“Preservation of our environment is not a liberal or conservative challenge; it’s common sense.”
Arguments
There they go again… Confronting the “Skeptic” Arguments Dealing with the “skeptic” claims that are continually propagated in the media (especially by Fox News and the Wall Street Journal editorial page [though the news sections of the WSJ do a great job of covering global warming]) is like playing Whack-a-Mole. Every time a claim is refuted, it pops back up in a slightly different form. Since I’ve been dealing with this for a long time, I can assure you that while the case for global warming has only strengthened with time, the “skeptic” arguments remain ever the same, just recycled into new forms. So what can you do when you hear someone claim that global warming isn’t a real problem, or is a hoax? First, always go back to the “global warming 1-2-3” argument at the top of this primer. To recap: There is (1) no doubt that carbon dioxide warms planets, and (2) no doubt that we are adding carbon dioxide to the atmosphere at a rapid rate. How could you draw any other conclusion but to expect that our actions will cause global warming? Arguing otherwise is like arguing that a ball would fall up if you dropped it from a building — not impossible (there could be a strong updraft), but highly unlikely, and even if an updraft catches it for a while, it’s still going to fall eventually. Then, arm yourself with the real facts, which will always undermine the skeptic claims. How do I know? Because the real science just isn’t that hard, as we’ve seen above, and the skeptics never have anything new to say. The best resource I’ve seen for explaining the failings of the skeptic claims is the Skeptical Science page on global warming arguments. But since you’re on my page right now, I’ll give you the facts behind a few of the most common claims:
- Let’s start with one of the most often repeated recent claims – that global warming stopped in the late 1990s. Well… a look at the graph in Figure 3 above might at first seem to support this claim — but you can also see that 15 years on a graph like this are not enough to establish a trend, and that this period has still been the hottest on record. Moreover, the apparent slowing is largely a result of one anomalously warm year (1998); if you remove 1998, it looks like a continuing warming trend. This fact should be completely clear from the video associated with Figure 3 above, as well as from Figure 6 (a and b) below.
Figure 6a. This graph shows global average temperature data since 1970. As you can see, the “skeptics” cherry-pick time periods, like the past 15 years or so, to claim that warming has stopped. But a realistic look shows an ongoing warming trend. See an animated version of this graph and of a similar graph for sea ice here. (Note: These are the same data shown in Figure 3, except starting from 1970 and shown as a line chart rather than a bar chart.)
Figure 6b. This graph (source) shows the temperature changes since 1880 plotted as running 5-year means, and also shows the close correlation with the rising carbon dioxide concentration.
- The so-called skeptic camp likes to say that “science is not done by consensus.” While it is true that science must be based on evidence rather than on votes, it is also still the case that science progresses only when the evidence becomes strong enough to lead to widespread acceptance in the scientific community. For example, Einstein’s theories might have died a quick death if not for the fact that evidence in support of them soon convinced the vast majority of scientists. Indeed, when people ask me for a brief statement on the purpose of science, I like to say that science is a way of examining evidence so that people can come to agreement. The so-called “consensus” view of global warming is nothing more sinister than this principle in action: The basic science and the available data are now so strong that the vast majority of scientists who have examined the issue in detail have become convinced that global warming presents a serious threat to our future.
- Another common claim is that the scientists are ignoring the fact that water vapor is a more important greenhouse gas than carbon dioxide or any of the other gases released by human activity. This claim starts with a grain of truth: water vapor is indeed the most important greenhouse gas in our atmosphere. However, the amount of water vapor in the atmosphere is self-regulated by the ocean and atmospheric temperatures. As a result, water vapor actually has the effect of amplifying any climate changes caused by changes in the concentration of carbon dioxide or other greenhouse gases: If the addition of other greenhouse gases raises the temperature, ocean evaporation increases, leading to more water vapor and even higher temperatures. Conversely, if the concentration of other greenhouse gases falls, the temperature drops, leading to less evaporation, less water vapor, and an amplified cooling cycle.
