How will climate change affect us?

The evidence of climate change

(Image: Dimitry Grigoriev)

Loss of critical life-supporting ecosystem services


  • Ecosystem services, which are provided free of charge by healthy natural environments supporting high levels of biodiversity, are critical to our existence because they are literally the life support systems we need to live on Earth. 
  • In the last few hundred years, and particularly the last 50 years, we have systematically fragmented natural environments so that the services they provideincluding a livable climateare no longer working properly or are disappearing altogether.
  • Now that the climate is changing, we, and the natural environments we need to provide these life-supporting services, are in even greater peril.
  • Restoring natural environments is a fundamental part of the solution to climate change but efforts to do so are largely overlooked in favour of economic, lifestyle, and technological choices.

“High levels of biodiversity have a positive impact on ecosystem functions and resilience which means that ecosystem services are more likely to be maintained despite disturbance and change. On the other hand, a loss of biodiversity has a negative impact on ecosystem stability and recovery and can result in resource collapse. Consequently, the loss of species and ecosystems, and the services they provide, threatens people’s existence, as the economy, along with individual livelihoods, health and food security all rely on nature.” Department of Conservation 

Ecosystem services

Earth is large so it can absorb some shocks and recover. But a continued attack on one system will cause a change others. A multi-pronged attack on all of these systems is now underway, so the quality and scale of what they can deliver is rapidly declining.

The benefits ecosystems bring to human wellbeing and the wellbeing of other species and ecosystems are known as ‘ecosystem services’ and fall into four main categories:

  • Supporting services these underpin the other service and include soil formation, primary production (plants making sugars and carbohydrates via photosynthesis) oxygen production (from plants) and nutrient cycles (fungi, bugs and the microorganisms in the soil that produce the essential nutrients we get from food).
  • Provisioning services: food, water, medicines, raw materials
  • Regulation: climate, waste removal, disease control
  • Cultural: social, recreational, spiritual, sense of well-being

The following are just a few examples. Figure. 3 summarises a more comprehensive list.

Food: Imagine a world without coffee or chocolate? Almost 90% of flowering plants rely on animals for pollination, and around 75% of our food crops rely on them. Pollinators, including bees and certain kinds of flies, wasps, butterflies, and birds are ‘keystone species’species that have a disproportionately large effect on their natural environment. If keystone species vanish then entire ecosystemsincluding food productioncollapses. While there may be technological solution in some instances, for example hand pollinating food crops or adding ever increasing amounts of fertiliser to deteriorating soils, they are time consuming, costly, and can have a destructive and dangerous side-effects, for example nitrogen fertiliser, know for its association with bowel cancer, entering waterways.

Waste removal: What happens after you flush the loo? Or dump leftovers and grass cuttings into the compost? Small insects, fungi, and microorganisms of all kinds digest waste and cycle it as part of the nutrient cycle. Imagine what would happen if all these bugs vanished?

Fig. 1: Meet the tidy midge that brings you chocolate: Forcipomyia sp.
Fig. 1: Meet the tidy midge that brings you chocolate: Forcipomyia sp.

Think you can just eat seafood? 90% of global warming has been absorbed by the ocean. That’s causing the water to warm and that’s killing plants and animals. While some species are moving to cooler weaters, the ocean is also absorbing a lot more carbon dioxide. That’s leading to ocean acidification which is threatening oceanic plants and animals, including the tiny plants in the ocean that produce around half the oxygen in the atmosphere that we breath.

“…at higher biodiversity, the impact of acidification on otherwise highly vulnerable key organisms can be reduced by 50 to >90%, depending on the species.” – Rastelli et al

Clean drinking water: doesn’t just appear from taps. It falls as rain or snow, flows over the ground as rivers or underground as aquifers, and then is pumped out, stored, and delivered to our homes.

Once upon a time the water in Canterbury was so clean you could drink it straight from the rivers and wells. But today, thanks to intensive dairy farming, Canterbury and Southland’s rivers are the most polluted in the country. Taking massive amounts of water from rivers, using it for irrigation and then allowing tonnes of fertiliser to flow back into the river means that what was once a free ecosystem service has been polluted for generations to come.

The cost of filtering and cleaning water is now something we have to pay for through rates or rent, and possibly with our health, as much of our water doesn’t meet the World Health Organisation’s standards for nitrates (which come from fertiliser and cow effluent).

‘Contaminant levels are on the rise in groundwater, rivers and lakes, with nitrate levels in particular emerging as a huge red flag. In the past 100 years, globally we have doubled the inputs of reactive nitrogen going into our natural environment. We have done this by using fossil gas to create synthetic nitrogen fertiliser, industrialising a job that used to be done for us by plants. – Dr Mike Joy, Victoria University of Wellington.

Medicines don’t just come from bottles: In March, the IUCN Red List declared the smooth handfish, Sympterichthys unipennis, extinct. It’s the first marine fish in modern times to be declared gone forever.

‘It might be hard to imagine why a little organism occupying a small niche in a place few humans ever visit might be important. But an enzyme from an extremophile microbe is being used in tests to diagnose COVID-19. Biodiversity matters, even if you can’t see it with your own eyes.’ – Katie Matthews, conservation scientist.

Climate control: carbon is the control nob on the planet’s thermostat (Fig. 2). Find out how carbon does this here (this website).

Fig. 2: Depending on conditions at the time, some dead plants and animals don’t decompose and the carbon in them is locked away underground until it’s recycled back to the surface through natural process. We’ve upset that balance by burning fossil fuels almost entirely of carbon.

Diseases: Destroying ecosystems changes the way that diseases interact between people and animals. Deforestation and extinctions make pandemics more likely as diseases jump from animal hosts to humans in a process called zoonosis. Covid-19 wasn’t the first, and it’s unlikely to be the last.

For a comprehensive list of ecosystem services, see the Intergovernmental Science-Policy Platform on Biodiversity (IPPBS): Global Assessment Report on Biodiversity and Ecosystem Services.

Fig. 3: The global trend in ecosystem services shows that they are mostly in decline. While we continue to gain more from energy, food, and materials (11 – 13) this is coming at the expense of other services. (Image:IPEBS)



Organisms that live and thrive in conditions that are hostile to most life on Earth. While plants use photosynthesis, for example, some extremophiles living around deep volcanic vents and in hot springs use chemosynthesis. While many of these organisms are tiny bacteria, some are much larger, such as shrimp. Tardigrades, sometimes called ‘water bears’, are tiny animals ranging from 1.5 mm to 0.1 mm that can survive extreme temperatures, extreme pressures (both high and low), radiation, dehydration, starvation, and air deprivation (they’ve survived exposure to outer space.)

References and further reading