Ok, I'm going to start from the top. The basic thesis of this post is:
Global Warming is caused by human activities, and it is important to take some specific actions to reverse it, and ignore efforts to produce FUD.
I'm going to work my way through this sentence sequentially.
"Global Warming is"
The term 'global warming' refers to an increase in the Earth's average surface temperature, which can be caused by several things. Of course, in the context of the modern era, it refers to
the observed increase in global average surface temperatures of 1.1C since the 1800s. To argue that
this warming hasn't happened is to insist that the Earth is flat -- that is to say, some people will believe it, but not people interested in rational argument. Of course, Senator Ted Cruz demonstrated one kind of very carefully constructed counter-argument -- that stratosphere temperatures have not increased significantly. Of course, 80% of the atmosphere's mass, the vast majority of weather activity, and 99.99% of the human species is in the troposphere, so perhaps his chart is less relevant than Mr. Cruz believed. But I'll get to these sorts of disingenuous arguments later.
"caused by human activities"It is possible to argue that the observed warming is not human-caused with a straight face. The atmosphere is a complicated system, of course, and intuition suggests that human beings aren't able to influence something so much larger than ourselves.
Nonetheless, there is strong evidence that the observed warming is caused by human activities. Of course, Sol is the primary source of energy to Earth's surface (
in comparison, geo-radiothermal heating is trivial). Most of that energy returns to space as radiated EM. This is where
the greenhouse effect comes in. Again, not controversial science. I won't waste time proving that greenhouse gasses cause the greenhouse effect, and of course, denying that atmospheric CO2 concentrations have increased dramatically over the past century is, as above, alike to claiming that the earth is flat.
One reasonable point of contention is to what degree the rise in atmospheric CO2 is associated with human activity. The least compelling argument in favor of the position that the rise is human-driven is that the rise in greenhouse gasses is correlated with the dramatic increase in human actions which emit greenhouse gasses, what I would call the "yeah, there's a bunch of pies here because I've been making pies" argument. Nonetheless, correlation is not causation, so I won't put a lot of weight on the idea.
The
carbon cycle is understood with a reasonable level of confidence. The short story is that yes, the ocean releases 90 gigatons of CO2 per year, while human action releases 9. If one stops reading there, one might be tempted to say that everything must be fine. Of course, that disregards the fact that
absent human activity, CO2 levels were stable (which we know from ice cores). In fact, the ocean releases
and absorbs 90 gigatons of CO2 per year. Human activity throws that cycle out of balance. Think of a swimming pool with a drain and a pump. The pool is half-full. 10 gallons of water drains out of the pool per minute, and the pump provides 10 gallons of new water. Clearly the pool will remain stable. But if someone adds a 1 gallon per minute hose, the pool will rise.
Unlike in that example, however, we can
identify some of the CO2 by source. I can't do it justice here, so I won't try. In brief, we can confirm that the proportion of CO2 in the atmosphere that includes isotopes found in fossil-fuel carbon matches the proportion of atmospheric CO2 we would anticipate is anthropogenic considering the amount of use we get out of fossil fuels.
"and it's important"While global warming will not kill all life on earth, will not kill the human species,
it has already had economic costs. More important than monetary costs, climate change (and the closely associated phenomenon of ocean acidification caused by CO2 absorbtion) is currently reducing the biodiversity of Earth, such as
the mass, terminal bleaching of the GBR. That is both an economic disaster and, I find, a moral wrong, to see an ecosystem that has predated human civilization be destroyed by accident and carelessness. Surely we can improve the welfare of all people without diminishing the beauty of the world, can we not?
The trends do not need elaborate calculation to reveal themselves. Increased CO2 and other greenhouse gasses will continue to compound the negative effects. And that is aside from things like the
clathrate gun hypothesis and similar latching mechanisms.
