weather…climate… climate change… ozone depletion…

Weather…Climate…Climate Change…Ozone Depletion…

…what does it all MEAN?

Question: What’s in the atmosphere?

• N2 (78%)

• O2 (21%)

• Ar (0.9%)

• WV

• CO2

• O3

• Particulates

(greenhouse gas)

(greenhouse gas)

Thermosphere

TROPOSPHERE

• Gases here moderate flow of energy to E.• 10 mi thick @ tropics; 5 mi thick @ higher

lats.• Contains all the WV & clouds.• Weather occurs here!• Temp ↓ as altitude ↑.• Pollutants can rise to top within days...• TROPOPAUSE caps it...temp stops

decreasing.

(higher...) STRATOSPHERE

• Temp ↑ as altitude ↑...

• Contains O3 (it absorbs radiation).

• Persistent substances

What happens to TEMP as you go farther away

from E?

Why does it warm up in the stratosphere?

What happens to the TEMP as you move farther from E?

Good to know...• Weather: day-to-day variations in temp,

precip, wind, pressure, & humidity.

• Climate: long-term regional weather patterns.

• Factors affecting climate:• Latitude• Atmospheric circulation• Oceanic circulation• Topography• Solar activity• Volcanic activity

Latitude

Latitude

• LOW latitudes close to equator receive more direct (vertical) rays; more concentrated E per surface area.

• No winter…no summer…all hot.

• HIGH latitudes receive less direct (oblique) rays; less concentrated E per surface area.

• Wider temp range, seasons!

Warm air rises (low pressure...)Cold air sinks (high pressure...)Pressure flows from HIGH to low

AtmosphericCirculation (wind…)

Latent Heat• Warm air holds more WV than cool air

• Warm air rises (less dense)

• As moist/warm air rises, it cools & WV condenses to liquid…clouds form…– Latent heat (“trapped” in WV) is released– Energy source for t-storms, tornadoes,

hurricanes.– QUESTION: will increased temps lead to

more WV…more latent heat…resulting in more intense severe weather?

How OCEANS affect temp...

• HEAT CAPACITY: water stores heat more effectively than solid earth (heats up &

cools more slowly than land).

• HEAT TRANSFER: ocean currents carry warm equatorial water towards poles.

• SOURCE for WV: when wv condenses in the atmosphere it releases latent heat.

Surface Currents

One cycle: 1,000 years

El Nino-Southern Oscillation (ENSO)

Solar Maximum - Increased UV - Increased O3

- Increased temps

- SO2 gas reaches upper atmosphere.- SO2 & dust & WV form haze.

- Haze reflects sun- light, global temps decrease.

And finally……the seasons!

Greenhouse Effect

• Analogy: sunlight pours into your car & heats up the interior (gets absorbed by seats, dash, etc) as it’s converted from light energy to heat energy (IR).– The light energy escapes back out

through the glass...but the heat energy is blocked by the glass and so cannot leave the car.

– Much like a “greenhouse.”

Greenhouse Effect

• The Greenhouse Gases - WV, CO2,CH4,& N2O are analogous to the glass in a greenhouse.

• Light energy from Sun passes through them, strikes E and is converted to heat energy (IR)...the converted IR is absorbed and re-radiated back into the troposphere by the GHGs.

Your diagram goes here!

ABSORBED: 70%REFLECTED: 30%

An important 70%...

• The solar energy not reflected back into space (70%) gets transferred to the atmosphere as IR energy...

• This warmed-up air becomes less dense, rises, and creates air currents called convection cells.

...it’s actually a good thing...

• The greenhouse effect moderates the temp and makes it warm enough for many ( a word that often leaves you guessing) life forms to exist...

...a force to be reckoned with.

• HOWEVER... If the concentration of these GHGs changes, their insulating effect changes also...and so will our climate.

Enhanced Greenhouse Effect

• 1958: Charles Keeling begins measuring CO2 levels on Mauna Loa

Anthropogenic warming

• Warming of the Earth derived from human activity

...climate change is such an important issue today

because we depend on those orgs for vital goods &

services we need to survive...

If the global climate changes, can these ecosystems change with it - so those vital goods

& services continue?

CLIMATES

• ...remember how ecosystems & biomes result from different combo’s of temp & precip?

