How to use critical thinking to spot false climate claims

File 20180207 58185 14cr2bh.jpg?ixlib=rb 1.1
Arguments against climate change tend to share the same flaws.
gillian maniscalco/Flickr, CC BY-ND

Peter Ellerton, The University of Queensland

Much of the public discussion about climate science consists of a stream of assertions. The climate is changing or it isn’t; carbon dioxide causes global warming or it doesn’t; humans are partly responsible or they are not; scientists have a rigorous process of peer review or they don’t, and so on.

Despite scientists’ best efforts at communicating with the public, not everyone knows enough about the underlying science to make a call one way or the other. Not only is climate science very complex, but it has also been targeted by deliberate obfuscation campaigns.

Read more:
A brief history of fossil-fuelled climate denial

If we lack the expertise to evaluate the detail behind a claim, we typically substitute judgment about something complex (like climate science) with judgment about something simple (the character of people who speak about climate science).

But there are ways to analyse the strength of an argument without needing specialist knowledge. My colleagues, Dave Kinkead from the University of Queensland Critical Thinking Project and John Cook from George Mason University in the US, and I published a paper yesterday in Environmental Research Letters on a critical thinking approach to climate change denial.

We applied this simple method to 42 common climate-contrarian arguments, and found that all of them contained errors in reasoning that are independent of the science itself.

In the video abstract for the paper, we outline an example of our approach, which can be described in six simple steps.

The authors discuss the myth that climate change is natural.

Six steps to evaluate contrarian climate claims

Identify the claim: First, identify as simply as possible what the actual claim is. In this case, the argument is:

The climate is currently changing as a result of natural processes.

Construct the supporting argument: An argument requires premises (those things we take to be true for the purposes of the argument) and a conclusion (effectively the claim being made). The premises together give us reason to accept the conclusion. The argument structure is something like this:

  • Premise one: The climate has changed in the past through natural processes
  • Premise two: The climate is currently changing
  • Conclusion: The climate is currently changing through natural processes.

Determine the intended strength of the claim: Determining the exact kind of argument requires a quick detour into the difference between deductive and inductive reasoning. Bear with me!

In our paper we examined arguments against climate change that are framed as definitive claims. A claim is definitive when it says something is definitely the case, rather than being probable or possible.

Definitive claims must be supported by deductive reasoning. Essentially, this means that if the premises are true, the conclusion is inevitably true.

Read more:
How I came to know that I am a closet climate denier

This might sound like an obvious point, but many of our arguments are not like this. In inductive reasoning, the premises might support a conclusion but the conclusion need not be inevitable.

An example of inductive reasoning is:

  • Premise one: Every time I’ve had a chocolate-covered oyster I’ve been sick
  • Premise two: I’ve just had a chocolate-covered oyster
  • Conclusion: I’m going to be sick.

This is not a bad argument – I’ll probably get sick – but it’s not inevitable. It’s possible that every time I’ve had a chocolate-covered oyster I’ve coincidentally got sick from something else. Perhaps previous oysters have been kept in the cupboard, but the most recent one was kept in the fridge.

Because climate-contrarian arguments are often definitive, the reasoning used to support them must be deductive. That is, the premises must inevitably lead to the conclusion.

Check the logical structure: We can see that in the argument from step two – that the climate change is changing because of natural processes – the truth of the conclusion is not guaranteed by the truth of the premises.

In the spirit of honesty and charity, we take this invalid argument and attempt to make it valid through the addition of another (previously hidden) premise.

  • Premise one: The climate has changed in the past through natural processes
  • Premise two: The climate is currently changing
  • Premise three: If something was the cause of an event in the past, it must be the cause of the event now
  • Conclusion: The climate is currently changing through natural processes.

Adding the third premise makes the argument valid, but validity is not the same thing as truth. Validity is a necessary condition for accepting the conclusion, but it is not sufficient. There are a couple of hurdles that still need to be cleared.

Check for ambiguity: The argument mentions climate change in its premises and conclusion. But the climate can change in many ways, and the phrase itself can have a variety of meanings. The problem with this argument is that the phrase is used to describe two different kinds of change.

Current climate change is much more rapid than previous climate change – they are not the same phenomenon. The syntax conveys the impression that the argument is valid, but it is not. To clear up the ambiguity, the argument can be presented more accurately by changing the second premise:

  • Premise one: The climate has changed in the past through natural processes
  • Premise two: The climate is currently changing at a more rapid rate than can be explained by natural processes
  • Conclusion: The climate is currently changing through natural processes.

This correction for ambiguity has resulted in a conclusion that clearly does not follow from the premises. The argument has become invalid once again.

We can restore validity by considering what conclusion would follow from the premises. This leads us to the conclusion:

  • Conclusion: Human (non-natural) activity is necessary to explain current climate change.

Importantly, this conclusion has not been reached arbitrarily. It has become necessary as a result of restoring validity.

Note also that in the process of correcting for ambiguity and the consequent restoring of validity, the attempted refutation of human-induced climate science has demonstrably failed.

Check premises for truth or plausibility: Even if there were no ambiguity about the term “climate change”, the argument would still fail when the premises were tested. In step four, the third premise, “If something was the cause of an event in the past, it must be the cause of the event now”, is clearly false.

Applying the same logic to another context, we would arrive at conclusions like: people have died of natural causes in the past; therefore any particular death must be from natural causes.

