Geoscience Reference
In-Depth Information
four degrees of global warming?
Yes, no and maybe …
Jean P. Palutikof, Jon Barnett and
Daniela A. Guitart
Introduction
Although global average warming of 2°C has been identified as the threshold
for dangerous climate change, it is increasingly becoming clear that current
mitigation efforts will miss this target by a substantial margin (Betts et al., 2011;
Stafford Smith et al., 2011). Even if we contemplate 'overshoot' emissions
trajectories, stabilization at or below 2°C is beginning to look like an impossible
dream. Although we may hope for a world in which warming will be limited to
2°C or less, we should certainly plan for more, including average warming of 4°C
by the end of this century … a Four Degree World. In this chapter, we explore
the potential for humanity to adapt to a world in which temperatures are much
warmer than the present day. It is uncertain if, in this much warmer world, as
many people will be able to live happy, healthy lives. We seek to explore this
uncertainty in this chapter.
Can we adapt to a Four Degree World? We do not yet know if we can adapt
to high rates and levels of warming. This is for two important social reasons.
First, the answer depends on how 'adaptation' is defined. If adaptation simply
means 'a response to actual or expected climate impacts', then we - as a society
- most certainly can and will adapt. However, if adaptation is defined in terms
of judgments about the outcomes of these responses as being
successful
in some
way, then the answer becomes far more elusive, as such judgements are a matter
of perspective and values (for reviews of the adaptation concept see Smit et al.,
2000; Smit and Wandel, 2006). Adaptation for whom? Adaptation by whom?
The second reason is because adaptation is at its heart a process of decision-
making. Whether or not adaptation is successful is determined by who has the
power and responsibility to make decisions, the basis on which decisions are
made, and the means of their implementation, as well as the material outcomes.
In other words, the answer to the question is largely a matter of choices made
across all levels of society and across many sectors, and the degree to which these
are aligned. Central to our argument is that high-level institutions and values are
powerful determinants of adaptation (Haddad, 2005; O'Brien et al., 2009) and
