Human civilisation has been evolving on Earth for tens of thousands of years. However it was not until the seminal work of Willem Köppen of the Hamburg Naval Observatory, and the publication of his Climate Classification Map in the early 20thcentury, that the nature of global climate and its pervading influence began to be recognised. Köppen's maps described climate classifications that linked local patterns of temperature and precipitation with characteristic vegetation types. Around the world, similar vegetation types were found in similar climatic regimes.
Fundamental to Köppen's climatic classification is the adaptation of plants and animals, each to survive within a limited range of variability about the normal seasonal patterns. The evolution of human civilisation is rooted in an ability to take advantage of prevailing local climates and their natural ecosystems that produce essential food and fibre. Humans have also adapted ecosystems to manage agriculture and animal herds, thus expanding production of those more beneficial plants and animals.
Notwithstanding the global pattern of climates, with their seasonal repetition, there is considerable local variability from year to year. Across tropical to middle latitudes it is the variability of precipitation to which life is most vulnerable; from the middle latitudes to the poles it is temperature variation and its impact on the length of the growing season that is most hazardous. Extreme events, including wind storms, flood rains or temperatures (either hot or cold), though short-lived can be destructive. Such events affect communities, their infrastructure, and the natural and managed ecosystems on which they depend.
A primary objective in the establishment of National Meteorological Services, many in the late 19thcentury, has been the gathering of data to better document local climates and their variability. Such information supports more productive agricultural and pastoral regimes and improves decision making when seasonal conditions depart from the expected climate pattern. Planning and early warning services for meteorological hazards have, to an extent, made rural land and water industries more resilient to climate variability and extremes.
For many meteorologists it came as a surprise when international delegates to a United Nations (UN) sponsored conference in Villach, Austria in 1985 issued a Statement that concluded:
"As a result of the increasing concentrations of greenhouse gases, it is now believed that in the first half of the next century a rise of global mean temperature could occur which is greater than any in man's history."
The Statement followed with:
Many important economic and social decisions are being made today on long-term projectsmajor water resource management activities such as irrigation and hydro-power, drought relief, agricultural land use, structural designs and coastal engineering projects, and energy planningall based on the assumption that past climatic data, without modification, are a reliable guide to the future. This is no longer a good assumption since the increasing concentrations of greenhouse gases are expected to cause a significant warming of the global climate in the next century.
The Villach Conference Statement was subsequently used as motivation for a series of national and international conferences to raise political and community awareness of the perceived danger from anthropogenic global warming. In Australia the government funded Commission for the Future and the CSIRO, supported by non-governmental environmental organisations, were the principal activists. At the behest of the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO), the UN in 1988 established an Intergovernmental Panel on Climate Change (IPCC) to assess and report on the perceived danger from unconstrained burning of fossil fuels and their emissions of carbon dioxide (CO2) to the atmosphere.
It should be noted that the basis for the Villach Conference Statement, and the subsequent international near-hysteria, was projections of future accumulation of CO2 in the atmosphere and its impact, as assessed by rudimentary computer models, on global temperature.
If present trends continue, the combined concentrations of atmospheric CO2and other greenhouse gases would be radiatively equivalent to a doubling of CO2 from pre-industrial levels possibly as early as the 2030's". Moreover, "The most advanced experiments with general circulation models of the climatic system show increases of the global mean equilibrium surface temperature for a doubling of the atmospheric CO2concentration, or equivalent, of between 1.5 and 4.5 °C. Because of the complexity of the climatic system and the imperfections of the models, particularly with respect to ocean-atmosphere interactions and clouds, values outside this range cannot be excluded".
The "general circulation models" (now referred to as global climate models – GCM) in reality were very rudimentary in construction. The oceans were represented as a water slab without internal dynamics and many important features, such as cloud types and amounts, were constrained to climatological values. There was no independent validation of the GCM predictions; the predictions were assumed to be valid because they gave a 'reasonable' representation of the global climate and were expected to respond appropriately when CO2concentration was changed.
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