Yesterday’s announcement of funding for a National Carp Control Plan – including the release of the carp herpes virus – has generated a lot of interest in the media. I welcome plans to release the virus by the end of 2018. In January I wrote an article here explaining the concept and why I think it could work in Australia.
Since the announcement I’ve listened to discussions on radio and television highlighting the concerns of the public. I hope to address some of the confusion and set the record straight.
What will we do with piles of dead fish?
Among people who live near the Murray River or one of its tributaries, this is the main objection to the release of the virus. This in itself suggests that those close to the rivers understand the implications of carp being 80% of the biomass in the Murray Darling Basin. Many people have lived through black-water events (where oxygen levels drop resulting in large fish kills) and they know how unpleasant it is to have a lot of dead fish at one time.
Their concerns are justified. Fortunately, Science Minister Christopher Pyne is aware that hundreds of thousands, possibly millions of tonnes of dead carp will need to be cleaned up, and this will require community consultation and potential legislative changes. Pyne says we can use dead carp as fertiliser, as pet food or bury them in large graves. It is interesting to note that the fertiliser company Charlie Carp welcomes the move and may expand their business into South Australia so they can respond to large fish kills there.
The trick will be disposing of the fish quickly because after 48 hours they will begin to rot and will not be suitable for use. My reading of the announcement suggests that planning for this one time big carp kill will be a large part of the $15 million spent over the next two years.
How is the virus transmitted?
There were some giggles about how this virus is transmitted among fish, given that herpes is a sexually transmitted disease in humans. However, all the fish have to do is bump into one another to transmit the virus, and they can also be infected by the virus that lives in the water, although the virus will only survive for a few days outside of the body of a fish.
Once infected, any survivors will carry the carp-specific herpes virus for life. Stress can re-activate the virus, causing it to persist in the carp population and allowing it to spread rapidly under crowded conditions.
What a waste – we could have sold these fish overseas!
It is true that Australians resist eating carp due a perception that they are “junk” fish. Some say they have a muddy flavour, or that they are too bony. Neither of these issues stop people in Europe, the Middle East and Asia eating carp, where they are a common part of the diet.
There are two problems with the suggestion that we are missing a commercial opportunity here. The first is the economic viability of shipping fish to the other side of the world. We cannot get them there alive so we will need to freeze or can the carp, and once we’ve done that, consumers must pay enough to cover the processing and shipping.
I was on a committee with the NSW Department of Fisheries 15 years ago that was looking for markets for carp products. Enthusiastic investors with support from government could not find a way to make money with this export.
The second problem is that any industry relying on carp as a product will not remove carp from our rivers. Carp are causing enormous damage to the ecology of rivers and lakes across our continent and fishing alone will never remove enough of them to return those ecosystems to health.
But biological control never works, does it?
“Myxomatosis and cane toads – need I say more?” was a text to my local ABC radio station by someone concerned about the failure of biological control in the past. Yes, cane toads were a disastrous introduction to Australia and it is now clear that the problem was insufficient research prior to release. The carp herpes virus has been researched in Australian laboratories for 7 years so far. See my previous article for more on why this looks like a safe bio-control option.
Myxomatosis actually worked beautifully, killing 500 million rabbits in two years after the first release in 1950. Resistance did increase in the decades to follow and in 1996 another virus (calicivirus) was released to further reduce rabbit populations.
The rabbit plague of 1860 onward was the fastest spread of any mammal in the world. Rabbits had an enormous environmental and economic impact right across Australia, leading us to build the rabbit-proof fence. In 1887 the state of New South Wales was offering a reward of £25,000 for any successful method not previously known for exterminating rabbits. Although srabbits were useful for food in the depression and to make lots of hats, nobody wants to return to pre-myxomatosis times.
And no, we didn’t kill all the rabbits, just like we will not kill all the carp. However, a virus transmitted by water may be more effective as suggested by the government’s goal of a 95% carp reduction by 2045.
