Consequences of Global Carbon Dioxide Rise | Environment

After reading this article you will learn about the consequences of global carbon dioxide rise and strategies for conservation of environmental changes induced by carbon dioxide rise.

Consequences of Global CO₂ Rise:

During primeval times, fairly good amount of CO₂ was present in the earth’s atmosphere, when water condensed to form oceans and CO₂ dissolved in the water forming carbonates. Subsequently, CO₂ level decreased with the evolution of photosynthetic organisms. In fact, the evolution of the earth’s atmosphere has been intimately linked with the development of life on earth.

Since the Industrial Revolution (1760 onwards) there has been an increase in the concentration of CO₂ in the atmosphere. In 1991, the concentration of CO₂ in the atmosphere was estimated to be 355 ppm. The overall trend is ever-increasing with time, with periodic fluctuation due to seasonal utilisation of CO₂ and excess liberation from the biological world.

There are a couple of reasons for rise of global CO₂ level. The burning of fossil fuels and the changing of land use pattern are the two important events that are intimately associated with global CO₂ rise. However, natural disasters like volcanic eruption and decomposition of forest litters also contribute considerable amount of natural CO₂ emission processes.

Predicting how fast the concentration of CO₂ in the atmosphere will rise depends on both the scale of human activity and the response of the natural carbon cycle. Undoubtedly there will be an increase in CO₂ output as a consequence of growth in the world population and economic development. These factors will increase the demand for energy and cause further land use changes.

The rate at which fossil fuels are burnt also depends on their availability and price, as well as the future development of alternative energy sources such as wind, solar and nuclear power. However, some of the greatest uncertainties lie on the reaction of the natural carbon fluxes—both oceanic and terrestrial: will photosynthesis increase as a consequence of the additional CO₂ in the atmosphere? How much will the oceans absorb and release? How might climate change feedback and increase or decrease these natural fluxes?

Atmospheric CO₂ constitute the major greenhouse gases which provide the insulation around earth surface as required for maintenance of life on earth. There is good evidence for a close relationship between the concentration of CO₂ in the atmosphere and the long-term climatic fluctuations.

The impact of CO₂ as greenhouse gas is manifold. If the other climatic factors remain stable, the concentration of CO₂ rise will directly affect the function of plants. In addition, elevated CO₂ induced temperature rise of atmosphere will also affect plant growth. Quantitative and qualitative changes in primary production will influence the animal and microbial communities that depend on this productivity.

In plants, there are three categories—C₃, C₄ and CAM type—depending on the CO₂ fixation pathways. At elevated CO₂ rise, C₃ plants will be benefited more. The rise of photosynthesis in C₃ plants is directly proportional to atmospheric CO₂ rise and rate of photosynthesis will definitely enhance. The water use efficiency in C₃ plants will also be enhanced significantly under elevated CO₂ level.

The pattern of carbon allocation is often altered when plants grow in elevated CO₂, but there seems to be great variation in the response of different species. In some species there is an increase in the allocation of resources to root growth at 700 ppm CO₂ than that of plant growth. Under conditions of non- limiting nutrient availability elevated CO₂ does appear to increase plant growth in a wide range of species, often by a considerable amount.

At elevated CO₂ level, the nitrogen use efficiency is reduced significantly that also limit the growth at certain time. In addition, CO₂-induced atmospheric temperature rise have a series of consequent changes on plants viz., alteration of photosynthetic rates, temperature induced plant growth process and productivity.

In contrast to plants, CO₂ is a waste product of metabolism in animals. CO₂ must be removed from the body parts for growth and survivality of species. There are a lot of biochemical changes in animals found due to elevated CO₂ level in atmosphere. The temperature changes in animal life induces the variation of species distribution.

The pathways by which temperature and changes in atmospheric CO₂ concentration could affect plant communities:

(a) Effect of temperature, and

(b) Effect of high CO₂ level.

It is very difficult to predict the future response of whole communities to rising CO₂ concentration, mostly because there is no recent precedent for the changes in CO₂ concentration that are taking place. In contrast, there is a lot of evidence of the effect of temperature on communities.

The impact of CO₂ rise on agriculture can be considered at three levels. On the level of individual crop response, changes in temperature, precipitation, and CO₂ concentration can have direct effects on crop performance by reasonably well-characterised mechanisms.

On regional scale, predicting changes in the yield potential of crops need to take into consideration the blend of environmental changes that occur in each region. Lastly, the extent to which agricultural practices can adapt to CO₂ and the implications for food security.

It is much more difficult to predict changes in aquatic life than in terrestrial environments, especially for large bodies of water.

The main problem is that we have a very poor understanding of the relationship between global climate and the oceans. However, climatic changes like CO₂ level rise have impact on aquatic environment which not only affects the individual species population but also whole assemblage of species.

A number of specialised aquatic environments will be affected by these changes viz., changes in coral reef life, changes in fishing ground, and overall productivity. The overall sea level changes have also direct impact on biotic life in aquatic system of ocean.

The higher atmospheric carbon dioxide levels will cause more acidity of sea water, and thus reduces the concentration of calcium availability in sea water. Many shelled animals and some types of phytoplankton that can fix calcium in their shells or skeletons and thus reduces their productivity. It may also shift the trophic relationship of the ecosystem.

With the rising CO₂ level induced global temperature change; there will be shift in plant communities, most probably the grasses, will encroach pole wards, deciduous hardwoods and grasslands will follow, temperate mixed forests are expected to lose their conifers and become dominated by broadleaf trees.

The extension of the monsoon rains towards the poles will increase the moist tropical forest cover in some areas, such as northern Australia.

A higher frequency of natural forest fires in a drier Amazon basin will not only release significant amounts of carbon into the air, it will also reduce the pumping of water by transpiration. There will be shift in cropping pattern and crop productivity in northern latitudes.

Strategies for Conservation of Environmental Changes Induced By CO₂ Rise:

Over past couple of decades, it was felt that rate of extinction of species increased due to rapid environmental changes and associated human activities. On the whole, many different threats of extinction of many different species make the conservation of genetic species and ecosystem diversity an urgent priority.

The threat of CO₂ is less immediate than others, but strategic decisions made now must take it into account. It is known that CO₂ can affect species in two ways: They may not be able to tolerate new conditions because of their physiology, and they may be affected by changing interactions with predators, parasites, competitors and mutualists.

In fact, it is needed to understand how CO₂ and climate and these interactions among species determine range, size and abundance, the effects of small size on how populations persist and why populations become small in the first place.

The main mechanism for controlling the rise in atmospheric carbon dioxide is to limit our emissions. Next would be to limit out deforestation programmes. It is estimated twelve per cent CO₂ sink could be by 2100 through above stated processes. The proposed extension of forest cover up to 865 million hectare (globally) can only reduce 54 per cent higher level of CO₂ in a hundred year time.

In addition, a variety of schemes are proposed to fix CO₂ by oceanic phytoplankton communities are proposed. But there is limitation of micronutrients like Fe⁺, which could be supplements through artificial application to increase the carbon sequestration level in oceans.

The combing of fossil fuel are to reduce CO₂ emission level is also equally important. Can planned reforestation be combined with a conservation strategy that protects the rise CO₂ level and also the biodiversity of the tropics? This may only be realistic in those countries currently able to feed themselves. Tropical reforestation can be a realistic prospect only where the needs of local people are taken into account.

However, some general rules for the design of nature reserves are given in the Table 20.1:

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