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Scientific Facts on Forests & Energy

Introduction – What role can forestry and agriculture play in energy production?


While the global demand for energy is soaring, the sources from which energy is derived are changing. This change is induced primarily by concerns over high fossil fuel prices, greenhouse gas emissions and fossil fuel import dependence.


Alternative forms of energy have gained popularity as a way to address these concerns. For instance, bioenergy derived from biological materials such as wood, agricultural crops and wastes, or dung is used. If sustainably managed, bioenergy derived from plants can be considered renewable because new trees or other plants can replace those that have been converted to energy. Its net benefit in terms of climate change mitigation depends on the balance between carbon dioxyde (CO2) captured during plant growth and CO2 released when producing, processing, transporting and burning the fuel.


Increasingly, agricultural crops such as oil palm, sugar cane, maize, rapeseed, soybeans and wheat, are being used to produce liquid biofuels, mainly to power vehicles. But the increased use of agricultural lands for growing energy crops may compete with food production, causing increased food prices and deforestation. This has raised questions about the true role of such biofuels in mitigating climate change. A new generation of biofuels derived from wood, agricultural and forestry residues, and certain grasses is being developed. It is expected to be more energy efficient and to generate less greenhouse gases than current generation biofuels (i.e. made from agricultural crops), without competing with food supply. If sustainably managed, large forested areas could serve as a source for these second-generation biofuels.


What are the trends and prospects of energy supply and demand?


In coming years, the world’s demand for energy is expected to increase considerably as a result of population growth and economic development, mostly in Asian countries. Although fossil fuels will play a major role in meeting that increased energy demand over the next 20 years, policy decisions will heavily influence the types of energy sources that will be used.


The share of renewable energy on the global energy market is expected to increase slightly until 2030. The biggest growth in renewable energy production will likely occur in North America, developing countries in Asia and Central and South America. The United States, China and India will remain the top three consumers of liquid biofuels. Overall, renewable energy sources will continue to be used primarily for heating and cooking, but their contribution to power generation and transport will increase.


Wood-based energy is used both for domestic and industrial purposes. Countries such as the United States, Canada, Sweden and Finland often use by-products of wood processing to produce electricity. Developing countries mainly use fuel wood and charcoal for domestic heating and cooking, but increasingly also for commercial activities such as fish drying, tobacco curing and brick baking. Their consumption is growing due to population growth, particularly in African and South American countries.


Future energy choices will primarily depend on the price of fossil fuels, on the availability of alternatives and on political priorities such as mitigating climate change or reducing dependence on fuel imports.


How is bioenergy produced?


Bioenergy can, for instance, be derived from solid woodfuels, such as fuel wood and charcoal or from liquid biofuels, such as black liquor (a by-product from the paper industry) and ethanol obtained from wood. Energy from woodfuels can be produced through various processes that differ in terms of energy efficiency, installation cost, carbon dioxide emissions and amount of work needed.


Burning solid wood fuel in an open fire only converts about 5% of the wood’s potential energy, but technologies exist that can increase efficiency up to 80%. Such efficiency is achieved by combined heat and power systems, which use wood to produce both heat and electricity, and by some modern furnaces that burn wood pellets made of dried, ground and pressed wood residues.
Other technologies include power boilers which burn wood wastes from sawmills to generate electricity and gasification, which is the process of heating wood residues to a very high temperature to produce gas that can in turn be burned very efficiently to produce heat and power.


First generation’ liquid biofuels include biodiesel and bioethanol and are derived from various food crops that vary by geographical location, for instance cereals, rapeseed and sugar cane. These biofuels have attracted a lot of attention because of their relatively low prices and advanced state of development. However, the increasing use of certain food crops for biofuels production can in some cases significantly raise global greenhouse gas emissions as a result of deforestation and land degradation. Recently, new plant species have been tested that grow well on marginal lands and could therefore produce biofuels without directly competing with valuable lands.


In addition, technological developments are expected to increase future interest in more efficient ‘second generation’ liquid biofuels, which are not derived from food crops, but from plant materials such as agricultural residues, forestry residues, and wood from forest plantations.


How much can forestry contribute to future energy demand?


To what extent forestry will contribute to future energy production will depend on a series of factors: the ability of wood-based energy to meet the recent energy policy objectives, the socioeconomic and environmental costs and benefits of wood energy production, and the policies and institutions that determine forestry practices. Developing countries often tend to have small budgets and will therefore need to carefully assess the risks and benefits of investing in bioenergy technologies.


