I regularly encounter the climate change skeptic. One of their points is the false assertion that sun cycles are causing climate change. Here is how to go about debunking the sun cycle myth.
I recently took an amazing sabbatical and explored the movement of sustainability in healthcare. I took 3 months and travelled to many countries, meeting with people working to make healthcare gentler on the environment. There have been some major strides in this arena and some very cool projects are out there!
What the Skeptics Say
But I also talked to some skeptics – people in or out of healthcare – who questioned various premises pertaining to our climate emergency. Some think Earth is warming because of the natural sun cycles, and there’s nothing we humans can do about it. Others think we’ll never get anywhere with climate action because China is the biggest polluter anyway, and why should we even try? Some wonder how much of a difference the field of healthcare can even make, as our contribution to greenhouse gases is “only” 5% of the total.
I didn’t know how to answer the skeptics at first. I didn’t know enough details to be able to refute these arguments for the myths that they are. But I have since armed myself with the ammo to answer the skeptics more completely. And I want to help inform you, dear reader, to be a bit more prepared than I was! I will talk about the sun cycle argument here; stay tuned for more myth-debunking posts.
The Myth that “Earth is warming because of natural sun cycles”
A few people think climate change isn’t man-made, that it’s due to the natural sun cycles. They point out that over time climate naturally changes because of these cycles, that these cycles are causing the radiation reaching Earth to go up. Some also think that “sun spots” may be blocking enough sun to induce a period of cooling.
They basically feel that climate change will happen regardless of what we humans do; that our actions are inconsequential.
What even are these cycles that affect the sun?
There are a few different cycles that affect the sun’s intensity. One of these is an 11-year cycle resulting from the magnetic pole of the sun flipping regularly. This causes the sun’s intensity to deviate up or down by 0.1% every 11 years. This has very little effect on the climate on earth.
There are also the Milankovitch cycles (thank you NASA for awesome graphics and clear explanations), which occur over 10Ks to 100Ks of years. These cycles are based on how Earth rotates around the sun, how its elliptical path bulges, and how Earth wobbles and tilts on its axis.
Rebuttal to the sun cycle argument
These cycles actually show that we should be in a period of cooling right now. And if these cycles were the cause of the global warming we are experiencing, that would be the case. But spoiler alert: it is NOT. We are feeling heat instead of the cooling that the Milankovitch cycles predict.
NASA has been looking into these cycles for decades, and has been measuring temperatures and solar irradiance on the planet. This graph on NASA’s website shows that even while the radiation Earth receives from the sun has been decreasing, temperatures on Earth have been steadily rising for nearly 50 years. So, if you look beyond the surface at what the sun cycles actually are, you will see that they do not explain why climate change is happening.
And sun spots have very little effect on the radiation that gets to Earth:
Sun spots are areas where the sun’s radiation is slightly bent because of big magnets within the sun that have a pull on the radiation. These ARE NOT areas where radiation doesn’t happen, like big stickers on the side of the sun. Scientists have found that sun spots have only a negligible effect on climate over a long period.
More evidence that global warming is not caused by the sun
“Over the last 45 years of monitoring, solar radiation and temperature has been steadily diverging”. NASA has been using sensors on satellites to monitor solar radiation since 1978, and these sensors show that there has been no upward trend in the amount of solar energy reaching our planet. The amount of sun we are getting is not increasing, even as the temperatures are.
And probably the most damning piece of evidence that our current global warming crisis is man-made: of the layers of atmosphere that we have on Earth, the lower atmosphere, closest to earth, is the one that is warming. The heat we feel is coming from within. The outer atmosphere, the one most likely to be affected by solar radiation, is actually cooling.
In summary, climate change is happening because of human actions. Yes, there are sun cycles, but these are not responsible for climate change. A closer look at the science clearly shows this. I hope this information helps you in your next discussion with climate change skeptics.
Where to go for more information to debunk the sun cycle myth:
I found these sources very helpful while researching for this post:
Skeptical Science: awesome website dedicated to the debunking of climate myths, with science based arguments separated into basic, intermediate and advanced reasoning
NASA: excellent website providing climate data and research, using clear language and graphics
Climate Denier’s Playbook – this entertaining podcast debunks climate myths with a humorous style.
