The arrival of refugees fleeing Syria's brutal civil war and other conflict zones has been the single most contentious issue in European politics over the past several years. Although the number of arrivals has fallen dramatically since peaking in 2015, many EU countries still host huge migrant populations, and remain deeply divided over refugee policy. Here's a look at where things stand today, based on the most recent available data.

International Literacy Day, which falls on September 8, was designated by UNESCO to celebrate advancements made in global literacy rates, and to highlight the chasm that still exists between education standards in different parts of the world. While in recent decades huge strides have been made in reducing illiteracy in low-income countries, 30 percent of adults from these regions will still be illiterate by 2030, according to UNESCO. Here's a look at the change in adult literacy around the world from 1987-2016.

August 29 marked International Day Against Nuclear Tests, which aims to call attention to the effects and dangers of nuclear explosions. The economic and human cost of nuclear testing over the past seventy years has been well documented, leading to a vocal movement calling for a total ban on nuclear tests. Partial test bans were agreed during the Cold War but in 1996 the US became the first of more than 180 countries to sign a treaty that completely banned nuclear tests. Just three years later, however, the US Senate rejected it over concerns it was unenforceable and would tie Washington's hands. The treaty has not been ratified by India, Pakistan or North Korea – all of whom have tested nuclear weapons since 1996. Overall, more than 2,000 tests have been conducted by just eight countries. Here's a look at who has exploded the most nuclear warheads over the past 70 years.

Wrecking the global economy's hopes for a relaxing late-August Friday, China and the US have taken fresh shots at each other in their deepening trade war.

First, China announced new tariffs on US goods in response to US levies on China's exports that are set to take effect next month.

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Over the past fifty years, the Amazon rainforest has shrunk by an area equal to the size of Turkey. In the 1960s and 1970s, the Brazilian government supported settlement of the sparsely populated region for security reasons. Since then, huge swaths of the forest -- which is crucial for limiting the world's greenhouse gasses -- have been cleared for farmland used to feed Brazil's population and support its massive agricultural exports. Greater awareness of the environmental impacts in the 1990s produced tighter conservation regulations, though plenty of illegal clearing continues. In recent years, the annual deforestation rate has begun to rise again, and Brazil's new president Jair Bolsonaro has pledged to weaken regulations further in order to support businesses.

The 20th of August marked 400 years since the first slave ship arrived in North America. Slavery would not be outlawed in the United States for another two-hundred and fifty years after that. And while most countries on earth have since abolished slavery (though some barely a generation ago) the practice of owning human beings and forcing them to work persists. Here is a snapshot of forced labor in the world today.

For facial recognition technology to work in the public sphere, you need two things: really good software and lots of cameras. Much has been made of China's use – and export – of facial recognition technology for security and policing purposes, but when it comes to Big Brother-style surveillance of public spaces, plenty of European and American cities have a huge number of eyes in the sky too. As these cities deploy facial recognition software with increasing frequency, the ethical and legal battles are only just beginning.

Boris Johnson is the latest in a long line of UK prime ministers who attended Eton College, an elite boarding school near London. Since the 1720s, just three schools – Eton, Harrow School, and Westminster School – have produced a majority of the country's leaders. Here's a snapshot of where other prime ministers spent their formative years.