Professor Menglin Jin San Jose State University, Department of Meteorology MET 112 Global Climate Change Ozone Hole and Human Connection

Connection between people to climate Examples 1: Example 2: CA Automakers

Why were automakers suing California? 1.For regulating emissions of CFCs 2.For limiting number of SUV sales emissions of nitrogen 3.For limiting number of minivan sales. 4.For regulating GHG emissions

Why were automakers suing California? 1.For regulating emissions of CFCs 2.For limiting number of SUV sales emissions of nitrogen 3.For limiting number of minivan sales. 4.For regulating GHG emissions

Suggest to read: The Ozone Hole Basic chemistry of ozone depletion

Vertical Layers of the Lower Atmosphere Ozone Ozone is found in boundary layer as well as in stratosphere layer. The former is one of greenhouse gases.

video videos/MET%20112%20Video%20Library- MP4/ozone%20hole%20and%20human% 20connection/ videos/MET%20112%20Video%20Library- MP4/ozone%20hole%20and%20human% 20connection/ Ozone Sequence since 1979 What is the seasonality of O 3 in stratosphere Ozone-1.mp4 Why Ozone occur? Where? When?

Lowest value of ozone measured by TOMS each year in the ozone holeTOMS

Ozone Hole: Ozone depletion describes two distinct, but related observations: a.a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earth's stratosphere since the late 1970s; andozoneEarth'sstratosphere b. a much larger, but seasonal, decrease in stratospheric ozone over Earth's polar regions during the same period. The latter phenomenon is commonly referred to as the ozone hole. In addition to this well-known stratospheric ozone depletion,stratospheric ozone there are also tropospheric ozone depletion events, which occur near the surfacetropospheric ozone depletion events in polar regions during spring.

This figure was prepared by Robert A. RohdeRobert A. Rohde

ultraviolet lightultraviolet light (UV light) harmful UVB wavelengths (270–315 nm)

Absorption of Ultraviolet Radiation by Ozone

Ozone Formation through Splitting of Oxygen by Ultraviolet Radiation

Ozone Hole: Reductions of up to 70% in the ozone column observed in the austral (southern hemispheric) spring over Antarctica and first reported in 1985 (Farman et al 1985)

Formation and destruction of ozone Sunlight is the major energy source for both making and destroying stratospheric ozone: When an Oxygen molecule absorbs a photon of light with a wavelength shorter than 200 nanometers (1 billionth of a meter) the energy splits the molecule into two Oxygen atoms. One of these atoms can react with another Oxygen molecule to form an Ozone molecule. Up to 98% of the sun's high-energy ultraviolet light (UV-B and UV-C) are absorbed by the destruction and formation of atmospheric ozone. The global exchange between ozone and oxygen is on the order of 300 million tons per day.

Ozone Hole Recipe Ingredients: Chlorine gasChlorine gas Cold Temperatures (~-80C)Cold Temperatures (~-80C)Instructions: Allow cold temperatures to form Polar Stratospheric Clouds (1-2 weeks).Allow cold temperatures to form Polar Stratospheric Clouds (1-2 weeks). Allow time for polar stratospheric clouds to convert chlorine gas into ozone destroying chemicals. (1 month)Allow time for polar stratospheric clouds to convert chlorine gas into ozone destroying chemicals. (1 month) Bake ingredients with sunlight.Bake ingredients with sunlight. bingo, a delicious ozone hole!bingo, a delicious ozone hole! Science interpretation Chlorine gas is abundant in atmosphere due to CFC’sChlorine gas is abundant in atmosphere due to CFC’s Cold Temperatures (~-80C) only occur over Antarctica during the cold winter.Cold Temperatures (~-80C) only occur over Antarctica during the cold winter. Polar Stratospheric Clouds allow ozone friendly chlorine to be transformed into ozone destroying chlorine.Polar Stratospheric Clouds allow ozone friendly chlorine to be transformed into ozone destroying chlorine. Ozone depletion then starts when sun returns to Antarctica in the springOzone depletion then starts when sun returns to Antarctica in the spring Ozone hole grows from late August through till October.Ozone hole grows from late August through till October.

