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Coastal areas of Peru and Chile are greening, but this is not positive discovery

A team of researchers has been exploring the complex changes in vegetation and greening along the Pacific coastal areas of Peru and northern Chile.

In a surprising study led by the Cambridge-based Cavendish Laboratory, these scientists have examined this unique and fragile environment over the past 20 years.

Their intensive analysis revealed some surprising trends. Some areas showed an encouraging increase in vegetation growth, termed “greening,” while others demonstrated disturbing negative growth patterns, known as “browning.”

As expected, these transformations were influenced by human activities. These include farming, urban development, and changes in land use practices.

However, a significant discovery that emerged from this study, recently published in MDPI Remote Sensing, was the identification of a massive section of the West Slope of the Andes experiencing notable greening over the past two decades.

Greening stretches from Northern Peru to Northern Chile

This substantial greening stretch spans about 2000 kilometers, stretching from Northern Peru to Northern Chile. Its vegetation varies with altitude, showcasing different types of plants at different heights.

The versatile research team, comprised of mathematicians, geographers, biologists, and earth scientists, harnessed the power of satellite images. They searched the images for changes in vegetation from 2000 to 2020.

The scientists meticulously plotted 450 data points and engineered a mathematical model to eliminate artificial variations such as cloudy days and seasonality. They also utilized rigorous statistical analysis to ensure they were only scrutinizing areas with a significant trend.

Hugo Lepage, a mathematician at the Cavendish laboratory and the study’s lead author, shared the challenging journey to this breakthrough.

“It took three years to sort the methodology and the statistical model,” said Lepage. “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.”

Verifying on the ground that Peru is greening

To corroborate their data, the team also conducted numerous field trips to observe the region’s conditions. Eustace Barnes, a geographer from the Cavendish Laboratory’s Environmental Physics Group that led the research, shared the team’s unexpected revelation.

“We started with a very local area to study the impact of mining on local vegetation. To our surprise, the data was suggesting that the area was greening instead of browning,” explained Barnes. “So, we zoomed out and realized other areas were also greening on a large scale. When we went to check on the ground, we observed a similar trend.”

The researchers also noticed some puzzling characteristics of the greening strip that defied expectations. Barnes stated, “First, the strip ascends as we look southward, going from 170-780 m in northern Peru to 2600-4300 m in the south of Peru. This is counterintuitive, as we would expect the surface temperatures to drop both when moving south and ascending in altitude.”

Adding to the perplexity, this substantial greening strip does not align with the established climate zones. This, according to the Köppen-Geiger classification — a vegetation-based empirical climate classification system used widely. In contrast, the greening and browning trends in the coastal deserts and high Andes align with this system perfectly.

What this greening trend means for Peru

The implications of these results reach far beyond academia. It also affects environmental management and policymaking in the region.

While the precise cause or effects of this greening remain uncertain, such a substantial increase (30-60% index increase) in vegetation will undeniably affect 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,” Barnes pointed out. “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 significantly advance the scientific community’s understanding of the intricate relationships between climate change and fragile ecosystems in arid and semi-arid environments.

“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,” Lepage concluded.

This pivotal research was carried out by the Environmental Physics Group. It was led by Prof. Crispin Barnes, and generously funded by the Universidad Nacional de Cañete (UNDC), dpto Lima, Peru.

More about the Peruvian coastal region

Peru’s coastal region, often referred to as the Costa, stretches along the Pacific Ocean. The area covers roughly 11% of the country’s land area but housing over half of its population.

This coastal region is narrow and long, spanning about 2,414 kilometers (1,500 miles) from north to south but only 100-150 kilometers (60-100 miles) east to west.

Geography and climate

The coastal plain is predominantly desert, making it one of the driest deserts in the world. It includes sandy deserts, rocky deserts, hills, and large dunes. Despite the arid conditions, numerous rivers descending from the Andes Mountains cross the region, creating fertile river valleys. These valleys, known as “lomas,” become verdant during the rainy season when humidity rises.

The region’s climate is heavily influenced by the cold Humboldt Current. Also known as the Peru Current, it flows northwards along the coast. It results in a subtropical desert climate with a cool, mild atmosphere and high humidity, with temperatures rarely exceeding 29°C (85°F). This current also leads to frequent coastal fogs and mist, known locally as “garúa.”


Despite its arid nature, the Costa is home to a unique array of flora and fauna. The ocean waters off the coast are among the most productive marine ecosystems in the world. They support a rich diversity of marine life, including a variety of fish species, sea birds, and mammals like seals and sea lions.

Human settlements and economy

The Costa is the economic and political heartland of Peru, home to the country’s capital, Lima, which is also the largest city. Lima and other cities along the coast are major industrial and financial centers.

The coastal region’s economy is driven by fishing, agriculture, mining, and manufacturing. Thanks to the fertile river valleys, agriculture thrives despite the overall arid conditions. The region produces a significant amount of Peru’s agricultural output. This includes crops such as cotton, sugar cane, and a variety of fruits and vegetables.

Historical importance

The coastal region has been a cradle of ancient civilizations, including the Moche and Nazca, known for their intricate pottery and enormous geoglyphs, respectively. The area was also central to the Inca Empire, with important administrative and ceremonial sites located along the coast.

In conclusion, Peru’s coastal region is an area of stark contrasts, with its desert landscapes, fertile valleys, bustling cities, and rich historical sites. Its unique combination of physical geography, climate, and biodiversity make it a fascinating region to study and explore.

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