Tea and rubber equally affected by global warming, climate change

20 March 2014 05:24 am

Be it swapping coffee for cocoa in Central America or bracing for drought in Sri Lanka with a return to ancient water storage systems, scientists and growers should jointly chart a path to adapt to climate shifts despite uncertainties over future growing conditions.
Tea, a beverage and rubber an industrial raw material, both need adaptation measures to overcome the adverse effects of global warming and climate change


Tea
Tea is one of the major plantation crops grown from nearly sea level to around 2200 m amsl. The total tea land is estimated to be 200,000 ha of which approximately 60 percent is managed by smallholders contributing to about 70 percent of the national production. In 2013, Sri Lanka’s tea production is around 335 million kg of tea earning over Rs. 155, 000 million. The industry is said to employ over 1.5 million people.

Close analysis of climate change impacts on tea production in Sri Lanka shows that tea cultivations at high elevations (>1200 m amsl) are least affected. Rising temperatures are beneficial to tea grown at high elevations as it helps to reach optimum temperature for tea (22 oC). However, it is predicted that rising temperatures and dry weather conditions in warmer regions where the present temperatures are above optimum for tea (low; <600m amsl and mid; 600-1200m amsl elevations) will mask the benefits of CO2 enrichment and limit tea production. In addition,  poor soil conditions and ageing tea bushes make tea lands highly vulnerable to the adverse impacts of climate change.  In order to mitigate such adverse impacts on tea lands in Sri Lanka, it is crucial to adopt good agricultual practices.



Adaptation measures
Proposed adaptation measures seek to minimize  adverse impacts of extreme (high) temperatures and moisture stress and, ensure that the beneficial effects of CO2 enrichment is properly exploited for sustaining tea yield. They are primarily aimed at improving soil conditions, aerial environment, and adaptability of the crop to stress conditions.


Use of drought and stress tolerant cultivars

•  Planting tea cultivars, grafted plants and improved seedlings that are able to withstand adverse weather conditions such as droughts and increasing temperatures.
• Use of a basket of tea cultivars including those with pest and disease tolerance.

Crop diversification

•     Utilize low yielding tea land (unsuited for replanting with tea or cash crops) for other uses such as Gliricidla (Glircidla seplum) thrives in poor soil conditions at low/mid elevations and minimal investment is required.
•     Exclusively, reserve lands with good soil conditions for tea, and areas with greater soil degradation for other economic uses.
•     Intercrop tea with other perennial tree crops (rubber and coconut) when soil conditions are favourable for such crops.
•     Convert unproductive tea lands to “thatch banks” i.e., planting of rehabilitation grasses such as Mana (Cymbopopgan confertiflorus) or Guatemala (Tripsacum taxum) thereby conserving and improving the soil whilst also spplying green manure to other tea lands.

Soil conservation, improvement and irrigation
Soil conservation and improvement are necessary to increase water and nutrient holding capacity to soil so that tea bushes are well established to withstand adverse weather conditions.

•    Mulching in young tea lands
•    Planting of green manure crops as SALT (Sloping Agriculture Land Technology) hedge rows.
•    Adoption of soil and soil moisture conservation measures
•    Generation of compost by planting green manure crps and rehabilitation grasses in vacant patches and along fences
•    Burying of tea pruning and envelope forking (fork soil without turning)
•    Irrigation of tea during dry months

Establishment and management of shade trees
Establishment and management of shade trees in tea lands will reduce ambient temperature around tea bushes, harvest rainfall, reduce drying up of soil, improve soil organic matter status in tea lands. Hence, establishment and management of high and medium shade trees in tea lands will minimize adverse impacts of climate change.



Challenges
The adoption and long-term implementation of strategies detailed above hinges on two factors; firstly, the profitability of tea cultivation which in turn, limits the capacity of the tea grower (affordability) to effectively adopt such strategies in the field, and secondly, the availability of labour and other resources and required materials which will facilitate such good agricultural practices that have so far  not been fully adopted in tea lands . It is believed that financial assistance to tea growers will markedly improve the rate of adoption of such strategies, whilst minimizing the adverse impacts of climate (.Reference; MA Wijeratne, TRI/ Sri Lanka)



Rubber
The latex yield of rubber trees is mainly determined by physiological factors and harvesting intensity. Both these factors are influenced by clonal characteristics, agronomic practices and environment. Given the physiological factors and agronomic practices, the major yield-limiting factor is harvesting intensity, which in turn is mainly determined by weather and price factors.

Extreme weather in terms of long and intense dry spells and heavy rains can substantially reduce harvesting intensity through reduced tapping days. The response of growers to the prevailing rubber prices is also reflected in harvesting intensity.

