Global warming deniers are posting olde timey photos of the Thames River Frost Fair of 1814 and claiming that a new scientific model reveals we are going to enter a mini-ice age in 2030. But they are skating on thin ice.
Here is the real story:
University of Northumbria mathematics professor Valentina Zharkova recently presented non-peer-reviewed results of new model of the Sun’s interior dynamo to the UK's Royal Astronomical Society’s national meeting. The model predicts that sunspots are going to decrease in coming years, matching sunspot levels seen in the 17th century. Astronomy Now reports thatthe model "shows that solar activity will fall by 60 percent during the 2030s, to conditions last seen during the Maunder Minimum of 1645-1715." However, Zharkova said nothing about the effect this will or will not have on the Earth's climate. This didn't stop right-leaning media from gleefully reporting that the Earth will enter a new mini-ice age as a result.
In fact, other studies have shown that a new grand minimum will have little or no effect on global warming. Here's what a 2010 article from Geophysical Research Letters said:
The Maunder minimum is connected to the Little Ice Age, a time of markedly lower temperatures, in particular in the Northern hemisphere. Here we use a coupled climate model to explore the effect of a 21st‐century grand minimum on future global temperatures, finding a moderate temperature offset of no more than −0.3°C in the year 2100 relative to a scenario with solar activity similar to recent decades. This temperature decrease is much smaller than the warming expected from anthropogenic greenhouse gas emissions by the end of the century.
What's more, The Washington Post reports that the mini-ice age that occurred during the Maunder minimum "wasn’t so much a global ice age as a cold spell in Europe, and it may have been caused more by clouds of ash from volcanic eruptions than by fluctuations in solar activity."
In addition, the reason the Thames used to freeze over has little or nothing to do with sunspot activity: it was because the old London Bridge's arches prevented sea water from moving upriver, keeping the freezing point of the water close to 0 degree Centigrade. Pure sea water freezes at -2 degrees Centigrade.
The construction of a new bridge in the 19th century, and other landscape changes that made the river flow faster, brought an end to those festivals — less so than the end of the Maunder minimum.
“I’d be surprised if it froze again to the extent where we’d be able to allow large numbers of people on the Thames,” said [Historical climatologist George Adamson].