Image copyright Ben Garrison Image caption Artist and cartoonist Ben Garrison was subjected to a barrage of abuse online - and he was far from alone

A social networking CEO is subjected to racist attacks on her own website. A cartoonist's life is trashed by trolls. Women get rape and death threats. There's a case to be made that online, 2015 was a year of increased hate.

Those of us who watch social media for a living - or who are long-time users of sites like Facebook and Twitter - realise that nastiness has always been a part of life online. But over the course of the past year or so, it seemed to some of us at BBC Trending that the steady background beat of online anger gradually turned into a pounding 24-7 drumbeat of angst, impossible to ignore.

So we set out to see if levels of hate speech did rise on social media this year.

First, definitions. The idea that abuse and harassment is on the rise seems to be common today among journalists and tech people, but defining the problem is itself problematic. Hate speech laws and norms vary from country to country. And there is - and always has been - profound disagreement on what constitutes online abuse, hate or trolling.

Take that last term for starters. The word "troll" used to be rather narrowly defined as a person who posts inflammatory or irritating comments on an internet message board, usually for their own amusement. But over time that definition seems to have broadened to encompass everything from sending death threats to expressing sharp political disagreements.

There's a similar debate about what constitutes "hate speech." A recent UN report puzzled over its definition, calling it a "generic term, mixing concrete threats to individuals' and groups' security with cases in which people may be simply venting their anger against authority."

'Astonishing' increase in racial slurs on Twitter

But if you think, like many online free-speech absolutists, that increased harassment and hate is a fiction, a product of loose language and sensitive flowers who revel in hurt feelings, well the statistics just don't bear that out.

A recent analysis by the think tank Demos found that on average around 480,000 racial slurs are tweeted every month. Compare that figure to just 10,000 three years ago. The researchers admit that the vast majority of those uses won't amount to hate crimes. But the numbers are still significant.

"A 4800 per cent increase is astonishing - far greater than the general increase in tweets over that time," wrote Demos research director Carl Miller.

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Other experts agree - something has definitely happened over the past year.

"2015 saw a greater normalisation of hate speech in society than in previous years," says Andre Oboler, chief executive of the Australia-based Online Hate Prevention Institute. "Where previously a person might make a vague negative allusion to race, religion, gender or sexuality, by the end of 2015 the comments on social media were blatant and overt."

"Where previously people hid behind pages and fake accounts, by the end of 2015 many people felt their hate was acceptable and were comfortable posting it under their real name or their regular social media account," Oboler noted.

Oboler flagged up anti-Muslim hate as a particular hot spot - perhaps predictable considering the continued fallout of the Syrian civil war, the refugee crisis and terror attacks. But other groups have also been among the top targets, he says, including women and Jews.

Even if you don't directly experience online hate yourself, there are wider impacts that affect us all, according to Paula Todd, an internet bullying expert and author of the book Extreme Mean. Todd points out that online abuse gives governments and corporations justification for censorship, and somewhat counter-intuitively, can have a chilling effect on free speech.

"Publications around the world are closing comment sections because they don't want to spend the money to edit out the haters, racists, sexists and the uniformed and frightened," she says.

Return to normal?

But why, then, does abuse seem to be increasing? If you regularly post sharply political tweets of any sort, it might seem like social media is a terrible miasma of vitriol - particularly if you're the one on the receiving end of some of it. But in part that's because in many places, the social fabric more or less holds in real life. People might shout racial slurs in ALL CAPS online, but we generally don't walk down the street shouting at random strangers - and in fact, if we do, and bystanders capture it on film, it becomes news.

But what's happening in our daily lives might be diverging from the world of digital mass conversation. Todd says increased hate online is in part a reflection of the wider culture of public discourse.

"Despite extraordinary efforts by community and educational groups to sensitise people to the pain they cause online, the countervailing trend, especially in politics and entertainment, is the use of demeaning and damaging language and communication," she says.

Todd's research has uncovered a "constellation" of motivations for online abuse - "everything from feelings of powerlessness to alcohol and drug abuse and on to mental illness."

One argument states that this rising wave of anger is a historical blip - a product of the phenomenal recent explosion of social networks. Once the novelty wears off, this argument goes, norms will be established, annoying and abusive people will get banned or bored, and calm will settle over the internet.

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The biggest social networks are aware of the problem - and Twitter is particularly worried. Back in February, the company's then-CEO was blunt: "We suck at dealing with hate". More recently, Twitter says new account verification and blocking tools have made the network safer - though it's debateable whether users have yet felt a difference. Twitter, along with Facebook and Google, recently agreed to actively combat hate speech on the behest of the German government.

Many, including the Demos researchers, point out that social media can be a useful tool to combat hate, as well as spread it. Oboler, of the OHPI, puts responsibility for quelling abuse squarely on the management of the big social networking companies.

"The social media companies promote the idea that the solution to hate speech is more speech," he says, "This approach evades responsibility with the suggesting that business as usual is the best they can do."

Todd agrees and says of the major networks: "Language filters, public action campaigns, internal detection and user technology are all within their reach."

Oboler warns that young people will be turned off from social networks if abuse continues to increase. But he also points out that one 2015 arrival might change the game - namely, Mark Zuckerburg's baby daughter.

"With the birth of his daughter, Mark Zuckerberg is reinventing himself. He is starting to show a greater concern for the future. This will have a ripple effect through Facebook, which is by far the largest of the social media platforms." But he cautions: "This change will take time and we don't expect to see any dramatic change in 2016."

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