Progress in Earth System Science: What Does It Take to Make Our Ideas Clear? - Towards an Interdisciplinary Approach in Earth System Science - page 23

IPCC 2007 , 2013 ). Future scenarios on the other hand will largely depend on future
societies and their decisions about energy consumption and greenhouse gas emis-
sions. The Report of the Intergovernmental Panel on Climate Change (IPCC 2007 ,
2013 ) can be viewed as a (still incomplete) compilation of what is known about
climate change, whereas several uncertainties are spelled out. The reliability of the
representation of climate processes such as clouds, the cryosphere and biogeo-
chemical cycles has strongly increased, but many details still need to be fully
elaborated. Non-specialists may be not aware of the limitations and assumptions of
Earth System Science. In contrast to many areas in pure physics, there is no lab-
oratory to test scenarios (other than numerical models of the Earth) since we have
just the one real live experiment, the Earth.
Let us think about the typical steps to produce an idea for a new discovery which
is usually the basis for a publication or a PhD thesis (as for our graduate research
school (Lohmann et al. 2013a )). As Peirce ( 1878 ) pointed out that when Descartes
( 1644 ) set about the reconstruction of philosophy, his

first step was to theoretically
permit scepticism and to discard the practice of regarding authority as the ultimate
source of truth. 2 That done, he sought a more natural fountain of true principles, and
thought to have found it in the human mind; thus passing, in the most direct way,
from the method of authority to that of apriority. Self-consciousness was to furnish
us with our fundamental truths, and to decide what was agreeable to reason. During
our scientific career the step from a school-like, more dependent situation to an
independent, self-critical approach is not trivial, and in some cases the transition
never takes place. One goal of modern PhD education shall be to make scientists
aware of the underlying principles, the limitations and open questions in the field.

Holding opposite opinions upon fundamental principles, Descartes was further led
to say that clearness of ideas was not suf

cient, but that they needed also to be
distinct. Kuhn ( 1962 ) argues in terms of evolution of scienti c theories where

different phases do not emerge from the straightforward accumulation of facts, but
rather from a set of changing intellectual circumstances and possibilities.
Climate science went already through a pre-paradigm phase in the sense of Kuhn
( 1962 ), in which there is no consensus on any particular approach. Somehow,
climate and Earth System Science in general are partly already in a second phase, in
which the open questions are solved within the context of the established methods
and these are documented in review articles, books and reports (e.g., Berger 1988 ;

2

'
point of view. Those are convinced that the rapid climate change theory is only a myth, a way of
turning attention of media and society to scienti c research (e.g., Singer 2007 ). Global climate
models often appear as a cornerstone of this disagreement. However, the majority of these
scepticists do not have a background in climate science and have not published papers in the peer-
review process (e.g., Lee and Bero 2006 ). This process is important to overcome a subjective view
and a way to distinguish between an idea seemingly clear and really being so. There are indications
for parallels between the climate change debate and earlier controversies over tobacco smoking,
acid rain and the hole in the ozone layer (Oreskes and Conway 2010 ) where spreading doubt and
confusion was the basic strategy of those opposing action in each case. The typical structure of
arguments is easily identi ed in this debate (McCright and Dunlap 2000 ).

Interestingly, there are people in and around Earth System Science assuming a more ' sceptical