global climate change -...

GLOBAL CLIMATE CHANGE

Adapted from K.Sturges @ MBHS

What is climate change?

◦ Climate change is the fastest-developing area of environmental

science

◦ Climate = an area’s long-term atmospheric conditions

◦ Temperature, moisture, wind, precipitation, etc.

◦ Weather = short-term conditions at localized sites

◦ Global climate change = describes trends and variations in

Earth’s climate

◦ Temperature, precipitation, storm frequency

◦ Global warming and climate change are not the same

Global warming

◦ Global warming = an increase in Earth’s average temperature

◦ Only one aspect of climate change

◦ Climate change and global warming refer to current trends

◦ Earth’s climate has varied naturally through time

◦ The current rapid climatic changes are due to humans

◦ Fossil fuel combustion and deforestation

◦ Understanding climate change requires understanding how our

planet’s climate works

Greenhouse gases warm the lower atmosphere

◦ As Earth’s surface absorbs solar radiation, the surface increases in

temperature and emits infrared radiation

◦ Greenhouse gases = atmospheric gases that absorb infrared

radiation

◦ Water vapor, ozone, carbon dioxide, nitrous oxide, methane,

halocarbons (chlorofluorocarbons [CFCs])

Introduction to Climate Change

◦ Evidence for Climate Change

◦ Warmest years since mid-1800s have occurred since 1990

◦ Phenological spring in N. hemisphere now begins 6 days earlier

(date the buds of specific plants open)◦ Retreat of glaciers◦ Thinning of polar ice◦ Weather change◦ Sea Level Rise

◦ Warming is not due to natural causes

◦ Human produced greenhouse gases are most plausible

explanation

◦ .

http://cartoonbox.slate.com/tonyauth/

http://cartoonbox.slate.com/tonyauth/

Climate in the Past

◦ Past◦ Record of past 100+ years only

◦ Since 1855 global temp. has fluctuated from warming to cooling

◦ Has increased 0.6 C

◦ Further back

◦ Proxies- tree rings, pollen deposits, changes in landscapes, marine sediment, corals, ice sheets

◦ Milankovitch cycles

◦ Oscillated between ice ages and warm periods

Milankovitch cycles influence climate

◦ Milankovitch cycles = periodic

changes in Earth’s rotation and orbit

around the sun

◦ Alter the way solar radiation is

distributed over Earth

◦ These cycles modify patterns of

atmospheric heating

◦ Triggering climate variation

◦ For example, periods of cold glaciation

and warm interglacial times

Direct measurements tell us about the present

◦ We document daily

fluctuations in weather

◦ Precise thermometer

measurements over the

past 100 years

◦ Measuring of ocean and

atmospheric chemistry

began in 1958

◦ Precise records of historical

events

◦ Droughts, etc.

Atmospheric CO2 concentrations have

increased from 315 ppm to 389 ppm

Introduction to Climate Change: Mean Annual Global Temperature 1960–2010

© 2012 John Wiley & Sons, Inc. All rights reserved.

Proxy indicators tell us about the past

• Paleoclimate = climate of the geological past

• Gives a baseline to compare to today’s climate

• Proxy indicators = indirect evidence that serve as substitutes for

direct measurements

- Shed light on past climate

- Ice caps, ice sheets, and glaciers hold clues to Earth’s climate

history

- Trapped bubbles in ice cores provide a timescale of:

- Atmospheric composition, greenhouse gas

concentrations, temperature trends

- Snowfall, solar activity, and frequency of fires

Ice cores from Antarctica

◦ Ice cores let us go back in time

800,000 years

◦ Reading Earth’s history across eight

glacial cycles

Ice cores can show us the CO2

data and more from the past. Air

gets trapped inside bubbles in the

ice and preserved!

https://www.bas.ac.uk/data/our-

data/publication/ice-cores-and-

climate-change/

More proxy indicators

◦ Cores in sediment beds preserve pollen grains and other plant

remnants

◦ Tree rings indicate age, precipitation, droughts, and fire history

◦ In arid regions, packrats carry seeds and plants to their middens

(dens)

◦ Plant parts can be preserved for centuries

◦ Researchers gather data on past ocean conditions from coral

reefs

◦ Scientists combine multiple records to get a global perspective

http://cartoonbox.slate.com/viewsamerica/

http://cartoonbox.slate.com/viewsamerica/

Climate Change Terminology

◦ Greenhouse Gas

◦ Gas that absorbs infrared radiation

◦ Water vapor, ozone, carbon dioxide, nitrous oxide, methane, halocarbons

[chlorofluorocarbons (CFCs)]

