The Defect in the "Climate Has Always Changed" Argument

Great Debates
41

Just a few points to keep the record straight. There are actually a whole host of different radiative forcings affecting the climate, mostly positive, some negative. This is a fairly good graphical summary of the main ones.

You mention albedo changes due to ice sheets and vegetation. It’s important to note that albedo changes are in two distinct categories: forcings and feedbacks, and need to be kept separate because they’re fundamentally different. An albedo forcing is an independent factor that drives the climate in and of itself – the primary example is land use and land cover changes from human activity, which you’ll find in the above chart. Ice cover changes, however, are feedbacks that are a direct consequence of Arctic warming and which amplify that warming when ice cover is reduced. They’re like the increase in water vapor that amplifies CO2 warming. Because they’re feedbacks intrinsically tied to the underlying forcings, these things don’t appear on the chart, but they’re obviously of critical importance in computing and modeling how climate responds to forcings.

Good point about climate sensitivity. Climate sensitivity is the measure of how much a given level of forcing will actually change the global average temperature under specified conditions, and is essentially a computation of forcings and all associated feedbacks on the earth’s total energy balance; the most common measure is equilibrium climate sensitivity which is defined as the temperature increase at equilibrium resulting from a doubling of CO2. Yes, the fact that we can observe the effects of CO2 changes in the paleoclimate record helps us estimate ECS, but it’s not the only source of input. We also have extensive modeling runs, the modern instrumental record, and other sources that all have strengths and weaknesses.

As a side note, ECS is a temperature delta so its unit is °C, not W/m[sup]2[/sup] which is a unit of the underlying forcing. After decades of research and refinement its estimated value remains basically unchanged at about 2 to 4.5 °C with a most probable value of about 3°C.

42

Paleoclimatologists opine that man’s influence on the climate started much earlier than that, when we started slash-and-burn clearing of forests for agriculture and generally burning stuff to keep warm ; some even believe that it’s only *because *we’ve been doing that at a specific point in time waaaaay back when that we’re not in an Ice Age right now.

Of course digging up older stuff to burn tipped the scale further, faster ; not to mention releasing high altitude sheets of hot CO2.

43

This doesn’t logically follow. All that would be required is to show that AGW doesn’t fit the facts. An alternative explanation would be nice, but not necessary.

What I notice in the psychology of “climate is always changing” types is a blase attitude that everything will work out anyway. They’re right that climate was a lot different in the ancient past, but a great many of those eras would be a disaster for human civilization.

44

By this I assume you mean in short time periods. If so, this just isn’t true. The very first one (well, one of the first ones) was simply the creation of oxygen over millions of years, changing the atmosphere and causing a mass extinction. There have also been other examples of fluctuations over long time periods (ice ages, snow ball earth, a couple of long term volcanic episodes coupled with large, slow burning coal fields such as the Siberian traps and the like).

I’m pretty sure that human generated pollution IS the current highest causation factor. I think the key part you might be missing (I’m unsure since your OP is a bit confusing) is that, even though there have been climate changes such as are happening today, most of the ones that aren’t the sorts of catestrophic rapid event you are talking about happened over millions of years. THIS one is happening in a geological eye blink…and that’s what makes it more frightening to many.

I think the ‘defect’ here is that Climate HAS always changed…but, usually, not so rapidly. And that’s the key difference this time. Obviously, some of those cataclysmic events you described (asteroid strikes, super volcanoes, Trump being elected, etc) happened even more rapidly. But USUALLY when the climate shifts as we are seeing it today it does so over much longer time periods. The earth has been much warmer than it is today, so it’s not the temperature per se…it’s how rapidly we’ve moved in the last 200 years that’s scary.

45

It’s all scary until we ask to see the math …

46

Yeah, it’s certainly difficult to see that 1+1=2. To some, math IS pretty scary…

:stuck_out_tongue:

47

At which point it moves to terrifying. For example, comparing the estimated costs of preventing climate change (huge) vs. the projected costs of unabated climate change (fuckmothering ginormous).

48

Post a link to those projections … I’m curious how actuaries divide up the cost of converting to nuclear powered electric transportation infrastructure between mitigating the cost of when we run out of fossil fuels and/or some yet-to-be-defined climate change …

I thought it was interesting this past fire season in The West that forest managers were specifically downplaying the causes due to climate change and were refocusing on the cause of excess fuels due to decades of fire suppression … very little of the cost of these major fires is due to rising temperatures …

And don’t forget return on investment … putting up solar cells on our roofs saves us money … and after so many years or decades the investment will pay for itself … the act of mitigating climate change in the long run will be profitable …

Let’s see the math here …

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Forest fires like those - as opposed to the human-set ones in Amazonia, Indonesia, and elsewhere - are CO2-neutral in the long term.

