The magazine of the european research area European Commission Copenhagen, a missed chance?

     Future

      Past

Risk to  

Many

Risk to  

Some

Large 

Increase

Increase 

Negative  

for Most  

Regions

Negative 

for some 

regions, 

Positive  

for Others

Negative  

in All  

Metrics

Positive or  

Negative, 

Market  

Impact,  

Majority  

of People  

Adversely  

Affected

High 

Low

5

4

3

2

1

0

-0.6

A

verage t

empera

tur

e incr

ease (

C°) abo

ve

 the 1990 lev

el

.

1

2

3

4

5

 Burning embers

From pale yellow to bright red, this IPCC graph illustrates increases in five 

risk categories associated with different levels of global warming. Published 

for the first time in 2001, it was updated in 2007 with a considerably increased 

level of alert.  

1   Risks faced by certain ecosystems (coral reefs, glaciers, living species, etc.).

2   Extreme meteorological risks (heat waves, floods, drought, fire, 

hurricanes, etc.).  

3   Increased regional disparities and vulnerabilities of impacts (in yellow, certain 

zones that benefit from warming could contrast with those that suffer from it; 

in the red areas the negative impact is generalised). 

4   Risks of impact on the economy and markets (same remark).

5   Risks of major upheaval (increased rate of increase in sea levels, 

ocean acidification, extreme heat levels).  

Expected rise in temperatures during the 

last decade of the century (2090-2099) 

given continued economic growth and use of 

a ‘mix’ of fossil and non-fossil fuels, 

according to the IPCC scenarios.  

S

our

ce: IPC

C

S

our

ce: IPC

C

 

 

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Is human activity the 

cause of climate change? 

The debate is far from 

closed.  

© Shutt

erst

ock/T

ranc

e Drumer

 research

*

eu No. 63 | APRIL 2010 

17

SPECIAL REPORT

 

CLIM

A

T

E

CLIMATE SCEPTICISM

They attribute the rise to natural factors. 

The second group and its members are not 

necessarily distinct from the former, and dis-

pute the scientific bases of the future scenarios 

predicted as resulting from global warming.  

What then are their arguments in opposing 

the opinions of the vast majority of climate 

experts? It is the sheer complexity of terrestrial 

systems and their relations with the universe 

that are the starting point for most of the ques-

tions and uncertainties that can still surround 

the origin and the consequences of present 

global warming.  

The sun as motor for warming

The argument most often put forward to 

refute the human origin of global warming 

relates to Earth’s position in relation to the sun 

and the latter’s activity. Throughout time, it is 

the intensity of solar activity, the pattern of 

Earth’s orbit around the sun and our planet’s 

inclination on this orbit that have governed tem-

peratures. “Over 800 000 years, if we set aside 

the past 200 years, we see effectively that it is 

natural factors, such as very gradual changes in 

the earth’s orbit and the position of the earth 

on this orbit, that triggered climate changes 

in the past,” admits Jean-Pascal van Ypersele, 

Vice-Chair of the IPCC and a  climatologist 

at  the Catholic University of Louvain (BE). 

“But while these parameters vary over very vast 

expanses of time, they are not enough to 

explain the sharp rise in temperatures seen 

since the industrial revolution. You must not 

mix up very different time scales.” (

1

)

Also, while CO

2

 was certainly not the sole 

causal factor at the outset, this gas is believed 

to have had an amplifying effect on the conse-

quences of changes to the distribution and total 

quantity of solar energy available on the earth’s 

surface. “Astronomical factors are the point of 

departure, and it is perfectly probable 

“All scientists 

must be sceptics”

As the IPCC scientists meet 

to assess and synthesise 

the studies enabling us 

to refine our knowledge 

of climate change, voices 

are being raised to question 

their conclusions.  

I

n science, a majority view never passes 

as a truth. While most climatology experts 

subscribe to the general view of the IPCC 

(International Panel on Climate Change) 

that human activities are very probably the 

cause of dangerous global warming, it is a thesis 

refuted regularly by the so-called ‘climate 

sceptics’. Lacking an expert knowledge of 

climatology, most mortals feel powerless in 

the face of the contradictory arguments. Cer-

tain sections of the media, more interested 

in generating controversy than in informing, 

add to the confusion.   

If we set aside those defending vested inter-

ests – using disinformation strategies reminiscent 

of those adopted by the tobacco giants in the 

1980s – and those who see the IPCC as no 

more than the armed wing of a global politico-

ecologist conspiracy, we are left with the no 

doubt sincere sceptics who back up their views 

with scientific arguments.  

Although the arguments take many forms, it 

is possible to roughly group the sceptics into 

two camps: those who deny or play down the 

anthropic nature of global warming, and those 

who contest its seriousness. The former put 

forward elements to show that greenhouse gas 

emissions originating in human activity bear 

very little if any responsibility for the tempera-

ture rises recorded since the mid-20

th

 century. 

   

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