Geoscience Reference
In-Depth Information
and conflicts over dwindling natural resources, including arable land, freshwater
supplies and (particularly for island coastal-dwelling communities) space for
settlements and daily living.
As we move down that list of primary, secondary and tertiary impacts, the
possibility of characterizing the type, timing and magnitude of future health
impacts under
1
4°C conditions, let alone how those impacts would differ
between different geographic regions and socio-economic groups, becomes
increasingly difficult. Tertiary impacts can mostly only be described in words, not
numbers, and in relation to each of a plausible future set of circumstances.
For health impacts higher up the list and able to be estimated in a
1
4°C
future, we should note again the Paris heatwave example. There will be many
such non-linear changes in future health impacts in Australia if 4°C of warming
occurs. Indeed, there would probably be rather rapid upwards step-changes in the
rates of occurrence of some health outcomes as critical thresholds or barriers are
breached, such as sufficiently altered wind and humidity conditions enabling the
southern movement of infected mosquitoes from Papua New Guinea across the
Torres Straits.
Indeed, a hotter future would not only be one in which, in health impact
terms, two plus two equals, say, ten, but one in which some
qualitative
changes
in the types and patterns of health risks would also occur. For example, we have
little capacity to foresee the range of physical and mental health disorders, along
with the health consequences of tensions and conflicts, which may arise if the
flow of asylum-seekers and climatic-environmental refugees from the Asian and
Pacific regions becomes a torrent of displaced and desperate humanity. Nor can
we know the full cascade of consequences likely to result from declines in the
productivity of agriculture in those regions (and in parts of Australia). How will
declining food yields combined with growing populations affect food prices, child
nutrition and development, adult health and economic productivity, trading
patterns, competition for arable land and regional geopolitical stability?
Plus 4°C: only a bit more warming than has been expected?
This first part of the chapter makes clear that it would be naïve to imagine we can
produce confident quantitative estimates of changes in the rates (and geographic
ranges) of many, perhaps most, of the adverse health impacts of a Four Degree
World for Australia. But we can certainly alert ourselves to the most likely
direction of those changes, and how the profile of disease, distress and depri-
vation across and within the population is likely to alter. Yet in addressing the
likely impacts of such warming we have no choice but to start with a knowledge
base derived from a world that we know, and to use it to project forward to one
that may actually not be a simple variation on a familiar theme. Indeed, it may
be a very unfamiliar world.
That point is easily underscored. In palaeo-climatic terms a Four Degree
World would equate to the Miocene world of 10-15 million years ago (Hansen
and Sato, 2008). There were no recognisable pre-humans then, let alone any
