Weather, Climate, Carbon Dioxide and Global Warming
Viv has a degree in Applied Science Geology and is a Fellow of the Australasian Institute of Mining and Metallurgy
There are three big drivers of weather for any place on Earth – the latitude, the local environment and solar system cycles.
The biggest weather factor is latitude – are you in the torrid, temperate or frigid zone? These climatic zones are defined by the intensity of heat delivered to Earth’s surface by the sun.
In the Torrid Zone the sun is always high in the sky. It is generally hot, often moist, with low atmospheric pressure, muggy conditions and abundant rain and storms, some severe. Places close to the Equator get two summers per year (really just one long summer) and very little winter. Further from the equator there are two seasons - “The Wet” and “The Dry”. The Torrid Zone produces many equatorial rain forests but also contains some deserts. Most people dream of vacations or retirement in the warm zone.
The Temperate Zone is cooler with more distinct seasons and sometimes severe droughts and floods. The granaries of the world lie within it. But the belt of sub-tropical high pressure zones also produces most of the world’s great deserts.
The Frigid Zone has low humidity and high atmospheric pressure, with just two seasons (one cool, with a sun that never sets, followed by a long, cold, dark, sunless winter). Only a few foolish people long for expansion of the frigid zone.
The second weather-maker is the local environment - geography, topography, winds, ocean currents and human activity.
Oceans dominate Earth’s surface and its weather. How near is the ocean with its moist changeable atmosphere and ocean currents? These can be warm, cold or variable. Sea-side places have less extremes of temperature and highlands are generally cooler than lowlands. Lands on the ocean side of mountains have more precipitation and forest vegetation while those behind the hills lie in rain shadows and have more grasslands and deserts.
Winds generally create or define weather. The rotation of the Earth generates semi-permanent trade winds which have an easterly component on the surface in both hemispheres. These are modified by convectional cells of rising and falling air created by differences in solar heating of Earth’s surface by the sun. Winds, ocean currents and ocean over-turnings combine to create longer term weather-makers such as El Nino. Contour maps of air pressure (isobars) are one of the most useful tools for short-term weather forecasting, and they can have daily or seasonal predictability.
Intense human activity also affects local weather. Mega-cities and urban sprawl generate and concentrate heat, producing their own artificial heat islands. People, houses, buses, trains, cars, trucks, aeroplanes, factories, motors, generators, stoves, heaters, coolers, concrete, bitumen and landfill all generate, absorb, reflect, exhaust or radiate heat.
As many temperature recording stations are located in or near such islands of man-made heat, this has distorted calculations of “global temperature”.
The third weather-maker relates to cycles in the solar system.
The daily rotation of Earth produces night and day with cold, fogs or frosts at dawn, warmer afternoons and the daily tides. It also influences surface wind direction, producing areas subject to the trade winds, the roaring forties or the doldrums.
The monthly lunar cycle produces tides in the atmosphere, in the oceans and in Earth’s crust – these affect winds, weather cycles, earthquakes and volcanic eruptions. The phases and orbit of the moon affect the moon/sun forces of gravity to reinforce or reduce the tides, creating Spring Tides, King Tides, Neap Tides and Slack Water. Funnel-shaped bays can magnify tides to create powerful Tidal Bores.
The annual cycle of Earth around the Sun produces the seasons from summer to winter, with more extreme seasonal effects over land than over oceans.
The 22 year sunspot cycle affects the frequency of droughts and floods. A lack of sunspots correlates with periods like the Little-Ice-Age. Periodic reductions in the sun’s Earth-shielding magnetic field allow more cosmic rays to strike the Earth, creating more clouds, more shading of Earth’s surface and producing colder, cloudier weather. The longer Milankovitch solar system cycles trigger warm eras like today’s Holocene and glacial eras like the one that ended just 12,000 years ago.
Trying to calculate something called “global average temperature” from this massive variety of ever-changing data covering diverse locations, elevations, times and weather is an exercise in statistical sophistry – either meaningless or misleading.
“Climate” is just the notional 30 year average of weather, so climate is controlled by the same big three factors that drive weather.
Notice one thing about the three big drivers of weather – not one is measurably affected by the trace amount of carbon dioxide gas in the atmosphere. Never does a daily weather forecast mention CO2, and never do weather-watching farmers or sailors note daily measurements of CO2. However, there are over one hundred massive computerised climate forecasting models run by bureaucracies that use CO2 as a key driver, with variable inputs and rules, and differing results.
No one knows which model may have stumbled on to an accurate climate forecast.
CO2 is a rare (0.04%) colourless natural atmospheric gas. It does not generate any heat – it just moves heat around. In the atmosphere, it may slightly reduce the solar radiation that reaches the surface, thus producing cooler days; and it may slightly reduce night-time radiative cooling, thus producing warmer nights. The net effect is probably a tiny net warming at night, in winter and in polar regions – all of which are probably welcomed by most people. Even this tiny effect reduces rapidly as CO2 levels rise.
This effect is not used by any practical weather forecaster. The theory that human production of carbon dioxide can control global climate is totally unproven and looks absurd.
Past records show that long term variations in atmospheric CO2 content are more a result of temperature changes than a cause of them.