Carp are natural by now – our native fish rely on them for food
Australian native fish have been seriously impacted by carp. Many of them are visual predators, such as the magnificent Murray Cod. The turbidity created by carp reduces their ability to hunt and thrive, even though the high biomass of carp may give them plenty to eat.
The muddy river that runs through my home town is a hazard for swimmers and boaters because you can’t see the snags. This is due almost entirely to the presence of carp. None of us can remember when the Murray River ran clear and native fish were more common than introduced fish, but Senator Anne Ruston, Assistant Minister for Water Resources, recalls her mother and grandmother talking about being able to see the bottom of the river.
If you cannot imagine why anybody cares what type of fish are living in our rivers, remember that native Australian fish and plants are not adapted to the muddy rivers we have now. Let’s give them a chance to grow and thrive again in an environment more similar to the natural situation.
Sounds like a waste of money
Our Deputy Prime Minister Barnaby Joyce says that carp cost the economy up to $500 million per year. I don’t know how he got that figure but it may include the extra water treatment we need for river towns like mine and tourism losses due to reduced biodiversity and frequent algal blooms. Even if it is only half of that, spending $15 million to remove carp from the system seems like a sound investment.
The future of Australia’s waterways are at stake. Is there anything more precious than clean, fresh water?
The electioneering has begun. In a campaign set to be dominated by economic issues, the Coalition and Labor are locking horns over who can best manage our finances, protect jobs and make housing more affordable. The Greens predictably decry the major parties, including their cavalier climate-change policies.
These are important issues, but are they highest priority on the political agenda? An arguably even greater issue exists that nobody is seriously championing, but which impacts all of us, socially, environmentally and economically.
Our natural heritage – the plants, animals and other organisms that help define Australia’s identity – are in dire straits. Yet this biodiversity crisis is barely mentioned in political discourse, nor is it foremost in the public consciousness.
The world economy is losing €50 billion (A$73 billion) a year through lost ecosystem services. It is predicted to lose €14 trillion per year by 2050 without action now. With potentially 7% of global economic product at stake by mid-century, nature conservation must surely be on the agenda in this election.
Actions needed to conserve our natural heritage, and reap substantial rewards, will challenge some of our most cherished ideas about social and economic policy. This demands reforms to reverse creeping losses to our democratic process.
Looking at the major parties’ platforms, it is clear that nature is not on the agenda. Labor lists 23 positive policies, none of which deals directly with conserving Australia’s plants and animals. The Liberal-National Party has done slightly better, claiming to believe in preserving Australia’s natural beauty and environment for future generations. However, its federal platform, released last year, shows no evidence of this belief.
Public concern has also shifted away from nature issues and towards other concerns like terrorism, as well as traditional areas of focus such as health care and the economy. This shift can be seen in some surprising places, such as the major grassroots lobby group GetUp – of its ten current campaigns only one, the Great Barrier Reef program, is directly about conserving wildlife diversity.
The value of biodiversity to humans is well established (for example, see here, here, and here). Biodiversity reduces stress, crime and disease. It also provides new economic opportunities and many other benefits, from climate control, to flood defence, to the many benefits delivered by birds.
These are just the tip of the iceberg, but like the polar ice they are at risk of disappearing through our neglect.
Despite biodiversity’s immense value, Australia’s natural heritage is not assured. Good news stories exist,
but as a succession of government State of the Environment reports over recent decades has shown, our natural heritage continues to be squandered.
The reports cite population growth, economic growth and climate change as key drivers of decline. Land clearing and invasive species also lead to biodiversity loss. All must be addressed to reverse the alarming trajectory of our wildlife.
These threats to our natural heritage should be high on the political agenda. But despite recent extinctions, caused in no small part by a failure to act quickly on conservation advice, bureaucrats and politicians have failed to rise to the challenge. Australia’s plants, animals and other wildlife continue to be swept aside with an enthusiasm and abandon reminiscent of the 19th-century pioneers.
