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Global Climate Change

“Warming of the climate system is unequivocal.” – International Panel on Climate Change, Fourth Report

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Outline

• The Atmosphere and Climate Convection Currents Greenhouse Effect

• Weather Winds Frontal Systems Cyclonic Storms

• Climate El Nino Climate Change Kyoto Protocol

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The Atmosphere and Climate

• Weather - daily temperature and moisture conditions in a place

• Climate - a description of the long-term weather pattern in a particular area

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The Atmosphere and Climate

• Troposphere Ranges in depth from 18 km over the equator to

8 km over the poles.- All weather occurs here.

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The Atmosphere and Climate

• Stratosphere Very stable, calm layer of the atmosphere.

- Used by aircraft. From tropopause up to about 50 km

- Has almost no water vapor, but 1000X more ozone than the troposphere

- Ozone absorbs ultraviolet light, which warms upper part of stratosphere.

- Ozone protects all life on Earth since UV radiation damages living tissues.

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The Atmosphere and Climate

• Mesosphere Middle Layer

• Thermosphere Aurora borealis (northern lights)

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Layers of the Atmosphere

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Energy and the Greenhouse Effect

• Solar Radiation Of solar energy reaching outer atmosphere:

- 25% reflected- 25% absorbed- 50% reaches earth’s surface

Of the solar energy that reaches the surface, much is reflected (albedo):

- Fresh clean snow 90%- Dark soil 3%- Net average of earth 30%

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Energy and the Greenhouse Effect

• Most solar energy reaching the Earth is near infrared (short wavelength). Energy reemitted by the earth is mainly far

infrared radiation (long wavelength, heat)- Longer wavelengths are absorbed in the

lower atmosphere, trapping heat close to the earth’s surface.

Greenhouse Effect Atmosphere transmits sunlight while

trapping heat.

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Greenhouse Effect

Gases in the atmosphere, especially carbon dioxide and water vapor, are the substances that retain heat.

Burning fossil fuels releases extra carbon dioxide.

Deforestation destroys carbon sinks. Positive feedback loop - poles covered with ice

reflect solar radiation back into space. Now that ice is melting, open water is absorbing more heat, which in turn is melting more ice, leading to more warming.

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Sources of Greenhouse Gases

• Carbon Dioxide - fossil-fuel burning- Atmospheric levels increasing steadily- Most important cause of warming

• Methane - ruminants, rice paddies- Absorbs more infrared than CO2 .

• Chlorofluorocarbons (CFC’s) - refrigerants- Declined in developed countries, but now

produced in developing nations.• Nitrous Oxide - burning organic material

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Sources of Greenhouse Gases

• U.S. has less than 5% of world’s population but produces 28% of carbon dioxide.

• China, with 1.3 billion people, is second.• Japan and Europe produce half as much carbon

dioxide per person as the U.S.

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Measuring Carbon Dioxide in the Atmosphere

• There is a carbon dioxide detector in Mauna Loa in Hawaii. This allows measurements far away

from cities and forests. The winds over Mauna Loa have come

thousands of miles across the Pacific Ocean, swirling and mixing as they traveled.

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Measuring Carbon Dioxide in the Atmosphere

• Keeling’s first measurement, in March of 1958, was 0.0314 percent. Slightly higher in the winter. Slightly lower in the summer. Why? Photosynthesis

• These levels have rose steadily over the last 50 years.

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Carbon Dioxide Concentrations on Mauna Loa

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Weather Happens

• Weather - physical conditions in the atmosphere (humidity, temperature, air pressure, wind and precipitation) over short time scales Rain

- Air cools as it rises, and water condenses as air cools.

- Cooling occurs because pressure decreases as air rises.

- Condensation nuclei (tiny particles) must also be present to have precipitation.

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Ocean Currents

• Warm and cold ocean currents strongly influence climate conditions on land. As surface water moves, deep water wells up to

replace it.- Ocean circulation also driven by differences in

water density due to temperature and saltiness of water

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Frontal Weather

• Cold Front - boundary formed when cooler air displaces warmer air Cold air is more dense, thus hugs ground and

pushes warm air up.• Warm Front - boundary formed when warm air

displaces cooler air Warm air is less dense and slides over cool air,

creating a long wedge-shaped band of clouds and precipitation.

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Cyclonic Storms

• When rising air is laden with water vapor, latent energy released by condensation intensifies convection currents and draws up more warm air and water vapor. Storm cell will exist as long as temperature

differential exists.- Hurricanes (Atlantic)

Katrina in 2005 caused greatest natural disaster in North American history.

