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Contrary to climate change alarmists’ claims, we are actually living in an excellent period of time for human flourishing. Warming trends are demonstrably natural and conducive to the growth of plants, and crops in particular.

For more than three decades, there have been ever shriller cries warning of a climate emergency. We are being told that carbon dioxide and other greenhouse gases produced by industry, agriculture, and our everyday lifestyles are contributing to dangerous irreversible global warming.

The nebulous, dangerous global-warming mantra has morphed into a climate emergency that suggests not only a sizzling planet but also a spawning of extreme droughts, floods, storms, and tempests. Every weather-related hazard is claimed to be getting more extreme and more frequent.

With each extreme weather event, there are self-styled experts linking the event to climate change and blaming emissions of greenhouse gases – particularly carbon dioxide from industry but more recently oxides of nitrogen from agricultural fertilisers. As with all matters related to the climate-change hysteria, the evidence is in the vibe and not in the data.

Yes, Earth has been warming. This is confirmed by data collected from all areas of the globe over the last 40 years of satellite monitoring. These data give a clear picture of how Earth has been warming.

While there is no discernible trend over Antarctica and the Southern Ocean, the tropics have warmed at a rate of near 0.1 degrees Celsius per decade and the high northern latitudes have warmed at a faster rate of about 0.4 degrees per decade.

The relatively high rate of warming over the Arctic should not be concerning. The warming is seasonal and strongest during the dark months of winter when temperatures are below freezing. Such warming will have little impact on dormant fauna and flora.

The regional and seasonal patterns of warming are natural and can be explained by considering the flow of heat through the climate system. The absorption of solar radiation is a maximum over the tropics. Some of the heat is immediately radiated back to space; the excess is transported to polar regions by the ocean currents and winds. Over polar regions, the radiation of heat to space exceeds the absorption of solar radiation and it is the heat transported from the tropics that sustains polar temperatures.

A critical factor in regulating local temperature is the nature of the surface. Land surfaces have little capacity for storing heat. Land surfaces warm rapidly during the day as solar radiation is absorbed but then cool overnight as the heat absorbed into the surface is either exchanged with the atmosphere or radiated to space.

In contrast, solar radiation penetrates the ocean surface and is absorbed in a layer below the surface. Wave action mixes the absorbed heat to depth to form a lens of warm water, up to 150 metres in depth, covering the tropical oceans.

The lens of warm water is a substantial heat reservoir that acts to modulate climate. Heat is lost from this ocean reservoir either by way of ocean currents to the polar regions or by exchange with the tropical atmosphere.

The 0.4 degrees observed warming of the tropical oceans over the last 40 years means that the rates of heat and latent heat (in the water vapour evaporated from the oceans) flowing to the atmosphere have also increased. The tropical atmosphere has warmed at the same rate as the oceans, but the latent heat is transported polewards to warm the middle and high latitudes.

There is strong seasonality in the poleward transport of heat by the winds because of the annual cycle of solar radiation absorbed over high latitudes. The rate of poleward transport of heat is a maximum during the winter months but declines during spring months because of the increasing absorption of solar radiation over polar regions. The rate of poleward transport of heat is at a minimum during summer months.

The warming over the Arctic follows the seasonal pattern of heat transport by the winds. The additional latent heat from the warming tropical oceans has mainly been transported to warm middle and high northern latitudes during autumn, winter, and spring when the winds are strongest. The northern hemisphere is largely land surface with little capacity for storing heat, thus the temperature responds to the additional heat inflow.

In contrast, it is oceans that dominate the southern hemisphere, and these absorb heat with only limited temperature change. There are no discernible temperature trends across the Southern Ocean, apart from some warming along the Antarctic Peninsula.

Although the pattern of observed temperature changes over the last 40 years can be traced to the warming tropical oceans, the question remains as to why the tropical oceans are warming. Was it because of a slowing phase of the ocean currents, or was it because of increased carbon-dioxide concentration, as many scientists have claimed?

Carbon dioxide does have an influence on surface temperature because, as with all greenhouse gases, carbon dioxide emits radiation from the atmosphere to be absorbed in the surface. It is the absorption of radiation emitted by the greenhouse gases that reduces net radiation loss from the surface and raises the surface temperature — the greenhouse effect.

The major greenhouse gas in the atmosphere is water vapour. Moreover, water vapour and carbon dioxide emit and absorb radiation across the same wavebands. In the warm moist atmosphere of the tropics, the water vapour largely masks the impact of carbon dioxide.

The Table shows how the magnitude of longwave radiation absorbed at the surface from greenhouse gases varies only marginally as carbon-dioxide concentration changes. Water vapour is the dominant greenhouse gas, alone producing 361.40 watts per square metre of radiation to the surface. The incremental changes in radiation absorption at the surface as carbon-dioxide concentration rises are very small in comparison.

About 20,000 years ago, at the last glacial maximum, the carbon-dioxide concentration was about 200 parts per million (ppm), deep ice sheets covered much of North America and Northwest Europe and the sea level was about 130 metres lower than today. By 10,000 years ago, as deglaciation occurred, the ice sheets had largely melted. Sea level had risen, and carbon-dioxide concentration had increased to about 300 ppm, much as it was in pre-industrial years.

With industrialisation, carbon-dioxide concentration is now a little more than 400 ppm but the change in sea level and temperature has been almost imperceptible.

Compared with the natural background emission by water vapour, the change in absorption over the tropical surface as carbon-dioxide concentration increases is insignificant. The increase in absorption from pre-industrial times to the present (0.62 W/m²) is of similar magnitude to the increase that occurred during the deglaciation period (0.63 W/m²). The relatively small change in climate characteristics during the industrial period when compared to that during deglaciation suggests that changing carbon-dioxide concentration contributed little to Earth’s deglaciation.

The negligible effect of carbon dioxide is further demonstrated from data covering the last 40 years. Over this period, atmospheric carbon dioxide increased from 377 ppm to 411 ppm, sufficient to raise the absorption of longwave radiation at the tropical surface by 0.3 W/m². Over the same period, the observed rise in tropical surface temperature of 0.4 degrees increased the loss of latent heat from the surface by about 3.5 W/m².

The increase in absorption of long­wave radiation (surface-energy gain for heating) is an order of magnitude less than the additional latent heat flow to the atmosphere (surface-energy loss to constrain heating). The surface temperature has risen even though the increased latent heat loss is so much greater than the claimed source of energy to raise surface temperature.

These data from the last 40 years clearly identify that the increase in carbon dioxide concentration could not have been the cause of the observed tropical-ocean warming. It is very likely that the warming is a natural outcome of a cyclic slowing of ocean currents and heat transport.

It is also clear that there is no impending climate emergency. Although most warming has been over the high northern latitudes in winter, this is when temperatures are below freezing. Such warming has advanced spring thaw and delayed autumn freeze to increase the duration of summer melting of land ice.

A continuation of the approximately 2-3 millimetre per year sea-level rise has proven quite manageable through adaptation measures.

The positive impact of the longer duration between spring thaw and autumn freeze is that growing seasons over middle and high latitudes have lengthened, thus contributing to increased plant growth and a greening of the planet. Not only has the biosphere flourished but agricultural productivity has also increased. More food is being grown to support the expanding global population.

In summary, there is no impending climate emergency and carbon dioxide concentration has little impact on climate. Government policies to reduce carbon-dioxide emissions will not alter the natural course of climate. Moreover, the lengthened growing season and greening planet mean we are living in the best of times.

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