- Thousands of fires are ravaging the Amazon rainforest - the most intense blazes for almost a decade.
- The smoke has been travelling as far as the Atlantic coast. It has even caused skies to darken in São Paulo - more than 3,200km away.
- The Amazon basin - home to about three million species of plants and animals, and one million indigenous people - is crucial to regulating global warming, with its forests absorbing millions of tonnes of carbon emissions every year.
Thousands of fires are ravaging the Amazon rainforest in Brazil - the most intense blazes for almost a decade.
The northern states of Roraima, Acre, Rondônia and Amazonas as well as Mato Grosso do Sul have been particularly badly affected.
However, images purported to be of the fires - including some shared under the hashtag #PrayforAmazonas - have been shown to be decades old or not even in Brazil.
So what's actually happening and how bad are the fires?
There have been a lot of fires this year with Brazil having seen the record number of them in 2019 according to the Brazilian space agency.
The National Institute for Space Research (Inpe) says its satellite data shows an 85 percent increase on the same period in 2018.
The official figures show more than 75,000 forest fires were recorded in Brazil in the first eight months of the year - the highest number since 2013. That compares with 40,000 in the same period in 2018.
CAUSE OF THE FIRES
Wildfires often occur in the dry season in Brazil but they are also deliberately started in efforts to illegally deforest land for cattle ranching.
"The dry season creates the favourable conditions for the use and spread of fire, but starting a fire is the work of humans, either deliberately or by accident," Inpe researcher Alberto Setzer told Reuters news agency.
Ricardo Mello, head of the World Wide Fund for Nature (WWF) Amazon Programme, said the fires were "a consequence of the increase in deforestation seen in recent figures".
Activists say the anti-environment rhetoric of Brazilian President Jair Bolsonaro has encouraged such tree-clearing activities.
In response, Mr Bolsonaro, a long-time climate sceptic, accused non-governmental organisations of starting the fires themselves to damage his government's image.
He later said the government lacked the resources to fight the flames.
MOST AFFECTED AREAS
The north of Brazil has been the worst-affected region.
Roraima, Acre, Rondônia and Amazonas all saw a large percentage increase in fires when compared with the average across the last four years (2015-2018).
Roraima saw a 141 percent increase, Acre 138 percent, Rondônia 115 percent and Amazonas 81 percent. Mato Grosso do Sul, further south, saw a 114 percent increase.
Amazonas, the largest state in Brazil, has declared a state of emergency.
SMOKE AND CARBON
The fires are emitting large amounts of smoke and carbon.
Plumes of smoke have spread across the Amazon region and beyond.
According to the European Union's Copernicus Atmosphere Monitoring Service (Cams), the smoke has been travelling as far as the Atlantic coast. It has even caused skies to darken in São Paulo - more than 2,000 miles (3,200km) away.
The fires have been releasing a large amount of carbon dioxide, the equivalent of 228 megatonnes so far this year, according to Cams, the highest since 2010.
They are also emitting carbon monoxide - a gas released when wood is burned and does not have much access to oxygen.
Maps from Cams show this carbon monoxide - toxic at high levels - being carried beyond South America's coastlines.
The Amazon basin - home to about three million species of plants and animals, and one million indigenous people - is crucial to regulating global warming, with its forests absorbing millions of tonnes of carbon emissions every year.
But when trees are cut or burned, the carbon they are storing is released into the atmosphere and the rainforest's capacity to absorb carbon emissions is reduced.
OTHERS COUNTRIES AFFECTED
A number of other countries in the Amazon basin - an area spanning 7.4m square km - have also seen a high number of fires this year.
Venezuela has experienced the second-highest number, with more than 26,000 fires, with Bolivia coming in third, with more than 17,000.
The Bolivian government has hired a fire-fighting airtanker to help extinguish fires in the east of the country. They have so far spread across six square km of forest and pasture.
Extra emergency workers have also been sent to the region, and sanctuaries are being set up for animals escaping the flames.