News sources around the world have reported the death of Wallace Broecker. As a climate scientist, he penned an article that was published in the journal Science in 1975. This article was among the early warning calls of the effect of atmospheric carbon dioxide (CO2) to cause a rise in the global mean temperature. Dr. Broecker titled the article “Are we on the brink of a pronounced Global Warming”. Through his article, and many others that followed, the term “global warming” has come into common use and is readily understood by all to imply a continuing rise in the global temperature to the point that it has a detrimental effect on the oceans, wildlife, agriculture, and human society.
As Broecker stated in his 1975 article, “… the exponential rise in atmospheric carbon dioxide content will tend to become a significant factor and by early in the next century [the ‘next century’ started in 2000] will have driven the mean planetary temperature beyond the limits experienced during the last 1000 years.”
Further in the article
Broecker predicted, “As the CO2 effect will dominate, the uncertainty … lies
mainly in the estimates of future chemical fuel use and the magnitude of the
warming per unit of excess atmospheric CO2.” When any of us is outside we can
see and often smell the exhaust of the continuing use, and increased use, of
fossil (chemical) fuels by the world’s expanding population.
So when in his article
Broecker asks, “Are we in for a climate surprise?”, the answer is both yes and
no. Yes, it is happening, CO2 continues to clog our atmosphere. But no, in 2019
it is not a surprise.
The 1975 article may be found at – https://blogs.ei.columbia.edu//files/2009/10/broeckerglobalwarming75.pdf
Many things lie at the heart of climate change. Fundamental in this is global warming due to the rise in atmospheric carbon dioxide (CO2). The primary source of the CO2 is the consumption of fossil fuels by each and every one of us. We drive our cars, and CO2 is emitted in the exhaust. We turn on lights and use electricity generated from burning coal or gas. These methods of generating electricity result in the emission of CO2. These emissions have a direct effect on wildlife, the oceans, and the weather.
The mention of automobiles might put us in the mind that this problem only started since cars have been around. But it is not just the recent use of fossil fuels, we have been burning coal for a long time. Once emitted by burning of fossil fuels CO2 does not dissipated; it accumulates. Some of the CO2 may be taken up by trees and other plants in their respiration cycle. They take in CO2 and during photosynthesis the CO2 is converted into oxygen (O2). Carbon can be locked up in dead plant material too. When a tree falls in the forest its use is not over. There are kingdoms of plants and animals that will use the dead tree for food and homes in their own lives. As these plants and animals devour the now decomposing tree, they consume the carbon and lock it in their own bodies. But then as they die their carcasses, as small as they are, store some tiny bit of carbon to be released into the atmosphere and earth as the plants and creatures decompose into the earth. Over millions of years the decomposition of ancient organic matter, dead plants and animals, has produced the current fossil fuels that we use.
But how do we know that the level of atmospheric CO2 is increasing? First we can read the levels of atmospheric CO2 in ice cores. These cores are from specialized drills that penetrate deep into glaciers. When the core is drilled and extracted for examination, the levels of CO2 from past centuries can be measured. As the drill goes deeper and deeper into the glaciers the cores show what the atmosphere was like in the times past. The deeper the core is drilled, the further back in time the sample goes. When snow and ice accumulated on the surface of the glacier centuries ago it captured a signature of the gases that made up the atmosphere. From these cores the CO2 from ancient fires, and human use of wood and coal as a fuel, and emissions by ancient volcanoes can be studied. It has been established that accumulation of CO2 in the atmosphere has been going on from preindustrial times, hundreds of years ago. Since the introduction of factories and industry that used fossil fuels to operate and manufacture goods, the CO2 in the atmosphere has increased at a higher rate.
A key tool in understanding the increase of CO2 in the atmosphere has been the work of Charles D. Keeling. In 1956 he began a program to measure atmospheric gases, including CO2, at the Mauna Loa observatory in Hawaii. As these observations are plotted over time, they show an increasing level of CO2 with each passing year. The graph that shows this increase, known as the Keeling Curve, also shows the change of the seasons in the northern hemisphere. The upwards spikes of the saw-tooth curve indicate rising CO2 in the Winter months when the leaves are off the trees and are not converting CO2 into O2. The downward slope of each “tooth” indicates the activity of the trees and other plants in the growing seasons of Spring and Summer as they remove CO2 from the atmosphere and convert it into O2. But with each passing year the curve goes every upward.
From these two studies, we can determine that CO2 continues to increase based primarily on human activity. The rising levels of CO2 in the atmosphere result in a continually rising average global temperature. This is due to the greenhouse effect as the CO2 and other gases trap energy from the sun in the atmosphere. The rising levels of CO2 also result in ocean acidification.
A copy is the
Keeling Curve from the Scripps Institute CO2 program is inserted below.