The amount of energy that can be generated from the residues of forestry operations is considerable. Efficient methods of harvesting and transportation could further reduce the cost and environmental impacts of producing such energy. Most of the wood for future bioenergy production will likely come from existing forestry operations unless economically competitive technologies for the production of second-generation biofuels become available. Forest plantations are another major source of wood energy that will likely increase in the future. To be economically viable, such plantations will require efficient harvesting, good logistics, and high-productivity.


The efficiency of liquid biofuels in terms of greenhouse gas emissions compared to petroleum motor fuels varies from one type of biofuel to the other. The greatest decreases in greenhouse emissions result from the conversion of whole plants to liquid biofuels. In terms of cost efficiency, sugar cane is currently the most economically attractive option for liquid biofuel, but future technological developments could make wood-based second-generation biofuels competitive.


What are the implications of increased use of bioenergy?


Bioenergy has the potential to promote economic well-being, allow better use of unproductive land, increase energy security and reduce greenhouse gas emissions. However, this potential can only be realized by also addressing problems associated with the large-scale production of biofuels, such as poverty, impacts on biodiversity and climate change, and water scarcity.


The expansion of bioenergy can have both positive and negative impacts on livelihoods. It may create more jobs and improve energy security. However, it may also lead to land disputes and human rights abuses, particularly when large energy plantations are involved. Competition for land and agricultural products may raise farmers’ incomes but also food prices


A growing demand for bio energy could result in deforestation to make way for agricultural land, but on the contrary agricultural land could be converted into wood plantations if wood becomes the main resource for bioenergy. Depending on how it is done, using degraded lands for the expansion of bioenergy plantations could have either positive or negative effects on soil fertility, erosion, ecosystems,biodiversity, water flow and food availability. Given the many advantages and drawbacks to bioenergy development, countries must consider the long-term environmental, social and economic impacts of various energy alternatives.


How should bioenergy policies be developed?


To counteract the potentially adverse socio-economic and environmental impacts of large bioenergy projects, effective land-use planning is needed. In addition, information transfer from developed to developing countries should be encouraged.


National forestry and energy goals should reflect the principles of sustainable development and sustainable forest management. In particular, forestry and energy policies should:
• integrate bioenergy issues into forestry, agricultural and other land-use policies;
• consider environmental, economic and social impacts;
• ensure information is readily available to anyone involved in the management of forest resources;
• consider areas such as land-use management, rural employment, and environmental protection to seek synergies and avoid negative impacts;
• facilitate bioenergy development through research, education and training, and through transport and infrastructure measures;
• find a balance between agriculture and forestry, as well as between domestic and imported sources of biomass;
• consider the impacts of bioenergy on other economic sectors;
• undergo regular monitoring to avoid negative environmental and social impacts; and
• prevent the destruction of natural resources and the loss of biodiversity.
The current situation represents a major opportunity for the forestry sector to contribute to increasing energy security and mitigating climate change by reducing dependence on fossil fuels.


Conclusions


In coming years, the world’s energy consumption is expected to increase dramatically, particularly in Asia. While fossil fuels will account for most of the increased energy supply, renewable sources of energy will also gain importance, as a result of concerns over high fossil fuel prices, increasing greenhouse gas emissions and energy import dependence.
Bioenergy, including energy derived from wood and other plant materials, accounts for a significant proportion of the current energy supply from renewable sources. In many of the world’s developing countries, fuel wood and charcoal (traditional bioenergy) remain the primary source of energy. In industrialized countries and particularly countries with large wood processing industries, wood energy is used for both domestic and industrial purposes.
Currently most liquid biofuels are produced from food crops and yield low economic and environmental benefits compared to fossil fuels. The increased use of these crops for energy production may even compete with food supply and lead to increased deforestation. However, it is expected that a new generation of liquid biofuels will become available in the next decade using wood as well as agricultural and forestry residues. This technology is expected to become commercially competitive and generate much less greenhouse gases compared to fossil fuels. Such second-generation liquid biofuels produced from woody biomass rather than from food crops would also reduce competition with food production.
Wood-based energy is among the most efficient sources of bioenergy. At present, it is particularly competitive when using wood residues from the wood processing industry.
To avoid negative environmental and socioeconomic impacts, the expansion of biofuel production will need to be accompanied by clear and well enforced regulations.
Future demand for bioenergy will depend largely on the policy measures that will be adopted.

What is causing the present-day changes in climate?