- A related claim has to do with the correlation in ice core data between past temperatures and carbon dioxide concentration shown in Figure 2 above. These data show clearly that the temperature and the carbon dioxide concentration have risen and fallen together over the past million years. However, the data show that the temperature changes tend to begin first — seemingly the opposite of what you’d expect if carbon dioxide changes cause temperature changes. But once you understand the water vapor feedback cycle, it’s easy to realize what’s really going on: Over tens to hundreds of thousands of years, Earth’s climate goes through cycles of ice ages and warm periods governed largely by small, cyclical changes in Earth’s orbital and rotational properties. Once a rise or fall in temperature is initiated through these natural cycles, the temperature change leads to changes both in the water vapor concentration and in the ocean’s ability to hold carbon dioxide. The positive feedback that occurs between water vapor and carbon dioxide then causes both temperature and carbon dioxide concentration to rise or fall rapidly. Moreover, closer examination of the data (Figure 7) show that after the natural cycles initiate the warming, the carbon dioxide concentration does indeed rise before the temperature rises, proving that carbon dioxide is the cause of the the rising temperature. In other words, the past data actually provide strong evidence not only for causality of carbon dioxide leading to global warming, but also for an amplification process that is likely to make global warming much more severe of a threat than we might otherwise expect.
Figure 7. This graph shows a close examination of carbon dioxide concentration (yellow dots) and global average temperature (blue) during the warming period that began about 20,000 years ago (“kyr” means “thousands of years”). As you can see, carbon dioxide rises ahead of the temperature chance, demonstrating that rising carbon dioxide causes rising temperature. (The red curve is Antarctic temperatures, for which you can see more details at the following source.) Source: Shakun et al, Nature, 484, p. 49-54 (2012).
- Another claim that begins with a grain of truth is that Earth has been much warmer in the past than it is now (we are still in an ice age by long-term standards of millions of years), and that this therefore proves both that Earth will be fine if it is warmer and that there are natural ways by which the temperature will eventually come back down. True enough, but irrelevant to the current situation. The fact that Earth has been much warmer in the past does not alter the fact that the warming process will mean great changes in sea level, local climates, and ecosystems — changes that could have severe consequences for our civilization. And while it is true that Earth has a natural cycle that self-regulates the climate (it is usually called the carbon dioxide cycle, and you’ll find it explained in my book Beyond UFOs, Chapter 6), this cycle operates over a time scale of hundreds of thousands of years. In other words, even if we completely wreck the planet through global warming, the planet will recover on its own — a few hundred thousand years from now. Nice to know, but irrelevant to the time scales that matter to our current civilization. Additional note: Based on some questions I’ve received, I should clarify the difference between global warming as a threat to our species and as a threat to our civilization. As a species, the question is whether global warming poses a threat of extinction, and the answer is almost certainly no; Homo sapiens have survived much warmer climates in the past, and presumably could do so again. But most of us care not just about the survival of our species, but of the survival of our own families, our nations, and our civilization. Our civilization today is a deeply interconnected system supporting some 7 billion people — far more than Earth could support without technology, trade, and other aspects of what we call “civilization.” We have developed this civilization in the climate that exists today. Could we adapt in principle to a much warmer world? Sure — but we’d have to move and rebuild all the coastal cities, change the places and ways in which we do agriculture, and reshuffle the geopolitical map to accommodate the new reality. Moreover, if the projections are correct, we’d have to do all this in less than about a century or two. I don’t think we could pull it off without plunging into wars and other terrible problems. And even if we could pull it off, it would be far more expensive than simply dealing with the problem of carbon dioxide emissions, which we could solve right now with a little political willpower.
- One more “skeptic” claim that began with a kernel of truth is the claim that satellite data about atmospheric temperatures contradict data showing that Earth is warming. It’s true that there was once some controversy over these data, but the apparent discrepancy has long been resolved (in essence, the discrepancy was traced to errors in the data calibration, and once those were understood the discrepancy went away). For a summary of how both scientific sides came to agreement this issue, see Science Magazine, 12 May 2006, p. 825.
