Climate change measured in coffee rain

In Kodagu, the changing climate is making rainfall erratic. With erratic rainfall, famers are opting to use irrigation, reducing their need for shade trees. When they let the shade trees die, there is an adverse effect on the water flow into the Cauvery River, as well as climate resilience in the surrounding hills and plains. By S. Gopikrishna Warrier, for India Climate Dialogue. (Photo: Coffee farmer B.B. Thammaiah’s rainfall record, photo by author.)

Coffee planters in the hill district of Kodagu in Karnataka are meticulous in keeping rainfall records in their estates. For some, the data goes back for decades. Their numbers tell the story of changing rainfall patterns, an indicator of climate change. The changing patterns also have an impact on the way they grow coffee, which has an effect on climate resilience in the hills and the plains.

Due to the presence of this decentralised network of rainfall measuring stations, it is easier to obtain a nuanced picture of the precipitation trends for Kodagu, earlier known as Coorg, than in other parts of India. The average annual rainfall varies from above 5,000 mm in the western edge of the district to 1,200 mm in the east.

This data was used as part of the baseline survey by an international collaborative project to study the unique coffee agro-forestry system of Kodagu district. The College of Forestry at Ponnampet in Kodagu, as a participant in the Coffee Agro-forestry Network (CAFNET) project, has analysed the rainfall data of over 60 years from 116 coffee farms.

“Keeping meticulous rainfall data is part of the culture we inherited from the British,” said C.G. Kushalappa, university head for forestry and environment sciences at the College of Forestry.

The CAFNET report noted that the length of the rainy season had decreased by 14 days over the past 35 years. It also noticed a strong fluctuation in annual rainfall with an apparent cycle of 12 to 14 years.

 

Low rainfall in coffee land

Whether it is due to being the lowest point in this cycle or an El Nino changing rainfall patterns, 2015 and 2016 have been years of low rainfall in Kodagu. This is the second year of deficit rainfall in Kodagu. During 2015, it was deficient by 19%. As a result, the storage in the Krishna Raja Sagara dam reservoir, built across the Kaveri River immediately downstream of Kodagu district, has a 31% deficit this year.

On the ground measurements by coffee grower K.K. Naren in Kunda village near Ponnampet confirms this. “Our normal rainfall is 90 to 100 inches (2,200 to 2,500 mm). This year we have got 38 inches, whereas by this time we should have received 70% of the year’s rain.”

A farm worker measures rainfall in K. K. Naren's coffee farm. (Photo by S. Gopikrishna Warrier)

A farm worker measures rainfall in K. K. Naren’s coffee farm. (Photo by K. K. Naren)

Coffee planters are confused by the erratic rainfall of recent years. “Rain and weather patterns have become increasingly unpredictable in recent years,” said M.B. Ganapathy, head of plantations for Tata Coffee. “Even though the quantum does not seem to have changed, the rainfall is not well distributed any longer. There are long dry periods followed by heavy rain and high-velocity winds. This has made farm management difficult for us.”

 

Blossom showers affected

According to coffee farmer B.B. Thammaiah of Kolagadalu village, the erratic rainfall has meant that blossom showers, which usually take place between February and April, are missing in some years. This has an impact on coffee production, since this helps coffee flowers to blossom, ensuring good yields later in the year.

There is an ecological impact of this, according to Kushalappa. When the blossom showers became erratic, coffee farmers started irrigating during these months. For traditional coffee cultivation, it was a combination of mixed-shade trees plus blossom showers that gave a good yield. When the blossom showers were replaced by irrigation, the shade from the trees did not matter. The farmers’ dependence on the native trees decreased, resulting in their proclivity for letting the native trees die. These trees are being replaced by silver oak.

There is also an issue of ownership that is leading to the clearing of forests. Thammaiah’s farm is in Kolagadalu village, not far from the western crest of the plateau deep in a forested valley. His farm receives more than 5,000 mm of rainfall every year. While in the valley floor he continues to grow rice as his forefathers did, he cultivates coffee in the shade of the forest trees. Though the forest may not be as thick as it was during his grandfather’s time, he plans to conserve it.

The landscape of Thammaiah’s farm is typical of what the people of Kodagu inherited. While historically joint families cultivated the rice paddies where they owned the land, they used the forest for collecting mulch and firewood and grazing cattle. The families do not have property rights over the trees, which belong to the government.

 

Economics of silver oak

Silver oak, on the other hand, can be planted, cut and sold. M.C. Cushalappa, a coffee farmer from Siddhapura, said that silver oak yields a two-fold benefit to coffee farmers. One, it can supplement the family’s income in times of need. Two, its straight trunk can be used as a support for pepper vines, which bring more additional income. With no ownership and no economic stake on the native trees, farmers do not have an incentive to keep them alive.

Cushalappa’s family has paid the price of the native trees to the government and obtained ownership over them. “This encourages me to maintain the native tree species in my farm, unlike most of the other farmers in Kodagu.”

The coffee agro-forestry system of Kodagu is of immense importance ecologically; not only does it provide climate resilience to the hill communities but provides water to millions downstream through the Kaveri. The current acrimony over the waters of the Kaveri between Karnataka and Tamil Nadu have led to violent protests.

There is a problem though. Unlike in other parts of the country where the forests are fully under the control of the forest department, in Kodagu they are under the combined control of the department and thousands of coffee farmers. It means that it is difficult to give them a protected status. It is not as if the forest department it always the best protector; but uniformity in control has the potential to improve conservation practices.

Geographical location of coffee farms where rainfall data has been collected for 70 years and a map of rainfall distribution generated with these data points as an exmple for the year 2002. ( Image by College of Forestry, Ponnampet)

Geographical location of coffee farms where rainfall data has been collected for 70 years and a map of rainfall distribution generated with these data points as an example for the year 2002. ( Image by College of Forestry, Ponnampet)

“The majority of forests in Kodagu are not notified and hence for their upkeep thousands of coffee farmers have to be incentivised,” a forest department official said, speaking on condition of anonymity. “About 90% of the catchment of the Kaveri river before the Krishna Raja Sagara reservoir is in Kodagu. There is need for a mindset change so that the farmers conserve the native trees and biodiversity.”

Through the CAFNET study, the ecosystem services could be quantified. “We looked at the role of native trees and silver oak to study their hydrological impact. Our team studied how much of the rain was intercepted, how much came through the stem, how much got run off, and how much got recharged,” noted Kushalappa.

 

The magic of native trees

The study found that increasing the proportion of exotic species such as silver oak in the shade cover composition had little impact on rainfall interception since trees intercept less (1% to 6%) than coffee plants (9% to 22%). Although there are lower quantities of water from native tree plots going to rivers than from the exotic tree plots, the higher contribution of evaporated and transpired water from native trees have a positive impact on the microclimate. Further, large canopy and deep-rooted systems of the native species help in the percolation of water to deeper aquifers, mainly during the monsoon.

Thus, native trees held the rainwater as it fell torrentially, and released it gradually into the rivers. At the same time they created a climate-resilient environment in the farms.

The mixed agro-forestry systems also helped in sequestering carbon. The CAFNET studies showed that Arabica coffee grown under the shade of mixed species sequestered more than the reference forests. Arabica coffee grown under silver oak sequesters marginally less than Robusta grown under native trees. Robusta grown under silver oak sequesters substantially less than the other combinations.

The missing blossom showers could be adding to the reasons for coffee farmers opening their canopies. On the flip side, the farmers’ actions could result in more carbon in the atmosphere, making rainfall more erratic in Kodagu.

 

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