◦ Positive Feedback

◦ Change in some condition triggers a response that intensifies the changed

condition

◦ Infrared Radiation

◦ Radiation that has a wavelength that is longer than that of visible light, but

shorter than that of radio waves

◦ Greenhouse Effect

◦ Increase of heat in a system where energy enters (often as light), is absorbed as

heat, and released sometime later

◦ energy that travels downward, warming the atmosphere and the planet’s

surface

Greenhouse gas concentrations are rising fast

◦ The greenhouse effect is a natural phenomenon

◦ Greenhouse gases have always been in the atmosphere

◦ We are not worried about the natural greenhouse effect

◦ Anthropogenic intensification is of concern

◦ We have added new gasses (CFCs) and increased concentrations of

others

◦ Human activities increased atmospheric CO2 from 280 parts per

million (ppm) to 396 ppm in 2013

◦ The highest levels in more than 800,000 years

◦ Likely the highest in 20 million years

The fate of solar radiation

• The atmosphere, land, ice, and water absorb 70% of incoming solar

radiation

Greenhouse Gases

◦ Carbon dioxide

◦ Water vapor

◦ Methane (CH4)

◦ Nitrous oxide (N2O)

◦ CFCs and other halocarbons

◦ Ozone (tropospheric)

CFC

The Greenhouse Gases

◦ Water Vapor (H2O)

◦ Most common

◦ Absorbs more IR radiation but not as persistent

◦ Natural contributor to global warming

◦ Concentrations have not changed

◦ Positive feedback loop

◦ Traps energy, heats ocean surface and lower atmosphere

◦ As temp rise over land ocean, evaporation will increase and water vapor concentration will rise, causing more warming

◦ Carbon Dioxide (CO2)

◦ Greatest contributor to GH effect because of abundance

◦ Natural- volcanoes

◦ Anthropogenic- fossil fuel combustion and deforestation


◦ Methane (CH4)

◦ Most potent greenhouse gas

◦ Because of its ability to absorb IR and it’s abundance

◦ Natural- wetlands (largest natural source of methane), termite

digestion (second natural source)

◦ Anthropogenic- Animal Husbandry (cows), landfills,

production/storage/transport of natural gas when methane

leaks, rice cultivation (plant decay), biomass burning

◦ If it’s decaying/decomposing think methane!


◦ Nitrous Oxide (N2O)

◦ Natural- denitrification turns nitrates into N2O before converting

to N2

◦ Anthropogenic- fossil fuel combustion from cars, from

agricultural soilssynthetic fertilizers, manure, nitrogen fixing

crops

◦ Side note: N2O contributes to Stratospheric O3 depletion in

addition to CFCs


◦ CFC’s (and other halocarbons)

◦ No natural causes

◦ Long loved

◦ Anthropogenic- coolants in refrigerators and air conditioners,

pressurized aerosol cans

◦ Ozone (O3)

◦ Tropospheric

◦ Short lived

◦ Nox + VOCs + sun

Sources of various greenhouse gases:

Greenhouse

Gas

Natural Sources Anthropogenic

Carbon Dioxide * Cellular respiration and

decay

* Natural fires

* Volcanoes

* Warming oceans

* Combustion of fossil fuels

* Land use conversion

* Cement production

Methane * Animal digestion

* Methane hydrates


* Rice paddies

* Livestock

* Landfills

Nitrous Oxide * Temperate and tropical

soils

* Oceans


* Fertilizer

* Industrial processes

Chlorinated Fluorocarbons * None * Liquid coolants

* Foam production

◦Greenhouse gas concentrations are

increasing


The greenhouse effect is natural

◦ Greenhouse gases have always been in the atmosphere

◦ We are not worried about the natural greenhouse effect

◦ Anthropogenic intensification is of concern

◦ Global warming potential = the relative ability of one molecule

of a greenhouse gas to contribute to warming

◦ Expressed in relation to carbon dioxide (potential = 1)

◦ GWP span wide ranges because they can differ in how much IR

they absorb and how long they persist

◦ Expressed in relation to carbon dioxide (potential = 1)

