TCS Daily

Where Have All the Flowers Gone?

By Iain Murray - June 20, 2003 12:00 AM

The British newspaper The Independent warns us of a serious threat to our aesthetic appreciation of the world. "Global warming may wipe out a fifth of wild flower species, study warns," is the alarming headline. But there's more to the story.

What the researchers did was take a small section of California grassland in the San Francisco Bay area where 43 species of grasses and small flowers called forbs grow together in harmony. Forbs are plants like vetches, buttercups and ragweeds, often delightful, but often thought of as weeds. This was hardly the White House rose garden. They divided a small area of this grassland into 128 study plots, each about one square yard in area. To each of these plots they then applied variations in the climate over a period of three years. Those variations consisted of increased carbon dioxide in the air, increased precipitation, increased nitrogen deposition and a warming of around 1° C, or a combination of these factors.

After the end of three years, the researchers found that under increased carbon dioxide, the combination of increased carbon dioxide and elevated temperature, the combination of carbon dioxide, warming and nitrogen and the full combination of all four effects, the numbers of forbs in those plots had decreased by 20 percent. This sounds dramatic. In fact, the numbers had decreased from an average of 4 species in each plot to around 3.2. Most of these losses related to the loss of two of the forb species - the Autumn Willowweed and the Long-beaked Filaree. In only one scenario (increased carbon and warming) was the change statistically significant to a notable degree (a probability of less than 1 in 100 that the result was happenstance). The change in the case of increased carbon, warming and nitrogen wasn't significant at all.

Moreover, the slight loss in wild flower growth did not mean that there were patches of bare ground. Other plants, especially perennial grasses, reacted well to the changed conditions. Importantly, these weren't the dominant plants already, which meant that in all but a handful of cases, the diversity of plants - the number of different species - remained the same or actually increased. Some plants prefer different conditions to others.

This does not, however, mean that global warming will kill off even the two unfortunate plants mentioned above, as The Independent seems to think. The researchers studied the effects on only one particular type of grassland in California. As they say, "certain characteristics of Mediterranean grasslands, such as a winter growing season and a water-limited, rather than a cold-limited, growing season length, are not shared by all other systems." Now it may well be that climate change will make other forms of grassland more like the current Californian grasslands, meaning that flowers that formerly thrived there will now thrive elsewhere.

No doubt the same would be true if the Earth cooled slightly; plants that formerly thrived in California might have to move elsewhere too. The idea that any such change is automatically a bad thing has led British science writer Matt Ridley to dub this the "Goldilocks" view of climate change - any colder is bad, any warmer is bad. What we have now is just right. From what we know of natural variability in the climate it is interesting to realize that this view of sustainability is itself unsustainable.

In addition, the use of the phrase "global" in the study and in The Independent article suggests something that is unwarranted by the data - that one in five wild flowers all over the world will die as a result of global warming. It is indeed true that if something like that were to happen, there would be tremendous impacts on wildlife and the ecosystem. Yet this is completely unsupported and unsupportable from the evidence of one Californian meadow. Extrapolating such a global catastrophe from this study is to replace sound scientific reasoning with unconscionable spin.

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