Effects: More extreme weather
Image: NASA
Effects
- Planetary Boundaries & Tipping Points
- Extreme weather & event attribution
- ENSO: El Niño & La Niña
- Feedback effects of warming
- Wildfires increasing
- Antarctica melting
- Antarctic sea ice disappearing
- Arctic sea ice disappearing
- Greenland melting
- Ocean currents changing
- Oceans warming
- Ocean acidification
- Melting permafrost & burning ice
- New Zealand’s disappearing glaciers
- Black carbon & ash on snow
- Seasons changing
- How we know about past climates: proxy data
Home > Climate wiki > Effects
More extreme weather
Summary
A 1.5°C average increase in temperature doesn’t seem like much, but averages don’t generally kill you or destroy your home or the agricultural systems that we depend upon for food. The effects of rising temperatures are becoming more evident, through unprecedented disintegrating ice caps, oceans becoming more acidic, more frequent and intense floods, and longer droughts. But how do we know if a specific extreme weather event is due to climate change?
‘Event Attribution’ is the term for how scientists work out what percentage, if any, climate change is responsible for the frequency and scale of extreme events such as the 2020 Australian wildfires, the 2021 Canterbury floods and 2021 Pacific Northwest heatwave that killed an estimated billion marine animals and over 500 people, Cyclone Gabrielle in Aotearoa in February 2023, and the 2025 Los Angeles fires.
If we understand how likely an event occurs because of climate change versus natural fluctuations, or how much climate change has turbo-charged the effects of large scale weather patterns such as El Niño we can better plan to mitigate future climate costs.
Insurance underwriters use climate attribution tools to help calculate the cost of insurance, or to decline your insurance; for example if you live in an area at risk from floods or rising sea levels.
For too long, weather’s randomness has kept events such as these from being blamed squarely on climate change… Now, we can specify increased chances for specific events. This extends to forecasts: we can identify the places that are more likely to see wildfires, mudslides and fish die-offs. Such calculations dent both climate denial and a false sense of security. They take away the argument that ‘extreme weather happens anyway, so we don’t need to worry about it’. Extreme weather happens—and these metrics pinpoint what is becoming more likely, by how much and why… Such evidence is also useful for legal proceedings when citizens call corporations or governments to account for their role in climate change. – Richard A. Betts
Effects
- Planetary Boundaries & Tipping Points
- Extreme weather & event attribution
- ENSO: El Niño & La Niña
- Feedback effects of warming
- Wildfires increasing
- Antarctica melting
- Antarctic sea ice disappearing
- Arctic sea ice disappearing
- Greenland melting
- Ocean currents changing
- Oceans warming
- Ocean acidification
- Melting permafrost & burning ice
- New Zealand’s disappearing glaciers
- Black carbon & ash on snow
- Seasons changing
- How we know about past climates: proxy data
Home > Climate wiki > Effects
Summary
A 1.5°C average increase in temperature doesn’t seem like much, but averages don’t generally kill you or destroy your home or the agricultural systems that we depend upon for food. The effects of rising temperatures are becoming more evident, through unprecedented disintegrating ice caps, oceans becoming more acidic, more frequent and intense floods, and longer droughts. But how do we know if a specific extreme weather event is due to climate change?
‘Event Attribution’ is the term for how scientists work out what percentage, if any, climate change is responsible for the frequency and scale of extreme events such as the 2020 Australian wildfires, the 2021 Canterbury floods and 2021 Pacific Northwest heatwave that killed an estimated billion marine animals and over 500 people, Cyclone Gabrielle in Aotearoa in February 2023, and the 2025 Los Angeles fires.
If we understand how likely an event occurs because of climate change versus natural fluctuations, or how much climate change has turbo-charged the effects of large scale weather patterns such as El Niño we can better plan to mitigate future climate costs.
Insurance underwriters use climate attribution tools to help calculate the cost of insurance, or to decline your insurance; for example if you live in an area at risk from floods or rising sea levels.
For too long, weather’s randomness has kept events such as these from being blamed squarely on climate change… Now, we can specify increased chances for specific events. This extends to forecasts: we can identify the places that are more likely to see wildfires, mudslides and fish die-offs. Such calculations dent both climate denial and a false sense of security. They take away the argument that ‘extreme weather happens anyway, so we don’t need to worry about it’. Extreme weather happens—and these metrics pinpoint what is becoming more likely, by how much and why… Such evidence is also useful for legal proceedings when citizens call corporations or governments to account for their role in climate change. – Richard A. Betts
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The chances of getting a warm year are increasing all the time. The chances of getting a cold year are decreasing all the time. When you look at shorter time frames, from day to months, it’s really about the chances of getting a very hot event, extreme high temperatures, or heavy rainfall, are what’s really impacting both ecosystems and human activities. It’s how extreme are changing that’s really important…As temperatures rise, the number of rain days decrease. So moderate rain decreases while extreme rain increases…more and more extreme rainfall events and floods, with concurrent impacts, including erosion and landslips. – Prof. James Renwick 2022
When Cyclone Gabrielle struck Hawkes Bay in January 2023 it provided some insight into the limitation of climate models. The 2020 NIWA report, Climate change projections and impacts for Tairāwhiti and Hawke’s Bay projected that under the RCP8.5 (worst-case) scenario the average maximum annual 5-day rainfall by the year 2081 would be 151.3 (+14.8)mm at Glengarry.