◦ Methane is 25 times more potent than carbon dioxide

◦ Nitrous oxide is 298 times more potent than carbon dioxide


◦ Methane levels have increased 2.5-fold since 1750

◦ Highest level in over 800,000 years

◦ Released by tapping into fossil fuel deposits and from livestock,

landfills, and crops such as rice

◦ Nitrous oxide has increased nearly 20% since 1750

◦ Produced by feedlots, chemical manufacturing plants, auto

emissions, and synthetic nitrogen fertilizers


◦ Tropospheric ozone levels have risen 36%

◦ Halocarbon gases (CFCs) are declining

◦ Water vapor is the most abundant greenhouse gas

◦ Contributes most to the natural greenhouse effect

◦ Concentrations have not changed

Feedback complicates our predictions

◦ Tropospheric warming will transfer more water to the air

◦ The effects of increased water vapor are uncertain. Two possible

feedback loops could result

◦ A positive feedback loop: more water vapor … more warming … more evaporation … more water vapor …

◦ A negative feedback loop: more water vapor … more clouds

… shade and cool Earth …less evaporation

◦ Because of the feedback loops, minor modifications of the

atmosphere can lead to major effects on climate

U.S. emissions of major greenhouse gases

◦ Carbon dioxide is not the most potent greenhouse gas BUT

◦ It is present in the largest concentrations

◦ It exerts six times more impact than methane, nitrous oxide, and

halocarbons combined

Carbon dioxide

◦ Primary concern

◦ Most carbon is stored in the upper lithosphere

◦ Deposition, partial decay, and compression of organic matter

led to formation of coal, oil, and natural gas

◦ These deposits remained buried for millions of years

◦ Burning fossil fuels transfers CO2 from lithospheric reservoirs into

the atmosphere

◦ The main reason atmospheric carbon dioxide concentrations

have increased so dramatically

What caused levels of CO2 to increase?

◦ Burning fossil fuels transfer CO2 from lithospheric reservoirs into the

atmosphere

◦ The main reason atmospheric carbon dioxide concentrations

have increased dramatically

◦ Deforestation contributes to rising atmospheric CO2

◦ Forests serve as reservoirs for carbon

◦ Removing trees reduces the carbon dioxide absorbed from the

atmosphere

◦ Human activities increased atmospheric CO2 from 280 parts per

million (ppm) to 389 ppm

◦ The highest levels in more than 800,000 years

Increased concentration of CO2

◦ Burning fossil fuels in

cars, industry and

homes

◦ Deforestation

◦ Burning of forests


Seasonal Fluctuations of Carbon Dioxide

◦ Carbon Dioxide

◦ Seasonal fluctuations of photosynthesis and respiration in terrestrial ecosystems

◦ The N. Hemisphere has more land area and thus more vegetation, therefore more CO2 is absorbed during the northern summer

Fluxes of carbon dioxide

Ocean Sinks

◦ The ocean is the largest reservoir of CO2

◦ Ocean absorption = the ocean holds 50 times more carbon than

the atmosphere

◦ Gas dissolved directly in ocean water

◦ Not absording as much CO2 as emitting

◦ Slowing global warming but not preventing it

◦ Warmer oceans absorb less CO2

◦ Rate of absorption is slowing down

◦ A positive feedback effect that accelerates warming

http://app.discoveryeducation.com/player/view/ass

etGuid/155D1E9C-517C-492C-B840-9E0AA2AEA353

Pollutants That Cool the Atmosphere

◦ Atmospheric Aerosols

◦ Aerosols = microscopic droplets and particles

◦ Both human and natural sources

◦ Tiny particles (or sulfur) that remain in troposphere for weeks or months

(can be created by volcanoes)

◦ Sulfur-laden layer in the atmosphere reduces the amount of sunlight

reaching earth

◦ They have either a warming or a cooling effect

◦ Soot (black carbon aerosols) causes warming by absorbing solar energy

◦ But most tropospheric aerosols cool the atmosphere by reflecting the

sun’s rays

◦ Sulfate aerosols produced by fossil fuel combustion may slow global

warming, at least in the short term

◦ Volcanic eruptions reduce sunlight reaching Earth’s surface and cool

the Earth

Core Case Study: Studying a Volcano to Understand Climate Change

◦ NASA scientist correctly predicted that the 1991 Philippines explosion would cool the average temperature of the earth by 0.5Co over a 15 month period and then return to normal by 1995.