• ...and the orgs that inhabit a particular biome are adapted to those limits?

• HUMANS can live anywhere (we don’t have to adapt – we control the environment...)

Past Climates• Global surface temps

fluctuate!• This chart is

modern... stats

come from actual

weather stations.

...but what about long ago?• Proxies are used to provide info about

ancient climate conditions.• Pollen deposits...marine

sediments...coral...ice cores... historical data…

Pollen!

Marine sediments• Biological

– Changes in fossilized orgs (type & amount)

– Oxygen isotope concentrations in shelled remains

• Inorganic– Clay mineralogy– Aeolian dust

Coral• “Greer and Swart were investigating the

relationship between non-radioactive or stable isotopes of oxygen in the calcium carbonate of the coral. The ratio of normal to heavier oxygen depends on the temperature of the water the coral grew in and its salinity. In warmer water, the coral incorporates more of the normal oxygen into its structure, but if the water is cooler, the coral will incorporate a higher percentage of the heavier oxygen isotope.”

Medieval Warming PeriodLittle Ice Age

What does it MEAN?

• E’s climate has oscillated between ice ages and warm periods.

• Milankovich cycles : Earth rotational & revolutionary movements combine to affect global climate.

• Theory: Ice ages are caused by 100,000 year coincidences of these cycles.

...during the ice ages, major amounts of water were “tied

up’ in glaciers & ice sheets...sea levels dropped

hundreds of feet below current levels.

Rapid changes...

• Younger-Dryas Event: at the end of the last ice age, E warmed up 7o C in just 50 years!

• Scientists scratch heads: most likely due to atmosphere / ocean / global temp combo... kind of an El Nino gone bad...

THERMOHALINE Circulation

• What’s THAT mean?

• Thermo: heat......Haline: salty...

• Cold water is more dense than warm water ; Saltier water is more dense than fresher water.

• Warm salty water cools; sinks @ poles...flows along ocean bottom towards equator where it warms & rises.

One cycle: 1,000 years

...could the conveyor belt be STOPPED?• Recent evidence shows that it has been

interrupted in the past...six times.

• Large quantities of fresh water in the North Atlantic (glacier/ice pack melting...) would lower the salinity (density) of the water up there... water would stop sinking...

• The northward flow of warm water would be blocked and the belt shifts south.

• Results in ABRUPT global cooling.

• Scientists are monitoring salinity in the northern ocean...

Climate Change: the DATA.

#1: CO2

• Released by burning of fossil fuels!• Annual oscillations are due to seasonal

changes in NH terrestrial ecosystems photosynthesis: Apr-Sep: CO2 ↓

respiration: Oct-Mar: CO2↑• As of 2012, CO2 levels @ 399ppm (40%

higher than before the Industrial Revolution)...higher than they’ve been in 400,000 years!

Sources & Sinks

• 1 kg combusted fossil fuel = 3kg CO2

• 6.6 GtC (gigaton: billion metric tons) per year of fossil fuel carbon.

• 1.6 GtC per year from burning forests.

• Sinks: carbon sequestration.– Oceans: uptake by phytoplankton @ 2

GtC/year– Forests: @ 3 GtC/year

#2: WV

• Absorbs IR...the most abundant GHG! Atmospheric concentration variable...

• Major factor in “Supergreenhouse effect”: in South Pacific, wv traps/reradiates heat over ocean, resulting in MORE evaporation, thus more wv, thus more greenhouse effect...positive feedback.

#3: Methane (CH4)

• Sources: microbial fermentation (swamps, livestock, landfills, coal mines, natgas production, rice cultivation, manure).

• Atmospheric methane has doubled since Industrial Revolution; is leveling off!

#4: Nitrous Oxide (N2O)

• Sources: agriculture & biomass burning; fossil fuel combustion

• 15% increase in past 200 years.

• Particularly unwelcome because it’s so persistent: residence time 114 YEARS!

• Also bad for O3...

#5: O3

• Sources: motor vehicle exhaust, biomass burning.

• Short-lived, but potent.

#6: CFC’s & Halocarbons, et al• Entirely anthropogenic.

• Sources: refrigerants, fire retardants, solvents.

