lecture 2 anthropogenic climate change - the current state of knowledge and skepticism

LSGI1B022013-2014 (Semester 3)

Leung Wing-mo

Climate Change and Society

Anthropogenic climate change: the current state

of knowledge and skepticism

Lecture 2

More about greenhouse effect

Climate as a system consisting of the atmo

Global warming and Climate change :

It’s all about energy and energy balance

Energy transfer

Energy in the form of Electromagnetic Wave

3G Earth

Sun

Temperature and radiation

max

b/T

energy 0°C = 273.15K

Stars inside the globular cluster Omega Centauri

Lovejoy, Jan 2015

Electromagnetic spectra : Sun vs Earth

The Electromagnetic Spectrum Song - by Emerson & Wong Yann

song

Hyperlink:

http://www.youtube.com/watch?v=bjOGNVH

3D4Y

Atmospheric influences on radiation

Reflection Scattering Absorption

(absorber

warms)

Reflection

Scattering – why the sky is blue

Scattering – why sunset is beautiful

Atmospheric absorption and scattering of main Greenhouse Gases (GHG)

Water vapour

windows

Water vapour is an

important GHG, but:

• a gap in

absorption

• very little high up

• a feedback rather

than driver

Greenhouse effect

http://www.youtube.com/watch?feature=play

er_detailpage&v=ZzCA60WnoMk

Earth’s energy budget (approximate, averaged

over the whole globe and over a long time)

At the top of the atmosphere:

Incoming shortwave = Reflected Shortwave + Emitted longwave

At the surface:Incoming shortwave = Reflected shortwave + Net emitted longwave (emitted - incoming)

+ Latent heat flux + sensible heat flux

Sensible

heat 7%

Latent heat

23%

Net Longwave 21%

Yellow:

shortwaveRed:

longwave

Energy budget of the Earth (accurate)

Trenberth et al, AMS, 2009

Increasing GHG is

equivalent to reducing

the size of the drain in

the bathtub.

Our Earth – resembling this car?

Global

warming =

4 Hiroshima

bombs every

second !

Where does the extra energy go to?

What is scary is that many of

us don’t even know about it!

Key points

Shortwave radiation from the sun is the ultimate source of energy for

Earth’s climate system.

About 30% of incoming solar radiation gets reflected directly back to

space.

Earth absorbs energy from 2 sources: incoming solar energy and

energy re-emitted back toward Earth by GHG.

Earth therefore heats up to a temperature at which it can radiate

enough energy such that its energy outflow will balance its energy

inflow.

Earth is currently out of balance, with inflow exceeding outflow. It’s

temperature will rise until inflow and outflow are back in balance.

Key points (cont)

GHG are those that absorb and re-emit IR in the wavelength range of

IR emitted by Earth.

The major components in our atmosphere, N2 and O2, are symmetrical

and are not GHG. CO2, H2O etc have many modes of vibration which

facilitate absorption of IR.

When GHG emit IR, they emit it in random direction:

Some goes back towards Earth and gets re-absorbed

Some goes toward space

Some goes to another GHG molecule which repeats absorption and re-emission

and sends the energy in another random direction.

GHG slow the passage of IR from Earth’s surface to space, warming

the planet.

Changes associated with global warming

‘You don’t need people’s opinions on a fact’

1.1 Temperature - annual global temperature anomaly (wrt 1979 – 2010)

(satellite)

(surface)

1.2 Temperature – cold nights and days

1.3 Temperature – warm nights and days

1.4 Temperature – spatial variation

2 Ocean - warming of the upper layers

Global ocean heat content 較深的海水攝取更多熱能

較淺的海水

1022J = 150,000,000 Hiroshima bomb

4 Sea ice - the decrease in the last 30 years is unprecedented in the past 1450 years

1-3月

4-6月

10-12月

7-9月

Nov 1, 2011

Nov 1, 1980

5 Ice sheet - accelerating loss

Greenland ice sheetAntarctica ice sheet

RED:loss of iceBLUE:increase of ice

2003-2012

南極冰蓋 格陵蘭冰蓋

5 Melting ice sheet

6 Snow cover in N. hemisphere -decreasing

6 Vanishing glacier

vanishing glacier

http://www.bbc.co.uk/news/world-south-asia-15216875

2012

1983

6 Melting glacier

阿拉斯 (Muir Glacier, Alaska's Glacier Bay)

13 August 1941 31 August 2004

The glacier retreated by more than 12 km and thinned out by more than 800 m

7 Sea level – rising since mid 19th

century

7 Rising sea level

Source: WMO, http://www.wmo.int/pages/mediacentre/news/documents/400ppm.final.pdf

鑑古知今Current concentration

CO2 concentration now is the highest in the past 800,000 years

800,000 yr

8 Carbon dioxide concentration

https://www.youtube.com/watch?v=bak50U6HiRk

White elephants in the sky :

9 Acidification of the ocean

Independent analyses of many components of the climate system that would be expected to change in a warming world exhibit trends consistent with warming (AR5)

Overwhelming evidence of climate change

John Oliver HBO show “Climate debate”:

‘You don’t need people’s opinions on a fact.’

http://www.washingtonpost.com/blogs/erik-wemple/wp/2014/05/12/john-

oliver-on-climate-change-skeptics-you-dont-need-peoples-opinions-on-a-fact/

Skepticism

“I say the debate is over.

