Geoscience Reference
In-Depth Information
harvest failure, dire weather and high mortality, including in central Sweden,
beginning in 536 ad.
These are three very different examples, from hunter-gatherer times,
pre-agrarian settlements and a period of well-developed agrarianism. All indicate
the central importance to human wellbeing and health of food supplies and
nutrition. When climates change, whether with significant warming
or
cooling,
or with either substantial increases
or
decreases in rainfall, harvests and livestock
are at risk. Nutrition, health and survival are then jeopardized and social
disorder, tensions and conflicts frequently result.
Unfortunately, there are no documented
1
4°C warming periods during the
Holocene from which we can draw further relevant insights. At the spatial level
of hemisphere and major geographic region (Western Europe, China, Central
America, etc.), temperatures did not vary up or down from the Holocene average
by more than about 1.5°C, on decadal or centuries-long timescales (McMichael,
2012).
Health risks from
1
4°C warming in Australia: overview
Extremes of heat stress, in community and workplace
Higher average temperatures mean large increases in the frequency of extreme
heat episodes. As Australia's temperature rose from 1960 to 2010 by 0.9°C the
number of record hot days more than doubled (CSIRO and BoM, 2007). With
a rise of 2°C, the annual number of very hot days (over 35°C) is estimated to
increase by around fourfold in the majority of capital cities and by twentyfold to
twenty-fivefold in Darwin and Brisbane. Across northern Australia the extreme
daily temperature that currently occurs about once per 20 years is projected to
occur every one to two years by later this century (IPCC, 2012). These increases
will presumably be very much greater with twice that amount of warming.
For the Australian population in general, and especially the more vulnerable
(low-income families, the elderly, those with underlying cardio-respiratory
diseases, etc.) living in a Four Degree World, summer accompanied by more
short-term heat extremes would be potentially lethal and widely damaging. If
Australia's average temperature increased by around
1
4°C this century, the
estimated total national number of yearly temperature-related deaths would
increase from around 5,800 in 1990 to 6,400 in 2020, 7,900 in 2050 and
17,200 in 2100 (Bambrick et al., 2008), with estimates including adjustment
for population growth and ageing. Meanwhile, adverse health effects from cold
extremes would recede.
A particular and under-recognized health threat will impinge on segments
of the workforce. Heat exposure is intrinsic to some jobs (outdoors, foundry-
workers, unventilated factory settings, etc.). In a
1
4°C Australia there would
be a substantial increase in the number of health-endangering episodes and
situations in the workplace, affecting cardiovascular risks, severe dehydration
and kidney damage/failure, impairments of judgement (leading to injuries),
