During each of the last four ice ages, CO2 concentration fell below 190 ppm. At the end of the last ice age, it fell to 182 ppm, thought to be the lowest in the Earth’s history. Why is this alarming? Because below 150 ppm, most terrestrial plant life cannot exist. We came within about 30 ppm (30 molecules out of every one million) to the extinction of most plant life on land, and with it the extinction of all higher terrestrial life-forms that depend on it.
The Central England record (Fig. I-24) began in 1659, during some of the coldest temperatures in the last 4,500 years. Its earliest data was captured during a period of extreme cold from 1670 to 1715 that is known as the Maunder Minimum...The Maunder Minimum was the coldest period during the 600-year Little Ice Age (1250 – 1850), which brought famine, poor harvests, disease and widespread loss of life.
As we shall see, humanity has historically suffered greatly during cold periods. The Little Ice Age was no exception, so the gradual warming that began in the late 1600s was welcome relief to the inhabitants of that period.
The population of northern Europe, who had suffered the most during the Little Ice Age (Iceland, for instance, lost half its population), could not realize it at the time, but the beneficial warming that began in the late 17th century would be used 300 years later by climate alarmists to assert that dangerous man-made greenhouse gases were increasing temperature.
As we saw in Figure II-3, research has revealed that, over the last 25 years, the Earth has been growing greener, not turning into a desert (de Jong 2013). Confirmation of this comes from a recent study using satellite data from NASA showing increasing leaf cover over the last 35 years (Figure II-11). According to Zhu (2016) 25% to 50% of the Earth’s surface has shown significant greening, while only 4% of the globe is browning. Importantly, the authors attribute the bulk of the greening to CO2 fertilization effect.
Warming temperatures are benefiting agricultural food production through lengthening growing seasons, which allow additional plantings (see Figure II-12). Killer frosts end earlier in the spring and arrive later in the autumn.
The world’s remarkable ability to increase food production year after year is attributable to mechanization, agricultural innovation, CO2 fertilization and warmer weather. World grain production and amount harvested per acre (Figures II-13 & II-14) show that crop and food production has steadily increased, with only positive effects from our changing climate.
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