)

6. Thawing of permafrost20-30% of earth land contains

permafrost.In Alaska, the mean annual

temperature of the layer above the frozen subsoil rose 3.4C (6.3F) between 1980s and 1998 in the area north of Yukon River. Along boundary of areas of with or without permafrost, the permafrost is thawing at a rate of 3 ft/10 years. Most thawing occurred since 1980s.

In China, the permafrost is estimated to be thawing northward at the rate of 1 mile/year

Theory of global warming1. Changing level of CO2Seasonal change: peaks in spring and

minimum in late September or October (small in tropical area 5ppm; largest in middle latitude-more than 15ppm in Long Island, New York.

Irregular change: due to volcanic activities, change in rate of chemical weathering, changes in volume of vegetation on earth

Ocean stores 50 times more CO2 than atmosphere, The amount of CO2 ocean stores or release is depend on a variety of physical, chemical, and biological processes.

Historically, CO2 has been decreasing until about 50 million years ago. The present level exists about 34 million years.

Currently, since industrial time, it increases about 1.8ppm annual (0.5%) due to human activities

Theory of warming (continue)

The natural greenhouse effect of the atmosphere keep earth some 33C (59F) warmer than it would be otherwise.

Increase in CO2, more earth’s radiation will be absorbed, more radiation is radiated back to the earth’s surface, increases the storage of the energy on the earth, hence raising the temperature of the earth and atmosphere.

Sources: burning fossil fuel and natural vegetation to clear land for agricultural. Current global emission from energy use is 6 gigatons (Gic) of carbon each year; it is projected by year 2025, will increase to 8-15 Gic.

Three ways that deforestation and burning vegetation affect CO2:(1) Directly release CO2 into atmosphere(2) Reduce the removal of CO2 from atmosphere(3) Disturb soil processes that affect the CO2 exchange with atmosphere 40% of CO2 release to atmosphere is absorbed by biomass and ocean, the

rest remains in the atmosphere. Where do they go and how they can be removed?

Other contributions to global warming

Methane: 20 times more effective than CO2.Changes in methane can be studied through ice cores in Greenland

and Antarctic. 500ppb in 100,000 years ago; 650ppb at 70,000 years ago; 350ppb at 20,000 years ago (height of last glacial advance); mid-1990s, rose up to 1600ppb.

Sources: livestock raising, rice cultivation, industry, mining, and landfills.

Large amount of it trapped under the permafrost.The Chlorofluorocarbons (CFCs): 10,000 times more effective than

CO2 (now probably account for 25% of greenhouse effect even it is a very fraction amount)

Ozone in troposphere: 30 times more effective than CO2.Sources: nitro-oxides by aircraft engines.Thermal pollution: discharge of waste heat to atmosphere and ocean

by human energy consumption.

Future changesThe earth now is as warm as it has been anytime in the past 125,000 years. Natural

changes in temperature due to unknown interannual variations are as large as changes predicted due to changes in CO2

Global population and economic processes is now dominates changes in our atmosphere on a global basis

Mathematical models of atmosheric proceeses estimated T will increase 1.5C-4.5C (3F-8F) if CO2 doubles from pre-industrial level of 280PPM

There are other complex factors uncertain: SO2 that reflect solar radiation has cooling effect

High latitude warms2 or 3 times as much as equatorial regionsSea level will continue to rise (15-95cm (6-38in); uncertainty is the ice cap grow or

shrink? If warming not enough to raise temperature over ice above freezing, there might be increase in snowfall and glacial expansion (lower sea level)

In some areas, the rise of coastlines due to crustal decompression from last ice age is taking place faster than sea level rise, the net effect is lower sea level

More Uncertainties:1. Natural sinks for CO2 and future CO2 additions2. Role of clouds in a warmer climate is not fully understood3. Role of oceans on timing and pattern of climate change in is not understood.Certain: atmosphere will continue to warm for several centuries

IPCC (intergovernmental panel on climate change) by world meteorological organization and the UN environment program reports:

CO2 has been responsible for over half o the enhanced greenhouse effect in the past and is likely to remain so in the future

Long-lived gases CO2, N2O, CFCs adjust only slowly to changes in emissions. To stabilize concentrations at their present level, emission of these gases would need to be decreased by 60%

Civilization on this planet some 6000 years ago, the mean temperature has not varied more than 1C from the average. The forecast change in temperature from 1.5C to 4 C by 2100 has no equal in the recent history of the planet

In US, large oil, coal and automobile companies have maintained a continuous campaign to denounce the reality of global warming and advocate that no action should betaken to reduce carbon emission.