Researchers from the University of La Laguna are studying the sedimentary records of ancient lakes and wetlands to identify signs of heat waves, torrential rains, and, in particular, haze, of which they have found evidence that it has accompanied the islands for millennia.
The paleoclimatic research is unearthing "fascinating secrets" about the environmental history of the Canary Islands, and one of the most prominent findings is the confirmation that haze is an event that has accompanied the islands for millennia and has a profound footprint in the Canarian subsoil, according to the center on Monday.
The research is led by Margarita Jambrina, tenured professor of the Department of Animal Biology, Soil Science, and Geology at the University of La Laguna, who explains that it involves diving into the sedimentary records of ancient lakes and wetlands of Tenerife, La Palma, and La Gomera.
These "natural archives" of the climate, as the researcher calls them, are analyzed layer by layer, unraveling the environmental history of the islands "with amazing precision," as these data can be used to calibrate and validate current climate models.
"The more data we have on the natural variability of the climate, the better we can distinguish between changes induced by humans and natural processes," says Jambrina.
She adds that they want to determine if haze has occurred in the past, how often, with what intensity and duration," and for this, geochemical, mineralogical, and sedimentological analyses are key in this process.
For example, the researcher details, changes in the mineralogy of the sediments can indicate a significant contribution of Saharan dust, differentiating it from other origins.
Haze in the Holocene
The first results of the research are already shedding light on the behavior of haze in the Holocene, the current geological era that spans the last 12,000 years.
Thus, during the period called Norgripian (between 8,000 and 4,000 years ago), the arid conditions that were established in the region favored an increase in the frequency and intensity of these events.
"During the beginning of the Holocene, in the so-called African humid period, the Sahara was green, with vegetation and rivers, and that reduced dust emission, but when that period ended and the region became more arid, the haze intensified," details Jambrina.
This suggests that the presence of haze in the Canary Islands is intrinsically linked to the climatic dynamics of North Africa, particularly to the desertification of the Sahara.
In the Canary Islands, this type of research is allowing us to reconstruct what the climatic conditions of the recent past were like—especially the Holocene—from sedimentary records.
Sedimentary deposits in ancient basins
In ongoing projects on the three islands mentioned, researchers are studying deposits in lakes and sedimentary fillings in ancient basins to infer humid or arid periods.
Although in the geological past of the planet there have been CO₂ concentrations even higher than the current ones, the rates of change were radically different, and, according to researchers in the field of paleoclimatology, the rate of increase in current carbon dioxide is unparalleled in the last two million years.
Margarita Jambrina specifies in this regard that although 70 million years ago there were higher levels of CO₂, the configuration of the continents was different, since the ocean circulation, known as thermohaline, did not work as it does now, and only for about two million years "we can compare systems similar to the current ones, and within that framework, the speed of the current change is unprecedented."
Understanding the history of haze and other climatic phenomena through sediments is not only an exercise in environmental archeology but also in forecasting, adds Jambrina, who emphasizes that to predict the future, we must understand the past.