Figure 20-1

Radiative forcing expresses change in energy

◦ Radiative forcing = the amount of change in

thermal energy that a given factor causes

◦ Positive forcing warms the surface

◦ Greenhouse Effect

◦ Greenhouse Gases (GHGs)

◦ Negative forcing cools it

◦ ~50% covered by clouds, reflecting 21% solar

rad. back into space (known as albedo)

◦ Volcanic eruptions (aerosols reflect radiation)

◦ Anthropogenic aerosols (smog)

Arctic Albedo Feedback

The U.S. Global Change

Research Program

◦ In 2009, scientists reported and predicted:

◦ Temperature increases

◦ Worse droughts and flooding

◦ Decreased crop yields

◦ Water shortages

◦ Health problems and diseases

◦ Higher sea levels, beach erosion, destroyed wetlands

◦ Drought, fire, and pests will change forests

◦ More grasslands and deserts, fewer forests

◦ Undermined Alaskan buildings and roads

Effects of Global Climate Change- Melting Ice and Rising Sea Levels◦ IPCC projects sea-level rise of18-59cm by 2100

◦ Sea level rise caused in 2 ways

◦ Thermal Expansion

◦ Melting of land ice

◦ Melting has positive feedback

◦ Increased melting decreases ice, which decreases albedo

leading to further warming

◦ Permafrost melting can increase methane which is a

greenhouse gas


EFFECTS OF GLOBAL WARMING

◦ Between 1979 and 2005, average Arctic sea ice dropped 20% (as shown in blue hues above).

Figure 20-8

Muir Glacier in the Past

Muir Glacier Today

Rising Sea Levels◦ If seas levels rise by 9-88cm

during this century, most of

the Maldives islands and

their coral reefs will be

flooded.

Figure 20-11

Central Case: Rising seas may flood the Maldives

◦ Tourists think the Maldives Islands are a paradise

◦ Rising seas due to global climate change could submerge them

◦ Erode beaches, cause

flooding

◦ Damage coral reefs

◦ Residents have evacuated the

lowest-lying islands

◦ Small nations are not the cause

of climate change, yet they

suffer

Case-In-Point Impacts in Fragile Areas

◦ Eskimo Inuit live traditional life dictated by freezing climate

◦ Climate change is altering their existence

◦ Wildlife displaced

◦ Reduced snow cover and shorter river ice seasons

◦ Thawing of permafrost (right)


Effects of Global Climate Change-Changing Precipitation Patterns

◦ Some areas will get more water, some areas will have greater

droughts


Effects of Global Climate Change- Effects on Organisms

◦ Zooplankton in parts of California Current have decreased by

80% since 1951

◦ Affecting entire food chain

◦ Species have shifted their geographic range

◦ Migrating birds are returning to summer homes earlier

◦ Ecosystems at greatest risk of species loss (short term): coral reefs,

mountain ecosystems, coastal wetlands, tundra, and polar spas


Effects on Organisms - Coral Reefs

◦ Coral reefs can be bleached (right) due to increase in water

temperature

◦ Affects coral symbiotes and makes them more susceptible to

diseases


Effect on Organisms - Vegetation


Climate change affects people

◦ Societies are feeling the impacts of climate change

◦ Agriculture: shortened growing seasons, decreased production,

crops more susceptible to droughts

◦ Increasing hunger

◦ Forestry: increased fires, invasive species

◦ Insect and disease outbreaks

◦ Health: heat waves and stress can cause death

◦ Respiratory ailments, expansion of tropical diseases

◦ Disease and sanitation problems from flooding

◦ Drowning from storms

Effects on Human Health

◦ Increased number of heat-

related illnesses and deaths


Effects on Agriculture

◦ Difficult to anticipate

◦ Productivity will increase in some areas and decrease in others

◦ Rise in sea level will inundate flood plains and river valleys (lush farmland)

◦ Effect on pests is unknown- warmer weather increases range of mosquitoes that can carry disease

◦ Warmer temperatures will decrease soil moisture - requiring more irrigation

◦ Location (i.e., elevation and altitude) where certain crops can be grown may have to change

International Implications of Climate Change

◦ Developed vs. Developing countries

◦ Differing self-interests

◦ Differing ability to meet the challenges of climate change


Dealing with Global Climate Change

◦ Two ways to manage climate change

◦ Mitigation: Limiting greenhouse gas emissions to moderate global climate change