Restoring validity by identifying the “hidden” premises often produces such glaringly false claims. Recognising this as a false premise does not always require knowledge of climate science.

Flow chart for argument analysis and evaluation.

When determining the truth of a premise does require deep knowledge in a particular area of science, we may defer to experts. But there are many arguments that do not, and in these circumstances this method has optimal value.

Inoculating against poor arguments

Previous work by Cook and others has focused on the ability to inoculate people against climate science misinformation. By pre-emptively exposing people to misinformation with explanation they become “vaccinated” against it, showing “resistance” to developing beliefs based on misinformation.

Read more:
Busting myths: a practical guide to countering science denial

This reason-based approach extends inoculation theory to argument analysis, providing a practical and transferable method of evaluating claims that does not require expertise in climate science.

The ConversationFake news may be hard to spot, but fake arguments don’t have to be.

Peter Ellerton, Lecturer in Critical Thinking, Director of the UQ Critical Thinking Project, The University of Queensland

This article was originally published on The Conversation. Read the original article.


Cape Town is almost out of water. Could Australian cities suffer the same fate?

Ian Wright, Western Sydney University

The world is watching the unfolding Cape Town water crisis with horror. On “Day Zero”, now predicted to be just ten weeks away, engineers will turn off the water supply. The South African city’s four million residents will have to queue at one of 200 water collection points.

Cape Town is the first major city to face such an extreme water crisis. There are so many unanswered questions. How will the sick or elderly people cope? How will people without a car collect their 25-litre daily ration? Pity those collecting water for a big family.

Read more:
Cape Town’s water crisis: driven by politics more than drought

The crisis is caused by a combination of factors. First of all, Cape Town has a very dry climate with annual rainfall of 515mm. Since 2015, it has been in a drought estimated to be a one-in-300-year event.

In recent years, the city’s population has grown rapidly – by 79% since 1995. Many have questioned what Cape Town has done to expand the city’s water supply to cater for the population growth and the lower rainfall.

Could this happen in Australia?

Australia’s largest cities have often struggled with drought. Water supplies may decline further due to climate change and uncertain future rainfall. With all capital cities expecting further population growth, this could cause water supply crises.

Read more:
This is what Australia’s growing cities need to do to avoid running dry

The situation in Cape Town has strong parallels with Perth in Australia. Perth is half the size of Cape Town, with two million residents, but has endured increasing water stress for nearly 50 years. From 1911 to 1974, the annual inflow to Perth’s water reservoirs averaged 338 gigalitres (GL) a year. Inflows have since shrunk by nearly 90% to just 42GL a year from 2010-2016.

To make matters worse, the Perth water storages also had to supply more people. Australia’s fourth-largest city had the fastest capital city population growth, 28.2%, from 2006-2016.

As a result, Perth became Australia’s first capital city unable to supply its residents from storage dams fed by rainfall and river flows. In 2015 the city faced a potentially disastrous situation. River inflows to Perth’s dams dwindled to 11.4GL for the year.

For its two million people, the inflows equated to only 15.6 litres per person per day! Yet in 2015/6 Perth residents consumed an average of nearly 350 litres each per day. This was the highest daily water consumption for Australia’s capitals. How was this achieved?

Tapping into desalination and groundwater

Perth has progressively sourced more and more of its supply from desalination and from groundwater extraction. This has been expensive and has been the topic of much debate. Perth is the only Australian capital to rely so heavily on desalination and groundwater for its water supply.

Volumes of water sourced for urban use in Australia’s major cities.
BOM, Water in Australia, p.52, National Water Account 2015, CC BY

Australia’s next most water-stressed capital is Adelaide. That city is supplementing its surface water storages with desalination and groundwater, as well as water “transferred” from the Murray River.

Australia’s other capital cities on the east coast have faced their own water supply crises. Their water storages dwindled to between 20% and 35% capacity in 2007. This triggered multiple actions to prevent a water crisis. Progressively tighter water restrictions were declared.

The major population centres (Brisbane/Gold Coast, Sydney, Melbourne and Adelaide) also built large desalination plants. The community reaction to the desalination plants was mixed. While some welcomed these, others question their costs and environmental impacts.

The desalination plants were expensive to build, consume vast quantities of electricity and are very expensive to run. They remain costly to maintain, even if they do not supply desalinated water. All residents pay higher water rates as a result of their existence.

Since then, rainfall in southeastern Australia has increased and water storages have refilled. The largest southeastern Australia desalination plants have been placed on “stand-by” mode. They will be switched on if and when the supply level drops.

Read more:
The role of water in Australia’s uncertain future

Investing in huge storage capacity

Many Australian cities also store very large volumes of water in very large water reservoirs. This allows them to continue to supply water through future extended periods of dry weather.

The three largest cities (Sydney, Melbourne and Brisbane) have built very large dams indeed. For example, Brisbane has 2,220,150 ML storage capacity for its 2.2 million residents. That amounts to just over one million litres per resident when storages are full.

The ConversationIn comparison, Cape Town’s four million residents have a full storage capacity of 900,000 ML. That’s 225,000 litres per resident. Cape Town is constructing a number of small desalination plants while anxiously waiting for the onset of the region’s formerly regular winter rains.

Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University

This article was originally published on The Conversation. Read the original article.