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How a quietening Sun could help slow (but not stop) our warming climate

How a quietening Sun could hel...
A new study suggests that the Sun may be heading towards a quiet period known as a Grand Minimum
A new study suggests that the Sun may be heading towards a quiet period known as a Grand Minimum
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A new study suggests that the Sun may be heading towards a quiet period known as a Grand Minimum
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A new study suggests that the Sun may be heading towards a quiet period known as a Grand Minimum

Although it looks like a pretty consistent fireball to us, the Sun has its highs and lows. It goes through a regular cycle of maximum and minimum activity over a period of about 11 years, but there are longer term trends as well. New research suggests the Sun might be headed towards a "grand minimum" of a centuries-long cycle, during which the Earth would receive much less ultraviolet radiation. If so, it may even help slow – but not stop – the progression of the climate's general warming trend.

Solar activity is associated with sunspots of increased magnetism, visible on the star's surface as darker areas. The numbers of these sunspots generally rises to a peak, coinciding with the 11-year solar maximum, before they slowly fade away as the Sun heads towards its minimum. Larger amounts of sunspots is also accompanied by events like solar flares and coronal mass ejections.

Historically, astronomers have noted that one of the most drastically low periods of solar activity occurred in the late 17th century. Normally, scientists would expect to observe between 40,000 and 50,000 sunspots over a period of 30 years, yet between 1672 and 1699 less than 50 were recorded. That staggeringly quiet period became known as the Maunder Minimum.

Interestingly, the time frame of the Maunder Minimum lines up with historical records of much colder-than-average temperatures across Europe. Often described as the "Little Ice Age", the winters during this time were apparently so chilly that the Thames River in London regularly froze over, droughts and famines increased, and glaciers in the Alps grew much larger than they had been before or since.

While the Maunder Minimum is the most extreme example on record, it may not really be indicative of what to expect in a similar future event. The new study, headed up by scientists at the Scripps Institution of Oceanography, set out to determine the likelihood of another grand minimum event in the near future, and how much dimmer the Sun would become during that time.

To do so, the researchers reviewed 18 years' worth of data gathered by the International Ultraviolet Explorer. Part of this satellite's mission was to study the activity of stars, and the Scripps researchers identified Sun-like stars that were experiencing their own minima periods. They found that during a grand minimum, a star's UV radiation drops about seven percent lower than the trough at the minimum phase of its regular cycle.

"Now we have a benchmark from which we can perform better climate model simulations," says Dan Lubin, lead researcher on the project. "We can therefore have a better idea of how changes in solar UV radiation affect climate change."

According to the researchers, there's a "significant probability" of a grand minimum event occurring by the middle of the 21st century. Sunspot numbers appear to be trending downwards in recent solar cycles, with solar physicists at NASA even saying in 2009 that "This is the quietest sun we've seen in almost a century."

That might sound like good news for our rapidly-warming world, but unfortunately, it wouldn't be enough to halt the progression of climate change. The researchers say that the warming caused by increasing CO2 levels will far outweigh any cooling effects that a grand solar minimum would bring.

In short, no Earth isn't headed for a global-warming-reversing "mini ice age."

The research was published in the journal Astrophysical Review Letters.

Source: University of California San Diego

8 comments
aksdad
I guess one person’s modest warming is another one’s rapid warming. So far the theory that human CO2 emissions are causing the planet to warm remains unproven despite statements about “settled science” and “97% consensus”. In fact, it’s obvious that El Niños have a far greater effect as we saw in 2016 and previously in 1998. See the global temperature time series (UAH or RSS) from satellite telemetry at, for example, https://www.nsstc.uah.edu/climate/
Guillaumé
Depending upon the media you read or listen to, earth is either warming or cooling. If it is warming then the data, since 1942, that I have is not correct. Climate change is not new but has been going on since the planet formed.
watersworm
OMG ! The SUN would have an influence on Earth Climate? I could'not believe it ! Please note "slow" our warming climate ouf !
Rumata
They said that "Little Ice Age" itself was caused by lower sun activity. Hence, the global warming since that was caused by higher sun activity. But if it is so, then why are they still talking about CO2 emissions?
Douglas Bennett Rogers
Shutting down desert irrigation would have a larger effect than shutting off CO2. The math is pretty easy to do.
Nik
As CO2 has never caused 'Global Warming' in 600 million years, even when it was 17 times present concentrations. In fact, during that time, when CO2 levels increased, global temperatures decreased, for several million years, and when CO2 levels decreased, global temperatures increased, also for several millions of years. Therefore, the expectation of a solar minimum, and a significant cold period can be expected to occur as predicted. As the Earth is also approaching the end of the Malenkovitch, inter ice age cycle, the cold period may well extend into centuries, or even millennia. The alleged ''warming caused by increasing CO2 levels'' is a political myth, no more, no less. For another possible reason for climate warming, try this; When the glaciers retreated at the end of the last Ice Age, the ground up rock dust left behind, provided ample nutrients for trees to grow. [Ground up rock dust is an excellent all round fertiliser.] Over the following 10-15 thousand years, the nutrients were gradually washed down through the soils, until most were out of reach of tree roots. Trees cool the climate, by absorbing the suns energy, and by transpiring water. One mature tree can transpire 150,000 litres of water per year. Multiply that by trillions of trees, and you have a significant cooling effect. As they suffer the equivalent of malnutrition, they get weak, and transpire less water. They also become drier, are more susceptible to forest fires, and to infections, and eventually death. Both of these are very evident at present. When trees are removed, either by natural causes, or by mans deforestation, the climate gets hotter, and extreme cases of total deforestation, can create hot desert. In addition, Earths present atmosphere, at 400 ppm, is CO2 impoverished, regardless of the carbon tax propaganda, and so this also weakens tree growth. 1000 ppm would be far preferable for all plant growth, which is why commercial greenhouses have CO2 pumped into them at not inconsiderable cost. Graph of 600 m.y. CO2 and climate here; http://www.geocraft.com/WVFossils/PageMill_Images/image277.gif In addition, for the last 30-50 million years, the Earth has been experiencing the effects of a 'galactic ice age' and so will continue to get steadily but by human time scales, imperceptibly, colder.
ljaques
Note to UCSD (and other) alarmists: In between ice ages, the Earth warms. This is normal. Get used to it. Once Earth and/or the solar system reach some point unknown to us, temps start heading the other direction. Pat yourselves on the back for making every soul on Earth aware of warming. You will find that most of us are trying to live with a lighter footprint on her. Why are you not happy yet? Wake up. // P.S: You could take the Copenhagen, Kyoto, Paris, and all other protocols and accords, quintuple them all, and it still wouldn't make one ten thousandth of a percent of difference in the global climates after 300 years.
Jose Gros
Global Warming is real and dangerous. The Paris and Marrakech meetings wanted setting a limit of 1.5º C, then 2º C heating over pre-industrial (before steam machine came in) average that may have been surpassed today. Besides changes in Sun activity, it's radiation is increasing; sooner or later, Planet Earth won't be able to sustain life, perhaps just in a transient way, leaving opportunity for someone from outside to take over the planet after we faded. Another element besides a long time with scarce Sunspots may have contributed to 'Little Ice Age': plague outbreaks, that killed much more than global wars, both in absolute and relative terms, with its associated reduction in agriculture activity, sent many lands back to wilderness, thus reducing the CO2 concentration in air, today over 400 ppm, this way contributing to cooling, because of a reduced global greenhouse effect; in the lack of the greenhouse effect, Earth surface temperatures would be below water freezing point. This is it!