VULNERABILITY OF FOREST ECOSYSTEMS

Irshad Khan

According to the Inter-government Panel on Climate Change (IPCC) Working Group II report land use change and cover (LUCC) is both a cause and consequence of climate change and constitutes a major driver of changes in a natural ecosystem and biodiversity. The major ongoing changes in subtropical and tropical regions are clearance of forests and woodlands for conversion to agriculture, pasture and commercial cash crops (such as soy, palm oil and rubber). These changes have been causing green house gas (GHG) emissions and their increased concentrations in the atmosphere. The green vegetation is both a source and sink of GHGs. Deforestation for many people in tropical countries creates economic opportunities that is encouraged by growing demand for food products and also creates export potential.

Forests help mitigate climate change impact through removal of large quantities of carbon from the atmosphere, through absorption or reflection of solar radiation (albedo) the production of aerosols that form clouds and also some cooling effect through evapotranspiration.

The IPCC fifth assessment report (AR5) claims with high confidence that the global forests currently are net sink. The intake of carbon by well-stocked and regenerating forests was counterbalanced by release of GHG due to land use change, deforestation and forest degradation between 2000 and 2007 resulting in a net balance of 1.1± 0.8GtCyr-1. However, there are also recent scientific findings that point out that the forest carbon sink is gradually becoming weaker as a number of complex drivers are causing deforestation and forest degradation.

Interestingly, the impact of climate change on temperate forests is that there is an increase in growth rates of trees and corresponding carbon stocks. This is attributed to increased length of growing season, atmospheric CO2 concentration, nitrogen deposition, and forest management involving regeneration of area heavily harvested in the past. On the contrary the impact of climate change on tropical forests is still not very clear with degree of certainty and there are conflicting views. There is no clarity regarding the rates of photosynthesis due to increased CO2 concentrations, erratic patterns of precipitation, frequency of drought, forest fires and pests and pathogen epidemics. Climate models have not been able to provide reasonable conclusions. However, there is agreement that many tree species in moist tropical forests are sensitive to drought and may face migration and mortality. There is also agreement that forest fire frequency and severity is also increasing.

Dry tropical forests have characteristics that develop under seasonal rainfall regime. Monsoon rains occur only in a certain part of the year for 2-3 months and these forests face long periods of heat and drought. There is likelihood that significant parts of these forests are going to be under severe climate change stress due to over exposure to high temperatures and lower rainfall. The productivity of these forests is likely to decrease due to climate change and associated increased risk of fires, pest and pathogen attacks and other drivers.

There are evidences that plantation forests created by afforestation and reforestation are showing increased growth rates and productivity due to increased CO2 the atmosphere. However, the effect of increased fire frequency and intensity, drought, pathogen, and storms have not been taken into account that will affect or offset the increased productivity. The plantation forests are also vulnerable due to their even aged and single species composition that makes them less resilient. It is believed by scientists that uneven aged and mixed species tree plantations are better equipped to face climate change stress, are more resilient and have better chance of surviving.

It is well recognized that earth’s forest ecosystems are vulnerable to climate change impacts; the only question remains is the severity in different regions. Certain changes are being observed in forest ecosystems and are being attributed to rising global temperature and changed precipitation patterns. On the other hand, there are indications that the productivity of boreal forests is increasing due to increased temperature. There is likelihood that the climate change will lead to species migration, tree mortality, early tree flowering and seed production, early leave fall among deciduous species, pest and pathogen epidemic, droughts, absence of natural regeneration as well as loss of biodiversity and even species extinction. Changes are likely to increase both forest fire frequency and intensity.

Some forests in temperate regions may expand northward and in some tropical regions forest cover and area may reduce. Unsustainable land use and non-availability of water in many tropical regions may result in forest species die back. There are observations in south Asia that Tectona grandis (teak) and Shorea robusta, two valuable timber species, are showing top dying phenomenon and it is expanding to large areas. Although scientific research and data are lacking, the changes are closely associated with climate change.

