As a heatwave tapers off in parts of the northern hemisphere, a new forecast system has predicted the years 2018 till 2022 are going to anomalously warm, with a greater chance of extreme temperatures.
UK and Dutch researchers have developed a statistical model that provides reliable predictions of global mean air and sea surface temperatures, taking into account external forces such as greenhouse gases and aerosols, along with natural variability. Although natural variability is harder to predict, their systems suggest it will temporarily reinforce long-term global warming trend.
The Science Media Centre gathered expert commentary on the paper. Please feel free to use these comments in your reporting.
Dr Sam Dean, NIWA Chief Scientist, Climate, Atmosphere and Hazards, comments:
“The article finds that it is likely global average temperatures will be warmer than normal over the next few years.
“This is not just saying that things will be warmer as a result of the increasing temperatures we would expect from ongoing climate change, but suggests we should expect extra warming on top of that for the next few years as a result of natural variability in the climate system.
“Another way to think of this is that there is less chance of having fortuitously cool years thanks to natural processes. We can’t be sure of course but we do know that predictions like this are usually a bit better than guessing, because of variability in ocean circulation that can change slowly over many years.
“As an example, during the 2000s the world had more La Niñas, which led to cooler global temperatures, and the oceans took up lots of extra heat. Since 2014 this appears to have changed, with more El Niños and much hotter years.
“This article, as well as work by forecast centres such as the UK Met Office, are predicting that these particularly hot years could carry on for a while now as part of this natural variability in the oceans. While we can’t be sure exactly how things will play out, at the moment the odds are higher for hot years.
“So what does this mean for New Zealand? Not every hot year globally is a hot year in New Zealand. This is because whether we get hot weather or cold is also dependent on whether our wind blows more from the north or the south, and this is a very local effect. But it is also true that all things being equal the odds of a hot year here are higher when global mean temperatures are higher. For example, 2016 was the hottest year globally since records began, and it was also the hottest year recorded here in the NIWA national temperature series.”
No conflict of interest declared.
Professor James Renwick, Victoria University of Wellington, School of Geography, Environment and Earth Sciences, comments:
“The goal of ‘decadal forecasting’ – predicting the state of the global climate over the coming 2 to 20 years, is one of the frontiers of climate prediction research. If such forecasts could be made reliably they would clearly be of great value in many sectors: agriculture, energy, emergency management, public health, etc. Most research is focused on using dynamical global climate models (GCMs, as used for climate change simulations), where the ocean state is very carefully specified for the present day.
“This paper reports on a statistical approach to make a five-year forecast starting in 2018. Statistical models are attractive as they can be run very quickly on any laptop or phone, while GCM simulations take days or weeks on supercomputers. The downside is that statistical models do not capture the physics of the climate, so can be unreliable when used to extrapolate.
“The paper reports on a clever statistical approach using climate model results to assess short-term trends in global temperatures, above or below the overall global warming signal. It performs well on recent past fluctuations in global temperatures. The system predicts that 2018 is likely to be a relatively warm year (warmer than expected form the global warming trend alone), something that appears to be happening.
“The prediction for 2018-2022 suggests that global sea surface temperatures are likely to be warmer than the background greenhouse gas-induced global warming trend would imply, while air temperatures are more likely to be close to the overall trend line. It will be very interesting to see if this forecasting system performs well into the future and whether it can be used to reliably predict other aspects of medium-term climate variability.
“As the climate warms, getting extra-warm years will translate to a much greater occurrence of extreme heat, dryness, and a greater chance of wild fires, as we are seeing in the Northern Hemisphere summer this year. This paper suggests that the coming few years are likely to see such extremes continue.
“If the warming trend caused by greenhouse gas emissions continues, years like 2018 will be the norm in the 2040s, and would be classed as cold by the end of the century.”
No conflict of interest.
The Australian Science Media Centre also gathered comments about how the predicted temperatures would affect Australia.
Dr Joe Fontaine is lecturer and fire ecologist from Murdoch University
“The record-breaking heat and bushfires in California are a harbinger of what Australia could expect in the coming years. The forecast of four years of warmer temperatures promises to dry out vegetation and promote extreme fire hazard for much longer parts of the year across Australia. Warmer temperatures mean that the moderating effects of rain on bushfire will be reduced substantially. These changes are yet another reflection of how climate change is happening now and is no longer a problem for future generations.
“Warmer climate forecasts of the next four years greatly increase the risk of heat waves throughout Australia. Heat waves have been clearly linked to greater human death rates, accelerated global warming, and a raft of ecological impacts. For example, in Western Australia the heat wave in summer 2010-2011 left behind dead coral and sea grass, dead trees, depleted fisheries and decreased populations of penguins and endangered black cockatoos.”
No conflict of interest declared.
Dr Susie Burke, Senior Psychologist in Environment and Disaster Response, Australian Psychological Society
“Extreme heat has been noted to increase hospital admissions for mood and behavioural disorders, like depression, anxiety disorders, schizophrenia, and dementia.
“Some prescription medications interfere with the body’s ability to regulate temperatures, which can prevent people from being able to cool down which can be extremely dangerous in the heat.
“Researchers have also found links between heat and increases in violence, aggression, crime, domestic violence, riots and civil war.
“Extreme heat is also linked with an increase in bushfires and drought, which are also well-documented climate hazards that affect mental health.
“We urgently need climate policies that will reduce the threat of climate change to protect people from the direct physical and mental health impacts of extreme weather, as well as the existential threat that climate change poses to civilization.”
No conflict of interest declared.
Professor Wasim Saman, Sustainable Energy Engineer, University of South Australia
“The latest research findings confirm actual data trends and a number of international and Australian research forecasts carried out in the last decade that anticipate the number and severity of heat waves to be trending upwards. Research has also shown the likely detrimental impact on people and the need for larger air conditioning capacities and higher peak electrical demand to maintain thermal comfort in existing buildings.
“One potential area requiring immediate attention to reduce the imminent impact of heat waves is to incorporate future climatic conditions in building design calculations and to design our future buildings (both domestic and commercial) to minimise the impact of heat waves on occupants. This approach needs to be incorporated in setting minimum thermal comfort requirements during extreme weather events in building design guidelines and to include these requirements in the Building Code of Australia.”
No conflict of interest declared.
Dr Paul Read, Senior Research Fellow, Melbourne Sustainable Society Institute, University of Melbourne
“I wouldn’t like to comment on the veracity of the model just yet as I think I’d need to teach myself a bit more about it first. But what strikes me about this paper is the potential it has to put the power of prediction and testing into the hands of the population.
“If there’s one thing we need more than ever is to help all people understand the science of climate change before they touch the politics, and the authors say they can deploy this model on mobile phones for people to make their own predictions.
“From that I imagine it’ll allow everyone to see what climate scientists see and to test it themselves with good accuracy any time up to five years. It can do this because it does the maths in two seconds compared to past models that needed big computing power that’s unavailable to most people.
“The other thing is the model works for both land and sea measures since 1880 so it has internal validity as well as reliability in testing backwards in time. So it works forward in time. In my area it’ll be extremely useful for planning in emergency services for natural disasters like bushfires, although their predictions to 2022 don’t bode well for the next few years on that front.
“We’ll expect more fires for the next few summers unless we can control fires at the source of ignition, which means more engagement with community.
“We need good management and leadership and, at risk of dipping a toe where I’m unwanted, I for one will be missing the dedication and hard work of the recently resigned Victorian Commissioner Craig Lapsley.”
No conflict of interest declared.