BANGKOK, Feb 28 (IPS) - The good news is that with new satellite imagery, scientists can now find out exactly how much forest is left in the world and of what kind.

The bad news is: they have found forests, especially in Asia, are disappearing faster and faster.

The U.N.'s Food and Agriculture Organisation (FAO) carries out a study of tropical deforestation every 10 years. In 1980, the estimated deforestation rate for the Asia-Pacific region was two million hectares per year.

According to FAO's latest estimates, the annual rate of deforestation in Asia increased during 1981-1990 to 3.9 million hectares -- about 1.3 percent of the total forest. This is 50 percent more than the loss rate for Latin America, and Asia's forests are disappearing so fast that FAO now says it may have to do its 10-year forestry survey more frequently.

''One percent may not look like a lot, but when you consider that it has occurred over a period of 30 years, it is enormous,'' says Klaus Janz, a senior FAO forestry official.

FAO figures show the rate of deforestation is highest -- two million hectares a year -- in insular South-east Asia (Brunei, Indonesia, Malaysia, the Philippines, Papua New Guinea).

In continental South-east Asia (Cambodia, Laos, Burma, Thailand, Vietnam), the rate is 1.4 million hectares a year while in South Asia it is 1.7 million hectares.

Thanks to recent advances in science and technology, it is now possible to track down the exact amount of forests that the world loses each year as well as their causes and effects.

The state of forest lands can be determined by satellite imagery. Remote sensing can monitor and assess land use patterns. Data can be digitised and analysed using geographical information systems (GIS).

Having found a method of assessing the problem, however, forestry experts from different regions often find it difficult to arrive at a common understanding of their subject. ''When we want information on 'lowland dipterocarpus forests' from a group of countries, we may receive data about 'tropical moist forests', 'tropical rainforests', 'tropical broadleave evergreen forests', and so on. But do they all encompass the same things?'' asks FAO's regional representative for Asia-Pacific, Obaidullah Khan.

International forestry experts are meeting in the Thai capital this week to review the state of forest resources monitoring systems in the Asia-Pacific region.

Deforestation is among the most serious of the environmental problems facing the region, indiscriminate felling of forests having occurred with particular severity during the last three decades, according to the U.N. agency.

This uncontrolled dissipation of forest resources was at the centre of concern at the 1992 U.N. Earth Summit in Brazil, said Khan. The Agenda 21 blueprint for environmental action stressed the importance of forest resources monitoring and assessment for proper conservation and utilisation measures, he said.

The five-day Bangkok meeting, which ends Friday, will discuss ways to standardise forest type classification systems, assess and improve the accuracy of information, and enhance the capacities of the various countries for carrying out this work.

Incompatibility of figures over forest types among countries is only the first obstacle in collecting accurate forest resources information in many developing countries in the region, said FAO regional forest resources officer M. Kashio.

Countries have differing technological and institutional levels, with some having fully utilised modern technologies such as remote sensing information and GIS while many are still on the development stage in these technologies.

The objectives of the forest assessment work itself may also need to be reviewed to include not just volume and value of timber but also other resources of the forest such as biodiversity, soil and water conservation functions.

FAO experts now say their present forest resources assessment exercise every 10 years may not be sufficient to monitor the accelerated deforestation in developing countries.

Meeting participants include forestry officials from Bangladesh, Bhutan, Burma, Cambodia, China, India, Indonesia, Laos, Malaysia, Nepal, Pakistan, the Philippines, Papua New Guinea, Sri Lanka, Thailand and Vietnam.

They are joined by experts from Britain's Cambridge University, the Bangkok-based Asian Institute of Technology (AIT) and from other U.N. agencies, the United Nations Environment Programme (UNEP) which monitors the global environmental situation by satellite and the Mekong Secretariat which recently launched a forest resources assessment programme.