Over the last two decades, analysis of satellite data has unveiled notable shifts in vegetation along the Pacific coast of Peru and northern Chile. Researchers from the University of Cambridge emphasise that these changes serve as a crucial 'warning sign’, signalling significant environmental changes on a large scale.
Published in the open access journal Remote Sensing, the study analyses two decades of data focused on the Pacific slope of Peru and northern Chile, a region characterised by its biologically unique and highly sensitive arid and semi-arid environments. The researchers uncovered a substantial portion of the West Slope of the Andes, spanning approximately 2000km, has experienced significant greening over the past two decades. More importantly, the geographical characteristics of this greening strip do not align with previously established climate zones.
Using satellite imagery from 2000 to 2020, the research team observed changes in vegetation across the designated region. Plotting 450 data points, they crafted a mathematical model aimed at eliminating artificial variations, such as those caused by cloudy days, and seasonality. Statistical analysis was then applied to focus exclusively on areas exhibiting significant trends.
“It took three years to sort the methodology and the statistical model,” says Hugo Lepage, author on the paper. “We really needed to bulletproof it to make sure that something was really happening on a massive scale, and it was not just a fluke.”
The researchers explain how understanding the spatio-temporal responses to climate change in this region is vital in predicting the impacts on ecosystem services and resource availability while conserving biological endemism.
“This is a warning sign, like the canary in the mine. There is nothing we can do to stop changes at such a large scale. But knowing about it will help to plan better for the future,” adds Lepage.
To verify what they were seeing in the data, the researchers conducted numerous field trips to make observations on the ground and corroborate their numerical statements, starting with a local area to examine the impact of mining on local vegetation.
“To our surprise, the data was suggesting that the area was greening instead of browning. So, we zoomed out and realised other areas were also greening on large scale. When we went to check on the ground, we observed a similar trend,” says Eustace Barnes, author on the paper.
The researchers discovered that the extensive greening strip does not align with the climate zones established by the Köppen-Geiger classification - a widely used, vegetation-based, empirical climate classification system. However, the trends of greening and browning observed in the coastal deserts and high Andes do align well with this classification.
The team highlights the broad implications of their findings for regional environmental management and policymaking. While the exact cause and consequences of the observed greening remain unknown, any substantial change (30-60 percent index increase) in vegetation is bound to impact ecosystems and the environment.
“The Pacific slope provides water for two-thirds of the country, and this is where most of the food for Peru is coming from too,” says Barnes. “This rapid change in vegetation, and to water level and ecosystems, will inevitably have an impact on water and agricultural planning management.”
The researchers believe their findings will contribute significantly to the scientific community's understanding of the complex interactions between climate change and delicate ecosystems in arid and semi-arid environments.
If you're interested in learning more about this research, you can access the paper published in Remote Sensing here: shorturl.at/lvPW9
MDPI