Environmental Health Indicators

About climate change and health

The World’s climate is changing

There is clear international evidence that the world’s climate is changing due to human actions. Between 1880 and 2012, the world warmed by an average of 0.85°C. Other impacts include rising sea levels, melting ice sheets and glaciers, and increasing ocean temperatures [1].

Climate is different from weather. Weather can change from day to day. Climate describes the average weather conditions for an area for at least 30 years. We use the following definition, in which climate change refers to

a change in the state of the climate,
which can be a change in the average ‘normal weather’, or how varied the weather patterns are,
and which continues for decades (or longer) [2].

Similarly, in New Zealand, the Resource Management Act 1991 defines climate change as:

‘a change of climate that is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and that is in addition to natural climate variability observed over comparable time periods.’

New Zealand’s weather patterns will intensify

New Zealand climate scientists predict that New Zealand’s weather will very likely change in the following ways [3], [4], [5], and [6]:

Predicted change	Explanation
Temperature	New Zealand will warm between 0.7°C and 1.0°C by 2040, and between 0.7° and 3.0°C by 2090 (relative to 1986-2005). There will be more days with temperatures above 25°C and fewer days with temperatures below 0°C.
Rainfall	Rainfall will vary around the country, especially with the seasons. The west and south of New Zealand will experience more annual rainfall, while the north and east will experience less. There will be more extreme daily rainfalls in western New Zealand and in the south of the South Island, increasing the risk of flooding.
Drought	Droughts will occur more often and will be more severe, especially in eastern and northern New Zealand.
Fire danger	There will be an increased fire risk in the east and south of the South Island and the west of the North Island.
Wind	Westerlies over central and southern New Zealand will be stronger. Extreme daily winds will increase in eastern regions, especially in the South Island.

Note: For more information about predicted changes under different greenhouse gas concentration pathways, please read [3] and [4].

Climate change has many impacts on health

Climate change has been described as “the biggest global health threat in the 21^st century” [7].

Climate change affects health in three ways [8], [9]:

Direct: Injuries or deaths caused by weather itself e.g.

Physical injury or death: due to more extreme events such as floods, storms and fires
‘Heat stroke’: due to more hot days

Indirect: Health effects that happen when a changing climate alters biological processes e.g.

Water-borne ‘tummy bug’ diseases: changing rainfall patterns and higher temperatures can affect drinking-water and recreational water quality (for more information, please visit our Drinking-water quality and Recreational water domains).
Salmonellosis: higher temperatures can affect food safety
Respiratory problems: higher temperatures can extend the pollen season and increase fire risk
Mosquito-borne infectious diseases: changing temperature and rainfall patterns increase the geographical distribution of mosquitoes of concern (for more information about mosquito-borne diseases, please visit our Border Health domain).

Diffuse: Health effects that happen when people need to substantially change their lives as a result of climate change

Mental health issues: displacement due to sea level rise, damage to property through flooding, loss of livelihood.

Some population groups will be more affected by climate change than others

Experts believe that some groups of people will be more vulnerable than others to the effects of climate change.

In New Zealand, key populations vulnerable to climate change include:

young children (aged under five years old), as they can become more quickly dehydrated on hot days and are less able to regulate their body temperature.
older adults (aged 85 years and over) who also can become more quickly dehydrated on hot days and by gastrointestial disease.
Māori: Māori communities are often more dependent on climate-sensitive primary industries such as farming and fishing
people living in poverty: People with low incomes have fewer resources to be able to protect themselves from exposure to extreme weather

If we know what vulnerable groups exist in an area, and how big those groups are, we can anticipate what additional support might be needed to help those groups adapt to climate change.

For more information, please visit our Population Vulnerability domain.

References

IPCC. 2013. Summary for Policymakers. In: Stocker TF, Qin D, Plattner GK, et al (eds). Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (pp. 3-30). Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.
Cubasch U, Wuebbles D, Chen D, et al. 2013. Introduction. In: Stocker TF, Qin D, Plattner GK, et al (eds). Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (pp. 119-158). Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.
Ministry for the Environment. 2016. Climate Change Projections for New Zealand. Atmospheric projections based on simulations undertaken for the IPCC 5^th Assessment. Wellington: Ministry for the Environment.
Reisinger A, Kitching R, Chiew F, et al. 2014. Australasia. In: Barros VR, Field C, Dokken D, et al (eds). Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part B: Regional Aspects Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.
Pearce HG, Kerr J, Clark A, et al. 2011. Improved estimates of the effect of climate change on NZ fire danger. MAF Technical Paper No: 2011/13. Wellington: Ministry of Agriculture and Forestry.
Clark A, Mullan B, Porteous A. 2011. Scenarios of regional drought under climate change. Prepared for Ministry of Agriculture and Forestry. Wellington: National Institute of Water & Atmospheric Research Ltd.
Costello A, Abbas M, Allen A, Ball S, Bell S, Bellamy R, et al. 2009. Managing the health effects of climate change. The Lancet 373(9676): 1693-1733. DOI: 10.1016/S0140-6736(09)60935-1 (accessed 4 December 2018).
McMichael AJ. 2013. Globalization, Climate Change, and Human Health. New England Journal of Medicine 368(14): 1335-1343. DOI: 10.1056/NEJMra1109341 (accessed 4 December 2018).
Royal Society Te Apārangi. 2017. Human health impacts of climate change for New Zealand. Evidence Summary. Wellington: Royal Society Te Apārangi.