• Extraordinary capability for IR absorption (x10,000 CO2’s rate)

• Long residence time (100+ years)

• Double whammy: GHG AND O3 destroyers!

• Good news: manufacture & use has been curtailed.

IPCC• Intergovernmental Panel on Climate

Change.

• est. 1988 by UN and World Meteorological Society to provide accurate, relevant information on anthropogenic climate change.

• Three working groups:– I: Assessment of scientific issues– II: Impact of climate change & possible adaptations– III: Mitigation of effects

IPCC

• More than 2,000 experts from over a hundred countries.

• Unpaid...recoup only the cost of their research & associated professional activities.

Most recent report: Sep 2013

The report finds that it is “very likely” that emissions of heat-trapping gases from human

activities have caused “most of the observed increase in globally averaged temperatures since the

mid-20th century...”

”...evidence that human activities are the major cause

of recent climate change is even stronger than in prior

assessments...”

“It is unequivocal that Earth’s climate is

warming...”

“...as is now evident from observations of increases in global average air and ocean

temperatures, widespread melting of snow and ice, and

rising global mean sea level...”

“...atmospheric concentrations of CO2 and methane exceed by far the natural range over the last

650,000 years.”

Further findings/evidence• 11 of last 12 years rank among top 12

hottest years on record since 1850.• Tropical storms, precipitation, and

severe drought incidence have all increased.

• Mountain glaciers and snow fields are in world-wide decline.

• Summer Arctic sea ice has decreased 20% since 1978.

• Global mean sea level is rising.

What’s been done...• Rio ’92: Earth Summit calls for voluntary

reduction of GHGs.– Failure: all increased...

• Kyoto ’97: binding agreement to reduce emissions.– Failure: major players non-participants.

• Copenhagen ‘09: ill-will…mistrust between developed/developing nations.– Details of the “accord:”

Latest IPCC Report (Sep 2013)

• The warming is unequivocal.• Humans caused the majority of it.• The warming is largely irreversible.• Most of the heat is going into the oceans.• Current rates of ocean acidification are

unprecedented.• We have to choose which future we want very soon.• To stay below 2°C of warming, the world must

become carbon negative.• To stay below 2°C of warming, most fossil fuels

must stay buried in the ground.

Carbon Credit Trading

• Countries (both developed & developing) receive an allowance of carbon production.

• Developing countries can initiate cleaner technologies using less carbon.– They can trade unused carbon credits to

other countries and use the profit to grow.

• Developed countries will either pay or change…

• Market based.

The future...?

• Confidence in computer models to predict future scenarios has increased...

• Human influences will continue to change atmospheric composition throughout the 21st century.

B1 scenario pop↑ then↓, economies & governments cooperate to achieve sustainability

A1T scenario pop↑ then↓, global shift to non-fossil fuel energy sources

B2 scenario pop↑, significant efforts to achieve sustainability

A1B scenario pop↑ then↓, balance of all energy sources

A2 scenario pop↑ then↓, countries act independently with varied economic/technological change

A1F1 scenario pop↑ then↓, fossil fuel intensive society

Temp.

(oF

Change

@ yr 2090)

Sea-Level Rise

(“ @ yr 2090)

Case Best Estimate Likely Range

Model-based range (excluding future rapid dynamical changes in ice flow)

Constant Year 2000 concentrations

1.1  0.5 - 1.6  NA

B1 scenario 3.2 2.0 – 5.2  7.1 - 15.0A1T scenario 4.3 2.5 - 6.8  7.9 - 17.7B2 scenario 4.3  2.5 - 6.8  7.9 - 16.9A1B scenario 5.0  3.1 - 7.9  8.3 - 18.9A2 scenario 6.1  3.6 - 9.7  9.1 - 20.1A1F1 scenario 7.2  4.3 - 11.5  10.2 - 23.2

Projected Surface Temp./Sea-Level Rise at Year 2090

Temp.

