Global warming threat to natural rubber

Dr N Yogaratnam

Global warming and climate change are aspects of our environment that cannot be easily or quickly discounted.

Many factions still strongly feel that the changes our Earth is seeing are the result of a natural climatic adjustment. Regardless of one’s perspective the effects of global warming are a quantifiable set of environmental results that are in addition to any normal changes in climate. That is why the effects of global warming have catastrophic potential.

Global warming may well be the straw that breaks the camel’s back. Global warming as caused by greenhouse gas emissions can lead us to a definite imbalance of nature.

The premise of global warming as an issue of debate is that industrial growth coupled with non-structured methods we as humans use to sustain ourselves has created a situation where our planet is getting progressively hotter.

We have seemingly negatively effected our environment by a cycle of harmful processes that now seem to be feeding upon themselves to exponentially increase the damage to our ecosystem.

Natural rubber

Natural rubber (NR) is mostly cultivated in the developing countries in South and South East Asia, parts of South America and Africa falling in the equatorial belt. These are some of the most populous nations in the world and they are highly vulnerable to the adverse effects of climate change. NR cultivation will not remain immune to the adverse effects of global warming and climate change.

There are more than 10 million small growers who depend on NR cultivation for their livelihood in these countries and climate change has the potential to pose serious threats to their well-being.

Adverse effects of climate change can seriously diminish the supply of NR and thus jeopardize the rubber goods manufacturing industry.

Shortage of NR will eventually result in increased consumption of synthetic rubbers which will lead to increase in the emission of carbon dioxide into the atmosphere.

Issues

During the past 30 years, it has been a realized that most of the warming that has been observed is triggered by the release of carbon dioxide through burning of fossil fuels. The evidence of human induced climate change is accumulating every day.

Most glaciers are retreating and there is increase in the incidence of heat waves and lower incidence of frost.

The pace of climate change will accelerate in the 21st century if human beings continue to depend upon fossil fuels as the primary energy source.

Some developed countries have not taken the threat of climate change seriously because they think that they have the resources to adapt to a warmer world. The major impact of climate change will be, however, seen in the developing world where in many people will not have the resources to adapt.

A warmer world will increase heat stress in tropical countries and hence have an adverse impact on the performance of the workers in industries. The rise in sea level will affect a large number of cities located on the coast in Asian countries.

The changes in pattern of rainfall and higher evaporation will lead to more water scarcity. The warmer night temperature will have an adverse impact on agricultural production. The higher temperatures will increase the incidence of attack by insects and pests on crops.

During the past 50 years the number of heavy rainfall events has increased by almost 50 percent. This has lead to urban flooding. If the global mean temperature increases by more than two degrees centigrade above that in the 19th century, then the threat of an abrupt climate change cannot be ruled out.

Abrupt climate changes have occurred in the past due to natural causes but may be triggered by human actions in the future.

Many scientists and engineers have shown that we can move away from our addiction to fossil fuels and meet our energy needs through renewable energy technologies. The transition from the present fossil fuel based society to one dependent only on renewable energy will be slow and painful. We need, however, to take urgent actions now to promote this transition in order to avoid irreversible changes to the earth’s climate

The major physical dimensions of climate change viz., global warming, weather instability and occurrence of extreme and unusual climatic events have short-term and long-term impact on supply of agricultural crops and their price.

The magnitude of the impact of weather factors on price of a crop would depend on the characteristics of the crop, nature and pattern of weather factors in the major crop growing regions and market situation.

NR Yield

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.

The share of Asia in world NR production remained above 90 per cent ever since the dominance of plantation rubber. But the relative shares of Asian countries in world NR production changed considerably during the recent decades.

Asian region

However, Southeast and South Asian regions accounted for 77.1 and 10.1 per cent of world NR production respectively in 2009. The tropical regions of Southeast Asia are most vulnerable to climate change and these regions face frequent storms and other extreme weather events.

The major expressions of climate change in the rubber South Asian regions are decrease in the number of cool days and nights, increase in the number of hot days and warm nights and decrease in the number of rainy days per year.

Intermittent heavy showers and prolonged dry spells have marked the weather in the recent years in South Asia with an accompanying increase in average temperature. Incessant rains and flooding has also become a regular event. The frequency of occurrence of natural disasters related to extreme weather events also has risen globally and in South and Southeast Asia. All these point to increased inter and intra year variability in weather leading to instability in NR supply, which will have a direct bearing on the NR market, mainly depending upon the demand from the consuming industry

NR price

The impact of NR supply instability on price as a result of climatic variations depends on market situations such as demand-supply balance, marketing framework and factors influencing NR prices. The major factors on the supply side are level of inventories and relative production in relation to normal production. The normal production of NR is determined by planted area, age of the trees and yield profile.

However, actual production would depend on weather and price factors; the former directly affects tapping and the latter indirectly influences tapping through grower behaviour. Relatively high levels of inventories and actual production of NR being substantially below normal production would lessen the impact of weather factors on NR price.

NR is mainly used globally in the transportation sector as tyres and other auto components. The transportation sector is highly sensitive to the trends in the world economy. The balance between NR demand and supply is a crucial factor determining the impact of weather factors on price particularly when the economy is on a strong footing. The increasing process of market integration has led to more harmonisation of commodity price trends around the world. For example, the emergence of TOCOM price as an international trendsetter in NR market.

The sentiments of market players in TOCOM are easily influenced by weather events occurring in major rubber growing areas of Southeast Asia and these sentiments get reflected in TOCOM rubber prices, almost instantly.

