examined the impact on global warming if the sun fell into a Grand Solar Minimum. The global mean temperature difference is shown for the time period 1900 to 2100 for the (relative to zero for the average temperature during the years 1961 to 1990). The red line shows predicted temperature change for the current level of solar activity, the blue line shows predicted temperature change for solar activity at the much lower level of the , and the black line shows observed temperatures from the NASA GISS dataset through 2010. The authors found that the average global surface temperature would be diminished by no more than 0.3°C due to the lower solar activity, which would offset only a small fraction of human-caused global warming.
Impact of Volcanic Eruptions on Decadal to Centennial Fluctuations of Arctic Sea Ice Extent during the Last Millennium and on Initiation of the Little Ice Age
Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea‐ice/ocean feedbacks
This implies that low solar activity, which is expected by some researchers for the coming decades, cannot considerably slow down global warming caused by humankind’s greenhouse gas emissions.
“The impact of variations in solar activity on the climate is often overestimated,” says Georg Feulner of the Potsdam Institute for Climate Impact Research (PIK). He is the author of the article just published in Geophysical Research Letters. “This is what our new analysis shows for the past – and we can learn from this to understand future climate change.”
Research has suggested that the solar minimum around the year 1650 played a relatively small role in the cool temperatures during the Little Ice Age. Instead, heightened volcanic activity (pumping ash into the atmosphere that blocks sunlight) and a drop in atmospheric carbon levels were the main contributors to the cooling during that time. Third, the Little Ice Age wasn’t even that cold, globally. The following chart shows the most comprehensive global surface temperature reconstruction to date, from the PAGES 2k Consortium. In just the past few decades the planet has warmed more than it cooled during the entire Little Ice Age.
This ‘impending mini ice age’ myth is incredibly easy to debunk. In fact it just takes asking one simple question – if the sun is such a key driver of the Earth’s climate, then why has the entire planet (air, oceans, land, and ice) warmed rapidly over the past 60 years while solar activity has declined?
Annual global temperature change (thin light red) with 11 year moving average of temperature (thick dark red). Temperature from NASA GISS. Annual Total Solar Irradiance (thin light blue) with 11 year moving average of TSI (thick dark blue). TSI from 1880 to 1978 from Krivova et al 2007 (data). TSI from 1979 to 2009 from PMOD.
Peer-reviewed research, physics, and math all tell us that a grand solar minimum would have no more than a 0.3°C cooling effect, barely enough to put a dent in human-caused global warming.
The idea of a Grand Solar Minimum (GSM) causing weather extremes, specifically cooling on parts of our planet today is deeply flawed (just wrong) and has no basis in reality. I clearly explain here how variability in sunspots cause tiny changes in solar output (0.5/1361 or 1 part in 2722), and changes in climate impact of about 0.05 in 2.7 which is eeny-weeny-teeny compared to greenhouse gas impacts. Also, solar cycles, reflected in sunspot counts, are on an 11 year timescale, which clearly cannot explain the abrupt climate change occurring.
Even if the sun got stuck in a permanent Maunder Minimum, the warming from our CO2 emissions will still warm our planet and continue to change our climate:
"Thus if the sun remains “out”, i.e., stuck for a long period in the current solar minimum, it can offset only about 7 years of CO2 increase. The human-made greenhouse gas climate forcing is now relentlessly, monotonically, increasing at a rate that overwhelms variability of natural climate forcings. Unforced variability of global temperature is great, as shown in Figure 4, but the global temperature trend on decadal and longer time scales is now determined by the larger human-made climate forcing. Speculation that we may have entered a solar-driven long-term cooling trend must be dismissed as a pipe-dream."
"this "solar activity" refers to a fall in the number of sunspots, not a dramatic fall in the life-sustaining light emitted by the sun."
And to complete the debunking:
"In plain English, the small change in sunlight reaching the Earth during a new Maunder minimum wouldn't be enough to reverse climate change. For the technically minded, even a 3 W per m2 change in irradiance corresponds to a radiative forcing of just 0.5 W per m2 (because the Earth is a sphere and not a flat circle), which is less than the radiative forcing produced by anthropogenic greenhouse gases.
So that brings us to the more important issue of the impacts. The Little Ice Age (so-called) is certainly ‘real’, although many questions remain. When did it begin? I’ve seen dates of anywhere from 1300 to 1450 – both well before the start of the Maunder Minimum in 1645.
When did it end? Again I’ve seen dates as late as 1850 (well after the end of the MM in 1715), which might well imply that the only reason it did end is the onset of global warming!
Was it global, or regional? There is plenty of evidence from Europe and some from North America. I’ve seen a suggestion of some evidence from New Zealand. However there do seem to be many questions around the uniformity of the cooling.
So that brings us to the really key question of the causes/drivers. Solar activity is certainly one possibility, although as I’ve indicated the MM certainly couldn’t have started it. It may have made things just a little bit cooler – say 0.2 C – but it wasn’t the cause! Other suggestions have been a slowing of the Gulf Stream (it has slowed significantly in the past. ~11,000 years ago); volcanic activity (a couple of major eruptions followed by some feedbacks); and ‘orbital forcing’. We know that changes in the Earth’s orbit are the drivers of the glacial-interglacial cycle (something one of the authors of the paper in question is clearly ignorant of!), and these drivers don’t stop and start, but are on-going. We probably are heading ever so slowly for the next glacial.
Like most scientists who have made ‘meaningful’ comments, my view is that, if it does happen, it will reduce global warming by ~0.1 C – or delay it by ~10 years. And that delay would only be temporary, and temperature would zoom ahead in the years that followed.