"to take some specific actions to reverse it,"Of course we need to migrate away from fossil fuels. We also need to use more efficient source of protein. Honestly I think we're more likely to perfect and sell lab-grown meat than get Americans to stop eating beef, and I don't care. As long as it gets the footprint down. But the problem is that we've waited so long to take these actions that we've already begun to see consequences of global warming. We already need to perform some kind of geoengineering -- even if it's just amine-based carbon sequestration or something -- to return the atmosphere to an earlier state.
Fortunately, photovoltaics are closing in on the cheapest per-kwh energy source, so transitioning to it is only a matter of overcoming inertia, not of opposing market forces. This is where a few years ago I would argue that it was a cost we'd have to bear. It turns out that procrastinating enough leads to things getting easier, which is probably the wrong message to send but hey, it is what it is.
I make this point separately from the rest because there remain people who accept that anthropogenic global warming is a big problem, but that there is nothing that can be done. But this is also untrue; we put the gasses up there, an if we're willing to pay the energy debt incurred in oxidizing all that carbon, we can take it back down.
"and ignore efforts to produce FUD."
Because some political parties have made it their position to oppose climate science as a matter of
clannish identity politics, there are intentional propoganda efforts to oppose action against climate change. The main effort of propoganda in general is not to produce an alternate reality, but rather to convince a populous that they can trust no story, that there is no "real" truth. This is known as fear, uncertainty, and doubt, or FUD. In general, the opposition to climate science will attempt to sow fear of "elitist scientists" or of a government-mandated change in lifestyle, will attempt to emphasize uncertainty wherever it exists, and manufacture doubt by propping up pseudoscience as a legitimate alternative to real science.
I've included here a few specific refutations.
"Models are Inaccurate!": Models are irrelevant. They help us estimate the potential upcoming costs, but you don't need a model to tell you that a continuation of the trends we already see happening would be very bad. Moreover, cherry-picking the most inaccurate models to tar them all is bad science.
Strawmen: No, you don't have to live in a commune/treehouse. No, you don't need to eat bugs and use a composting toilet. The thing I find most bizzare about the extreme levels of strawman hoisting are the far-right survivalists furious that the government might force them to live in an off-the-grid solar-powered compound. None of these are particularly likely. What I would recommend, and doubt I'll ever see, is a new-deal scale project of infrastructure investment that provides new resources (and jobs), combined with a well-enforced set of greenhouse-gas emission bans, coupled with what is effectively paying back the energy debt incurred with the two-century oxidation spree of the industrial revolution (i.e., a government-funded carbon sequestration project). None of this means you can't live pretty much as you do now, except with a newer car and a better job.
Nor do climate scientists think that everyone is going to burst into flames next week. They're generally a pretty cautious bunch. I don't deny that there are some pretty ignorant people who have their own ideas about climate change destroying all life on earth, but let's again compare them to the gentleman with the five-year spam stash on the other side.
Divine Interventionalists: I really didn't think it would be neccessary, but no, God won't prevent climate change from hurting us. Regardless of what you or I believe, we can pretty much all agree that He, She, or They aren't taking an active role in things nowadays. Seriously, Senators believe this.
Carbon Dioxide lag: Yes, there is a feedback loop, thank you for pointing that out. Rising temperatures tend to cause more CO2, which produces rising temperatures. Who's side were you arguing for, again?
Previous Warming Nonsense: Yes, the climate has changed before. It's been difficult for everyone involved, and it's much, much faster now.
XKCD summarized it fairly well, actually. It's never been on this scale or speed in human history. Before you mention various islands or subcontinents, remember that we're talking about global temperatures here, not if Icelanders had a two-week-longer growing season.
Plant Food Woo:
I'm going to tag in Skeptical Science for this one because it's nearly 2AM here."But Global Cooling!" It was a headline in a few newspapers, not a scientific paper.
Too Late Doomsaying: Look, did we waste time with political nonsense up until now? Yes. Are we going to have harsher consequences because of it? Also yes. But these problems are trivial next to the amount of capital and energy we have available now and in the near future. We need to move past the debate and get on with planning for mitigation, reconstruction, and overcoming the challenges of global warming.