The interplay of weather and price factors in determining NR production makes it difficult to measure the influence of weather factors on price.

Climate change would have a negative bearing on future yield. Rain and drought affect tapping days and disrupts harvesting. The higher temperature especially in the morning will affect latex flow and as a result, the yield of rubber will be low.

Furthermore, climate change may cause new diseases which are detrimental to rubber trees. The existing clones that have tolerance to climate change is limited. Therefore, it is necessary to develop clones which are tolerant to an extreme climate.



Human impact
The human impact on the environment associated with economic growth and development is believed to be a primary cause of global warming.  Such warming has profound impact on living beings and plant life. For instance, photosynthesis, the process by which plants produce organic compounds is largely governed by ambient temperature, carbon dioxide concentration and soil moisture (rainfall). Changes to these environmental factors can  incur profound impact on photosynthesis and in turn, affect crop growth and yield.

Temperature rise, enrichment of ambient carbon dioxide (CO2 ) and  variation of total and pattern of rainfall distribution change crop environments, thus affecting crop growth and yield of non-irrigated plantation crops such as tea. Pest behaviour and disease infestations which are impacted by environmental changes are also closely linked to the productivity of tea land. 

Moreover, changing environment can adversely affect product quality. In the recent past, scientists have begun to explore climate change and assess its impact on crop growth and yield. Fortunately, such studies have paved the way for scientists to identify appropriate measures in which adverse impacts of climate change on agricultural crops such as tea can be mitigated.



Exploitation by the US and Europe
Greenhouse gas output of China and elsewhere is increased by making goods that are then used in the US and Europe. The world’s richest countries are increasingly outsourcing their carbon pollution to China and other rising economies, according to a draft UN report.

Outsourcing of emissions comes in the form of electronic devices such as smartphones, cheap clothes and other goods manufactured in China and other rising economies but consumed in the US and Europe.

A draft of the latest report from the Intergovernmental Panel on Climate Change, says emissions of carbon dioxide and the other greenhouse gases warming the planet grew twice as fast in the first decade of the 21st century as they did during the previous three decades.

Much of that rise was due to the burning of coal, the report says. And much of that coal was used to power factories in China and other rising economies that produce goods for US and European consumers, the draft adds.

Since 2000, annual carbon dioxide emissions for China and the other rising economies have more than doubled to nearly 14 gigatonnes a year, according to the draft report. But about 2 GT a year of that was produced making goods for export.

The picture is similar for other rising economies producing goods for export, the report finds.

“A growing share of CO2 emissions from fossil fuel combustion in developing countries is released in the production of goods and services exported, notably from upper-middle-income countries to high-income countries,” the report says.

Other middle income countries, with smaller exports, saw a more gradual rise in emissions. For the poorest countries in the world, however, emissions have flatlined since 1990.

Factories in China and other rising economies now produce more carbon pollution than industries in America and Europe.

“A growing share of global emissions is released in the manufacture of products that are traded across international borders,” the draft says.

The newly wealthy elites of China, India and Brazil are flying more, buying more cars and otherwise fuelling the consumption that is driving climate change.

But their per capita greenhouse gas emissions are still below those in America and Europe – a gap that China and India regularly cite at climate talks to deflect pressure to cut emissions.

In addition, a large and growing share of the carbon pollution attributed to China and those rising economies was generated in the production of goods that ended up in America and Europe.

The outsourcing of those emissions has skewed efforts to account for all global emissions, which typically was conducted on a national basis. Those accounting efforts are no longer accurate, according to analysts.

“If we are just looking at our national inventory to understand the emissions trends, it is just not telling the full picture of our impacts,” said Cynthia Cummis, an expert on greenhouse gas accounting at the World Resources Institute. “We need to understand the full life cycle of all the goods and services that we are purchasing and selling.”

There is now growing debate about how to assign responsibility for emissions generated producing goods that were made in one country but ultimately destined for another.

“The consumers that are importing those goods have some responsibility for those goods that are happening outside of our boundaries,” Cummis said.

The 29-page draft, a summary for policy makers, was dated 17 December, 2013. An edited version is due to be published in Germany in April.

The report is the third in a series by the IPCC, summing up the state of the climate crisis since 2007 and prospects for solutions. The first part was released in September. It is stark about the chances of avoiding dangerous climate change – especially if deep cuts in greenhouse gas emissions are pushed back beyond 2030.
Temperatures have already risen by 0.8C since the dawning of the industrial age, the report says.

Unless there are deep cuts in emissions – up to 70 percent of current levels by 2050 – or a near-quadrupling of renewable energy, governments may have to fall back increasingly on experimental technologies for sucking carbon dioxide from the air to avoid dangerous warming, the report says.


(The writer can be contacted via treecrops@gmail.com)