In past articles here, I have made my piecemeal attempts to string together why confidence is so high that the ongoing warming climate is fueled by human activity. That is, the current warming is NOT part of a natural cycle.
World-renowned climate scientist Professor Katharine Hayhoe did a much better job of stringing together the disparate elements – and she did it via Twitter!
Me? I’m not at my best limited to 280 characters … ask any of my former local news producers who knew of my problems with 3 minutes of air time. I ran across this instructive string of tweets and graphics through Meteorologist Dan Satterfield’s “Dan’s Wild Science Journal” on the American Geophysical Union’s blog. Being a master of good timing, I thought a cold autumn day with our first set of frost advisories for most of WNY and even a freeze warning for the far southeast corner of our region coming up Friday night would be perfect for writing of warming.
The refrain scientists in the relevant disciplines (climate science, oceanography, hydrology, atmospheric chemistry, meteorology and atmospheric physics, to name a few) endlessly hear from denialists, politically driven critics and genuinely sincere skeptics is “climate is ALWAYS changing. This (warming) is just part of the natural cycle.” From there, some take an accusatory leap to political agendas and the like, but those charges are beyond the scope of this article and, as I hope you will see, quite irrelevant in the face of overwhelming evidence.
The natural cycles are not the driving force underneath the irrefutable warming. Some skeptics point to the sun, and speculate an increase in solar input is getting the earth hotter. Professor Hayhoe, on the foundation of a tremendous wealth of peer-reviewed daily and worldwide measurement of solar energy, demonstrates otherwise.
Note the observed global temperatures (red) are veering off in the opposite direction from solar irradiance (blue), which is slowly declining. She also makes mention of what’s called a Maunder Minimum, which would be a lengthy absence of normal sunspot activity. The latter has been inconclusively linked with past periods of cooling, such as the “Little Ice Age’’ a couple of centuries ago. While we are not in a minimum lengthy enough to qualify as a Maunder, sunspot activity has been running unusually low for more than a decade. If a minimum can be linked with global cooling, there is no evidence it is having any such theoretical impact on the earth’s current warming. If the link is real, which is uncertain, it is being overwhelmed by the scope of our increasing warming.
What about volcanoes? I’ve seen assumptions from some laypeople volcanoes produce more greenhouse gases than human do, and must pay a big role in the allegedly natural warming. That is quite incorrect, says Professor Hayhoe.
Ironically, if there were a major increase in volcanic activity, particulates and gases such as sulfur dioxide would cause temporary significant cooling, not warming.
There most assuredly HAVE been regular cycles of warming and cooling, glacial advance and retreats, through much of earth’s history. The earth’s orbit has complex but calculable eccentricities which have major effects on solar input. One such feature is the gradual change from a more nearly circular orbit to an elliptical orbit. The problem for warming denialists with that truth is this.
In other words, the stage in the earth’s orbit at this time would be sending us toward a new ice age. The natural cycle for us now is global cooling. For the mathematically inclined, here are a few more particulars.
Some denialists who believe they possess a scientific bent claim if there were true warming on a global basis, only part of the climate system would be warming, and the other part would be cooling. Again, that’s not the case.
As you can see, all systems are up, especially oceans, in which about 90% of the excess warmth has been absorbed.
Katharine Hayhoe has some other opinionated thoughts on the state of science as delivered to much of the public today. Unlike much opinion, hers is based on evidence-based science, rather than prejudiced conjecture.
There can be nearly no doubt human activity has disrupted the natural cycles which have governed the world’s climate prior to the industrial revolution. Increased carbon dioxide, secondarily methane and even extra water vapor evaporated into the atmosphere by the warming are enough of an extra greenhouse gas load to turn the climate in the opposite direction it would naturally take.
The problems revolve around the degree of change.
We are already seeing large and destructive extremes tied to the warming and we are going to see these extremes inevitably multiply and worsen. What’s still in our hands is how much adaptation we may be able to engineer (at great cost) and how much mitigation of the worst impacts we can still limit by more drastic reductions in the burning of fossil fuels.