Nature is missing in action from the political agenda for many reasons. Here are two key ones: questionable political donations and processes, and the gagging of the public service, government and university scientists. Both issues go to the heart of our democracy.
Australia has some of the weakest electoral laws concerning political donations and spending. Time lags between receiving donations and declaring them means that appropriate scrutiny of policy motivations, particularly at election times, is uncommon. This is concerning, because links between political favours for donors, while hard to prove, are frequently noted.
These correlations are not surprising. Corporate political activities are typically not gestures of goodwill, but a widely accepted corporate strategy aimed at securing better outcomes. Because many companies depend on using land for activities such as digging up resources and clearing native vegetation, the success of their political donations can often be reflected in damage to nature.
Equally concerning is the deafening silence from people who really know how damaging government policies can be for the environment. Inconvenient truths might challenge government policies. So public servants, including government scientists, are prohibited from speaking, or tweeting. Governments will go to extremes more often seen in the pages of crime thrillers to track down and punish whistle-blowers.
Governments attempting to silence academics hit the spotlight over cattle grazing trials in Victorian national parks. A senior Victorian public servant reportedly threatened to withdraw further funding from the University of Melbourne if the university did not agree to oversee the government’s grazing trial, despite the trial being widely regarded as flawed and unnecessary. Faced with this type of pressure, many university scientists simply avoid public debate for fear of damaging their job prospects or government funding.
In this climate of silence, major biodiversity issues and damaging government policies aren’t appropriately aired. The public don’t hear about it and so can’t make informed decisions at the polling booth. Consequently, government and public service barriers to honest media coverage undermine an informed democracy.
There are things that can be done, at a political level, to help stop this erosion of Australia’s natural heritage before it’s too late. In addition to adequately funding conservation, we should reform political funding rules. We should also encourage, even legally require, honest and open disclosure of how government policy impacts our environment.
Don Driscoll, Professor in Terrestrial Ecology, Deakin University and Euan Ritchie, Senior Lecturer in Ecology, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University
Drought, fires, floods, marine heatwaves – Tasmania has had a tough time this summer. These events damaged its natural environment, including world heritage forests and alpine areas, and affected homes, businesses and energy security.
In past decades, climate-related warming of Tasmania’s land and ocean environments has seen dozens of marine species moving south, contributed to dieback in several tree species, and encouraged businesses and people from mainland Australia to relocate. These slow changes don’t generate a lot of attention, but this summer’s events have made people sit up and take notice.
If climate change will produce conditions that we have never seen before, did Tasmania just get a glimpse of this future?
After the coldest winter in half a century, Tasmania experienced a warm and very dry spring in 2015, including a record dry October. During this time there was a strong El Niño event in the Pacific Ocean and a positive Indian Ocean Dipole event, both of which influence Tasmania’s climate.
The dry spring was followed by Tasmania’s warmest summer since records began in 1910, with temperatures 1.78℃ above the long-term average. Many regions, especially the west coast, stayed dry during the summer – a pattern consistent with climate projections. The dry spring and summer led to a reduction in available water, including a reduction of inflows into reservoirs.
Tourists and locals alike enjoyed the clear, warm days – but these conditions came at a cost, priming Tasmania for damaging bushfires. Three big lightning storms struck, including one on January 13 that delivered almost 2,000 lightning strikes and sparked many fires, particularly in the state’s northwest.
By the end of February, more than 300 fires had burned more than 120,000 hectares, including more than 1% of Tasmania’s World Heritage Area – alpine areas that had not burnt since the end of the last ice age some 8,000 years ago. Their fire-sensitive cushion plants and endemic pine forests are unlikely to recover, due to the loss of peat and soils.
Meanwhile, the state’s emergency resources were further stretched by heavy rain at the end of January. This caused flash flooding in several east coast towns, some of which received their highest rainfall ever. Launceston experienced its second-wettest day on record, while Gray recorded 221 mm in one day, and 489 mm over four days.
