NOAA’s ‘Global Climate Report — April, 2018 indicates that the atmosphere is back to its trend line after two years of ominous deviations in the direction of excessive warming, almost certainly due to El Niño.
As the mild La Niña that followed the El Niño fades to neutral in the central tropical Pacific, all eyes will be on the next move of global temperatures. Meanwhile, back on trend does not mean there’s nothing to worry about.
Temperatures are rising, extreme weather events are getting more frequent, and atmospheric carbon dioxide, the basic cause of global warming, increases unabated. Let’s check out the climate.
New Temperature Records For April Set In Many Places
April temperatures were above the 20th century average nearly everywhere. The lone exception was North America, where a rare all-time low was set in the north-central US.
April, 2018 was the warmest in 138 years of record-keeping in the following locations:
- Most of central and eastern Europe
- A good part of central South America
- A small patch of southern Africa
- Parts of Indonesia, Malaysia, and Australia
- Substantial parts of the North and South Atlantic, the North and South Pacific, and the South Indian Oceans
Atmospheric Carbon Dioxide Continues To Rise
This is a good time to take stock of atmospheric carbon dioxide. April set a new record for the modern era, and significant milestones have been passed.
The following measurements were taken on Mount Mauna Loa in Hawaii. Though lava flowing out of Kilauea volcano is capturing immediate interest, inconspicuous (colorless, odorless) CO2 poses much more of a long-term threat to the world.
- April’s average CO2 reading was a new all-time monthly record, surpassing 210 parts per million (ppm) for the first time for any month.
- Three of the last four weeks averaged above 211 ppm. That level had never been reached before.
- Though no daily reading has exceeded the anomalous mark of over 412.5 ppm set last May, ten individual days in the last two weeks surpassed the second highest previous daily reading, and the record is certain to fall soon.
Putting It In Perspective
There is certainly no doubt that atmospheric carbon dioxide levels have fluctuated in the past and that there has been much more carbon dioxide in the atmosphere at times than at present. However, as the accompanying graphic shows, CO2 levels are now rising at an unprecedented rate.
Where Did Our Atmosphere Come From?
For more than a billion years after Earth formed, conditions would not have been comfortable for humans — if there had been any. For one thing, though the sun was dimmer, the earth and its atmosphere were too hot. For another, the earth was being bombarded by space junk left over from solar system formation.
But in addition to that, there was no oxygen to breathe. The oxygenation of the atmosphere had to wait for photosynthesizing organisms to arise. This took about two billion years. Then the oxygen created combined with other elements in the earth’s crust, mostly iron, to form a variety of oxides. Basically, the world rusted, and this took another billion and a half years. About a billion years ago, most of the iron had turned to rust, so the oxygen percentage of the atmosphere built up, fluctuating between 18 and 35%; it now stands at 21%.
About 78% of the atmosphere is nitrogen. Why so much nitrogen? The simple answer is that nitrogen doesn’t particularly like to be incorporated in rocks, so it has accumulated in the atmosphere, where it is very stable.
The atmosphere is currently 99% oxygen and nitrogen. The misbehaving greenhouse gases, primarily carbon dioxide and methane, make up only about three one-hundredths of one per cent the air. So what’s that other one percent?
Strangely, the missing one per cent of the atmosphere is argon, a virtually-ignored element, but the third-most-common component of the air we breathe. And, whereas oxygen reacts with almost anything (luckily for us, as it allows us to use the oxygen to create energy), argon reacts with nothing. It is known as a noble gas (I guess it was considered noble not to combine with anything when elements were being named), of which there are six that occur naturally on Earth and one that can be created in particle accelerators. Argon sits in the middle of the right side of the periodic table of elements, heavier than helium and neon, but lighter than the other noble gases.
Argon occurs in the cosmos, mostly the isotope with atomic number 36, while terran argon is mostly atomic weight 40. This fact is the crucial clue to argon’s abundance in the atmosphere. Potassium 40 (potassium with atomic weight 40) undergoes radioactive decay into argon 40. This element is heavy enough to survive in the atmosphere, as opposed to neon and helium, which may have occurred in greater abundance at the formation of Earth, but simply floated away.
The next Climate Change Checkup will be published after NOAA’s May 20018 Global Climate Report in mid-June.
The next Weather Around The World will be published on June 5, 2018.