MET 112 Global Climate Change – Lecture 10 Recent Climate Change Dr. Craig Clements San Jose State University Outline  Recent trends in temperature  Recent trends in GHGs  Time scales

(b) Additionally, the year by year (blue curve) and 50 year average (black curve) variations of the average surface temperature of the Northern Hemisphere for the past 1000 years have been reconstructed from “proxy” data calibrated against thermometer data (see list of the main proxy data in the diagram). The 95% confidence range in the annual data is represented by the grey region. These uncertainties increase in more distant times and are always much larger than in the instrumental record due to the use of relatively sparse proxy data. Nevertheless the rate and duration of warming of the 20th century has been much greater than in any of the previous nine centuries. Similarly, it is likely 7 that the 1990s have been the warmest decade and 1998 the warmest year of the millennium. 7

Time series of climate data

Time series of climate data

Examples of Temperature Change  Trends  Periodic Oscillations  Random Variations  Jumps

Examples of Temperature Change  Draw the following: 1.Trend 2.Oscillation 3.Trend + Oscillation 4.Random variations 5.Random + trend 6.Jump 7.Random + jump

Trend Time Temperature

This graphs represents 1. Trend 2. Oscillation 3. Trend+Oscillation 4. Random variation 5. Random+Trend 6. Jump 7. Random+Jump Time Temperature

This graphs represents 1. Trend 2. Oscillation 3. Trend+Oscillation 4. Random variation 5. Random+Trend 6. Jump 7. Random+Jump

This graphs represents 1. Trend 2. Oscillation 3. Trend+Oscillation 4. Random variation 5. Random+Trend 6. Jump 7. Random+Jump

This graphs represents 1. Trend 2. Oscillation 3. Trend+Oscillation 4. Random variation 5. Random+Trend 6. Jump 7. Random+Jump

This graphs represents 1. Trend 2. Oscillation 3. Trend+Oscillation 4. Random variation 5. Random+Trend 6. Jump 7. Random+Jump

This graphs represents 1. Trend 2. Oscillation 3. Trend+Oscillation 4. Random variation 5. Random+Trend 6. Jump 7. Random+Jump

Oscillation Time Temperature

Trend + Oscillation

Random Fluctuations

Random Fluctuations + Trend

Jump

Jump + Random Fluctuations

Time Frames -- Examples  Seconds to minutes –  Hours – Diurnal Cycle (Caused by Earth’s Rotation)  Hours to Days –  Months – Seasonal Cycle (Caused by tilt of axis)  Years –  Decades -- Pacific Decadal Oscillation  Centuries – Warming during 20 th Century (Increase in greenhouse gases?)  Tens of thousands of Years –  Millions of Years –

Time Frames -- Examples  Seconds to minutes – Small-Scale Turbulence  Hours – Diurnal Cycle (Caused by Earth’s Rotation)  Hours to Days – Weather Systems  Months – Seasonal Cycle (Caused by tilt of axis)  Years – El Niño  Decades -- Pacific Decadal Oscillation  Centuries – Warming during 20 th Century (Increase in greenhouse gases?)  Tens of thousands of Years – Irregularities in Earth’s motions  Millions of Years – Geologic Processes Climate Change Climate “Variability”

Latest global temperatures

…“Over both the last 140 years, the best estimate is that the global average surface temperature has increased   What does this mean?   The Uncertainty (± 0.2°C ) is critical component to the observed trend

…“Over the last 140 years, the best estimate is that the global average surface temperature has increased by 0.6 ± 0.2°C” (IPCC 2001)  So the temperature trend is: 0.6°C ± 0.2°C  What does this mean?  Temperature trend is between 0.8°C and 0.4°C  The Uncertainty (± 0.2°C ) is critical component to the observed trend

Current CO 2 : ~383 ppm

What Changed Around 1800?  Industrial Revolution –  Also, extensive changes in land use began –

What Changed Around 1800?  Industrial Revolution –Increased burning of fossil fuels  Also, extensive changes in land use began –the clearing and removal of forests

