You probably looked at the headline above and thought: Another article on climate change, ho-hum. Right? I can tell you that even I had to think hard about writing yet another one, given that climate change is one of my greatest environmental concerns. Over the past several years, the topic has taken up a great deal of my writing time (see Will Climate Change Increase Antarctica’s Biodiversity — Or Diminish It and Wildfire Risk: Will Future Forests Be Treeless, for a small sample).
However, when I saw this new study, I couldn’t help myself. On April 6, 2014, in the online journal Climate Dynamics, physics Professor Shaun Lovejoy of McGill University in Montreal, Canada, reported that he statistically analyzed — without the assistance of computer climate models — temperature data over the pre-industrial period and the industrial period and found that the hypothesis that global warming is due to natural variability can now be rejected with a confidence level greater than 99 percent.
That’s big. So is this just another study on climate change, or will it be the one that makes us all believe that our rapidly warming planet is human caused?
Back to nature: ice cores, lake sediments, and tree rings
Over the past several decades, there have been numerous studies indicating that the current warming of our planet is largely due to human activities. The large majority of them, though, were based on analyses obtained by using computer-driven global climate models (GCMs). Much of the resistance to believing in climate change has been attributed to these models. Skeptics ask if we can really infer connections between anthropogenic (caused by human activities) factors and global warming; after all, computer analyses could be wrong for a number of reasons and overrelying on them when making assertions lessens their credibility.
In his new study, Professor Lovejoy, however, made no use of the computer models commonly used by scientists to estimate the magnitude of future climate change. In an op-ed piece he wrote for the online magazine LiveScience, he stated: “Last year, the Quebec Skeptics Society threw down the gauntlet: ‘If anthropogenic global warming is as strong as scientists claim, then why do they need supercomputers to demonstrate it?’ My immediate response was, ‘They don’t.’ ”
So Lovejoy set out to prove it. Instead of GCMs, he used a variety of gauges found in nature — such as ice cores, lake sediments, and tree rings — from the pre-industrial period (1500–1900) and carbon-dioxide production from the burning of fossil fuels as a surrogate for all human influences on the climate during the industrial period (1880 to 2000, a simplification Lovejoy justifies by the close relationship between global economic activity and the emission of greenhouse gases and particulate pollution). He then applied fluctuation-analysis techniques, which make it possible to understand temperature variations over wide ranges of time.
The results were clear: Lovejoy states that we can now reject natural variability as the cause for our current climate change with a 99 percent assurance.
Just one more to ignore
Lovejoy believes his new study provides incontrovertible evidence to climate change deniers. Their two staunch arguments — that global warming is natural in origin and that computer models can’t be trusted — are either directly contradicted by his results or simply don’t apply to it.
Critics have already pointed out, however, that temperature data was not recorded five hundred years ago, so the methods Lovejoy used for the pre-industrial era are indirect and cannot be taken as 100 percent accurate. And while his study may seem to show that we can now finally reject natural temperature fluctuations as the cause of our current global warming crisis, proving that the cause is anthropogenic is another matter.
In a press release published by McGill University on April 11, 2014, Lovejoy stated: “We’ve had a fluctuation in average temperature that’s just huge since 1880 — on the order of about 0.9 degrees Celsius. This study shows that the odds of that being caused by natural fluctuations are less than one in a hundred and are likely to be less than one in a thousand.”
But as Tim Radford wrote yesterday in Climate News Network, people tend to think in unpredictable ways when contemplating an uncertain future predicted decades ahead. In 2010, University of California, Berkeley psychologists conducted an experiment on undergraduates and discovered that people tend to discount the most apocalyptic warning if it challenges their view of an orderly world. Fear-based appeals often backfire and undermine the intended effects of the messages. And even when people are prepared to accept that climate change is a substantial threat, there is resistance to the costs of mitigation.
Do you think that the Lovejoy study will be the one that climate change deniers can no longer ignore? Will this mark a turning point? Or is this just one more study on climate change?
Here’s to finding your true places and natural habitats,