Temperature anomaly for the 5 years 2014-2018, relative to 1880. You can watch the full time series video on NASA’s website: climate.nasa.gov
Note to my readers: This is the first in a series I’ve written on climate change for our local monthly newspaper. I wanted to go back to the basics of the science behind climate change, as there is so much misinformation (and disinformation) out there. I thought you might be interested in reading the series, so I’ll post them in coming Yarns. Cheers, Nan
Carbon dioxide, like chocolate, is a good thing in moderation. Without carbon dioxide gas in our atmosphere, life as we know it could not exist. This is because carbon dioxide molecules are nature’s own tiny solar panels—absorbing, retaining and re-emiting heat from the sun.
However, as the concentration of carbon dioxide increases, the atmosphere is able to retain more and more heat, with consequences for life on our planet.
That’s what’s happening now. Over the next few issues of this newsletter, I’ll explore the science behind climate change and talk about the consequences for our local area.
The first direct physical measurement of what we now refer to as human-induced climate change was an unprecedented rise in atmospheric carbon dioxide (CO2), measured atop the extinct volcano Mauna Loa in Hawaii, starting in the late 1950s.
Scientist Charles Keeling chose remote Mauna Loa to get away from local sources of CO2 that could bias the high precision background measurements he wanted to make.
Between 1960 and 2020, the level of CO2 in Keeling’s observations rose by 30%, or a rate of 1.7 ppm per year.
Keeling was surprised and perplexed by his results, as he had not set out to measure the effects of fossil fuels on atmospheric CO2, but rather was focused on making high precision measurements of CO2 for other applications.
Keeling was a senior researcher at Scripps Institution of Oceanography when I was there as a young scientist, and I remember him as a quiet, scholarly man, who found himself unexpectedly in the middle of the controversy about whether humans are indeed responsible for increased CO2, and the many long-term consequences for humanity.
Over time, researchers in other branches of science expanded the ‘Keeling Curve’, as it came to be known, using innovative techniques to extend the record back in time as far as previous glacial and inter-glacial periods.
CO2 is the bet-known character in the climate change drama, but there are other ‘greenhouse’ gases, like methane (CH4) and nitrous oxide (N2O, also known as laughing gas), which are capable of retaining even higher levels of heat in their molecular bonds than does CO2.
Methane will emerge as a particularly contentious gas as we explore the consequences of climate change, as herbivores emit methane as part of their digestive process. This has prompted calls to reduce livestock numbers around the world.
Overall, due to increased concentrations of greenhouse gases the globe has warmed by about 1 deg C since the pre-industrial era; some areas, notably the polar regions, have warmed by twice that much.
In the next instalment of Science Insights, I’ll explain how we know that Keeling’s CO2 rise is the result of burning of fossil fuels rather than simply a natural change in CO2 as is seen earlier geologic eras. (Spoiler alert: the answer is carbon isotopes.)
Nan Bray is an oceanographer and climate scientist who has farmed superfine merinos near Oatlands since 2000.