The (Almost) Complete Long-Term Carbon Cycle (Diagram) Atmosphere (CO 2 ) Ocean (Dissolved CO 2 ) Biosphere (Organic Carbon) Carbonates Buried Organic Carbon Subduction/ Volcanism Silicate-to- Carbonate Conversion Organic Carbon Burial Oxidation of Buried Organic Carbon

Burning of Fossil Fuels  Fossil Fuels: Fuels obtained from the earth are part of the buried organic carbon “reservoir” –  The burning of fossil fuels is essentially –A large acceleration of the oxidation of buried organic carbon

Burning of Fossil Fuels  Fossil Fuels: Fuels obtained from the earth are part of the buried organic carbon “reservoir” –Examples: Coal, petroleum products, natural gas  The burning of fossil fuels is essentially –A large acceleration of the oxidation of buried organic carbon

Land-Use Changes  Deforestation: –The intentional clearing of forests for farmland and habitation  This process is essentially an acceleration of one part of the short-term carbon cycle: –

Land-Use Changes  Deforestation: –The intentional clearing of forests for farmland and habitation  This process is essentially an acceleration of one part of the short-term carbon cycle: –the decay of dead vegetation  Also causes change in surface albedo (generally cooling)

Natural Short-Term Carbon Cycle – Quantitative Atmosphere BiosphereOcean Carbon Content: 750 Pg* 1 Pg = g Carbon Content: 2000 Pg Carbon Content: 38, 000 Pg Carbon Flux: ~ 120 Pg/year Carbon Flux: ~ 90 Pg/year

CO 2 Measurements: Present

Carbon Budget Example Atmosphere 1.5 Ocean Land Land emission =1.3 Ocean emission = 3.0 Land uptake = -2.3 Ocean uptake = ? Note: Number are not real…only for practice Positive values refer to carbon going into the atmosphere What is the ocean uptake required to produce an atmosphere at 1.5?

The ocean update is:

Carbon Budget Example Atmosphere 1.5 Ocean Land Land emission =1.3 Ocean emission = 3.0 Land uptake = -2.3 Ocean uptake = ? -0.5 Note: Number are not real…only for practice What is the ocean uptake required to produce an atmosphere at 1.5?

Carbon Budget Example Notes… Land/atmosphere Flux = Land emission + Land uptake Ocean/atmosphere Flux = Ocean emission + ocean uptake

Carbon Budget Changes  Units in Peta-grams (x10 15 ) of Carbon per year (PgC/yr)  Atmosphere increase –  Emissions (fossil fuel, cement) –  Ocean-atmosphere flux –  Final component is Land/atmosphere flux:

Carbon Budget Changes  Units in Peta-grams (x10 15 ) of Carbon per year (PgC/yr)  Atmosphere increase3.3 ± 0.1 –Observations  Emissions (fossil fuel, cement)5.4 ± 0.3 –Estimates from industry  Ocean-atmosphere flux -1.9 ± 0.6 –Estimates from models/obs  Final component is Land/atmosphere flux:  What is the land/atmosphere flux?

Carbon Budgets Atmosphere Ocean Land Fossil fuel burning 5.4 PgC-1.9 PgC 3.3 PgC Land/atmosphere flux Ocean/atmosphere flux

Please make your selection

Carbon Budgets Atmosphere Ocean Land Fossil fuel burning 5.4 PgC-1.9 PgC-0.2 PgC 3.3 PgC Land/atmosphere flux Ocean/atmosphere flux

Carbon Budget (II)  Land atmosphere flux – Land atmosphere flux partitioned as follows  Land use change –  Residual terrestrial sink –

Carbon Budget (II) Land atmosphere flux partitioned as follows  Land use change –From observations -0.2±  Land atmosphere flux –Must be to balance budget  Residual terrestrial sink  Calculated to balance land/atmosphere flux

Carbon Budgets Atmosphere 3.3 PgC Ocean Land Fossil fuel burning 5.4 PgC-1.9 PgC-0.2 PgC Land use change 1.7 PgC So, now considering the land use change, what is the new Land/atmosphere flux? Land/atmosphere flux

What is the residual land sink?