Dobson Units 0° 60° E 120° E 180 ° 60° W 120° W 180 ° March 1990 Halley Bay Total Ozone Content from Nimbus 7 TOMS

0° June 1990 Total Ozone Content from Nimbus 7 TOMS 180

September 1990 Total Ozone Content from Nimbus 7 TOMS

Dobson Units °N 60°N 30°N 0° 30°S 60°S 90°S Decembe r 1990 Total Ozone Content from Nimbus 7 TOMS

August ° 90 ° W 180 ° 90 ° W 90 ° E 0° 60° S 30° S Septem ber 1990 October 1990 Novem ber 1990 Total Nimbus 7 TOMS Ozone Content from

October ° 90 ° W 180 ° 90 ° W 90 ° E 0° 60° S 30° S Octob er 1982 Octob er 1985 Octob er 1988 Total Ozone Content from Nimbus 7 TOMS

Global Ozone

Human activity Climate and Weather Climate Change Science Understanding Policy Maker successful example is Response to Ozone Hole

Class Activity When Ozone occur? Why Ozone occur? Do you think Ozone hole related to Human activity? How What people can do to avoid ozone hole?

Where are the highest concentrations of ozone located? 1.In large cities 2.The stratosphere 3.The troposphere 4.Near volcanoes

Ozone Depletion Topics  History of Ozone Depletion  The Ozone Hole: what, where, why?  Ozone into the future

Past Events Deepest ozone hole: –September 30, 1994 –Levels fell to 73 DU Largest ozone hole: –September 1, 2006 –10.6 million sq. miles –Antarctica (5.4 million sq. miles)

Causes of Depletion Chlorofluorocarbon (CFC) Presence of UV, Chlorine dissociates from (CFC’s) –Produces chlorine radicals –Decompose ozone molecules Polar stratospheric clouds –Occur in winter at -80 °C –CFC reacts with nitric acid to liberate chlorine –Other factors: Methyl bromide Aerosols & refrigerants Agricultural pesticides

Early concerns of ozone depletion

History of Ozone Depletion: Connection between human and nature Chlorofluorocarbons (CFCs) developed in 1940’s and 50’s as:Chlorofluorocarbons (CFCs) developed in 1940’s and 50’s as: – 1970’s CFCs detected in upper atmosphere.1970’s CFCs detected in upper atmosphere. –Many of these have long atmospheric lifetimes: –1974 Rowland and Molina propose that CFC’s can destroy ozone in the stratosphere. –CFC contain chlorine (Cl) –

History of Ozone Depletion: connection between human and nature Chlorofluorocarbons (CFCs) developed in 1940’s and 50’s as:Chlorofluorocarbons (CFCs) developed in 1940’s and 50’s as: – 1970’s CFCs detected in upper atmosphere.1970’s CFCs detected in upper atmosphere. –Many of these have long atmospheric lifetimes: –1974 Rowland and Molina propose that CFC’s can destroy ozone in the stratosphere. –CFC contain chlorine (Cl) – Refrigerants, propellants, fire retardants –(10’s to 100’s of years) Chlorine can destroy ozone rapidly

Video:

video videos/MET%20112%20Video%20Library- MP4/ozone%20hole%20and%20human% 20connection/ videos/MET%20112%20Video%20Library- MP4/ozone%20hole%20and%20human% 20connection/ Ozone-1.mp4

