No the Earth is not 20 years from an ice ageI was a bit too consumed writing about Pluto to cover th

No the Earth is not 20 years from an ice ageI was a bit too consumed writing about Pluto to cover this yesterday, but during my normal readings I had a moment where combining “oh no” with anger over thinking “really, you’re going to make me write this?”. This article is the end result.You may have seen yesterday articles saying “An Ice Age could begin in the 2030s” or something to that effect, even picked up on Facebook. As anything that seems to question climate science gets big boost in the media, this study got that same treatment, appearing in many, sometimes-reputable media sources.Let’s first tackle the actual study. The Earth’s Sun has activity cycles that are represented by sunspots. As the Sun’s magnetic field evolves, sunspot numbers go through a cycle of increasing and decreasing, typically with a period of about 11 years. Sunspots form from complex interactions between the Sun’s surface layers and its magnetic field; there are ideas for why the Sun has this particular cyclicity but to my knowledge the full origin of these cycles is not yet agreed. Some scientists argue they relate to major convection currents within the Sun, others argue they relate to patterns of magnetic currents deep within the Sun, and so on. This image is the Sun at a sunspot minimum: virtually no visible sunspots.Sunspots slightly increase the energy released from the Sun. When the sunspot cycle is high, the Earth receives a tiny bit more energy, when the sunspot cycle is low the earth receives a tiny bit less energy. You probably don’t notice this cycle though, it produces about 0.1°C difference over the planet, easily within the normal yearly temperature variation. You’d notice an El Niño easily before you noticed that change.In the 17th century, there was a long period of time with few to no sunspots. This period is known as the Maunder Minimum and its origin is, like the sunspot cycle, poorly understood.Also from about 1600-1800, in some areas, particularly in the northern hemisphere, there was a period of slightly cooler weather that has been nicknamed the “Little Ice Age”. Because this period of time lines up roughly with the Maunder Minimum, it is a favorite of climate change deniers as they can point to it and say that the Sun is clearly the only thing controlling the global temperature.That leads us into this study. A report presented at an international physics conference showed a model of the Sun where the sunspot cycle is dominated by interaction between multiple magnetic “waves” and over the next couple solar cycles those waves will interact to produce another multi-decade sunspot minimum. This minimum would reduce overall sunspot activity by >60%.That’s where this article entered the press. The first mistake was that people picked it up as a prediction that the Sun’s activity would decrease by 60% total (not just sunspot activity), leading to comments on an upcoming ice age, because that would be like the Sun shutting down completely. Those predictions were basically a misreading of the actual science presented.Beyond that, any link with the sunspot cycle draws in climate change deniers because of the Maunder Minimum and the Little Ice Age. If the Maunder Minimum was associated with cooling, shouldn’t this one be as well?The first major issue with that is that globally, there was no single little ice age. Over a period of several centuries, some areas show glacial advances and abnormally cool temperatures, but the location of those cool temperatures moves around. North America was particularly cold in the 1800s, Eurasia was particularly cold in the 1700s, but there was no single global pattern. Temperature averages across the globe show larger variations during that time, but no single pattern of “multiple cold years in a row” emerges. Since historical records, particularly in this language, are dominated by writings in Europe and North America, the cool periods in those areas have taken on extra historical meaning not supported by the best science.At most, the “little ice age” reflects a couple tenths of a degree of cooling. That’s actually more cooling that the planet would get from the Maunder Minimum alone; several recent studies have argued that the period of about 1500-1815 was a time when there were slightly more volcanic eruptions above average than normal as well, potentially accounting for any other global variation.If there were to be a similar “Maunder type Minimum” in solar activity in the 2030s (and let’s note, this is one model presented at a conference that has yet to be published and many other scientists may yet disagree with it), the similar cooling load would likely be on the order of 0.1°C due to the small decrease in the Sun’s energy output.However, that 0.1°C is actually tiny. Due to greenhouse gas emissions, the planet Earth has warmed by about 1°C over the past century. During the last century, global temperatures increased on average by 0.1°C per decade – due to increased greenhouse gases in the atmosphere, the current rate of warming would swamp out a “Maunder Minimum” type event within a decade. Even if one started right now, we’d hardly notice it compared to the 1°C the global temperature has already risen.In some cases, the framing of this study was just an outright mistake, and some sites have basically issued corrections. Other pages and news organizations, though, continue to push the study in the original framing: a hint that their real motivation is not understanding the science.Although distracted by Pluto, I felt it important to tell this tale, both of the real science and of how it is misinterpreted, both by accident and deliberately, because understanding how that interpretation happens is a good way to recognize when someone is pushing an unsupported agenda. Yesterday was a prime example of that happening. Now can I go back to writing about Pluto?-JBBImage credit: NASA/SOHOhttp://1.usa.gov/1OaJGEpBetter presentations:http://slate.me/1HtHxiuhttp://bit.ly/1K5ZOWjhttp://bit.ly/1TyzmsMhttp://slate.me/1HsGOAmWorse presentations:http://bit.ly/1dWh30Ehttp://bit.ly/1UZkky4Other notes:http://nar.ucar.edu/2013/hao/origins-sunspot-cyclehttp://www.ipcc.ch/ipccreports/tar/wg1/070.htm -- source link

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