The Brian Aldiss novel, Hothouse, is set on an Earth completely covered by a tangled jungle. This short piece looks at how such a world might have come about. It isn’t completely consistent with the world of the novel, but that is set hundreds, if not thousands of years hence. It is also a piece of alternate history, given the start date.

I don’t know when they arrived. It may have been centuries ago. Perhaps they were here all the time. Perhaps they have been here longer than mankind. It doesn’t matter in the end. Because that’s probably where we are – the end. The end for humanity, anyway.

We first noticed them in 1962. Reports came in from the Congo basin of a parasitical vine that appeared to be taking over in some areas. Just another Third World problem. Then the next year it appeared in South East Asia. Meanwhile, it continued spreading inexorably across tropical Africa, no longer just in the rain forest but affecting agricultural areas too. Where ever it grew, everything else died. And it grew at a phenomenal rate. A given plant could double in size in a week. Every week. Cutting it down gave only a temporary respite. Within five years tropical Africa had gone, transformed into an impenetrable mass of poisonous virulently green creepers. South East Asia took longer, but despite prodigious efforts, by 1971, the vine covered almost all the open land of Cambodia, Laos, Burma, Thailand and Vietnam.

The cities held out for a while, but the vines found their way, erupting through the tarmac overnght, undermining the foundations of buildings until within a couple of years every city was as buried from sight as the Mayan ruins of South America. Despite this, despite the problems of refugees and famine in the affected areas, the Western world remained broadly unconcerned. The US even welcomed it to a degree. After all this virulent growth had solved their problem in Vietnam. Just in case the VC were still hiding in there, the US carried on spraying defoliants, but to no effect. They tried flamethrowers too, but after they lost a couple of crews to the vines growing up behind them they stopped. They were in any case now sure no one was hiding in the middle.

So, happy that they no longer had a problem of communist incursions into the area, they lost interest in it. Then one day in 1974 someone stumbled into a police barracks on the edge of Manaus with a story of his village being overrun by poisonous green vines. The Amazon Basin went as quickly as Africa had, so by 1980 the Amazon rainforest was no more. That was when we realised other things were going on too. Oxygen levels in the atmosphere were rising. So was the temperature. The vines themselves appeared to be radiating heat. More significantly, with increased temperatures and increased oxygen, the growth of the vines accelerated and the area they covered began to spread north and south away from what were formerly the tropical zones.

As temperatures continued to rise, the ice sheets also began to melt. The rising sea levels flooded major cities of course, adding to our problems, but also percolating beneath the ice sheets covering Greenland and Antarctica, allowing them to slowly slide into the surrounding seas raising the sea levels even more.

And this is where we are. The survivors are huddled into a narrow strip around the Northern Hemisphere. Nowhere south of Denver is habitable, except at extreme altitude. A few survivors hang on in Tibet, the dogged remnants of Mao’s China hacking away at any vines that struggle onto the plateau. The Southern Hemisphere has otherwise gone other than a few tiny islands so far unaffected by the vines spread, and a few camps strung out along the Andes. Even the arid central desert of Australia has succumbed, even Ayres Rock, buried now under a writhing green carpet of vines. The ice on Antarctica has all gone, leaving bare rock behind, occupied now by greenhouses built by Australia and Brazil, which just manage to grow enough food for the few thousands now living there. So far, the northward advance of the vines has stopped. How long though?