English Abstract In this report on possible impacts, scenarios of the
IMAGE 2 model and Safe Landing Analyses we have shown that selecting an
appropriate ecological target can assist in defining 'adaptable' levels of
climate change and that impacts of climate change do matter. Impacts,
especially those on ecosystems, could be large. Ecosystems play a major
role in global biogeochemical cycles. Changes in ecosystems can change this
role and surprise in their response and functioning cannot be ruled out, all
leading to pronounced effects on current biomes, landscapes, community and
biodiversity. Many of these effects are judged as being irreversible.
Global cumulative emissions, averaged concentrations and series of mean
annual temperatures are all commonly used to specify and quantify impact
levels. However, such global indicators do not adequately identify regional
and local impacts. Important climatic aspects, such as seasonality, have to
be considered. The current question put to ecologists and other impact
assessors, is how to develop appropriate indicators and quantify them in
such a way that 'dangerous interference with climate' becomes more obvious
when indicators are exceeded. The discussions and indicator analysis
presented in this report represent only a first step, one strongly
determined by the availability of coarse global models and data. The
challange to ecologists is to synthesise the observed changes in ecosystems
over the past decades, determine their causes and unambiguously resolve the
climate components. This will enhance our understanding of quantifying
ecosystem change and attributing causes.
