Venice Biennale

As the curator of the Venice Biennale, Okwui Enwezor, said this week, the festival this year is dedicated to addressing "the disquiet of our time". The festival cannot ignore the "ruptures that surround and abound around every corner of the global landscape". And it does not. This is one of the more politically charged Biennales of recent times.

Enwezor's curated show, All The World's Futures, is set at the very large central pavilion at the Giardini, and continues into the equally extensive Arsenale. The festival in the city, though, goes beyond those shows. And of course the overall tone and message of any one Biennale - with dozens of national shows, dozens of fringe or 'collateral' events (a strange word, with allusions to military damage) - is always diffuse and fractured. So many shows and artists in some many venues, from palaces to huts, from purpose-built spaces to the grand National pavilions: there is not one story or narrative.

But after spending a day at Graham Fagen's excellent Scottish show, it became clear that some of his exhibition's preoccupations - the stark toll of history, the fragility of the body under stress, slavery and its consequences - are also felt elsewhere across the 56th International Exhibition of Art in Venice, and in Enwezor's exhibition of a multitude of artists.

In a beautiful new venue, a classic Venetian palace called the Palazzo Fontana, right on the banks on the Grand Canal, the reverberating themes of Fagen's work - a towering malevolent tree cast from bronze coir ropes, a tree of death masks, a gorgeous musical and video work in collaboration with Sally Beamish, Ghetto Priest, the Scottish Ensemble and Adrian Sherwood - resonates anew once you have taken in more of the festival. Fagen's work is both direct - a bronze tree looped like a noose - and multi-layered. The music is also gorgeous. Scotland will return to this festival in 2017, but it will do well to stage a show as strong and resonant as this.

There are others of equal power here, of course. For example, the wonderful joint show by artists from India and Pakistan, My East Is Your West, held at the Palazzo Benzon as a collateral event (as is Scotland's), does not only make a political and social message merely be existing. The Gurjal Foundation, a non-profit trust, is behind the show, which features the art of Shilpa Gupta (of Mumbai) and Rashid Rana (Lahore). Neither country has a permanent national pavilion in Venice, and this show is not officially backed by either country.

Rana's work is video- and film-based, and is tricksy and immersive. A time-delayed camera shooting onto both a chair and a wall allows you to "meet yourself", while in another room you are confronted with a live feed to an identical room, albeit one that has been set up in Lahore. A child in Lahore waves and gives you the thumbs up - their backdrop of a Venetian palace, with a late Renaissance painting and stone fireplace, must seem particularly artificial. But you can communicate, as if through a time portal, and most people on the other side of the world, and on the wall, smile and wave.

Gupta's work is more formal and intense, a series of exhibits and musings on the India-Bangladesh borderlands. In one room a man patiently works on a huge pile of linen, while at the end you are given an envelope to carry 150 yards and then open. A box of bone china reminds you that its contents are mainly cow bones. The whole show is beautifully produced and moving.

So too, in their different ways, are the shows of Belgium and the US in the main Giardini venues, and so is, in altogether more spectacular and vast form, the main curated show of the festival.

Enwezor has radically changed the internal structure of the Central Pavilion - a large auditorium is now in place, and a stage. This stage, while home to other theatrical or performance events (I saw Jeremy Deller's Broadsides And Ballads Of The Industrial Revolution, expertly performed by Manchester's Jennifer Reid), will primarily be home to a seven-month epic project dedicated to staging Karl Marx's signature work in three volumes. Capital: A Live Reading will see a series of performers reading Das Kapital. It is the curator's most obviously political move of many in the exhibition. One wonders what the series of live readings will mean to the owners of the numerous private super-yachts which are parked, like unlovely floating jumbo-jets, along the lagoon shoreline of the Giardini.

Belgium's show, presented by Vincent Meesen and guests, is an intense and multi-layered exploration of European colonialism in Africa. As well as appealing films (one on the role of Congolese intellectuals within the Situationist International) there is a perpetually moving robotic machine, by James Beckett, which swiftly and randomly moves "dead spaces", in the form of wooden blocks, back and forward. No solution to the apparent problem is attained.