◦ Adaptation: Learning to live with environmental changes and

societal consequences brought about by global climate

change


Relationship Between Mitigation and Adaptation


Dealing with Global Climate Change - Mitigation

◦ Locate/invent alternative fuels to fossil fuels

◦ Increase efficiency of cars and trucks

◦ Carbon Capture and Storage

◦ Plant and Maintain trees to naturally sequester carbon


Dealing with Global Climate Change - Adaptation

◦ Rising sea levels and coastal populations

◦ Move inland

◦ Construct dikes and levees

◦ Adapt to shifting agricultural zones

◦ NYC sewer line - http://www.climatecentral.org/news/climate-

change-could-cripple-new-yorks-transportation-network-studies-

show


http://www.climatecentral.org/news/climate-change-could-cripple-new-yorks-transportation-network-studies-show

International Efforts to Reduce Greenhouse Gas Emission

◦Kyoto Protocol**

◦ Provides operational rules on reducing greenhouse

gases

◦ By 2010, 183 countries had ratified it

◦ US has not signed it - it will be difficult to implement without US

backing

◦ EPA is taking it upon itself to define laws associated with CO2

reduction in US


The Kyoto Protocol tried to limit emissions• This treaty took effect in 2005

◦ After Russia became the 127th nation to ratify it

◦ The United States will not ratify the Kyoto Protocol

◦ It requires industrialized nations to reduce emissions

◦ But it does not require industrializing nations (China and India) to

reduce theirs

◦ Other countries resent the U.S. because it emits 20% of

the world’s greenhouse gases but won’t take action

◦ In 2007, one delegate said, “If for some reason you are not willing to

lead...please get out of the way.”

The Copenhagen conference ◦ The conference in 2009 tried to design a successor treaty to the

Kyoto Protocol

◦ Nations hoped the U.S., under President Obama, would participate in a full international agreement

◦ Obama would not promise more than Congress had agreed to

◦ In a last-minute deal, developed nations will help developing nations pay for mitigation and adaptation

◦ Nations that reduce deforestation will be rewarded

◦ Nothing is legally binding and no targets are set

States and cities are advancing policies

◦ The U.S. federal government is not taking action

◦ State and local governments are

◦ By 2010, 1,000 mayors signed the U.S. Mayors Climate Protection Agreement

◦ To meet or beat Kyoto Protocol guidelines

• California passed the Global Warming Solutions Act

- To cut emissions 25% by 2020

• Regional Greenhouse Gas Initiative (RGGI) in 2007

- 10 northeastern states

- Set up a cap-and-trade program

Market mechanisms address climate change

◦ Permit trading programs harness the economic efficiency of the free

market to achieve policy goals

◦ Businesses have flexibility in how they meet the goals

◦ Polluters choose how to cut their emissions

◦ They are given financial incentives to reduce them

Cap-and-trade emissions trading programs

◦ The approach of the Regional Greenhouse Gas Initiative:

◦ Each state decides which polluting sources participate

◦ Each state sets a cap on total CO2 emissions it allows

◦ Each emissions source gets one permit for each ton they emit,

up to the amount of the cap

◦ Each state lowers its cap over time

◦ States with too few permits must reduce emissions, buy permits

from others, or pay for carbon offsets

◦ Sources with too many permits may sell them

◦ Any source emitting more than permitted will be penalized

Cap-and-trade programs already exist

◦ Chicago Climate Exchange = the world’s first emissions trading

program for greenhouse gas reduction

◦ 350 corporations, institutions, etc.

◦ Voluntary but legally binding trading system aims for a 6%

reduction in emissions by 2010

◦ The European Union Emission Trading Scheme

◦ The world’s largest cap-and-trade program

◦ Governments had allocated too many permits

◦ Permits only work if government policies limit emissions

Carbon taxes are another option

◦ Critics say cap-and-trade systems are not effective

◦ Carbon tax = governments charge polluters a fee for each unit of greenhouse gases they emit

◦ Polluters have a financial incentive to reduce emissions

◦ European nations, British Columbia, and Boulder, Colorado have carbon taxes

◦ Polluters pass costs on to consumers

◦ Fee-and-dividend = funds from the carbon tax (fee) are passed to taxpayers as refunds (dividends)

Carbon offsets are popular

◦ Carbon offset = a voluntary payment intended to enable

another entity to reduce the greenhouse emissions that one is

unable to reduce oneself

◦ The payments offset one’s own emissions

◦ Popular among utilities, businesses, universities, governments,

and individuals

◦ Trying to achieve carbon-neutrality, where no net carbon is

emitted

◦ Carbon offsets fall short

◦ Needs rigorous oversight to make sure that the offset money

accomplishes what it is intended for

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