Climate change: a skeptic’s guide

May 24, 2007 at 3:00 am thinkingshift

New Scientist has done a fabulous job of putting together a climate change guide for the skeptical or perplexed amongst us. I’ve looked before at some of the alternative arguments to global warming and it is important that we critically scrutinise the for and against positions, especially as the global warming debate becomes increasingly politicised. New Scientist has gathered 26 climate myths and misconceptions and also has a guide to assessing the evidence, which is extremely helpful considering that there are many amateurs (and a considerable number of whackos) out there purporting to have scientific credentials, yet offer merely opinion, rather than peer-reviewed scientific papers. To the layperson, pseudo-scientific blogs and articles look “scientific” but in reality are merely cuckoo science.

Of course, peer review spots some, but not all, flaws in argument. A paper in Science in the early 1990s claimed there was a striking correlation between variations in the solar cycle length and temperature between 1880 and 1980, which suggested that greenhouse gases may not be the major culprit. But the correlation hasn’t held up since 1980 and, despite being discredited, the graph is still trotted out as evidence against human-induced global warming. See The Great Global Warming Swindle entry in Wikipedia for more background.

Anyway, back to the myths: I won’t list all 26 as you can check them out yourself, but let’s look at a summary of some of the key ones:

It’s been warmer in the past, so what’s the big deal? even though I firmly believe that the world is heating up, I’ve wondered about the occurence of warm spells of weather in the past, particularly in the 1930s (no, I wasn’t alive then!) – the so-called Modern Warming Period. The warmest period in Earth’s history was the Paleocene-Eocene Thermal Maximum, (PETM) around 55 millions years ago and the Arctic Ocean reached a very subtropical temperature of 23°C/73°F. Mass extinctions resulted. The PETM was caused by a massive build-up of greenhouse gases in the atmosphere resulting from either a catastrophic volcanic eruption or the release of huge amounts of CO 2 from the thawing of methane clathrates in deep ocean sediments. Either way, the Earth then cooled down but as recently as 125,000 years ago, temperatures may have been about 1°C to 2°C degrees warmer and sea levels were 5 to 8 metres higher than today. What is clear from the study of past climate is that many factors can influence it: solar activity, oscillations in Earth’s orbit, greenhouse gases, ice cover, vegetation on land (or the lack of it), the configuration of the continents, dust thrown up by volcanoes or wind, the weathering of rocks and so on. As New Scientist asks: what is the cause of the current warming period? It should not be dismissed as a natural variation just because we’ve had warmer periods in the past. And when sea levels were higher, coastal cities were wiped out. In fact, a number of scientists consider that reports on the current climate crisis are watered-down by Governments who do not wish us to know the frightening reality.

Global warming is caused by the sun, not humans. I talked about this in an earlier post. Have solar changes contributed to recent global warming? According to solar physicists, the sun emitted a third less energy about 4 billion years ago and has been steadily brightening ever since. Yet for most of this time, Earth has been even warmer than today, a phenomenon sometimes called the faint sun paradox. The reason: higher levels of greenhouse gases trapping more of the sun’s heat. Milankovitch cycles ( (caused by wobbles in the planet’s orbit) have caused fluctuations in solar heating, which in turn have affected cooling and warming during the ice ages and interglacial periods. But scientists have found that there is no correlation between solar activity and the strong warming during the past 40 years. For the period for which we have direct, reliable records (since 1978), the Earth has warmed dramatically even though there has been no corresponding rise in any kind of solar activity.

The Hockey Stick Graph is Just Plain Wrong. The Hockey Stick graph shows average Northern Hemisphere temperature over the past 1000 years based on numerous indicators such as tree rings. It shows temperatures holding fairly steady until the latter part of the 20th century and then suddenly shooting up. You can see the graph here. Since 2001, the graph has been the subject of heated debate with accusations of using outdated statistics thrown at it. The US National Academy of Science waded into the fray in 2006 and confirmed that an array of evidence supports the Hockey Stick graph’s temperature reconstructions.

Mars and Pluto are heating up too. This is one of my personal favourites! This myth tries to prop up the ‘sun is to blame’ argument. Apparently, temperatures on Mars and Pluto (recently demoted or ‘plutoed’) have been increasing and this is due to changes in solar activity. Not quite sure why the sun would pick on Mars and poor old Pluto – why not include the rest of the planets in a solar fry-up? And since a year on Pluto lasts 248 Earth years, I’m not sure how conclusions about warmer temperatures have been reached.

Cosmic Rays are the culprit. Another personal favourite, smacks of 1950s sci-fi films with gamma rays and so on. But the argument goes like this: increased sunspot activity is known to strengthen the Sun’s magnetic field, which deflects more of the galactic cosmic rays entering the solar system and thus reducing the number hitting Earth. This would reduce cloud formation in the atmosphere, trapping heat and leading us to all say “it’s getting hot in here”. You can read more about cosmic rays in an earlier post.

Well, maybe it’s true, but we can’t do anything about it. This myth is for the passive individuals out there or those who don’t want to acknowledge that An Inconvenient Truth will ultimately disrupt their hedonistic lifestyles. Climate change is happening, we can’t stop it. But we can all go on low carbon diets. The developing world, and particularly the big players India and China, can learn from the stuff-ups of the developed world and work towards reducing our fondness for fossil fuels. Developing countries need to be given technology and incentives to not use chemicals, fossil fuels etc.

If you happen to be talking to a climate change skeptic, as I was the other day, you’ll also find Grist’s How to Talk to a Climate Skeptic indispensable.

Share this: Twitter

Facebook

Like this: Like Loading... Related

Entry filed under: Climate Change, Education and Awareness, Skepticism, Useful resources.