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The Changing Debate on Global Warming. by Dr. Eric J. Barron Hot Science - Cool Talks Volume 51.

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The changing debate on global warming l.jpg

The Changing Debate on Global Warming

by Dr. Eric J. Barron

Hot Science - Cool Talks Volume 51

Produced by and for the Hot Science - Cool Talks Outreach Lecture Series of the Environmental Science Institute. We request that the use of any of these materials include an acknowledgement of Dr. Eric J. Barron and the Hot Science - Cool Talks Outreach Lecture Series of the Environmental Science Institute of the University of Texas at Austin. We hope you find these materials educational and enjoyable.


The changing debate on global warming eric j barron jackson school of geosciences l.jpg
The Changing Debate on Global WarmingEric J. BarronJackson School of Geosciences


Every credible scientist recognizes that increases in greenhouse gases promote warming l.jpg

Incoming solar energy (hot sun, short wavelengths) largely pass through the atmosphere and heat the surface

Earth’s surface radiates to space (cooler body, longer wavelength)

Gases like carbon dioxide selectively absorb longer wavelengths – reradiate to space and back to the surface

Without selective absorbers Earth is 5°F

With selective absorbers Earth is 64°F

Every credible scientist recognizes that increases in greenhouse gases promote warming


The real issue in the debate l.jpg

How much will it warm – in response to humans adding more greenhouse gases?

How fast will it warm?

How significant will be the impact?

The first two questions will likely remain uncertain for decades.

So, for decision-makers the last question is key.

It is not just a science question.

It depends on what you value.

The Real Issue in the Debate


My debate with an economist l.jpg

Suppose I got a contract to cut down all greenhouse gases?

of the trees for lumber on the west side

of Austin. Good or bad?

My debate with an Economist


My debate with an economist6 l.jpg

Suppose I got a contract to cut down all of the trees for lumber on the west side of Austin. Good or bad?

GOOD – a product - brings in dollars; jobs bring in dollars

My debate with an Economist


My debate with an economist7 l.jpg

Suppose I got a contract to cut down all of the trees for lumber on the west side of Austin. Good or bad?

GOOD – a product brings in dollars; jobs bring in dollars

WAIT – what about beauty, habitat, ecosystem services (water)?

My debate with an Economist


My debate with an economist8 l.jpg

Suppose I got a contract to cut down all of the trees for lumber on the west side of Austin. Good or bad?

GOOD – a product brings in dollars; jobs bring in dollars

WAIT – what about beauty, habitat, ecosystem services (clean water)?

But in one generation people won’t know what they have missed – it doesn’t have value

My debate with an Economist


Slide9 l.jpg

The Changing Debate on lumber on the west side of Austin. Good or bad?Climate ChangeWhat do scientists really believe about global warming?What are the predictions for the future?What are the potential impacts?


What do climate experts say about global warming l.jpg

What do climate experts say about global warming? lumber on the west side of Austin. Good or bad?


Foundations l.jpg

Carbon dioxide is a selective absorber lumber on the west side of Austin. Good or bad?

Greenhouse gases are increasing (due to burning oil, coal and deforestation)

Increased greenhouse gases promote warming

Draw down of gases will take centuries

Aerosols have human sources

Many aerosols promote cooling

The planet has warmed 1°F in a century

Foundations


Slide12 l.jpg

1 lumber on the west side of Austin. Good or bad?

0.8

0.6

0.4

0.2

0

-0.2

-0.4

-0.6

The Smoking Gun

Temperature Change

Temperature Change °F

380

360

340

320

300

280

260

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

1000 years of global CO2 and temperature change

CO2 Concentrations

CO2 Parts per Million by Volume (PPMV)

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

8

6

4

2

0

Carbon Emissions

Billions of Metric Tons

Land-use Change

Fossil-fuels

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

U.S. Global Change Research Program

Year


Slide13 l.jpg

Global Land-Ocean Temperature Anomaly ( lumber on the west side of Austin. Good or bad?°C)

Base Period = 1951-1980

0.6

0.4

0.2

0

-0.2

-0.4

Annual Mean

5-year Mean

1880

1900

1920

1940

1960

1980

2000

Year

J. Hansen, R. Ruedy, M. Sato, and K. Lo (NASA and Columbia University)


2001 2005 mean surface temperature anomaly c l.jpg
2001-2005 Mean Surface Temperature Anomaly ( lumber on the west side of Austin. Good or bad?°C)

Global Mean = 0.54

-2

-1.6

-1.2

-.8

-.4

-.2

.2

.4

.8

1.2

1.6

2.1

J. Hansen, R. Ruedy, M. Sato, and K. Lo (NASA and Columbia University)


Predictions that are virtually certain l.jpg

The stratosphere will cool. lumber on the west side of Austin. Good or bad?

Predictions that are virtually certain

Lower Stratosphere

(13-19 km) Cooling

Upper Troposphere

(8-13 km) Warming

Thickness of atmospheric layers exaggerated for clarity.

Lower Troposphere

(0-8 km) Slight Warming

Earth’s Surface

Warming

NASA


Predictions that are very probable l.jpg

Surface temperature will increase: lumber on the west side of Austin. Good or bad?

•0.5 to 2.0°C by 2050

• 1.5 to 4.5°C for a CO2 doubling

• 2.5°C most likely

Global precipitation will increase

Sea ice will retreat in Northern Hemisphere

Arctic warming

Predictions that arevery probable


Predictions that are very probable17 l.jpg

Sea level will rise, 5 to 40 cm by 2050 lumber on the west side of Austin. Good or bad?