Joan Jonas's US show, They Come To Us Without A Word, by contrast, is largely adrift from politics, and indeed adrift from reality. A series of animal-themed rooms form a kind of story, albeit one within a continuum of music, intoned stories and fairy tales. There are also creepily beautiful films of children and youths wearing animal masks, acting out obscure rites. There are wall paintings and Murano mirrors, the dreamlike and the gorgeous as well as the unsettlingly pagan and the surreal. Unsettling, too, is the Finland show, in a tiny space. There, the IC-98 team (shortly to exhibit a show at the DCA in Dundee) have staged Hours, Years, Aeons, a frightening image of a tree in a bleak, black landscape. Underfoot is charcoal. The focus of the image suddenly tightens, black stars gleam and the tree seems to move.

Equally outside of the main political thrust of the curated festival is Sarah Lucas's brazenly priapic (and very yellow) show, nattily named I Scream Daddio, at the UK pavilion at the head of the Giardini. The most interesting parts of this show are Lucas's (decapitated) casts of the bodies of her friends, renamed as Muses, which are placed on chairs or furniture, lean over a toilet or just sit splay-legged. The bodies and their various intimate parts are real. So are the cigarettes stuck into them. Asked about the cigarettes, Lucas suggested they were a provocation of sorts. But also "for titillation mostly". They are also on-the-nose and feel uncomfortable.

There are depictions of cats - perhaps the most Venetian element of the show - in gloopy black plastic, and a washing machine with its concave door made convex and painted yellow at the its centre: a nod to Lucas's egg motif of previous artworks. The huge phalluses, both named after the Argentinian footballer Maradona, are, as the artist says, "super-sized", but are also something and nothing. Made in plastic but spray-painted like sports cars, they are big and erect and a little mundane, for all their size. The show is coherent and well made throughout, but it leaves you wanting more, or something else.

Next to the UK sit the Canadian and French pavilions. The French show, by Celeste Boursier-Mougenot, while making slightly overheated claims, is essentially three trees on wheels. They move very slowly, like pensioner Triffids. You could get run over by them, but it would be a pretty boring death.

Canada's show, by the BGL Collective, looks at another aspect of Capital - money. In a false shop, all the boxes and goods wrappers and packages have been blurred so you feel out of focus and seasick, while above the shop, an enormous coin run (rather like a massive version of the coin run in Glasgow's Botanic Gardens) clatters and bangs.

Close by is Japan's very beautiful show by Chiharu Shiota, The Key In The Hand. Intricately made from thousands of red yarn strings and keys from around the world, assembled into a complex series of woven crimson clouds, the pavilion is a dream. Dreamlike, too, is the Russian show by Irina Nakhova, who creates a series of internal environments, including a disorientating floor which may be water or sky. It dares you to walk across. I did, but on central beam of darkened floor.

Back to stress and war, Labour and Capital. The Arsenale, the former boat building and naval yard, is replete with turbulent imagery curated for the director's show. The first room is fairly stunning, a dark chamber full of Bruce Nauman's American Violence - clutches of swords are stuck into the floor like razor-sharp flowers, lit by the flashing illuminated signs. Next door, Monica Bonvicini has hung dangerous fruit - black painted clusters of chainsaws. Pino Pascali's cannon points at imaginary enemies in the sky. In another room, Katherine Grosse has piled destroyed masonry, metal and dust into a multi-coloured ruin. There are ruminations on working and being made to work in the contributions of Joachim Schonfeldt and Im Heung Soon.

And beyond these rooms is another reminder, or message. In a nearby national show, Tuvalu has flooded a room, although you can still precariously walk across it, to remind us all of the destruction to be wrought by climate change. Not only to that Pacific island, but to the city in which this deeply troubling, brilliantly challenging, frustratingly enormous festival of art and artists once again stands, resplendent amid the terrors and troubles of the world.

The Venice Biennale continues in the Giardini and Arsenale venues until November 22, www.labiennale.org