Flooding and road closures isolated parts of the state for several days, and many businesses (particularly tourism) suffered weeks of disruption. The extreme rainfall was caused by an intense low-pressure system – the Climate Futures for Tasmania project has predicted that this kind of event will become more frequent in the state’s northeast under a warming climate.
This summer, an extended marine heatwave also developed off eastern Tasmania. Temperatures were 4.4℃ above average, partly due to the warm East Australian Current extending southwards. The heatwave began on December 3, 2015, and was ongoing as of April 17 – the longest such event recorded in Tasmania since satellite records began in 1982. It began just days after the end of the second-longest marine heatwave on record, from August 31 to November 28, 2015, although that event was less intense.
As well as months of near-constant heat stress, oyster farms along the east coast were devastated by a new disease, Pacific Oyster Mortality Syndrome, which killed 100% of juvenile oysters at some farms. The disease, which has previously affected New South Wales oyster farms, is thought to be linked to unusually warm water temperatures, although this is not yet proven.
Tasmania is often seen as having a mild climate that is less vulnerable to damage from climate change. It has even been portrayed as a “climate refuge”. But if this summer was a taste of things to come, Tasmania may be less resilient than many have believed.
The spring and summer weather also hit Tasmania’s hydroelectric dams, which were already run down during the short-lived carbon price as Tasmania sold clean renewable power to the mainland. Dam levels are at an all-time low and continue to fall.
The situation has escalated into a looming energy crisis, because the state’s connection to the national electricity grid – the Basslink cable – has not been operational since late December. The state faces the prospect of meeting winter energy demand by running 200 leased diesel generators, at a cost of A$43 million and making major carbon emissions that can only exacerbate the climate-related problems that are already stretching the state’s emergency response capability.
Is this summer’s experience a window on the future? Further study into the causes of climate events, known as “detection and attribution”, can help us untangle the human influence from natural factors.
If we do see the fingerprint of human influence on this summer, Tasmania and every other state and territory should take in the view and plan accordingly. The likely concurrence of multiple events in the future – such as Tasmania’s simultaneous fires and floods at either end of the island and a heatwave offshore – demands that governments and communities devise new strategies and mobilise extra resources.
This will require unprecedented coordination and cooperation between governments at all levels, and between governments, citizens, and community and business groups. Done well, the island state could show other parts of Australia how to prepare for a future with no precedent.
Alistair Hobday, Senior Principal Research Scientist – Oceans and Atmosphere, CSIRO; Eric Oliver, Postdoctoral Fellow (Physical Oceanography and Climate), University of Tasmania; Jan McDonald, Professor of Environmental Law, University of Tasmania, and Michael Grose, Climate Projections Scientist, CSIRO
To have any chance of preventing dangerous climate change, the world needs to reduce greenhouse gas emissions to net zero or even negative by mid-century. Many experts suggest this means we need to completely phase out fossil fuels and replace them with renewable energy sources such as solar and wind.
Several studies have concluded that 100% renewable energy supply systems are technically and economically feasible. This informs the widespread view that fossil fuels can be more or less “swapped out” for renewables, without significant economic consequences.
We are strongly sympathetic to the need for a rapid global shift away from fossil fuels. But new modelling conducted independently and made publicly available by my colleague at the Understandascope, Josh Floyd, suggests that such a transition may face significant challenges.
Analyses of how to get to 100% renewable energy typically look at how future energy sources can supply enough energy to meet a given future demand.
This is what’s known as an “energy balance”. The high-quality work of Mark Diesendorf and his colleagues on the transition of Australia’s electricity supply to 100% renewables typifies such modelling.
But this approach doesn’t tell us what will happen to overall energy supply during the transition.
This new modelling suggests a significant decline in availability of overall energy services during the transition phase. This reflects the increased energy demand associated with the transition task itself.
Such an energy “trough” would significantly impact the economy during the transition. This has flow-on consequences for how to maintain the massive renewables roll-out.
To investigate what might happen to energy availability during transition, the model looks at “net energy services” at a global scale.
