I don’t know much about this topic. I could use Google to answer this, but I find it’s easiest to post questions here, because I might have follow-up questions, and I need them in layman’s terms. (That means I ain’t none too bright).
My friend is a conspiracy theorist. I posted about before. We get into CRAZY arguments, but in a way I feel it’s enjoyable to best him when I can.
So… He claims that the Earth is cooling, not warming up. And we’re going to have a ‘solar minimum’ over the next few decades.
I DID look for some information on it. But I don’t know what sourses are legit these days.
Anyone wanna help me rub some truth in his face? Or, I’ll settle for someone who knows enough about the subject and is bored.
The solar minimum is, or at least plausibly might be, truth. Over the course of an 11-year cycle, the amount of sunspot activity increases and decreases, but a few hundred years ago, for reasons that aren’t well understood, this cycle stopped and there were almost no sunspots, from about 1645 to 1715 (a phenomenon called the “Maunder Minimum”). And recent sunspot cycles have been much less active than usual, leading to some speculation that we’re entering another such minimum.
And there’s some speculation that the Maunder Minimum was a cause of the “Little Ice Age”, a period roughly coinciding with it when global temperatures were unusually cool. But last I heard, there was some debate about that, and it might be coincidence.
But even if the effect is real, it’s much smaller than the change due to anthropogenic global warming. So even if we do go into another solar minimum, it’ll just mean a slowing of the warming, not a cooling.
Plus, even though the last such minimum lasted 70 years, we have no idea if that’s typical, since we don’t understand the mechanism, and we haven’t seen any others. Maybe we will have another such minimum… but it only lasts 20 or 30 years this time, and then we’re even more screwed by coming out of it at the same time as greenhouse warming continues apace.
We’re clearly near the bottom of the current cycle. We might also benear the bottom of a 110 year cycle. But that last is hard to prove as we’ve only seen it sort of repeat 4 times.
Unfortunately, the Maunder minimum, 1645-1715, happened before we started taking reliable sunspot counts. Claiming that we’re heading into a new little ice age because the sunspot cycle is at the bottom of a possible 110 year cycle takes quite a leap of face.
Things would be different if someone spotted a Bok globule 0.25LY off in the direction the solar system is heading.
Without human interference, the earth may well be in a cooling phase, but no one has proven that yet.
There are many answers to your friend’s ridiculous claim that the earth is cooling.
First and most plainly, it isn’t. The land-ocean temperature record here makes that abundantly clear. You can also scroll through the time series graph below, which shows the earth getting dramatically and progressively hotter as you move from the year 1884 toward 2017.
Second, this article does a fairly thorough job of analyzing what would happen if solar output fell to the Maunder Minimum levels of the Little Ice Age. The answer: not much. We currently have more than a +0.9 °C temperature anomaly relative to 1951-1980; the decrease in solar forcing would likely reduce that by about 0.1 °C. The radiative forcing changes associated with these solar variations are extremely tiny compared to the radiative forcing associated with all the CO2 and other greenhouse gases we’ve emitted into the atmosphere, as one can see in the graph further down.
Third, the actual global temperature drop during the so-called Little Ice Age was actually very small, and the period made an impact on history because there was significant regional cooling in major population centers, particularly in some parts of the Northern Hemisphere and most notably Europe. The Little Ice Age (LIA) was basically a fairly regionalized and seasonal phenomenon and not particularly globally synchronous, and the so-called Medieval Warm Period (MWP) that preceded it even less globally synchronous.
Fourth, other effects have been hypothesized as big contributors to the cooling of the LIA, notably volcanic activity and land use changes.
Fifth, one might note that for more than a million years the earth has been undergoing somewhat semi-regular ice age and interglacial cycles that are truly global and dwarf the small and regionalized changes of the LIA and MWP. These graphs show these cycles well, and one notes that the difference between the depths of an ice age where much of North America is covered in mile-thick ice sheets and interglacials where temperatures are warm and temperate is the difference between an atmospheric CO2 content of about 180 ppm at glacial maxima to about 285 ppm at the peak of interglacials. Our present CO2 level is over 400 ppm and bound to go much higher, with committed temperature increases following behind. We’ve added more CO2 to the atmosphere than the total natural difference between ice ages and interglacials. Given the power of greenhouse gas radiative forcings, it’s absurd to believe that the earth could cool in these circumstances, unless there were some other drastic change producing negative climate forcing, like major global effects from massive volcanic eruptions. The solar variations that we’ve experienced throughout the span of human history are not nearly enough to do it.