The effects of solar variability will not be significant over the next 50 years compared to those of CO2

Predictions that are very probable


Predictions that are uncertain l.jpg

Climate variability changes lumber on the west side of Austin. Good or bad?

Regional climate changes

Tropical storms

The next 25 years & biosphere feedbacks

Predictions that are uncertain



Summer maximum winter minimum temperature change l.jpg
Summer Maximum & Winter Minimum Temperature Change 2090 to 2100?

+15°F

+10°F

+5°F

0°F

-5°F

+15°F

+10°F

+5°F

0°F

-5°F

Canadian Model 21st Century

Canadian Model 21st Century

Summer Maximum

Winter Minimum

Hadley Model 21st Century

Hadley Model 21st Century

+15°F

+10°F

+5°F

0°F

-5°F

+15°F

+10°F

+5°F

0°F

-5°F

Summer Maximum

Winter Minimum

U.S. Global Change Research Program


Precipitation change l.jpg
Precipitation Change 2090 to 2100?

Canadian Model 21st Century

100%

75%

50%

25%

0

-25%

-50%

-75%

-100%

Observed 20th Century

100%

75%

50%

25%

0

-25%

-50%

-75%

-100%

Hadley Model 21st Century

100%

75%

50%

25%

0

-25%

-50%

-75%

-100%

U.S. Global Change Research Program



Ecosystem models current models l.jpg
Ecosystem Models agriculture and health?Current Models

Tundra

Taiga/Tundra

Conifer Forest

Northeast Mixed Forest

Temperate Deciduous Forest

Southeast Mixed Forest

Tropical Broadleaf Forest

Savanna/Woodland

Shrub/Woodland

Grassland

Arid Lands

U.S. Global Change Research Program


Ecosystem models l.jpg
Ecosystem Models agriculture and health?

Canadian Model

Tundra

Taiga/Tundra

Conifer Forest

Northeast Mixed Forest

Temperate Deciduous Forest

Southeast Mixed Forest

Tropical Broadleaf Forest

Savanna/Woodland

Shrub/Woodland

Grassland

Arid Lands

Hadley Model

U.S. Global Change Research Program


Even hadley model says no sugar maples in the u s l.jpg

Projected Changes in Distribution agriculture and health?

of Sugar Maple Trees

Even Hadley model says no sugar maples in the U.S.

Iverson et al. 1999


July heat index change l.jpg
July Heat Index Change agriculture and health?

Canadian Model 21st Century

Hadley Model 21st Century

+25°F

+20°F

+15°F

+10°F

+5°F

0°F

B. Felzer, UCAR


Heat mortality and climate change heat related deaths in chicago in july 1995 l.jpg
Heat Mortality and Climate Change agriculture and health?Heat-related deaths in Chicago in July 1995

180

160

140

120

100

80

60

40

20

0

120

115

110

105

100

95

90

85

80

75

Heat Index

Max Temperature

Deaths

Maximum Temperature (°F) or Max Heat Index

Number of Heat-related Deaths

7/11

7/12

7/13

7/14

7/15

7/16

7/17

7/18

7/19

7/20

7/21

7/22

7/23

NOAA/NCDC


Vector borne disease reported cases of dengue 1980 1999 l.jpg
Vector-borne Disease agriculture and health?Reported Cases of Dengue 1980 - 1999

Texas:

64 Cases

Border States:

62,514 Cases

Mexico

HIH, Mexico; TDH; U.S. PHS


High precipitation and flashy streams observed changes in streamflow and precipitation 1939 1999 l.jpg
High Precipitation and “Flashy” Streams agriculture and health?Observed changes in streamflow and precipitation (1939-1999)

20

15

10

5

0

-2.5

Percentage of Total Change - % per 100 years

0

20

40

60

80

100

Light/Low

Moderate

Heavy/High

U.S. Global Change Research Program


Slide30 l.jpg

Changes in Western Snowpack agriculture and health?

20

0

-20

-40

-60

-80

-100

20

0

-20

-40

-60

-80

-100

Percentage Change from 1961 - 1990 Base

Percentage Change from 1961 - 1990 Base

2023

2071

2083

2095

2023

2071

2083

2095

1999

2011

2035

2047

2059

1999

2011

2035

2047

2059

U.S. Global Change Research Program


Slide31 l.jpg

More tendency towards drought agriculture and health?

Projected Trends in the PDSI

21st Century Hadley Model

Trends

Palmer Drought

Severity Index / 100yr


Slide32 l.jpg

More tendency towards drought agriculture and health?

Projected Trends in the PDSI

21st Century Canadian Model

Trends

Palmer Drought

Severity Index / 100yr


Corn yields and weather events corn yields in u s 1950 1999 l.jpg
Corn Yields and Weather Events agriculture and health?Corn Yields in U.S. 1950 - 1999

140

120

100

80

60

40

20

0

Bushels per Acre

1950

1960

1970

1980

1990

1999

Year

U.S. Global Change Research Program


Projected summer sea ice change canadian model an ice free arctic summer l.jpg
Projected Summer Sea Ice Change agriculture and health?Canadian Model: An ice-free Arctic summer

Current Sea Ice Extent

2030 Sea Ice Extent

2095 Sea Ice Extent

U.S. Global Change Research Program


The changing debate on global warming35 l.jpg

What do scientists really believe about agriculture and health?

global warming?

What are the predictions for the future?

What are the potential impacts?

The Changing Debate on Global Warming