It is very likely that a significant part of temperature variability in the Northern hemisphere during the past seven centuries prior to 1950 is due to volcanic eruptions and changes in the intensity of solar radiation. However, most of the observed increase in global temperature since then is very likely due to the observed increase in atmospheric greenhouse gas concentrations due to human activities. Human activities now clearly affect other aspects of climate, including ocean warming, continental-average temperatures, temperature extremes and wind patterns.

It is likely that these increases in greenhouse gas concentrations alone would have caused more warming than observed, had volcanic and human-induced aerosols not offset some of the warming that would otherwise have taken place.

Current climate models that simulate the observed temperature evolution on each of six continents provide stronger evidence of human influence on climate than was available in the 2001 Third Assessment Report (TAR). Difficulties remain in simulating temperature changes at smaller scales, where natural climate variability is larger and makes it harder to estimate the current and future impact of greenhouse gas increases due to human activities.

How has climate changed in the past?

Studies of past climate have allowed inferences to be made about past changes in global climate on time scales ranging from a few decades to millions of years. The uncertainties related to these conclusions on past climate generally increase with time into the past.

This information on past climate show that the overall temperatures of the last half century is unusual in at least the previous 1300 years. The last time that the climate was significantly warmer than now for an extended period (about 125,000 years ago, during the last interglacial period), reductions in polar ice volume led to 4 to 6 metres of sea level rise

What changes have been observed so far in climate?


Since the Third Assessment Report (TAR), improvements in terms of data, geographical coverage, understanding of uncertainties, and variety of measurements have allowed for a better understanding of how climate is changing in space and time. The warming of global climate is unequivocal and is evidenced by numerous observations of increasing air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.Eleven of the last twelve years (1995 -2006) rank among the 12 warmest years ever recorded since global surface temperatures are measured (1850). Over the last 100 years, (1906–2005) there has been an increase in surface temperature of 0.74°C, which is larger than the 0.6°C increase given in the TAR for the 1901-2000 period. And the warming trend over the last 50 years (0.13°C per decade) is nearly twice that for the last 100 years. Temperatures in the higher atmosphere and in the oceans (to depths of at least 3000m) have also been rising, along with the water vapor content of the atmosphere. Mountain glaciers, snow cover and ice caps have declined on average in both hemispheres, contributing in part to the rise of global sea level. The Greenland and Antarctic ice sheets have also contributed to the observed rise of sea level, which amounted to 17cm in total over the course of the 20th century.
At continental, regional, and ocean basin scales, numerous long-term changes in climate have been observed. These include changes in Arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather including droughts, heavy precipitation, heat waves and the intensity of tropical cyclones.Some aspects of climate have not been observed to change. The difference of temperature between day and night, for example, has remained the same, since daytime and nighttime temperatures have risen by the same amount. Contrary to sea ice in the Arctic, there has been no significant decrease in sea ice in Antarctica, which fits with the lack of observed warming in Antarctica

What makes the climate change?


The Earth’s climate is influenced by many factors, such as the amount of greenhouse and aerosols in the atmosphere, the amount of energy coming from the sun or the properties the Earth’s surface. Changes in those factors, through human-related or natural processes, have a warming or a cooling effect on the planet because they alter how much of this solar energy is retained or reflected back to space.
The concentrations in the atmosphere of greenhouse gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) have all increased markedly since 1750, and now exceed by far their pre-industrial levels.
Carbon dioxide is the most important anthropogenic greenhouse gas. Its concentration in the atmosphere (379 ppm in 2005) is now far higher than the natural range over the last 650 000 years (180 to 300 ppm) and is growing faster than ever since the beginning of its continuous direct measurement in 1960, mainly due to fossil fuel use and to a lesser extent to land use change. For instance, emissions of carbon dioxide from fossil fuel use increased from 6.4 Gt per year in the 90s to 7.2 Gt of carbon per year over the period 2000-2005. Concentrations of methane and nitrous oxide in the atmosphere have also greatly increased since pre-industrial times, and those increases are mostly due to human activities such as agriculture and fossil fuel use.
The effect on climate of each of the different drivers is expressed in terms of “radiative forcing”, with positive forcing causing a warming of the surface and negative forcing a cooling of it. The overall effect of human activities since 1750 is very likely (> 90% certainty) to be one of warming, with an estimated increase of energy, or radiative forcing, of 1.6 Watt per square meter over the whole planet. The relative contribution of various factors can be seen in figure 2. The main warming drivers are the various greenhouse gases and it is likely that the warming that they cause has been increasing during the industrial era at a higher rate than at any time over the last 10 000 years. The main cooling drivers are aerosols and the changes in cloud cover that they cause.

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