The condition of our atmosphere and climate is important for many reasons. The following section provides information on economic effects, water availability, changes in glacier extent, and health effects.
Our dependence on our climate means that extreme weather has a significant impact on our economy – especially our agricultural sector, which is reliant on a temperate climate. Although extreme weather events have always occurred, these are expected to become more frequent due to climate change (NIWA, 2009).
Extreme weather events can cause millions of dollars of damage (Insurance Council of New Zealand (ICNZ), 2014) and lead to injury or the loss of life. Extreme weather includes storms that cause flooding or wind damage, droughts, and snowstorms.
In 2014, the ICNZ identified eight extreme weather events – mainly storms and floods – that caused over $150 million in insurance costs for damage to homes, businesses, and farms (ICNZ, 2014) – though the total costs are likely to be much higher. For example, the North Island floods of 2004 cost more than $140 million in insurance payouts, but the full cost of damage was an estimated $355 million. About half (around $185 million) was for damage to agriculture (Horizons Regional Council, 2004).
Droughts are costly to the agricultural sector. The 2013 drought contributed to an estimated 4.4 percent decrease in milk production per cow (DairyNZ, 2014). Rising temperatures and changes in rainfall patterns are expected to make drought more frequent and more intense, especially in the east and north of the country (Reisinger et al, 2014).
Changes in climate affect the tourism industry. For example, rising average temperatures could reduce snowfall, and in turn the number of days that ski fields operate.
Our cultural sites are vulnerable to climate change. Many sites significant to Māori are in low-lying or coastal areas, which may be affected by sea-level rise or increased coastal-storm activity (Reisinger et al, 2014).
Climate influences the amount of water in our lakes, rivers, streams, and aquifers, and therefore how much water is available for our use.
Climate affects rainfall and other forms of precipitation. The average annual outflow to sea is around 80 percent of the volume of precipitation. Evapotranspiration, or the loss of water to the atmosphere by evaporation, and from plants by transpiration, accounts for most of the remaining water from precipitation.
As well as the water that flows out to sea through New Zealand’s rivers and streams (see figure 10), a large amount of water is stored in the ground (in aquifers). An estimated total of 711 billion cubic metres is held in aquifers, about three-quarters of this in Canterbury.
This graph shows the influence of precipitation and evapotranspiration on outflow of water through rivers and streams to the sea between 1995 and 2014. Visit the MfE data service for the full breakdown of the data.
From current data, we cannot determine whether climate change has had an effect on surface or groundwater.
For more detail see Environmental indicators Te taiao Aotearoa: Water physical stocks: precipitation and evapotranspiration.
The volume of glacier ice decreased 36 percent since 1978 (see figure 11). Increased temperatures over the last century have caused glaciers to melt. If temperatures continue to rise, it is likely that the extent of glaciers will shrink further.
This graph shows the annual glacier ice volumes between 1978 and 2014. Visit the MfE data service for the full breakdown of the data.
For more detail see Environmental indicators Te taiao Aotearoa: Change in glacier ice volume.
Climate, and change in climate, can affect our health. This section provides information on the incidence of melanoma (skin cancer), and the impact climate change may have on the incidence of some food- and water-borne illnesses.
High ultraviolet levels affect our health
New Zealand has one of the highest rates of skin cancer (melanoma) in the world (Ministry of Health, 2015). This is linked to the high ultraviolet (UV) light in our atmosphere, with peak intensities 40 percent greater than comparable latitudes in Europe. This is partly due to Earth’s orbit bringing the Southern Hemisphere closer to the sun in summer. Air clarity or the effects of cloud also affect our UV levels (NIWA, 2015).
The ‘ozone hole’ does not have a significant impact on UV levels in our atmosphere as it occurs south of New Zealand. While ozone levels over New Zealand decreased slightly since 1978, our UV levels have not shown a consistent trend across monitoring sites.
There has been no discernible trend in the overall incidence of skin cancer since 1996, but there has been a statistically significant increasing trend for males. Long lag effects between exposure to UV light and the occurrence of skin cancer means any recent changes in exposure are not evident in our current skin cancer data.
Our high rates of melanoma are also linked to the relatively high level of exposure New Zealanders have to the sun, and the large number of fair-skinned people in New Zealand. Relative to population, New Zealand is estimated to have the highest incidence and death rate from melanoma in the world (Ferlay et al, nd). In 2011, 2,204 people were reported as having melanoma, while 359 died from it (Ministry of Health, 2014).
The incidence of cancer is strongly influenced by age. New Zealand has an increasing proportion of people in the older age groups so we can expect an increase in the incidence of melanoma. For this reason, we use ‘age-standardised’ data to compare data over time periods and between countries. The age-standardised incidence of melanoma in New Zealand between 1996 and 2013 showed no clear trend (see figure 12).
This graph shows the age-standardised rates of occurrence of melanoma per 100,000 people between 1996 and 2013. Visit the MfE data service for the full breakdown of the data.
For more detail see Environmental indicators Te taiao Aotearoa: Occurrence of skin cancer.
Rising temperatures may affect our health
International research suggests rising temperatures increase the incidence of some diseases, such as food-borne diseases caused by Campylobacter and Salmonella, and water-borne diseases caused by Cryptosporidium (Health Analysis and Information for Action, 2015; Lal et al, 2013). However, the incidence of other illnesses more common in colder months, such as influenza, may decrease as a result of rising temperatures (Tompkins et al, 2012).