Carbon Budgets Atmosphere 3.3 PgC Ocean Land Fossil fuel burning 5.4 PgC-1.9 PgC-0.2 PgC Land use change 1.7 PgC -1.9 So, now considering the land use change, what is the new Land/atmosphere flux? Land/atmosphere flux

Carbon Budget (II) Land atmosphere flux partitioned as follows  Land use change –From observations -0.2±  Land atmosphere flux –Must be to balance budget  Residual terrestrial sink  Calculated to balance land/atmosphere flux

Human Perturbation of the Carbon Cycle

Missing Carbon Sink Land or Ocean

Carbon Budget (III)  There are significant uncertainties related to these budget terms.  Main questions are related to: – –What are the carbon fluxes over different types of ecosystems  Tropical forests, Temperate forests, Boreal forests, Tropical savannas & grasslands, Temperate grasslands & shrub lands, deserts and semi deserts, Tundra, Croplands, Wetlands

Carbon Budget (III)  There are significant uncertainties related to these budget terms.  Main questions are related to: –Can biosphere/ocean take up more atmospheric CO 2 ? –What are the carbon fluxes over different types of ecosystems  Tropical forests, Temperate forests, Boreal forests, Tropical savannas & grasslands, Temperate grasslands & shrub lands, deserts and semi deserts, Tundra, Croplands, Wetlands –What happens if the land/ocean get ‘saturated’ with carbon?

Video – Global Warming – signs and the science  Explain the concept of ‘ancient sunlight’ and how it relates to the carbon cycle.

Carbon Budget (III)

Greenhouse Gases  Carbon Dioxide  Methane  Nitrous Oxide  CFCs (Chlorofluorocarbons)  Others

Methane

Anthropogenic Methane Sources  Leakage from natural gas pipelines and coal mines  Emissions from cattle –  Emissions from rice paddies

Anthropogenic Methane Sources  Leakage from natural gas pipelines and coal mines  Emissions from cattle –Flatulence…gas  Emissions from rice paddies

Nitrous Oxide

Anthropogenic Sources of Nitrous Oxide  Agriculture

CFCs CFC-11 CFC-12

Sources of CFCs  Leakage from old air conditioners and refrigerators  Production of CFCs was banned in 1987 because of stratospheric ozone destruction – Lecture on ozone depletion to follow later in semester…

Sources of CFCs  Leakage from old air conditioners and refrigerators  Production of CFCs was banned in 1987 because of stratospheric ozone destruction –CFC concentrations appear to now be decreasing –There are no natural sources of CFCs Lecture on ozone depletion to follow later in semester…

Latest global temperatures

Activity 1.Describe the 120 year temperature records in terms of the seven above described types of variations (trend, trend+oscillation etc.) by breaking up the time series into periods (i.e. from , oscillation + positive trend, from , negative trend) 2.Based on the past 120 years of globally averaged temperatures: a.What trend would you assign to this period. (i.e. 0.3°C over 120 years) b.If you were to break up the data into time sections provide trends over the following time periods i) ; b) and c)

How would you describe the last 30 years of temperature 1.Random 2.Oscillation 3.Oscillation+trend 4.Oscillation+jump 5.Random+jump 6.Trend 0 of 250

What is the approximate temp trend over the last 30 years? 0 of C/30 years 2.1.0C/30 years 3..1C/30 years 4.0.2C/30 years

What is the approximate temperature trend over the last 100 years? C/10 years C/10 years C/10 years 4.0.0C/10 years 0 of 250

Temperature over the last 10 years

Comparison of 1998 with 2005

The Land and Oceans have both warmed

Precipitation patterns have changed

Video – Donal MacIntyre and Climate  Glacier  Cities and climate  Future

Activity 11 Question  Explain how humans may affect precipitation in a city.