Debate at the University of Tasmania
(Launceston campus, 3 October 2006)

"This house agrees that global warming is the biggest threat humankind faces in the 21st Century"

William Kininmonth speaking in the negative

Ladies and Gentlemen.

In the context of pestilence, famine and warfare it is ludicrous to suggest that global warming might be considered the biggest threat that humankind faces in the 21st century.

The plague that ravaged Europe from the middle 14th to the middle 17th centuries is estimated to have killed between 30 and 50 percent of the population. Pneumonia killed about 20 million people in the 1920s. SARS, Ebola and other potential pandemics continue to hover in the background.

Famine and disease resulting from drought and floods killed more than 20 million people across northern China, India, southern Africa, northeast Brazil and the islands of the Pacific during the El Niño of 1877. Similar numbers of people died in 1888, including about one third of the population of Ethiopia. As recently as 1997 about one million people of Papua New Guinea were saved from starvation by Australian aid. Famine, disease and starvation again threaten vulnerable regions of the world as another El Niño event develops in the equatorial Pacific Ocean. The threat is very close to home as Australia suffers drought, water restrictions are imposed and fire danger will be extreme this coming summer.

Global warfare is an ever-present danger. Australia has troops deployed under international arrangements in Iraq, Afghanistan, East Timor and the Pacific in an attempt to promote democracy and maintain peace. In addition, there is civil unrest in Africa, Central and South America and across southern and central Asia.

Against this background of pestilence, famine and warfare the Earth's climate has warmed over the past 200 years from the cold of the Little Ice Age. The global population has expanded to more than 6 billion people. There is no doubt that there is enough food being grown to feed the global population. There are also resources available to clothe and house the people. Regions of scarcity and deprivation are caused by inhibiting social structures, including colonialism, corruption and conflicting tribal allegiances. In a perfect world, there are abundant resources to sustain the global population.

Why should we even think that global warming is a threat to humankind in the 21st century?

In 1988 the UN established the Intergovernmental Panel on Climate Change, or IPCC, to provide guidance to governments on the likelihood of human induced climate change. In its First Assessment Report of 1990 the IPCC stated:

  • There is a greenhouse effect that keeps the Earth warmer than it would otherwise be.
  • Carbon dioxide is a greenhouse gas and its concentration in the atmosphere is increasing because of human activities.
  • Increasing concentrations of carbon dioxide will enhance the greenhouse effect so as to make the Earth warmer.

The IPCC emphasised, however, that there were many uncertainties in our knowledge of the climate system. The report highlighted that it was not possible to quantify the timing, magnitude nor regional patterns of anthropogenic global warming.

Nevertheless, based on rudimentary computer models of the climate system, the IPCC then projected that the global average temperature would rise 3°C and sea level would rise 65 cm above 1990 values by 2100.

The IPCC issued further assessment reports in 1995 and 2001, each claiming advances in scientific understanding; each claiming greater confidence that recent global warming was due to human activities and that the warming is likely to increase. Almost exclusively, the additional confidence was based on access to more powerful computers that have enabled the formulation of more complex models to simulate the climate system.

But there is no evidence that the computer models are better representing reality. Indeed, we could be forgiven if we concluded that computer modelling is akin to the magician's smoke and mirrors!

The main greenhouse gas in the atmosphere is water vapour. Its concentration and distribution vary in space and time. Saturation and cloud formation occurs in ascending air and clouds change the earth's local radiation patterns even more strongly than greenhouse gases do. Representation of water vapour and clouds in computer models is recognised as being very difficult and a major source of error.

In contrast, carbon dioxide is a well-mixed gas and its interaction with the Earth's radiation fields can be calculated for cloud-free air.

We calculate that the Earth would radiate to space at the rate of 337 W/m2 in the absence of clouds, water vapour and carbon dioxide. If we add standard water vapour concentrations then the radiation would reduce to 286 W/m2. That is, the greenhouse effect of water vapour is about 51 W/m2.

Adding pre-industrial levels of carbon dioxide to the atmosphere, about 300 ppm, further reduces radiation to space by 27 W/m2. Carbon dioxide has about half of the greenhouse effect of water vapour.

However, 70 percent of carbon dioxide's greenhouse effect is due to the first 50 ppm of concentration. Carbon dioxide is essentially a spent force as far as the enhanced greenhouse effect is concerned and adding to the concentration by industrial activities has little impact.

The approximately 100 ppm of carbon dioxide added to the atmosphere since industrialisation has increased the greenhouse effect by a little more than 1 W/m2. A further doubling of carbon dioxide concentration to 800 ppm by the end of the 21st century will only increase the greenhouse effect by about 3 W/m2, a very small increase.

When we look at the numbers in perspective, the impact of the enhanced greenhouse effect from anthropogenic carbon dioxide is small and the threat is a mirage.

The suggestion that Earth's climate is about to cross a trigger point that will result in runaway global warming also does not stand up to scrutiny.

Convective overturning distributes heat from the warm tropical surface through the atmosphere. The buoyancy required for convective clouds mean that temperature rises in the atmosphere are constrained by the surface temperature.

However the temperature at the Earth's surface is strongly regulated by evaporation. Surface evaporation increases nearly exponentially with surface temperature and the warmest ocean temperatures are constrained to about 30&degC. Even tropical rainforests do not exceed 35&degC. High afternoon temperatures are only experienced over arid inland regions.

Seventy percent of the Earth's surface is ocean. Evaporation cooling will thus constrain the surface temperature against the minor enhanced greenhouse effect of anthropogenic carbon dioxide, much as a canvas water bag provides cool water in a desert.

An omission in any discussion of anthropogenic global warming is regional radiation imbalance. Most solar radiation is received over the tropics. In contrast, the polar regions radiate more energy to space than the solar radiation they receive. The global radiation balance is only maintained because of the transport of excess energy from the tropics to the poles by the atmospheric and ocean circulations.

The atmosphere and the oceans are interacting fluids with natural modes of variability. The oceans contain the thermal and mass inertia. They are the flywheels of the climate system. However the atmosphere transports about 80 percent of the energy to the poles and the surface winds drive the ocean circulations.

Climate varies from the interannual scale of El Niño to the multi-centennial scale of the Little Ice Ages. This is because of the internal variability generated by interactions between the oceans and atmosphere.

Computer models only respond linearly to radiative forcing and do not simulate the internal variability of the climate system. This is highlighted in the circular logic of the IPCC in its 2001 report. IPCC claims that "the warming of the past 100 years is very unlikely to be due to internal variability alone, as estimated by current models".

Computer models did not predict the development of the current El Niño event that is bringing drought to Australia and spawning natural disasters around the world. They are not capable of predicting the next Little Ice Age.

Nineteen different computer models give nineteen different projections for anthropogenic global warming for the 21st century, and they are all exaggerated.

Pestilence, famine and violence are ever present. Each is capable of killing millions of people and destroying the social fabric of the global community.

In contrast, the global warming of the past 200 years has been beneficial to human society and to the biosphere. Society and ecosystems have adapted and flourished. There is no reason to believe that life will not continue to adapt and flourish on Earth.

Global warming cannot be considered as a threat in the 21st century, and is certainly not the biggest threat to humankind.

Thank you.

Lavoisier the Man
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