Net energy services are the total work and heat that energy sources – for instance solar photovoltaic (PV) systems or petroleum – make available to end users, minus the energy services required to provide that supply.
Petroleum requires energy services to find, produce, transport and refine it. Solar PV systems require energy services for mining raw materials, manufacturing, installation, replacement and so on. The net services are what remains available for all other purposes, such as heating buildings and moving goods and people.
A rapid, large-scale energy transition creates extra demands for energy services. This demand will compete with other economic activity.
To start with, the model assumes that fossil fuels are phased out over about 50 years. Biomass, hydro and nuclear contributions are assumed roughly to double.
The model then attempts to maintain the net energy services to the global economy at the maximum level before the fossil fuel phase-out. To do this it uses electricity from onshore wind turbines and large-scale solar PV plants, buffered with lithium ion batteries.
The findings show that the faster the transition rate, the greater the energy services required by the transition task, and the lower the services available for other uses.
This is because of the time lag between energy investments and returns. It is exacerbated for sources where up-front energy investment is a relatively high proportion of the total life cycle, particularly so for solar PV.
A 50-year fossil-fuel phase-out represents a relatively modest transition rate. Even so, in the model’s baseline scenario, net energy services decline during that transition period by more than 15% before recovering.
And that recovery is not certain. The model doesn’t consider how this decline in energy services might affect the transition effort. If less energy services are available, then energy transition will come at the expense of other economic activity. That may impact the collective will to continue.
In the model’s baseline scenario – phasing out fossil fuels over 50 years – wind and solar plants need to be installed at eight to ten times current rates by 2035.
Financially, this corresponds with capital investment in wind and solar PV plants plus batteries of around US$3 trillion per year (in 2015 dollars) and average lifetime capital cost in the order of US$5 trillion to US$6 trillion per year.
This implies that total expenditure on energy supply will increase its share of world spending, reducing scope for other expenditure. Compounding the decline in energy services during transition, this has potential to apply contractionary pressure to the global economy. This has implications in turn for financing and maintaining the political will for the renewables rollout.
What if it were possible to roll out renewables even faster? This could reduce the depth and duration of the decline, but not eliminate it. Again, due to the time lags involved, accelerating deployment in the short term takes energy services away, rather than adding them.
Of course, this is “just” modelling. But good models can tell us a lot about the real world. If this modelling is right, and energy services fall and costs rise, we’ll have to complement building cleaner energy supply with other approaches.
The other key aspect of transition that we have control over is how much energy we expect to use. Usually discussions of transition focus on maintaining energy supply sufficient for a growing economy much like we see today – just with “clean” energy. But this is changing.
Growing numbers of analysts, business leaders and other prominent figures are calling for broader cultural change, as it becomes clearer that technological change alone is not enough to avoid climate catastrophe and myriad other consequences of energy-intensive consumer societies.
This is about more than efficiency. It is about a shift in our collective priorities and how we define progress, wellbeing and quality of living. Reducing energy demand within these redefined aspirations will markedly improve our prospects for successful transition.
This article was co-authored by Josh Floyd, advisor on energy, systems and societal futures at independent research and education organisation the Understandascope, and founding partner of the Centre for Australian Foresight.
Australia’s greenhouse gas emissions are on the rise. Electricity emissions, which make up about a third of the total, rose 2.7% in the year to March 2016.
Australia’s emissions reached their peak in 2008-2009. Since then total emissions have barely changed, but the proportion of emissions from electricity fell, largely due to falling demand and less electricity produced by coal. But over the last year demand grew by 2.5%, nearly all of this supplied by coal.
In 2015 I wrote about concerns that Australia’s electricity demand and emissions would start increasing again. This has now come true. So what’s driving the trend?
To understand this trend we need to look at data from Australia’s National Electricity Market (NEM), which accounts for just under 90% of total Australian electricity generation. While the NEM doesn’t include Western Australia or the Northern Territory, it has much better publicly available data.
The chart below shows electricity generation from June 2009 to March 2016.