The trends in TOCOM rubber prices percolate into the South and Southeast Asian rubber markets with immediate effect

Influencing factors

There are several factors apart from demand-supply balance and marketing framework that can influence the price of NR and these include price and supply of substitutes, oil prices and currency exchange rates. But with environmental virtues in terms of CO2 sequestration etc of tree crops gaining importance, the influence of synthetics, crude oil etc, which causes emission of Green House Gasses (GHG), may be insignificant.

Therefore, weather induced supply disruptions may have overriding role on NR supply and price.

Nevertheless, during the current decade, world NR production was adversely affected by extreme and unusual weather conditions especially in 2005, 2007 and 2009. But, the same period also witnessed very low rubber prices, recovery and boom which were primarily due to shifts in global economy.

NR production

There was a structural shift in NR prices from the late 1970s. The prices of NR reached a peak at the end of 1970s. In response to the booming prices, in the beginning of 1980s, a large scale new-planting and replanting of rubber happened in all major producing countries.

These new-planted and replanted rubber trees were expected to attain the replanting age from 2010 onwards, assuming a productive life span of rubber is 30 years.

To push the existing yielding area into a gestation phase, in 2003-09 there were a large-scale replanting in non-traditional regions, considering that the new-planting undertaken in the beginning of 1980s would enter the declining phase in 2010 because of ageing.

These new-planted and replanted areas in 2003 and 2004 would marginally add the global supply from 2010 to 2011. From 2012 to 2016 a substantial addition of supply is expected according to the new-planting/replanting which was undertaken from 2005 to 2009.

On the other hand, the new-planting and replanting undertaken during 2003-09 were mostly in non-traditional regions. These areas are agro-climatically marginal to grow rubber and their productivity are not expected to be significantly high.

Other limitations

The other limitations to improve the yielding areas are i) the existing areas are still occupied by low-yielding clones, ii) shortage of skilled tappers, iii) unscientific harvesting practices and iv) climate change. Spiraling wages, cost of input materials, lack of mechanical harvester etc can cause shortage of skilled tappers and scientific harvesting workers.

Hence, the existing marginal growers should be skilled in tree improvement, vegetative propagation, latex harvesting and processing technologies and so on.

Lack of other sources of income can cause postponed replanting of the aged trees especially when the rubber prices are high. In addition, the existing gap between prices of NR and SR is also a threat to the NR supply.

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.

Road ahead

To accommodate the issues and challenges in global supply of NR, some adjustments to improve the yield of rubber are needed. Mechanization for harvesting and processing is preferable to improve the quality of harvested rubber.

Dissemination of market information can be used to strengthen the existing system. Government incentives for replanting can minimize the ageing issues and attract farmers from rubber holding.

Early morning tapping

Over the years climate has undergone major changes in the areas where its rubber estates are located. Both the early morning (minimum) temperature and afternoon (maximum) temperature have gone up in recent years. It is felt that this has substantially affected the growth rate and productivity of estates.

Generally, tapping starts in rubber estates by 6.30 am and latex collection would start at 10.00 am and it will be over by 12.00 noon. Considering that the morning temperatures have gone up in the recent years and knowing that cooler temperatures will favour better yield. Some reports indicate that commencement of tapping to 3.00 am has resulted in 20 to 30 per cent increase in productivity with substantial reduction in the percentage of field coagulum.

It is suggested that likely higher turgor pressure prevailing in the cooler hours of early morning was responsible for the better yield.

Since the latex was collected only after sunrise there was adequate time for dripping to stop and therefore the percentage of field coagulum was less. Early morning collection of latex ensured better preservation of latex due to the congenial temperature during this time. In order to carry out effective tapping, the tappers were provided with superior quality headlights and better tapper productivity led to 20 per cent more earnings for the tapper. The increase in production and productivity ensured that the investment in these equipments was paid back within a period of less than a week in most cases

Nutrient balance approach

Nitrogen (N) is required in substantial amount in order to support growth and must be adequate to produce economically sufficient rubber yield. N constitutes 3-4 per cent of leaf dry matter. In both young and mature rubber, N deficiency tends to produce small and yellowish leaves resulting in stunted growth.

When the amount of soil N is deficient for satisfactory rubber yields, N fertiliser is added to supplement the soil N. If N is supplied in excess, it leads to environmental problems. When applied into the field, N fertiliser is largely converted to nitrate and this form is soluble and readily moves with the soil solution. This surplus N may be available to leach to groundwater. Alternately, N can also contribute in the nitrate, ammonium or organic form to surface water contamination by means of surface water runoff.

The other problem encountered from using N fertilizer is Green House Gas (GHG) emissions, as nitrate can be transformed into NH3, NO3, N2O, N2 etc. through mineralization process. As part of an effort to reduce environmental pollutants along with the emissions of GHG from using N fertiliser in rubber plantations, a nutrient balance approach is suggested.

It has also been reported that under short dry spell both Silicon (Si) and K were effective in reducing the adverse effects of drought stress. However, under prolonged water stress, K was more effective than Si. Tillage as well as life saving irrigation has been found to be effective in India. But, tillage is a more economic and feasible management practice in Sri Lankan plantations. Tillage is expected to provide additional soil conservation measure by blocking capillary pores in the soil.

In conclusion, export must orient to more finished rubber-based products than raw rubber, thus improving net farm income. More site specific technologies to maintain the existing yielding areas from negative effect of climate change together with other scientific practices should be evolved.