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https://www.washingtonpost.com/news/energy-environment/wp/2016/12/22/the-coming-battle-between-the-trump-team-and-economists-over-the-true-cost-of-climate-change/

More recent economical studies do show a lot of lost opportunities if we continue in the same path or a worst one as Trump and minions want.

http://web.stanford.edu/~mburke/climate/

51

Isn’t anything strictly plant-related CO2 neutral in the long run ? They suck it up to grow, then release it back when they burn, get eaten by bugs or die and decompose. The only CO2-positive application of forests is IKEA - provided those Künen last forever and don’t ever decompose.

(I’m no scientist by any stretch of the word, mind - I’m going by high school bio here)

52

The specific forest fires I’m speaking about are the ones that burn much hotter than a natural forest fire … such that the fire kills the trees … the past five years the headlines have been screaming “catastrophic climate change” … now that the hysteria is passing I’m hoping a return to the science we are sure about …

You’ve provided some links that themselves give a number of links … is there a specific paper in there you wish to discuss?

I did gloss through “Global non-linear effect of temperature on economic production” … to know what the economy in the USA will be like with +5ºC we need only look today at places that are already +5ºC … pretty much all impoverished third-world nations … thus the economy in the USA will be as an impoverished third-world nation …

Canada will be the new United States … we’ll have to migrate …

53

This study seems to be driven hugely by a correlation implies causation mentality. There are many reasons that the “cooler” countries of U.S., Europe and China are better developed and command more resources. These may have some historical roots in climate (in a Guns, Germs and Steel kind of way) but there’s no reason to believe those commanding positions would be “lost” by moving us out of some kind of ideal thermal envelope.

I’m guessing it would be pretty easy to falsify this one, for example, by looking at it within the U.S. for all 50 states. Hmm.

Ok, I just got average annual temperatures and GDP by state. There’s one cold place with high GDP - Alaska, land of oil where they pay for you to live there. Otherwise, no trend whatsoever.

Edit: sorry, there was a slight and noisy trend even without AK, this time driven at the other end by Mississippi.

54

Hmm, the paper actually makes the point that “warming raises productivity in cool countries” and there was a big increase in Alaska from 2012 to 2015. “warming harms productivity in countries with high average temperatures”. Anyhow, the effects that they are talking about are regarding what it is likely to happen in the future, not the past if we are not preparing. The problem right now is that several politicians and interest groups would like that we remain just the same… unprepared.

55

No, this is not the point of the study at all. You are even missing the graphs, North America is likely to get a diminished economy by 2100, but not as bad as many other nations. (And again, this is provided that no preparations or more emission controls are made, very likely considering the caliber of the current Republican leaders.)

56

Which graph are you looking at? … Figure 4a shows GDP per capita in Canada as doubling by 2100 …

57

The “business as usual” emissions scenario is a recipe for full-blown catastrophe. A few of the impacts are shown here and one can see the increasing severity as the temperature rise approaches 5°C. “Business as usual” emissions – the Republican program of denial and ignoring the problem – would take us beyond a catastrophically dangerous 8°C rise by 2150, and in point of fact we are very likely already committed to least a 5°C rise because of the time it will take to achieve emissions reductions and the lag of temperature behind the emissions forcings.

58

I think we are talking past each other a bit. My estimate that CO2 was responsible for about a third of the forcing is in reference to your statement that “The driving force between a mile-thick continental ice sheet and a hospitable temperate climate is the approximately 100 ppm of CO2 that separates glacial minima from interglacial maxima.” I.e., it applied to the forcing during the last glacial maximum relative to the interglacial period (pre-industrial). This is an estimate due to James Hansen.

The chart you reference above is for the current forcings relative to the pre-industrial era. Here, CO2 clearly plays a larger role … In fact, the best estimate is that it is roughly 3/4 of the net forcing, but with big error bars. It could even be over 100% of the net forcing…i.e., the other forcings could total slightly negative. The big error bars are due mainly the the large uncertainty in the forcing due to aerosols.

Right…The confusing thing though is that while it makes sense to consider such albedo changes (e.g., due to changes in ice cover) as feedbacks in the current situation, where the forcing is the changes in greenhouse gas concentrations (and other things like aerosols) that we are making, it is reasonable to think of them as forcings when one looks at the change from the last glacial maximum to the interglacial. The whole distinction between what one considers a forcing and a feedback and in what context gets a little dicey and leads into discussions of the different kinds of climate sensitivity one can usefully define, such as the Charney sensitivity vs. the Earth system sensitivity (discussed to some degree here: RealClimate: On sensitivity: Part I )

59

Figure 4 b, North America. And really, North America is also the USA and Mexico. Look it up.

60

Do you mean “business as usual” in the next 125 years to be the same as the last 125 years … when we had no powered flight, state-of-the-art electronics was the incandescent light bulb, and the closest thing to the internet was countries color-coding their postage stamps so all the other countries would have an idea of their cost? … or do you mean “business-as-usual” to mean spectacular technological development in all areas of human activities that we’ve seen these past 125 years? …

The United States is fond of alternating between liberal and conservative governments … two steps forward and one step back; it’s the American Way™ !!! … and remember, the corporate tax rollback will make solar panels cheaper as well …

Do you have a link to the math that came up with the +8ºC number? …