The most important things to note are that, until February 2015, overall generation fell and the amount of electricity supplied by coal also fell. These two trends are closely related.
In June 2009, coal was supplying 84% of electricity, while 7% came from renewables (mainly hydro and wind) and 9% from gas.
Because renewables have near-zero short-run marginal costs (because they don’t have to pay for fuel) they will nearly always be able to outcompete coal and gas. This will be particularly so when demand for electricity falls.
Since June 2009 coal has been squeezed out by falling demand and a growing supply of renewables and gas. Until February 2015, total demand fell 8%, gas supply rose 43%, renewable supply grew 55% and coal supply fell 18%.
Since February 2015, however, these trends have reversed, which is very bad news for Australia’s emissions. Demand grew 2.5% and, combined with falling electricity supply from gas and renewables, coal picked up the slack, driving emissions 2.7% higher.
Gas generation is being forced out of the market, as wholesale prices throughout eastern Australia have risen to levels set by the three new liquefied natural gas (LNG) plants in Queensland.
Renewable generation, mainly hydro, increased briefly thanks to the carbon price, further squeezing out coal, but this is of course now gone.
Growth in other renewable generation (mainly wind) has stalled because of the near-total freeze in new investment under the reduced large-scale Renewable Energy Target (LRET) precipitated by the Abbott government.
To understand why demand is increasing we can look at the three major consumer groups – industry, business and households – as you can see in the figure below.
After growing until 2012, industry demand fell sharply because of closures of several major establishments, most notably aluminium smelters in New South Wales and Victoria.
Since 2015 very rapid growth has occurred in Queensland, driven by the coal seam gas industry. Extraction of coal seam gas requires the use of enormous numbers of pumps, compressors and related equipment, to first extract the gas from underground and then to compress it for pipeline transport to the LNG plants at Gladstone.
Initially, the industry used gas engines to power this equipment, but then realised that electric motor drive would cost less. The government-owned Queensland electricity transmission business, Powerlink Queensland, is making major investments (paid for by the gas producers) in new transmission lines and substations to meet this new demand.
By the end of 2017-18, electricity demand could increase by 20% in Queensland and by 5% for Australia overall. All of this demand, at least initially, will be supplied by coal-fired power stations, increasing Australia’s total emissions by about 8 million tonnes, or roughly 1.5%.
As a side note, the LNG plants in Queensland will not themselves use electricity from the grid, but will use about 120 petajoules of gas each by 2017-18, adding another 6 million tonnes to national greenhouse gas emissions.
Household demand fell since 2010 due to energy standards on appliances, increasing electricity prices and a one-off behavioural response due to unprecedented political attention to electricity costs thanks to climate policy.
Now electricity prices have stabilised or are falling and attract much less attention. Moreover, fewer appliance energy standards are being introduced, slowing the decrease in demand.
The result is that average electricity consumption per household, which fell by 17% between 2010 and 2014, has stabilised. In the absence of stronger energy efficiency policies and programs, residential electricity consumption can be expected to grow in line with population.
Business is the largest of the three consumer groups. Electricity demand fell slightly between 2010 and 2014. This is because electricity intensity, the amount of electricity needed to produce economic value, fell 3% each year; that is, slightly faster than the economy grew.
It now appears, however, that in the past year the fall in electricity intensity has almost ceased, so that total consumption has increased in line with economic growth.
In December 2015 the federal and state governments announced the National Energy Productivity Plan to increase energy productivity 40% by 2030. This is part of the plan to meet Australia’s 2030 climate target.
Energy productivity is the economic value produced per unit of energy. The 40% goal is equivalent to a reduction of just under 30% in the energy intensity of the economy.
In the case of electricity, had the trend of the period 2010 to 2014 continued, this would have been achieved quite easily. It now appears to be a much more challenging goal, requiring the urgent introduction of a range of new energy efficiency policies and programs.
CORRECTION: The lead image has been corrected. It previously incorrectly showed aluminium works at Gladstone, Queensland.
