From time to time rays of hope for the survival of the Amazon rainforest shine through the ever-gloomy forecasts for the region. For example, Brazil recently reported that the rate of deforestation from Aug. 2011 through July 2012 was 27% lower than that of the previous 12 months and the lowest since its National Institute for Space Research (INPE) began issuing such reports in the 1980s. Despite such glimmers, though, the big-picture reality is one of a region under relentlessly intensifying pressure from expanded farming, ranching, road projects, human settlement, oil and gas drilling, mining, hydroelectric development and fires.

That’s the impression gained from a report issued last month by the Amazonian Network of Georeferenced Socio-Environmental Information (RAISG), a regional initiative to enable and promote cooperation in Amazon countries among institutions that work with georeferenced socio-environmental information. The report, based on data sources from each country, shows that during the first decade of this century, the Amazon lost 240,000 square kilometers (92,665 sq miles) of forest—an area larger than the whole of Guyana.

Titled “Amazonia Under Pressure,” the report includes an “atlas” of maps detailing the impact of six factors in particular: roads, oil and gas development, government-granted mining concessions, hydroelectric dams, deforestation and “hot spots” where fires were set—most likely on purpose to clear land. One of the study’s most striking findings is “the degree of threat in the Andean headwater regions of the Amazon because of mining, oil and hydroelectric plants,” says Beto Ricardo of the Socio-environmental Institute, a Brazilian think tank that is part of RAISG. Says Ricardo: “The atlas can be considered a baseline for monitoring these issues.”

The parts of Amazonia affected the least were protected areas and indigenous territories. But even these are feeling the pressure from infrastructure and extractive projects. “In [indigenous] communities, people value the forest,” says Richard Chase Smith, director of the Institute of the Common Good in Lima, which belongs to the RAISG consortium and contributed to the report.

Indigenous communities have an easier time defending their land when they have title to it, Chase Smith notes, because they have legal grounds to ward off outsiders. But many indigenous territories in the region remain untitled. In Peru, the Institute of the Common Good is part of a group of organizations lobbying the government to complete the titling of indigenous communities.

Scientists studying Amazonian ecosystems warn that besides causing the loss of biodiversity, deforestation fragments the forest, drying the understory and making it more susceptible to fire.

Because transpiration produces as much as half of the moisture over the Amazon, such forest loss also can reduce precipitation thousands of kilometers away. This causes the drying of more forest, threatens the livelihoods of small and large farming operations and depresses water levels in rivers that Brazil in particular depends on to generate hydroelectricity.

“Deforestation, fragmentation, regional climate, global climate and the implications for species—all these things are connected,” says biologist Kenneth Feeley of Florida International University, who studies the impact of climate change on tree species and is not connected with RAISG. “We’ve always recognized that at the individual level, or the species or population level; but these connections expand to a huge spatial scale and very large global processes.”

The jury is still out on whether the Amazon is nearing a “tipping point” that might throw it into unstoppable decline, but researchers say human pressures combined with a changing climate are raising the threat to unprecedented levels.

A “once-in-a-lifetime” drought in the western Amazon in 2005 was accompanied by fires that leapt as high as the forest canopy in the western Brazilian state of Acre. That was a first, says Foster Brown, a senior scientist at the Woods Hole Research Center in Massachusetts and professor at the Federal University of Acre, who studies land-use change in Acre.

Using satellite data, scientists calculate that some 700,000 square kilometers (270,000 sq miles) of forest were seriously affected by the drought. The trees had not yet recovered when an even more severe drought struck in 2010.

In one hard-hit area in Peru’s Ucayali region, the dieback is visible from the air, with the tree canopy appearing as a mottled gray-green. Flying over that area last September in a twin-engine plane equipped with spectrometers and a laser imaging system, tropical ecologist Greg Asner of the Carnegie Institution for Science at Stanford University estimated that the dieback could have affected as much as half the forest there.

From the plane, Asner had a clear view not only of that natural dieback, but also of human pressures—pastures, a large oil-palm plantation, deforestation along roads and thick columns of smoke rising from newly cleared farms.

Farming and ranching remain the main causes of deforestation in the Amazon, where farmers use fire to clear new land and to remove brush and ticks from pastures and fields. RAISG’s analysis of “hot spots”—fires that show up on satellite images, although without enough data to determine their exact size—shows about 1.32 million fires in the Amazon region between 2000 and 2010. Ninety percent were in the Brazilian Amazon, especially in an arc in the southeast, where farming and ranching have steadily encroached. Of the remaining 10%, the largest number was in Bolivia, followed by Venezuela, Peru and Colombia.

In the Amazon, a single human action sets off a chain reaction. Building or paving a road, which provides access to markets, encourages farmers to clear land and loggers to cut timber. Logged forests are more susceptible to fire, which further degrades them (See “Western Amazon losing fire-resistant image”—EcoAméricas, Oct. ’11).

Mines, oilfields and hydroelectric dams can attract thousands of construction workers, some of whom might eventually settle in the area to farm or operate businesses. Throughout the Amazon, cities are expanding, and in Peru the fastest population growth is in the Amazonian departments, as people migrate from the highlands to farm or work in mining camps.

Roads and settlement also follow other economic activities. For instance, Ecuador has the Amazon region’s highest density of roads largely because of roads built for access to oil fields, according to the RAISG report.

An earlier study in Peru raised a similar concern about the broader impact of hydroelectric dams. (See “Report calls for Amazon basin-wide assessment of dam plans”—EcoAméricas, April ’12). As of last year, 171 hydroelectric plants were operating in the Amazon region and another 246 were on the drawing board, according to the data gathered by RAISG. Dams alter river flows and disrupt fish migration, while construction may lure thousands of people to remote parts of the region, as has been the case with the project underway to build the 11,283-megawatt Belo Monte dam on Brazil’s Xingu River.

Although mention of the Amazon conjures images of trackless rainforest, there is also increasing demand for the region’s underground resources.

Amazonian mining runs the gamut from open-pit bauxite and iron mines in Brazil to dredges scooping up sediment along rivers in search of gold. Government-granted mining concessions cover 1.6 million square kilometers (617,763 square miles), or 21% of the Amazon basin, according to RAISG. Projects covering about half that area are in the application phase, while those encompassing most of the rest have progressed to exploration or production. These concessions overlap 281,000 square kilometers (108,495 square miles) of protected areas, or 15% of all protected areas in the region. If illegal mining could be tallied accurately, the footprint would be larger still.

There are also 232 oil and gas leases in the exploration or production phase, with over 100 more being developed on the drawing board. Although Ecuador has the largest number of Amazonian leases in production, Peru has the largest share of its Amazon territory—84%—allotted to oil and gas leases. Many of these concessions are in the biodiversity-rich area near the Andes mountains.

The RAISG report warns that while protected areas and indigenous territories provide a buffer against the deforestation that often follows human economic activities, both are still under pressure. Some 590 protected areas and 2,460 indigenous territories were affected by one or more of the activities—mining, oil and gas leases, highways, fires and deforestation—mapped by the researchers.

Deforestation dropped sharply in Brazil and Suriname between the first and second halves of the last decade, and also decreased in most other Amazonian countries, but it rose slightly in Peru and Colombia.

Feeley, who is studying how the ranges of tree species are changing to adapt to climate change, points out that every road, pasture or plantation creates barriers that some species may not be able to cross. The greater the pressure on the Amazon, he says, the greater the likelihood that species will not survive.

“I try to be optimistic,” he says, “but even under our most optimistic scenarios, it’s very depressing. There’s no way, I think, that we’re going to prevent mass extinctions. The question is just how massive are those extinctions going to be.”