What is Science?

It is impossible to understand climate science or the climate change debate without a basic understanding of how science works.

Science is about understanding cause and effect based on measurement and observation. Scientific certainty can be understood as a series of concentric circles. Mathematics, chemistry and applied physics are at the center of the circle. In these disciplines all the variables can be controlled in experiment and the same results can be obtained. From this observation scientific truths can be arrived at with complete certainty. These are the foundational disciplines of all science.

In the second circle sit those disciples that derive from the previous three. They include for example geology, electrical and mechanical engineering, astronomy, and geomorphology. These first and second circle disciplines are the ‘hard’ sciences which are reliable and provable.

In the next third circle are other empirical disciplines where it is more difficult to isolate the variables but results can be tested and confirmed. This includes genetics, veterinary and medical science, microbiology, psychiatry and plant science.

In the next fourth circle are disciplines that are more reliant on survey data and statistical analysis. They include meteorology, oceanography, zoology, and ecology.

In the next fifth circle are disciplines which require substantial amounts of interpretation based on assumptions. These include paleontology, anthropology, and the social sciences.

The first to fourth circles provide the scientific basis for industrial civilisation


What is the Climate Change Thesis?

The climate change thesis states that: human behaviours have released gases into the atmosphere which trap solar energy within the climate system. As a result of this, the amount of energy in the climate system is increasing. This is changing the climate.

The climate change thesis was first mooted in the 1970’s but there was insufficient data at that time to test the theory. As climate changes were observed the thesis began attracting policy interest and funding so that by the end of the 1990’s a substantial body of data from numerous disparate disciplines and sources had been obtained. Based on this data a number of climate models were developed and predictions made. These largely came to pass during the first decade of the 21st century and the thesis is now considered proven by the majority of scientists who have worked in climate change science or who have considered the data.

The climate change thesis does not say that everything will get hotter all the time.

How Does Climate Science Work?

In the case of climate science, it is not possible to put the world in a test tube and isolate all the variables. Similarly, we do not have two planet earths where we can use one as a baseline for comparison and conduct experiments on the other. Therefore, our understanding of climate relies on making observations over time (including historic observations), making predictions based on these observations, and then testing these predictions by further observation. There are many tools for making observations. Some key ones are:

  • Mapping
  • Survey sample data
  • Statistical analysis and trends


The natural scientist asks:

  • Does the data show a clearly defined trend?
  • Is the sample size big enough, and the time period long enough, to make a hypothesis or draw conclusions?
  • If my hypothesis is true, what would I expect to see, and do I see it?
  • Is there another, better explanation?
  • Is there any contrary data I have not considered?

Generally speaking, a big sample conducted on a frequent regular basis over a long period of time will yield reliable results. A small sample, conducted on an irregular basis or over a short period of time will be less reliable.

This is how all natural resource management works. It is how forestry, fisheries, game and conservation management work. It is also how climate science works. Climate science thus belongs in the third and fourth circles in that, while it is based on fundamental physics and chemistry, it relies extensively on projections based on survey and trend data. The climate change thesis is one aspect of climate science.

Is Climate Change Proven?

Outside of the first two circles of science absolute certainty is a rare thing. Rather decisions are made on the basis of high degrees of probability. A scientific theory is considered reliable or proven if it can be relied upon to make accurate predictions. Climate change scientists have predicted that climate change will lead to the following:


Prediction Observation
Glacial retreat with consequent temporary increase in melt water, river levels and erosion, but longer term reduction in fresh water


Break-up of major ice shelves in the Antarctic and Greenland


Reduction in Arctic sea ice


Re-distribution of plant and animal species in response to changes in ocean temperature and environmental conditions


Increase in global average temperatures on a trend basis


Permafrost melt and subsequent release of methane into the atmosphere


Ocean acidification from absorbed CO2


Increase in frequency and severity of weather events




Only the last of these is disputed by climate skeptics since the rest are clearly observed.

Also, with something as complex as global climate, there will be things which were not predicted. For example, Antarctic sea ice has thinned but the total amount of sea ice cover has expanded. That is because ice melt has made the sea water less saline. Being less saline it is lighter and migrates to the surface sea layer. Since temperatures are colder at the surface, and fresher water freezes at higher temperatures, large areas of ocean surface have now frozen. In the Arctic on the other hand, there has been more rain and less snow. The rain sometimes freezes into an ice layer and snow then falls on top. Caribou are able to dig through the snow but cannot always break through the ice to get to the moss they eat. As a keystone species, this presents a risk to Caribou numbers but also to the wider ecology of the Arctic.

Should we Act on Climate Change?

That depends on your values and agenda. For example, if you are a petroleum exploration company, global warming is in your interests because a reduction in land and ocean ice cover will open up the Arctic to oil exploration. If you are a farmer on marginal land in a developing country, changes in climate may bring famine. Really it’s about risk.

If the thesis is false and no action is taken nothing is lost.

If the thesis is false and action is taken, some costs will be incurred unnecessarily. However, we will be much better positioned in the longer term to manage other challenges such as increasing energy demand and reduction in the supply of cheap coal and oil.

If the thesis is true and no action is taken, the economic, social and environmental costs will be very high. In the lifetime of our great grandchildren they could be catastrophic.

If the thesis is true and action is taken, these costs will largely be avoided.

This basic logic reflects standard risk management methodology. In simple terms risk is assessed by charting the seriousness of the event against the probability of it happening. An event which is likely to happen and will have serious consequences presents a critical risk. On the basis of the same risk management methodology used in every other discipline, climate change now represents a critical risk.

Shows a standard risk matrix table

Why Do People Object to the Thesis?

Many people object because they don’t want it to be true, or they resent the implication that the world is limited and industrial civilisation is reaching ecological limits. See Policy Vignette #1 Irrational Beliefs. Some believe that other explanations fit the data better. Some object to the more alarmist predictions but then deny the evidence entirely.

However, the real reason that there is a debate about climate change is because vested interests have campaigned to prevent any change to the status quo. This campaign has used the same techniques used by the tobacco industry to deny the link between smoking and cancer. That is to cast doubt on the data by claiming that the link is not proven. This is done by focusing on statistical outliers rather than trends. So for example, great aunt Flo might have smoked a pack-a-day and lived to be 92. This proves that great aunt Flo is genetically gifted and a statistical freak, but does not disprove the link between smoking and cancer. Similarly, the fact that a city might experience a record cold winter sometime in the last 25 years does not disprove climate change. While there are genuine individuals who question the thesis, the campaign over-all is dishonest in that it is based in highly selective data.

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