During the cyclone, the Glengarry site recorded 546mm of rainfall with almost 400mm falling in 12 hours at a maximum intensity of 56mm/hour.
Over New Zealand, an average two to three fold rise in frequencies of extremes occurs irrespective of seasons due to anthropogenic influence, with a mean temperature increase close to 1°C. – Thomas et al, October 2022
The ‘close to 1°C’ threshold across Aotearoa has now been exceeded:
NIWA’s long-running ‘seven-station’ series shows NZ’s average annual temperature has increased by about 1°C over the past 100 years. – Annual Climate Summary 2025, Earth Sciences New Zealand
This helps explain why extremes are increasing in magnitude and number. The average global temperatures 2023-2025 exceeded 1.5°C. Moreover:
Extreme weather events are rising at a pace which exceeds expectations based on thermodynamic arguments only, changing the way we perceive our climate system and climate change issues…. The additional evaporation and rainfall tends to end up in heavy rain rather than alleviating drought: Half of it comes down in the wettest 6 d(ays) each year. Even once global warming is stopped, we will see unprecedented extremes for a long time to come. Just think of a former once-in-5000-year event which at 1.5°C warming may have become a once-in-50 year event. – Di Capua and Rahmstorf 2023
The takeaway message is clear. Existing climate models and weather forecasts are underestimating the frequency and magnitude of extreme (acute) events. This should be considered when looking at the flood hazard mapping tool below, as the statistical probability of any AEP1% event may no longer be valid. In some locations, the probability of recurrence may increase to decadal (AEP10%) or even annual (AEP100%). That is, they occur every year.
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Dr Fredi Otto, leading climate scientist and co-lead of World Weather Attribution (WWA) at Imperial College London, and Laura Tobin, broadcast meteorologist and weather presenter share stories from their careers shaped by the rise of extreme weather events, explain the science behind these phenomena, discuss the real-world impacts they are having on our lives, and explore how we can better adapt to a rapidly changing climate (Nov. 2024).
Podcast from The Conversation that takes you inside the UN’s era-defining climate report via the hearts and minds of the scientists who wrote it. In this episode, the presenters delve into one of the major shifts in the public communication of climate change: the attribution of extreme weather events to climate change (April 2023).
More information
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- 2025: Earth Sciences New Zealand (previously NIWA) Annual Climate Summary 2025
- 2025: Swain et al; Hydroclimate volatility on a warming Earth, Nature Reviews Earth & Environment 6, pp35-50
- 2024: Zhang et al; Incorporating extreme event attribution into climate change adaptation for civil infrastructure: Methods, benefits, and research needs, Resilient Cities and Structures 3 |1 pp103-113
- NIWA
- World Weather Attribution
- 2023: Di Capua & Rahmstorf; Extreme weather in a changing climate, Environmental Research Letters 18 | 6 October
- 2022: Thomas et al; Increasing temperature extremes in New Zealand and their connection to synoptic circulation features, International Journal of Climatology 43 pp 1251-1272 (PDF)
- 2022: Prof. James Renwick, O Tātou Ngāhere Conference: Regenerating our landscape with native forest, October
- 2022: Carbon Brief Mapped – How climate change affects extreme weather around the world
- 2021: Bodeker Scientific: Extreme Weather Event Real-time Attribution Machine (New Zealand)
- 2021: Philip et al; Rapid attribution analysis of the extraordinary heatwave on the Pacific Coast of the US and Canada June 2021. World Weather Attribution
- McSweeny; Pacific north-west heatwave shows climate is heading into ‘uncharted territory’ Carbon Brief analysis and interviews with the above researchers.
- 2021: Stone et al; The question of life, the universe and event attribution, Nature Climate Change 11 pp276–78
- 2021: Explaining Extreme Events from a Climate Perspective; Special supplement to the Bulletin of the American Meteorological Association (open access)
- 2020: Frame et al; Climate change attribution and the economic costs of extreme weather events: a study on damages from extreme rainfall and drought, (NZ) Climate Change 162, pp 781-797
- 2020: Betts; Heed blame for extreme weather, Nature article 26 Jan (open access)
- 2020: Raymond et al; Understanding and managing connected extreme events, Nature Climate Change, 10, pp611–621
- 2020: Climate change projections and impacts for Tairāwhiti and Hawke’ Bay Prepared for Envirolink, Gisborne District Council and Hawke’s Bay Regional Council
November 2020 - NZ Ministry for the Environment: Environmental Reporting – New Zealand Extreme weather events
- Carbon Brief: Extreme weather attribution Nature Climate Change 10 pp726–731
- 2020: Bonfils et al; Human influence on joint changes in temperature, rainfall and continental aridity Nature Climate Change 10 pp726–731
- 2020: Vargo et al; Anthropogenic warming forces extreme annual glacier mass loss Nature Climate Change
- 2020: Ortega; Unusual Arctic warming explained by overlooked greenhouse gases, Science
- 2020: Smith; The unexpected link between the ozone hole and arctic amplification The Conversation