The adverse impact on forest health and productivity will reduce availability of ecosystem services and goods from forests that will adversely affect local communities that depend on forests for sustenance and livelihood in the tropical countries of Africa, Asia and Latin America. These countries are likely to suffer the worst impact that may be difficult to visualize today.

It is a matter of concern that there appears to be no preparedness to face the climate challenges. The approach is one of watching passively and even a feeling of skepticism about the scientific forecast as emerges from climate change models. The adaptation strategies for forest ecosystems are lacking.cropped-IMG_2762.jpg

There is also a sense of lack of clarity as to what exactly would be the impacts, and what would be the intensity and which species and ecosystems will be more vulnerable than the others. It remains difficult to make exact or tenable forecasts on these issues. In view of the complexities of the natural ecosystems, modeling for scenario forecasting has its own limitations. Many people tend to argue that the best course is watch and observe the changes taking place and at what speed as well as resilience of these systems. The predictions point out that the impacts will be highly conspicuous and even irreversible in the second half of this century.

Human species will survive climate change?

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Irshad Khan

Catastrophic climate impacts threatening survival of human race are inevitable if business as usual continues resulting in ever increasing green house gas (GHG) emissions intensity and addition of GHG concentration to the earth’s atmosphere. However, if actions are taken by all members of the international community, both developed and developing countries aiming at reducing emissions of GHG and sincere efforts are made to reduce GHG concentration in the atmosphere, the future survival of human as well as other animal and plant species will be assured.

It is evident from the Paris Agreement on Climate Change (2016) that the global community has arrived at a consensus that that our planet’s average atmospheric temperature increase should be limited to 2 degree C from pre-industrial revolution temperature by 2050. Actions to mitigate climate change are found expression in the intended nationally determined contributions (INDC) submitted to the Secretariat of the United Nations Framework Convention on Climate Change (UNFCCC) by most countries have done it and the other are in the process preparing and submission.

It is a well recognised fact that GHG emissions have not peaked as yet and many developing countries and emerging economies are increasing their emission intensity as well as per capita emissions with the justification that they are at a development stage when they are compelled to use increasing energy from fossil fuels to make progress and reduce poverty in their respective countries. They also assert, from time to time, the principle of equity and climate justice along with that of common but differentiated responsibilities (CBDR), though these principles have been diluted in recent international climate change negotiations. For example, both China and India (China being the highest emitter) intend their emissions peaking around 2030. Similar is case with countries like Brazil, Russia and South Africa. Simultaneously these countries are also taking steps to reduce dependence on fossil fuel based energy and increase share of renewable energy gradually.

The Paris Agreement has given hope to our society. It is a scientific fact that the strongest instinct that all animals have is “survival”. They fight back attacks, resist threats and use all their energies both physical and mental to save their lives. A question arises whether human species has come to possess that collective consciousness and instinct today? Historically, it did not and this is one species that has been killing and destroying its own kind. The most primitive instinct of man has been to create security by killing others perceived as threat. The ancient tribal battles, invasions, occupation of other countries and land, extermination of villages and towns by invading and conquering armies, expansion of territories, colonisation other countries and exploitation of fellow human beings-have characterised human attitude and behaviour.  This trait appears to be deep rooted in our unconscious and subconscious mind and human egoistic approach is reflected in our social, economic and political system.

One striking difference in case of climate change appears to be that it is challenging one and all members of human community. The GHG emissions diffuse throughout earth’s atmosphere quickly irrespective of where the source is. Even the most powerful economies have no power to prevent the emissions from traveling.

Should collective risk and threats raise level of human consciousness to be ready to face climate change disasters or even to reverse these? Or will collective catastrophe and  miseries provide solace in accepting as a day of doom for all.

There is a hope in the wisdom of mankind that they will face this challenge collectively, unite to take remedial measures, change their life styles, mitigate impacts and mobilise resources and organise adaptation to climate change.  This and this alone will ensure survival of human species beyond 2050 and 2100 AD.