Science1 publisher3 min readPublished
Just 9% of field studies on climate and Mediterranean-type plants come from the Global South
South African researchers reviewed 128 field studies of climate impacts on Mediterranean-type plant communities and found 9% came from the Global South. That limits how far responses seen in California or the Mediterranean Basin can be carried to the Cape.
The Scientist · Science desk
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What happened
- Only 11 of the 128 studies in the review were represented in IPCC assessment reports.
- Most studies tracked vegetation condition and growth, far fewer looked at plant diversity, phenology or physiology, and some response types were missing from particular regions.
- Evidence tying drought, fire and other climate-related disturbances to vegetation responses earned relatively high confidence, while evidence that climate change itself caused the changes earned less.
- Few of the observational studies used modern causal inference methods to separate climate change effects from other drivers.
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Why it matters
- constraint Expectations for the under-observed regions, built largely on models and experiments, have little local field record to be checked against.
- decision Planners in these hotspots have firmer grounds to act on how drought and fire reshape vegetation than to blame a given change on climate change, and the two claims warrant different weight in a plan.
- capability Because much of the shortfall is analytical, the authors argue that reanalysing historical data sets with causal methods could produce attribution evidence from records already collected.
Nine percent of 128 is about 11.5. That puts the Global South's contribution at 11 or 12 studies, since either count rounds to the published share [17]. The review covered all five Mediterranean-type regions: the Mediterranean Basin, California, central Chile, southwestern Australia and South Africa [2].
That small count is easy to over-read. Hana Petersen led the study in Ecological Solutions and Evidence with Ryan Blanchard and Jasper Slingsby [3], and she compared the field record with other kinds of evidence. "Much of what we know about the future of Mediterranean-type ecosystems comes from models and experiments," she said. "But observations of what is actually happening in natural plant communities are much less common, and the observations we do have are not evenly distributed around the world." [6] The thing this doesn't tell you is where those models and experiments were built. The review counted observations only, so it cannot show whether forecasts for all five regions lean on work done in a few of them.
Coverage and drought severity only partly line up. The IPCC has reported extreme droughts across all five regions in recent decades, with particularly severe events in South Africa and California [5]. In Slingsby's example, California is the well-documented case. "This geographical imbalance matters because it limits how confidently we can generalize from one MTE region to another," he said. "A response documented extensively in California or the Mediterranean Basin may not necessarily tell us how vegetation will respond in the Cape Floristic Region, for example." [8]
The skew also muddies comparisons between regions. When research effort and region move together, a difference in findings could reflect ecology or could reflect sampling. The reviewers found they could not cleanly separate genuine ecological differences from differences arising from where the research was done [7].
In my view the weaker link sits inside the studies, and it applies to the well-documented regions as much as to the thin ones [13]. "Seeing that vegetation has changed at the same time as climate has changed does not necessarily tell us that climate change caused that vegetation change," Blanchard said. "There can be many other factors involved, including fire, land use, herbivory, invasive species and natural ecological variability." [10] Fire appears on both lists. Wildfire is among the disturbances the studies reported most often, alongside climate variability, drought, frost and pathogens or insect infestations [11], and it is also one of the confounders Blanchard names.
Petersen said the aim goes beyond coverage. "This is not simply a matter of filling gaps on a map," she said. "We need to understand whether the mechanisms driving resilience in one region can help us anticipate what will happen in another." [16] The authors propose coordinated research across all five regions that combines long-term monitoring, existing observational data sets, remote sensing, experiments and causal inference methods [15].
What to watch
- A per-region breakdown of the 128 studies, showing how the small Global South share divides among the five regions.
- Whether later IPCC assessments draw on more of this observational record than the 11 studies represented so far.
- Reanalyses of historical vegetation data from the Cape or central Chile that use causal inference to separate climate effects from fire and land use.