- Typhoons (Western Pacific)- Cyclones (Indian Ocean)

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Cyclonic Storms

• Tornadoes - swirling funnel clouds Generated by “supercell” frontal systems

where strong dry cold fronts collide with warm humid air

- Greater air temperature differences in the spring, thus more tornadoes

Downbursts - disorganized supercells that cause downdrafts and straight line winds

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Cyclonic Storms

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Studying Climate

• Ice cores - collected from glaciers reveal light and dark bands caused by annual snow accumulation on glacier Gas bubbles can be analyzed for atmospheric

composition. Ash and sulfur deposits correlate with volcanic

eruptions. Vostok ice core gives us a record back 420,000

years.

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Climate

• Data show that: Abrupt climatic change has catastrophic effect

on living things as organisms are unable to adjust before conditions exceed their tolerance limits. Species may become extinct.

There is a close correlation between carbon dioxide concentration and temperature of the atmosphere – allegedly.

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CLIMATE CHANGE IS A NATURAL PROCESS

• Changes in climate have been observed throughout history. There have been at least 5 major ice ages. The sun undergoes cycles where it

releases different amounts of energy. The Earth’s orbit can shift and tilt.

- Example: Magnitude 8.8 earthquake in Chile shorted the Earth’s day by 1.26 millionths of a second.

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Climate

Milankovitch Cycles - periodic shifts in Earth’s orbit and tilt which change distribution and intensity of sunlight

- Ice cores show drastic changes may have occurred over short periods of time (years to decades).

Volcanic eruptions can cool planet suddenly.

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Milankovitch Cycles

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Evidence of Global Warming

• According to the EPA, the global surface temperature has increased 0.9°F since 1880. The Earth’s surface is currently warming at a

rate of about 0.29ºF/decade or 2.9°F/century. The eight warmest years on record (since

1880) have all occurred since 2001, with the warmest years being 2005 and 2010.

Arctic temperatures have increased twice as fast as the rest of the Earth.

Source: http://epa.gov/climatechange/science/recenttc.html

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Global Warming

• Range of temperature increase predicted to be from 1.1 to 6.4°C (2 to 11.5°F) by 2100 depending on population growth, energy conservation, etc.

• Best estimate is 1.8 to 4°C (3.2 to 7.8°F) To put that in perspective, there has been a 5

degree C rise since the middle of the last ice age (about 20,000 years ago).

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Global Warming

• Most people will experience more extreme weather including droughts, floods, heat waves and hurricanes. These extremes have increased significantly in the last decade.

• In the worst outcome, we could see millions of human deaths.

• Sea levels are projected to rise 17-57 cm (7 to 23 in). If we do nothing, Greenland’s ice will melt and raise sea levels 20 ft.

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Global Warming

• If Greenland’s ice melts, a great deal of land will be flooded including: Most of Florida Some of the Gulf Coast Most of Manhattan Shanghai Hong Kong Tokyo

• Opponents say cuts in greenhouse gas emissions are too costly to business.

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Is Global Warming Human-Caused?

• The Intergovernmental Panel on Climate Change (IPCC) released its fourth report in 2007.

• Two important statements are made in the summary of this report: “Warming of the climate system is unequivocal,

as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level. ”

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Is Global Warming Human-Caused?

• Second statement of the IPCC fourth report summary: "Most of the observed increase in global average

temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations."

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Global Warming Timeline

• 19th century: Beginning of industrial revolution• 1958: Daily records of carbon dioxide levels start.

Venus found to have surface temperatures above boiling point.

• 1970: First Earth day.• 1973: Arab embargo -- energy crisis.• 1977: Scientific opinion converges on global warming as the

major climate risk.• 1981: Warmest year on record.• 1995: Reports on breaking up of Antarctic ice shelf.• 1997: Kyoto protocol established.• 1998: Strong El Nino produces warmest year on record.• 2003: Deadly European heat wave / major ice sheets collapse

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2005

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• Kyoto treaty goes into effect (not ratified by U.S.)

• Most active hurricane season in recorded history.

• Hurricane Katrina hits New Orleans.

Source: NOAA

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Hurricane Katrina

• Formed over the Atlantic in August of 2005. Crossed Southern

Florida as a category 1 hurricane.

Strengthened very quickly over warm waters of the Gulf of Mexico

• Made landfall over Louisiana as a Category 3 hurricane.

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New Orleans

• Parts of New Orleans are below sea level.• The levees holding back the Mississippi river and

the shoreline were not maintained properly.

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•Immediate connections were made

between global warming, the

unusually warm Gulf of Mexico,

and the hurricane.

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2007-Present

• Severe drought hits Australia from 2007-2009, followed by severe flooding in 2010.

