| |
 Research
Areas
1. Aims
Ecosystems and societies in the North Atlantic region
greatly profit from the warmth that the North Atlantic Current carries
to them. Climate models and data from the past show that the thermohaline
circulation (THC) in the oceans, of which the North Atlantic Current
is one branch, may abruptly weaken or even shut down altogether.
INTEGRATION explores the possibilities and consequences of future
changes of the THC, addressing the following guiding questions:
- How likely is a weakening or a breakdown of
the THC?
- What are the potential impacts of THC changes,
on ecosystems, economy, and society?
- What are possible strategies to reduce the risk
of changes of the THC?
2. Strategy
The approach to answer the guiding questions is
an Integrated Assessment, which comprises the following components:
- Climate scenarios.Several climate models (Climber-2,
Climber-3a and others) are driven with greenhouse gas emission
scenarios for the next three centuries. This long time scale reflects
the thermal inertia of the oceanic water masses.
- The impacts on ecosystems and societyare explored
along two impact chains (marine and terrestrial), using various
impact models. While a large part of the marine impact chain is
studied by the external project partners, the terrestrial and
socio-economic impacts are dealt with at PIK. Some of the models
used here are: AEZ for crop yield, LPJ for general impact on vegetation
an the carbon cycle, 4C for tree vegetation dynamics of specific
stands, EFISCEN for impacts on forestry in the economic sense.
In addition, the impacts of an additional sea level rise are explored.
- An expert elicitation collects the current knowledge
about the THC and its risks, addressing questions like the driving
mechanisms of the THC, future research needs to reduce uncertainties,
or the feasibility of an early warning system for the THC. An
important outcome of the interviews are experts' subjective probability
estimates for essential climate parameters.
- A dialogue with stakeholders explores their judgments
and their risk aversion, using subjective probabilities. Especially
the question of the potential dangerousness of a THC breakdown
(in the sense of Art. 2 UNFCCC) is discussed here.
- An uncertainty analysis addresses some of the
many dimensions of uncertainty. Parameter uncertainty is studied
in Climber-2 as well as Climber-3alpha. The propagation of this
type of uncertainty through the impact chain is explored in some
cases (e.g. for agriculture). Within Climber-3alpha, structural
uncertainty is another focus. The uncertainty analysis aims at
an likelihood estimate for a THC breakdown.
- An integrated assessment model (IAM) is employed
to outline mitigation options reducing the risk of a THC breakdown
using the Tolerable Windows Approach. With the inclusion of a
model of endogenous technical change more detailed socio-economic
guardrails can be formulated.
|
