So we’ve made it through my (perhaps too exhaustive) year-by-year chronicle of recent climate history. I do think it’s worthwhile to see, on a closer-up basis, the difference between some trends which are very clear and almost unabated (CO2 content in the atmosphere, global mean sea level, among others) and aspects which are, even with long-term trends, subject to intense year-to-year variation (regional temperatures and precipitation, storm activity).
Understanding where variability is most likely is an
important part not only of seeing the news clearly, but also of making plans. To
live robustly and resiliently in a world of increasing climate change means to
prepare for increasingly likely extreme events: torrential rains the northeastern
US, freezing weather in Texas, and serious drought along the US west coast—to name
just a few examples.
Awareness not only of the steady trends but of the
likeliness for erratic variation—the weirdness on top of the warming—is becoming
more important. Because it’s also becoming increasingly obvious that, in
addition to driving for meaningful change at the societal level, we need to
live individually and communally with the reality of a changing and
increasingly hostile environment. As a society, as humans, our goal is not
merely understanding, but action to mitigate climatic danger and survive as
well as we can.
With that in mind, I’m going to focus for the next set of
posts on pictorial representations of trends, both regional and global,
illustrating both the steady trends and the variation. Having just gone through
numerical and catalogued data from the past two-plus decades, it’s time for some
quick visual snapshots showing the progress of the planet’s climate.
Today’s pictures feature one I’ve shown before (not my first
repeat), in post no. 126, about climate normals. Normals are NOAA’s system of
thirty-year running averages of measurables like temperature and precipitation, which
give a meaningful baseline for present-day comparison. Every ten years a new
thirty-year normal is calculated. Presently, the normals used are averages from
1991-2020 (released last May). The series of temperature plots shows, in a
gridded US map, the difference between each 30-year normal and the overall 20th
century average. It is therefore an extremely robust set of comparisons,
composed of hundreds of thousands of individual measurements. Ten sets of
30-year normals, from 1900 to 2020, are shown.
The second is based on global satellite data, calculating differences in temperature between 1990-2020 (the current normal period plus 1990). The data set is not as extensive as the map of normals, but does show clear long-term trends. Due to the satellite tracks there are holes in the data at north and south poles. Of note are some of the cooling spots, at the southern tip of South America and Africa and in the North Atlantic, plus the very clear signature of a strengthening La Niña phase (which drives solar heat deeper into the ocean, increasing its overall heat content). Also of note are the lack of Antarctic amplification and the very real presence of Arctic amplification, which seems to also include northeastern North America, central Europe and the Mideast.
Tomorrow: Arctic sea ice, 2000-2021.
Be brave, and be well.
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