We know the science. We

see the threat. The time

for action is now.” – Arnold

Schwarzenegger, 2006

But is the debate over?

A fundamental question:“How do we know our current science is not wrong?” We don’t! But …

Examples of science of consensus overturned:

Geocentric universe

Fixity of species

Absolute nature of time and space, pervaded by aether

Fixity of continents

Yes, we could be wrong, and if scientific research

continues, it is almost certain that some aspects

of the current understanding will be modified,

perhaps in significant ways. But …

The robustness of climate science is thoroughly tested through:

(1) Induction (歸納法, generalizing from specific

examples): The more we know about a subject, the

more likely our conclusions about it are to be true.

Temperature records show a strong increase in temperature

when the amount of CO2 grew dramatically.

Instrumental records collaborated by independent evidence

from tree rings, ice cores, coral reefs etc.

Induction is not a sufficient condition. But the more

we know about a subject, the longer we’ve studied it,

the more likely our conclusions about it are true.

The robustness of climate science is thoroughly tested through: (2) Deduction (演繹推理, drawing inferences/predictions from

hypothesis): The most famous historical example of successful

deduction is that of Ignaz Semmelweis (1840s) about prevention

spread of infection by washing hands.

Svante Arrhenius, G S Callendar, Han Suess – independently predicted the

consequences of increasing CO2, and the prediction has come true.

Suki Manabe predicted warming strongest in polar regions, is not an induction

from observation but deduction from theory (Polar amplification – ice-albedo

feedback)

But still, we could be right for the wrong reason. One can never prove

a theory true, but you can prove it false – falsificationism (testability).

Climate predictions could be wrong, but if such mistakes are found,

there is no guarantee that correcting them will lead to a more

optimistic scenario. In fact, climate predictions have so far been

conservative than not.

The robustness of climate science is thoroughly tested through:

(3) Consilience of evidence

(independently derived data sets

coincide and explicable by the

same theory, coming together, like

a jigsaw puzzle.)

Instrumental records, tree rings, ice

cores, borehole … all point to the

same conclusion – things are getting

warmer.

Warming sea surface, melting glacier,

tree distribution… explicable only by

global warming.

Evidential standards – the evidence has been

subject to replication, corroboration and

peer review.

On the contrary, the contrarians are those

that fail the peer review

Climate science satisfies any criterion we put forward to test it

Merchants of doubts

Internal inconsistency of climate deniers–a denier holding 3 inconsistent beliefs at the same time

He was partly to be blamed

Interestingly, Reagan’s bonded ally, Margaret Thatcher, was a climate hawk

• The enormous changes

concentrated in such a short

time, … we have begun a

massive experiment with the

systems of this planet .

• No generation has a freehold

on this earth. All we have is a life

tenancy – with a full repairing

lease.

•We are not the lords, we are the

Lord's creatures, the trustees of

this planet, charged today with

preserving life itself—preserving

life with all its mystery and all its

wonder. May we all be equal to

that task.

Prominent scientists started the defamation campaign against climate scientists – motivated by politics/vested interest/ideology

William Nierenberg,

Director of Scripps

Institute of

Oceanography

Robert Jastrow

Head, Goddard

Institute for

Space Studies

Frederick Seitz

President, NAS,

Consultant to

Reynolds

Tobacco

George C Marshall Institute Think Tank, 1980’s

Challenged the scientific evidence, insisting that it was highly uncertain,

and there is no consensus;

No evidence of warming, or if there is warming, it is due to the sun (not

GHG);

Even if there is warming, it doesn’t matter, because we’ll just adapt to it;

Climate change is a hoax;

All because they have been fighting an enemy (Soviet Union) all life

long, and when Soviet enemy was gone, they had to find a new

enemy – environmental “extremism”.

They applied the “tobacco strategy” – unsettled science, no consensus.

“Doubt is our product” – infamous memo written by one tobacco

industry executive in 1969 – since it is the best means of competing

with the “body of fact” that exists in the mind of the public.