When we published a paper in 2013 finding 97% scientific consensus on human-caused global warming, what surprised me was how surprised everyone was.
Nevertheless, no-one I spoke to was aware of the existing research into such a consensus. Rather, the public thought there was a 50:50 debate among scientists on the basic question of whether human activity was causing global warming.
This lack of awareness is reflected in a recent pronouncement by Senator Ted Cruz (currently competing with Donald Trump in the Republican primaries), who argued that:
The stat about the 97% of scientists is based on one discredited study.
Why is a US Senator running for President attacking University of Queensland research on scientific agreement? Cruz’s comments are the latest episode in a decades-long campaign to cast doubt on the scientific consensus on climate change.
Back in 2002, a Republican pollster advised conservatives to attack the consensus in order to win the public debate about climate policy. Conservatives complied. In conservative opinion pieces about climate change from 2007 to 2010, their number one argument was “there is no scientific consensus on climate change”.
Recent psychological research has shown that the persistent campaign to confuse the public about scientific agreement has significant societal consequences. Public perception of consensus has been shown to be a “gateway belief”, influencing a range of other climate attitudes and beliefs.
People’s awareness of the scientific consensus affects their acceptance of climate change, and their support for climate action.
The psychological importance of perceived consensus underscores why communicating the 97% consensus is important. Consensus messaging has been shown empirically to increase acceptance of climate change.
And, crucially, it’s most effective on those who are most likely to reject climate science: political conservatives.
In other words, consensus messaging has a neutralising effect, which is especially important given the highly polarised nature of the public debate about climate change.
Consequently, social scientists have urged climate scientists to communicate the scientific consensus, countering the misconception that they are still divided about human-caused global warming.
But how do you counter the myth that the 97% consensus is based on a single study?
One way is to bring together the authors of the leading consensus papers to synthesise all the existing research: a meta-study of meta-studies. We did exactly that, with a new study published in Environmental Research Letters featuring authors from seven of the leading studies into the scientific consensus on climate change.
A recurring theme throughout the consensus research was that the level of scientific agreement varied depending on climate expertise. The higher the expertise in climate science, the higher the agreement that humans were causing global warming.
To none of our surprise, the highest agreement was found among climate scientists who had published peer-reviewed climate research. Interestingly, the group with the lowest agreement was economic geologists.
Seven studies quantified the level of agreement among publishing climate scientists, or among peer-reviewed climate papers. Across these studies, there was between 90% to 100% agreement that humans were causing global warming.
A number of studies converged on the 97% consensus value. This is why the 97% figure is often invoked, having been mentioned by such public figures as President Barack Obama, Prime Minister David Cameron and US Senator Bernie Sanders.
The relationship between scientific agreement and expertise turns out to be crucially important in understanding the consensus issue. Unfortunately, it provides an opportunity for those who reject human-caused global warming to manufacture doubt about the high level of scientific agreement.
They achieve this by using groups of scientists with lower expertise in climate science, to convey the impression that expert agreement on climate change is low. This technique is known as “fake experts”, one of the five characteristics of science denial.
For example, surveys of climate scientists may be “diluted” by including scientists who don’t possess expertise in climate science, thus obtaining a lower level of agreement compared to the consensus among climate scientists. This is partly what Senator Rick Santorum did when he argued that the scientific consensus was only 43%.
Another implementation of the “fake expert” strategy is the use of petitions containing many scientists who lack climate science credentials. The most famous example is the Oregon Petition Project, which lists over 31,000 people with a science degree who signed a statement that humans aren’t disrupting the climate. However, 99.9% of the signatories aren’t climate scientists.
The science of science communication tells us that communicating the science isn’t sufficient. Misinformation has been shown to cancel out the effect of accurate scientific information. We also need to explain the techniques of misinformation, such as the “fake expert” strategy.
This is why in communicating the results of our latest study, we not only communicated the overwhelming scientific agreement. We also explained the technique used to cast doubt on the consensus.