(oF

Change

@ yr 2090)

Sea-Level Rise

(“ @ yr 2090)

Case Best Estimate Likely Range

Model-based range (excluding future rapid dynamical changes in ice flow)

Constant Year 2000 concentrations

1.1  0.5 - 1.6  NA

B1 scenario 3.2 2.0 – 5.2  7.1 - 15.0A1T scenario 4.3 2.5 - 6.8  7.9 - 17.7B2 scenario 4.3  2.5 - 6.8  7.9 - 16.9A1B scenario 5.0  3.1 - 7.9  8.3 - 18.9A2 scenario 6.1  3.6 - 9.7  9.1 - 20.1A1F1 scenario 7.2  4.3 - 11.5  10.2 - 23.2

Projected Surface Temp./Sea-Level Rise @ Year 2090

What Must Be Done.• World-wide cap on GHG emissions.

• Investment in, & deployment of renewable energy technologies.

• Removal of fossil-fuel subsidies.– &10 billion/yr in Europe...$15-35 billion/yr

U.S.A.

• Develop nuclear power.– Cost-effective, reliable, waste, spent fuel...

• More stringent energy conservation measures.

What Must Be Done.

• Stop TRF loss; plant more trees.

• Reduce the amount of fuels used in transportation.

• Sequester CO2 emissions.

• Slow HPG.

Depletion of the Ozone Layer

UV that penetrates the atmosphere may be absorbed by biological tissues, where it

damages proteins and DNA molecules.

If the full amount of UV from the sun reached E’s surface (without being absorbed by

the atmosphere), it is doubtful that any life forms

could survive.

Fortunately, over 99% of UV is absorbed by ozone in the

stratosphere...

...the small amount that does reach E is responsible for more

than 700,000 cases of skin cancer/precancerous conditions per year, just in North America.

Formation and Destruction of Stratospheric O3

• O2 + UVB → O + O

• O + O2 → O3

• O + O3 → O2 + O2

• O3 + UVB → O + O2

Seasonal changes in distribution of solar

radiation cause ozone concentrations to vary...

(High in summer, low in winter)

Ozone concentrations are higher near the equator, and

diminish as latitude increases...also a function of distribution of solar radiation.

CFC (chlorofluorocarbon)

• Nonreactive, nontoxic, nonflammable organic molecules in which Cl & Fl have replaced hydrogens; gases @ normal temp & pressure...

• ...they liquefy at modest pressure, giving off heat in the process, becoming cold...

• ...used in refrigerators, heat pumps, production of foam plastic, & as propellants in aerosol cans.

CFCs break down O3 in stratosphere

• CFCI3 +UV → Cl + CFCI2

• CI + O3 → ClO + O2

• CIO + ClO→ 2 Cl + O2

Chlorine acts as a catalyst: a chemical that promotes a

chemical reaction without itself being used up in the reaction.

...each chlorine can last from 40 to 100 years in the

stratosphere...it has the potential to break down

100,000 molecules of ozone.

...it’s not really so much a hole...

...it’s more like a bald spot.

Rowland & Molina

• Called it in 1974...published a paper that concluded CFCs would damage the stratospheric ozone layer, increasing UV radiation on E’s surface, resulting in more skin cancer.

• Won Nobel Prize for their work (1995).

1985

• British researchers in Antarctica report a “hole” over the South Pole (about the size of the United States) in the fall of ’85...levels were 50% lower than normal.

• NASA satellites would have discovered it first; but they were programmed to reject anything over a 30% drop as an instrument failure!

Surprise...

• Scientists thought that ozone loss would be gradual & uniform all over the planet – not a “hole!”

• The “hole” came as a surprise...if it had happened anywhere other than South Pole, UV damage to life would have been extensive.

Why it happens where it happens:

• Summertime creates chlorine reservoirs (Cl gets “locked up” in methane & nitrogen compounds)

• Wintertime’s extreme cold traps stratospheric gases within a ring of air circulating around the Antarctic...clouds form...clouds provide surfaces on which Cl2 gets “unlocked” from its reservoir.

• When sunlight returns in spring, UV attacks the Cl2, releasing free Cl – which begins the ozone destruction cycle.

Sad days in the Outback, mate...

• Ozone-poor air shifts over the Southern Hemisphere...

• UV radiation increases up to 20% above normal in Australia...

• Three out of four in Queensland (thinnest layer) are expected to develop skin cancer.

Montreal Protocol

• 184 participating nations must phase out ozone-destroying chemicals by 2000 (developed countries) and 2010 (developing countries).

• ..in most industrialized countries, CFCs are no longer produced or used.

• Prediction: the ozone shield will reach full recovery by 2050.