BELEM, Brazil (AP) -- The Amazon rainforest is a massive area, twice the size of India and sprawling across eight countries and one territory. It's a crucial carbon sink for the climate, has about 20% of the world's freshwater reserves and boasts astounding biodiversity, including 16,000 known tree species.
But governments have historically viewed it as an area to be colonized and exploited, with little regard for sustainability or the rights of its Indigenous peoples.
Now, as those governments seek to clamp down on a Wild West atmosphere of resource extraction, human rights abuses and environmental crime, collaboration across borders is a must. That's a major goal of the two-day Amazon Summit that opens Tuesday in Belem, where Brazil will host policymakers and others to discuss how to tackle the immense challenges of protecting a critical resource in stemming the worst of climate change.
Here's a rundown of the Amazon's importance, the threats it faces and possible solutions.
WHAT ARE THE MAIN ENVIRONMENTAL THREATS TO THE AMAZON BIOME?
Deforestation ranks first. The Amazon biome has lost more than 85 million hectares (211 million acres), or about 13% of its original area, according to the Monitoring of the Andean Amazon Pact.
Most of that destruction has come in the past half-century, with Brazil -- home to two-thirds of the rainforest -- the main culprit.
Cattle ranching and soybean crops have expanded dramatically thanks to new technology, highways, and global demand for grain and beef. Mostly controlled by settlers of European descent who migrated from other parts of the country, the ranching and farming have reshaped local culture in aspects ranging from people's diet to their music.
Nowhere is the devastation more sweeping than in Brazil's Para state, where Belem is the capital. Forty-one percent of deforestation in Brazil's Amazon has come in Para state, where so much land has been converted to run some 27 million cattle that it's the leading emitter of greenhouse gases among Brazilian states, according to Climate Observatory, a network of environmental nonprofit groups.
It emits more than every other country with Amazon rainforest: Colombia, Peru, Ecuador, Venezuela, Bolivia, Suriname, Guyana and the territory of French Guiana.
Other environmental threats are large hydroelectric dams, especially in Brazil; illegal logging; mining; and oil drilling, with effects on water contamination and disruption of Indigenous lifestyles. Underinvestment in infrastructure also means much of the sewage from homes in the rainforest dumps directly into waterways.
The Amazon has also seen more extreme weather events -- flooding and drought -- in recent years.
HOW IMPORTANT IS THE AMAZON TO ARRESTING CLIMATE CHANGE?
Climate change is made worse when plants that take up carbon are lost. And the Amazon functions as a massive device to store carbon.
Atmospheric chemist Luciana Gatti, a researcher for Brazil's National Institute of Space Research, said deforestation leads to more greenhouse gases in the atmosphere and generally means reduced rainfall and higher temperatures.
"By deforesting the Amazon, we are accelerating climate change," Gatti told The Associated Press.
She co-authored a study published in the journal Nature that found that the heavily deforested eastern Amazon has ceased to function as a carbon absorber and is now a carbon source. Gatti said half of the deforestation in the eastern Amazon needs to be reversed to maintain the rainforest as a buffer against climate change.
COULD DEFORESTATION REACH A 'TIPPING POINT'?
Oft-quoted research by Earth system scientist Carlos Nobre and late environmental scientist Thomas Lovejoy estimated that 20% to 25% deforestation would be a critical threshold for the Amazon. The resulting decline in rainfall would transform more than half of the Amazon to tropical savannah, with great biodiversity loss, they said.
That kind of change is already happening in Xingu Indigenous Territory, in Brazil's southern Amazon, which has become an island surrounded by soybeans and pasture and where researchers have highlighted forest degradation due to persistent droughts, fires and agricultural practices.
But some researchers have questioned the tipping point theory for using computer models to predict outcomes in such a large and complex region.
Others have said that an even bigger threat is global climate change. Researcher David Lapola, who is part of a project that investigates how the Amazon responds to higher carbon dioxide levels, argues that even if deforestation in the Amazon basin were to cease immediately, the forest would still face the risk of reaching a tipping point due to what is happening worldwide.
WHAT OTHER THREATS FACE THE REGION?
Road paving and organized crime.
Governments initially hacked roads through forest so settlers could reach far-flung lands, but heavy rains and use regularly wrecked those dirt roads. Paving them made for easier access -- and made it easier to move agricultural products, too.
But that also helped lawbreakers reach pristine areas to extract ancient hardwood timber and clear forest for ranching. The roads have been called "arteries of destruction" and often generate deforestation resembling a fish skeleton, with smaller dirt roads branching off the spine of an official road.
Even more important for criminal organizations to take root has been political corruption and lax law enforcement. Few border areas are policed seriously and there has been scant international cooperation as rivals compete for drug trafficking routes. Drug seizures have increased in Colombia, Brazil, Bolivia and Peru over the past decade, the United Nations Office on Drugs and Crime (UNODC) reported in June.
Homicide rates in Amazon municipalities are sometimes double or triple already high national averages, said Rob Muggah, founder of the Igarape Institute, a security-focused think tank. Scarce opportunity helps criminal groups recruit poorer residents, especially those without education or employment. And the crime reinforces chronic underdevelopment, turning into a vicious cycle, Muggah said.
Traffickers have diversified into businesses like "narco-deforestation" -- laundering trafficking profits into land for agriculture -- as well as financing and logistics for illegal gold prospecting that lays waste to the forest and poisons waterways, according to the UNODC report.
CAN THE AMAZON BE DEVELOPED WITHOUT ENVIRONMENTAL DESTRUCTION?
The Amazon is so big and complex that there's no single solution for developing different regions, said Marcelo Salazar, a veteran of environmental nonprofit and consultancy work who now leads a company making food supplements with natural products from the Amazon.
But there are some commonalities, he said. First, governments must provide health, education and protection of land rights for a forest economy to function. Subsidies for products that come from the forest would help, too; for example, making traditional oil from babassu palm more competitive with soy oil from Brazil's vast plantations.
There also needs to be greater development of local expertise in communicating the Amazon's challenges and its promise, both to help outsiders understand and to attract investors.
"There are still few experiences we have as models that stand in opposition to the destructive models," he said.
Environmental activists have long advocated so-called bioeconomy alternatives for the tens of millions of people living in Amazonia, but investors have been wary. In order for such proposals to take off, risks must be low enough for larger enterprises to expect returns, which means stronger policing and anti-corruption measures, said Igarape's Muggah.
"Punctual interventions and pilot projects are excellent; we need those to be able to understand what's going to work and what doesn't. But we need to back that up with real punch, real investment, real economic resources," he said.