• Severe flooding in Pakistan in 2010.• In the last stages of President Bush’s term, global

warming was emphasized as a “scientific uncertainty”• In 2009, the U.S. House of Representatives passed a bill

meant to gradually limit the amount of carbon dioxide produced. Stalled in the Senate.

• In 2009, a series of emails from the researchers at the University of Anglia were made public; some implied data was being manipulated. This was nicknamed “Climategate.”

• 2010 ties 2005 for the warmest year on record.39

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Evidence of Climate Change is Overwhelming

• Ave. global temperature climbed 0.6°C (1°F) in last century. 19 of 20 warmest years in the past 150 yrs have

occurred since 1980. Hottest year since temperature records were

begun was 2005. Poles are warming fastest (4°C, 7°F over past 50

years). Permafrost is melting in Alaska and Canada and houses, pipelines and trees are being toppled.

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Global Warming Effects on Poles

• 99% of sheet ice is located in Antarctica and Greenland

• Ice is melting worldwide, but especially quickly at the poles. As a result…

- Ocean levels have risen about 3.0mm per year in the 10 years.

- Adelle penguin population is down to 1/3 its normal level.

- Multiple populations of polar bears are declining.

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Global Warming Effects on Glaciers

• Only about 1% of the world’s sheet ice is located in temperate (non-polar) regions, but these are close in proximity to human populations. Himalayan glaciers are the sources of

Asia’s biggest rivers Biggest single source of water for the

entirety of southern Asia.

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Effects on the Hydrologic Cycle

• Surface temperatures are measurably increasing. This effects the water cycle: Higher rate of evaporation (from land and

sea both) Warmer atmosphere is capable of holding

more water vapor.- Higher likelihood of heavy precipitation

(both rain and snow) weather events.• Ocean temperatures are also increasing.

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Flawed Predictions

• A statement was published by a journal that suggested the Himalayan glaciers could be melted by 2035. These numbers were based on unrealistic

calculations and this prediction was retracted.

Many dismiss global warming claims in general as a result of retractions such as this.

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Global Warming will be Expensive

• At present, reducing greenhouse gas emissions would cost 1% of world GDP according to Stern report. (IPCC report says less than that.)

• Energy production will need to be 80% decarbonized by 2050 to stabilize climate. Ethical issue Poor will suffer the most; at least 200 million

people will become refugees of flood and drought.

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Steps For Combating Climate Change

• Emissions trading markets already exist

• Technology sharing• Reducing deforestation• Helping poorer countries adapt to climate change

Tropical areas will not change as much as middle and high latitudes.

If both Greenland and Antarctica melt, 1/3 of Earth’s population will be displaced.- South Pacific island nation of Tuvalu already

abandoned due to climate change

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Combating Climate Change

• Insurance companies have $2 trillion in insured properties along U.S. coastlines at risk from flooding or severe storms.

• Infectious diseases will increase as insects that spread them are able to move to places where they could not live before. West Nile, malaria, and dengue fever have

appeared in North America.• Melting of permafrost may release stores of

methane hydrate. Uncertainty about whether that would increase warming or cooling.

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Controlling Greenhouse Emissions

• Reducing carbon dioxide levels Renewable energy sources

- Double average fuel economy- Switch to efficient lighting and appliances- Wind turbines- Biofuels

Capture and store carbon dioxide- Planting vegetation- Injection into wells

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Carbon Management

• Capturing and storing carbon dioxide• Build “trees” in which calcium hydroxide solution

would absorb carbon dioxide• Plant forests• Fertilize the oceans with iron to permit

phytoplankton growth, which would take up carbon dioxide

• Inject carbon dioxide underground or in ocean

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Synthetic “Trees” that Capture Carbon Dioxide

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Other Ideas?

• The stratoshield is an idea developed to combat global warming by blocking some of the sunlight entering the Earth’s atmosphere.

• Inject sulfur dioxide or particulate pollutants into the stratosphere. This would be too high in the atmosphere to be

directly breathed or cause acid rain. Blocks out just enough sunlight to bring global

temperatures down to acceptable ranges.

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Another quick solution: dropping ice cubes into the ocean.

Source: Futurama “Crimes of the Hot”

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Progress Made

• United Kingdom has rolled back its CO2 emissions to 1990 levels and is aiming for a 60% reduction by 2050.

• Germany has reduced CO2 by 10%. • Denmark gets 20% of its electricity from windmills,

and plans to increase that to 50%.• China reduced its emissions 20% between 1997

and 2005.• (At its present rate, U.S. will be 25% above 1990

emissions in 5 years. No progress.)