Global Climate Coalition, US, 1989 -2002 Amoco,

the American Forest & Paper Association,

American Petroleum Institute,

Chevron,

Chrysler,

Cyprus AMAX Minerals,

Exxon,

Ford,

General Motors,

Shell Oil,

Texaco,

United States Chamber of Commerce

2003 internal memo from Republican Advisor Franck Luntz to Candidates

The Party has lost the environmental communication battle, and is vulnerable on

environmental issue including climate change because people care about

environment and believe the government should do something.

The scientific debate is closing (against us) but not yet closed. There is still a

window of opportunity to challenge the science.

In order to address the vulnerability, Frank Luntz advised that we (Republicans)

should:

Insist that we don’t know whether climate change is a problem – that the science is

uncertain and hence it is premature for the govt to act on something which is not certain.

Act only with all the facts in hand (a recipe for inaction)

The scientific debate remains open. Should the public believe that the scientific issues are

settled, their views about global warming will change accordingly.

Use phrases “climate change” rather than “global warming”, since “climate change” is a lot

less frightening than “global warming”

He added, “A compelling story, even if factually inaccurate, can be more

emotionally compelling than a dry recitation of the truth.”

Doubt mongering strategies

Exploit complexity of issue

“Many unresolved questions”

Take details out of context

Confuse people with true but irrelevant information

Exploit scientific uncertainty – it isn’t proven

Create impression of scientific debate

Highlighting and exploiting real but minor dissent

Taking small disagreements about details out of context

Scientific Potemkin Village

Famous examples of doubt of contrarian : You can’t be sure that smoking cause cancer!

Smoking is not the only environmental factor

(besides asbestos, radon, air pollution…), hence you

cannot single it out as the cause.

But the fact is, through epidemiological studies:

among people who smoke but not exposed to

asbestos etc., they get lung cancer at much higher

rates than non-smokers. This leaves smoking as the

best explanation.

Dose-response relationship: more smoking > more

cancers (for the population).

A passage from the book “Merchants of Doubts” - Naomi Oreskes

"Imagine a gigantic, colossal banquet. Hundreds of millions of

people come to eat. They eat and drink to their hearts' content,

eating food that is better and more abundant than at the finest

tables in ancient Athens, or Rome or even in the palaces of

medieval Europe.

Then one day a man arrives wearing a white dinner jacket. He

is holding a bill."

"Not surprisingly the diners are in shock. Some begin to deny

that this is their bill. Others deny that there even is a bill. Still

others deny that they partook of the meal. One diner suggests

the man is not really a waiter, but is only trying to get attention

for himself or to raise money for his own projects. Finally the

group concludes that if they simply ignore the waiter, he will go

away.

It is up to the deniers to say that the current level of carbon dioxide is not

bad

1. Anthropogenic carbon dioxide levels are less important in driving climate

change compared to the greenhouse effect of clouds and water vapour.

2. There is no correlation between carbon dioxide and temperature, let alone a

demonstrated causal relationship. This is supported by the fact that the

steadily rising level of carbon dioxide, …, does not correlate with temperature

trends. There has been no global warming for 17 years, despite ever-

increasing levels of carbon dioxide.

3. …

Wyss Yim, Pok Fu Lam, Hong Kong

Anthropogenic carbon dioxide levels are less important in driving climate change compared to the greenhouse effect of clouds and water vapour - Yim

WarmingCooling

Aerosols partly

offset the warming

of GHG

“There is no correlation between carbon dioxide and temperature, let alone a demonstrated causal relationship” - Wyss Yim

But the fact is : CO2 absorbs IR was settled science more than

100 years ago.

“There is no correlation between carbon dioxide and temperature, let alone a demonstrated causal relationship” (cont.)

Svante Arrhenius, calculated in 1896 that cutting CO2 in half would suffice

to produce an ice age. He further calculated that a doubling of

atmospheric CO2 would give a total warming of 1.5-4.5 degrees Celsius.

“There has been no global warming for 17 years, despite ever-increasing levels of carbon dioxide” – Wyss Yim

Deliberately choosing 1998,

the warmest year on record,

as the starting point

“Global warming stopped 16 years ago !”Wyss Yim is not the first one to make this claim

69

January 2014, one of the

coldest in North America

A case of confusing

people with true but

irrelevant information

Trump controversies:

• Racial

discrimination – full

page newspaper ads

calling for death

penalty of black

teenage suspects in a

rape case; alleging

Obama didn’t get good

enough grades to

Harvard; “laziness is a

trait in blacks”…

• Vaccines cause

autism

Despite what Trump said, the Earth is still warming !

IPCC AR5 (2014) : “It is extremely likely (>95% confidence) that human influence has been the dominant cause of the observed warming since the mid-20th century.”

Is 95% confidence good enough to call for action?

Should we wait and see?

Uncertainty is inherent in every scientific judgment, demanding

absolute proof on issues as complicated as climate change does not

make sense.

95 % certainty regarding climate change is most similar to the

confidence scientists have that cigarettes are deadly.