- And then there’s the claims that have no basis in kernels of truth at all, and instead are just plain ridiculous. For example:
- Here’s a recent one that shows the lengths to which otherwise-respected media sources will go: The Wall Street Journal ran a long op-ed by Matt Ridley claiming that even a doubling of carbon dioxide would not cause warming of more than 1.2°C. But look at Figure 2 above: You’ll see that while natural variations over the past 800,000 years never caused the carbon dioxide concentration to rise more than about 50%, the temperature rose in some cases by more than 8°C. Clearly, if your “model” shows something that disagrees with actual data, the actual data win. How can an otherwise-respected newspaper publish such nonsense?
- Here’s one that assumes we’re all young: People who claim that back in the 1970s, the scientific consensus was that we were headed for global cooling and an ice age – a “fact” the hoax camp uses to support their claim that you can’t trust the scientific consensus today, either. However, this “fact” simply isn’t true. Perhaps the people stating this untrue “fact” are just confused, since by the ’70s we had learned that we are currently in an “interglacial” period following the last ice age (suggesting that we might be “due” for another ice age) and data showed (and still do) a slight global cooling during the mid-20th century. But with a few exceptions, scientists already recognized this cooling as an aberration, unrelated to long-term ice age cycles, and that the real issue for the future would be global warming. I know this from my own experience, since my ’70s science classes were already discussing global warming as the serious concern. If you want more proof, just look back at scientific publications from the 1970s. There are many examples, but here’s one to start with: The summary of an article published in Science Magazine, 8 August 1975, p. 460, states: “…the exponential rise in the atmospheric carbon dioxide content will tend to become a significant factor and by early in the next century will have driven the mean planetary temperature beyond the limits experienced during the last 1000 years.”
- The so-called skeptics love to repeat their claims of discrediting the “hockey stick graph” – a graph of data showing that global temperatures are now higher than at any time in the past thousand years. But their claims are simply not true. As you can see in Figure 8 below, more than a dozen separate research studies have looked carefully at the data and the conclusion, and all reaffirm the basic fact that temperatures today are certainly higher than at any time in the past 400 years and likely higher than anytime in the past 1,000 years. Indeed, based on a request from Congress, the National Research Council (NRC) investigated the “hockey stick” graph and found it valid (you can read the NRC report summary or order the full report here). This is a sad example of the close-mindedness of the “skeptics” — no matter how much data accumulates to the contrary, they are unwilling to revise their beliefs.
Figure 8. The “hockey stick” graph gets it name because it looks kind of like a hockey stick laying on the ground with its tip pointing up at the right. Here, we see numerous data sets all showing the same basic fact: Temperatures have indeed risen in recent years to become higher than they have been in the past 1000 years. Click here for additional details and source data.
- For an extreme example of the lengths to which some people will go to dispute something that is really indisputable, here’s a quote from Rush Limbaugh: “I’m not a scientist – in my common man way, I explained to this caller why I do not believe in global warming. I gave as my primary belief that I believe in God…. I’m saying as a believer of a loving God and a God of Creation, that there is a complexity to all this that makes it work; that we cannot understand; that we cannot really control; that we cannot destroy, and that we really can’t alter in its massive complexity.” So there you have it: If you believe that God has set things up so that it’s impossible for us to do anything bad to our planet, then you have nothing at all to worry about. But if you believe that God gave us free choice and helps those who help themselves, then we’d better get to work.
Finally, here is what planetary scientist (and co-author of my astronomy texts) Nick Schneider calls “the four levels of denial” for global warming:
- Level 1: “The Earth is not warming up.” (denying the data)
- Level 2: “It’s warming up, but it’s natural.” (denying the cause)
- Level 3: “It’s warming up, humans are causing it, but it’s actually beneficial.” (denying the consequences)
- Level 4: “It’s warming up, humans are causing it, it’s harmful, but it’s too expensive to solve.” (denying responsibility)
Don’t you think it’s time to get out of denial?