We continuously hear how it is imperative that humanity acts to limit any further increase in the Earth’s average air temperature. The International Panel on Climate Change (IPCC) experts maintain that Earth has warmed by approximately 1 degree Centigrade above its average value, as defined by the time span of 1850 to 1900..Many have said that if the Earth’s average air temperature increases by a further 0.5 degrees C, that a tipping point will be passed and the rest is equivalent to Climate Armageddon..I will show you that there has been between 2 to 2.5 C warming across most of the Northern Hemisphere since 1850 to 1900. This is more than twice the global average..To better illustrate this fact, I include here a figure from work by Christiansen et al of the change in air temperatures across the higher latitudes of the northern hemisphere over the past 500 years.. Fournier Global warming 1 .Christiansen’s meta-study on 91 publications examined the paleo-record extending back 2000 years and across the northern hemisphere. In this work, his team amalgamated and plotted the results as a change in surface air temperature relative to average from 1880 to 1960. This study used numerous proxies for temperatures, including lake and sea sediments, ice core samples, and tree rings to calibrate their findings up until the mid-to-early 1900s, when thermometers became widespread..First, it is important to highlight that this work very effectively illustrates the well-known Little Ice Age, which is a period of extended drought, expanding glaciers and reduced temperatures. The Little Ice Age followed a similar period of warming climate to the present, known as the Medieval Warm Period. These are natural climatic changes, which while occurring most intensely in the northern hemisphere, were global in extent..Secondly, this figure shows that around the middle of the 1800s, a sudden two degree increase in surface air temperatures occurred, that extended up until the 1940s and 1950s..Third, note that the peak in the 1940s to 1950s is again attained by 2000, following a brief period of cooling from the 1950s to the 1970s. The dual peak warming decades in the 20th century in the northern hemisphere is a hot potato, and will serve as a topic for another article..Many experts in the field of anthropogenic climate change argue that the approximately 1 degree C warming from the 1970s to 2000 was entirely man-made. Yet this recent 1 C increase in temperature is dwarfed by the increase in temperature from 1850 to 1950, and is largely ignored..Further evidence of the much larger warming from the 1800s to the 1950s is shown in the US Geological Survey map of Alaska’s Glacier Bay National Park. This map shows the terminus positions and dates of retreat of the Little Ice Age glacier that completely filled the bay somewhat more than 200 years ago..Similarly here we see glacial retreat was largely completed by the late 1940s and that the terminus of Glacier Bay’s glaciers have largely stabilized since the late 1960s..It is important that people understand the significance of the two-fold difference between the global average change and the northern hemisphere average change.. Fiurnier global warming 2 .In a nut-shell, this two-fold difference demonstrates that most of the global warming since 1850 to 1900, has been concentrated in the Northern Hemisphere. Changes in temperature in the southern hemisphere were much smaller, which is why the global average is pulled down in value relative to that in the northern hemisphere..This should not be a surprise as most of us are aware of the fact there was a mile deep ice shield across most of the northern hemisphere over 15,000 years ago. While the southern hemisphere experienced glacial advance at higher elevations, it was nothing compared to the accumulation of land ice in the north during the last glacial maximum. Climate change is always amplified in the northern hemisphere..In view of these findings, I ask how can a further 0.5 degrees C increase in temperature give rise to Climate Armageddon, yet the Modern Era occurred as we exited the Little Ice Age and the Northern Hemisphere warmed by over 2 degrees C?.Finally, here is what we also know to be true..Most of the world’s human population exists in the northern hemisphere, as does the majority of food production occurs between latitudes 25 to 55 degrees north. The last I checked, human populations and agricultural productivity have steadily risen from 1800s to the present, as has the entire terrestrial biosphere expanded during this time span, also..All this being said, I hope that you can appreciate why I am skeptical about the numerous stated risks associated with a further 0.5 degrees C increase in the global average air temperature.
We continuously hear how it is imperative that humanity acts to limit any further increase in the Earth’s average air temperature. The International Panel on Climate Change (IPCC) experts maintain that Earth has warmed by approximately 1 degree Centigrade above its average value, as defined by the time span of 1850 to 1900..Many have said that if the Earth’s average air temperature increases by a further 0.5 degrees C, that a tipping point will be passed and the rest is equivalent to Climate Armageddon..I will show you that there has been between 2 to 2.5 C warming across most of the Northern Hemisphere since 1850 to 1900. This is more than twice the global average..To better illustrate this fact, I include here a figure from work by Christiansen et al of the change in air temperatures across the higher latitudes of the northern hemisphere over the past 500 years.. Fournier Global warming 1 .Christiansen’s meta-study on 91 publications examined the paleo-record extending back 2000 years and across the northern hemisphere. In this work, his team amalgamated and plotted the results as a change in surface air temperature relative to average from 1880 to 1960. This study used numerous proxies for temperatures, including lake and sea sediments, ice core samples, and tree rings to calibrate their findings up until the mid-to-early 1900s, when thermometers became widespread..First, it is important to highlight that this work very effectively illustrates the well-known Little Ice Age, which is a period of extended drought, expanding glaciers and reduced temperatures. The Little Ice Age followed a similar period of warming climate to the present, known as the Medieval Warm Period. These are natural climatic changes, which while occurring most intensely in the northern hemisphere, were global in extent..Secondly, this figure shows that around the middle of the 1800s, a sudden two degree increase in surface air temperatures occurred, that extended up until the 1940s and 1950s..Third, note that the peak in the 1940s to 1950s is again attained by 2000, following a brief period of cooling from the 1950s to the 1970s. The dual peak warming decades in the 20th century in the northern hemisphere is a hot potato, and will serve as a topic for another article..Many experts in the field of anthropogenic climate change argue that the approximately 1 degree C warming from the 1970s to 2000 was entirely man-made. Yet this recent 1 C increase in temperature is dwarfed by the increase in temperature from 1850 to 1950, and is largely ignored..Further evidence of the much larger warming from the 1800s to the 1950s is shown in the US Geological Survey map of Alaska’s Glacier Bay National Park. This map shows the terminus positions and dates of retreat of the Little Ice Age glacier that completely filled the bay somewhat more than 200 years ago..Similarly here we see glacial retreat was largely completed by the late 1940s and that the terminus of Glacier Bay’s glaciers have largely stabilized since the late 1960s..It is important that people understand the significance of the two-fold difference between the global average change and the northern hemisphere average change.. Fiurnier global warming 2 .In a nut-shell, this two-fold difference demonstrates that most of the global warming since 1850 to 1900, has been concentrated in the Northern Hemisphere. Changes in temperature in the southern hemisphere were much smaller, which is why the global average is pulled down in value relative to that in the northern hemisphere..This should not be a surprise as most of us are aware of the fact there was a mile deep ice shield across most of the northern hemisphere over 15,000 years ago. While the southern hemisphere experienced glacial advance at higher elevations, it was nothing compared to the accumulation of land ice in the north during the last glacial maximum. Climate change is always amplified in the northern hemisphere..In view of these findings, I ask how can a further 0.5 degrees C increase in temperature give rise to Climate Armageddon, yet the Modern Era occurred as we exited the Little Ice Age and the Northern Hemisphere warmed by over 2 degrees C?.Finally, here is what we also know to be true..Most of the world’s human population exists in the northern hemisphere, as does the majority of food production occurs between latitudes 25 to 55 degrees north. The last I checked, human populations and agricultural productivity have steadily risen from 1800s to the present, as has the entire terrestrial biosphere expanded during this time span, also..All this being said, I hope that you can appreciate why I am skeptical about the numerous stated risks associated with a further 0.5 degrees C increase in the global average air temperature.
