WHAT DRIVES CLIMATE?
The two biggest drivers of climate are the sun and the oceans, with
numerous smaller influences (geography, land use, volcanoes, cloud
cover, ice and snow, etc.) and if you can predict trends for those two
elements you can make a pretty solid forecast for months and years
ahead…but you won't find those forecasts on TV or online. Like any
specialized skill it takes years of analysis and research along with an abstract, unquantifiable "feel" for weather and climate cycles. That's
where my passion for weather from a very young age helps. So what
am I seeing?
The sun is currently at the peak of Solar Cycle 24. The average person has no idea that the sun has cycles, but it does. It has an 11-year
cycle (on average) that features an energy peak in the middle with two
periods (valleys) of lower energy output on either side of the peak (see
Fig. 1).
Experts in astronomy and solar physics have been tracking solar cycles since the 1700s, and like everything else in nature they have observed a significant range in the strength of each cycle. The sun's
output is anything but stable or consistent and forecasting the strength
of future solar cycles is difficult at best, but much has been learned
about the sun in recent years and forecasts are getting slowly better.
The current cycle, Solar Cycle 24, is the weakest in the past 100
years and likely one of the weakest in the past 200 years based on the
number of sunspots showing up on the earth-facing side of the sun.
While there are numerous ways to measure solar output, the only way
to compare solar activity now with solar cycles since the 1700s is to
count sunspots, and based on that…and knowing that we are able to
see more spots now because of high-resolution satellites and telescopes…we're in a rather weak cycle comparable to what we saw in the
late 1700s leading into the early 1800s…the latter part of the Little
Ice Age. Cycle 25 (starting after 2020) is forecast to be even weaker.
Figure 2 is a recent image of the sun with a few sunspots from the
Solar Dynamics Observatory.
Since the sun is the primary driver of climate, even small changes
in solar output impact our weather and climate cycles. A weaker sun
Figure 2.
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