Ozone Hole Recipe Ingredients: Chlorine gasChlorine gas Cold Temperatures (~-80C)Cold Temperatures (~-80C)Instructions: Allow cold temperatures to form Polar Stratospheric Clouds (1-2 weeks).Allow cold temperatures to form Polar Stratospheric Clouds (1-2 weeks). Allow time for polar stratospheric clouds to convert chlorine gas into ozone destroying chemicals. (1 month)Allow time for polar stratospheric clouds to convert chlorine gas into ozone destroying chemicals. (1 month) Bake ingredients with sunlight.Bake ingredients with sunlight. bingo, a delicious ozone hole!bingo, a delicious ozone hole! Science interpretation Chlorine gas is abundant in atmosphere due to CFC’sChlorine gas is abundant in atmosphere due to CFC’s Cold Temperatures (~-80C) only occur over Antarctica during the cold winter.Cold Temperatures (~-80C) only occur over Antarctica during the cold winter. Polar Stratospheric Clouds allow ozone friendly chlorine to be transformed into ozone destroying chlorine.Polar Stratospheric Clouds allow ozone friendly chlorine to be transformed into ozone destroying chlorine. Ozone depletion then starts when sun returns to Antarctica in the springOzone depletion then starts when sun returns to Antarctica in the spring Ozone hole grows from late August through till October.Ozone hole grows from late August through till October.

Effects of Ozone Depletion Increased surface warming Promotes increased melting –Potential to increase sea levels Affects marine ecosystems –Increased UV will result in less phytoplankton –Building block of oceanic food chain –Adverse effects on other species

What is being done about ozone depletion? Montreal Protocol ~ (1988) international agreement to reduce ozone depleting chemicals Further amendments accelerated the phase out. –Developed countries have switched to HCFC’s (more ozone friendly!) –

What is being done about ozone depletion? Montreal Protocol ~ (1988) international agreement to reduce ozone depleting chemicals Further amendments accelerated the phase out. –Developed countries have switched to HCFC’s (more ozone friendly!) –Developing countries have until 2004/5 to phase out CFC’s.

The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of a number of substances believed to be responsibletreatyozone layer for ozone depletion.ozone depletion The treaty was opened for signature on September 16, 1987 and entered into force on January 1, 1989 followed by a first meeting in Helsinki, May 1989.September January Montreal Protocol

Is the Montreal Protocol working? Seems to be!!! Recent observations indicate that chlorine is beginning to decline in the atmosphere. Kyoto protocol uses similar approach Start off with small achievable steps Further amendments accelerate reductions

What are predictions for the future? Model simulations suggest: – atmospheric chlorine will return to pre-80’s level __________________. –Uncertainties still remain: ____________________

Model simulations suggest: – atmospheric chlorine will return to pre-80’s level __________________. –Uncertainties still remain: ____________________ In next 50 years or so Influence of global warming Phase out of CFC’s A slow ozone recovery should follow decreasing chlorine concentrations!!! What are predictions for the future?

Model Prediction for the future: OZONE RECOVERY!

What is the connection between ozone depletion and global warming? No direct connection between these environmental issues. Global warming produces: – 

What is the connection between ozone depletion and global warming? No direct connection between these environmental issues. Global warming produces: –Tropospheric warming & –Stratospheric cooling  However: Global warming may enhance ozone depletion

What is the connection between ozone depletion and global warming? An increase in greenhouse gases traps more heat and thus –The stratosphere tends to cool (stratospheric cooling) Therefore, if the stratosphere cools, then Ozone hole chemistry –

What is the connection between ozone depletion and global warming? An increase in greenhouse gases traps more heat and thus –The stratosphere tends to cool (stratospheric cooling) Therefore, if the stratosphere cools, then Ozone hole chemistry –PSCs will likely increase –So slightly more ozone depletion Global warming will delay recovery of ozone layer

Over the last 100 years, global tropospheric ozone levels have been 1.increasing 2.decreasing 3.nearly constant

The chemical that triggers rapid ozone loss associated with CFCs is 1.Carbon Dioxide 2.Nitrogen dioxide 3.Methane 4.Chlorine

The Antarctic ozone hole develops during 1.SH Spring 2.SH Summer 3.NH Spring 4.NH Summer

Global ozone values are expected to recover in the next 1.10 years 2.30 years 3.50 years years

Class Participation: Are the following statement correct?Antarctic Ozone Hole Ozone hole begins to develop in spring when the sun returns to Antarctica Occurs between (August-November) First detected by scientist in 1985 and has continued to increase in the years of observation Not technically a “hole”, but a diminishing or thinning of the ozone layer