The climate apocalypse depicted in The Drowned World is a thinly-veiled—and highly xenophobic—allegory for the fall of the British Empire. Following the mass casualties of World War II, the United Kingdom had a labor shortage that the government addressed by recruiting citizens of the broader British Commonwealth (the name for all the global countries under the U.K.'s colonial influence) to live and work in London and throughout the U.K. The British Empire had long consisted of a largely White "home island," which enriched itself by enslaving and otherwise exploiting Black and Indigenous communities in distant colonies around the world.
The new immigration policy turned the home island into a far more racially and ethnically diverse place. There was immediate backlash to the perceived encroachment of "outsiders" and their cultures. This backlash only grew more intense as social movements modeled on the US civil rights movement began to take root, pushing for better treatment of immigrants.
Ballard frames immigration as an existential threat on par with climate disaster. His portrayal of "the drowned world" draws heavily from the discourse of scientific racism, which held that dark-skinned people from Equatorial climates were less developed and more animalistic than White people. In the first part of the novel, Bodkin describes the way the "jungle" encourages a kind of regressive devolution in anyone who stays there too long. "Jungle" is a racialized term historically used by European colonists to describe not simply wilderness, but moreover the hot, sticky, often dangerous climates of South America and parts of Africa. When the "jungle" climate takes hold of London, the survivors of the floods lose Euro-centric cultural institutions like museums and theaters. Soon, Bodkin tells Kerans, the rising temperature will cause the survivors to lose the biological ability to form a civilization. They will all begin to behave more like the giant iguanas that have started to run rampant around the ruined city. The racism of Bodkins's argument is reified in the novel as Kerans begins to lose his sensitivity to "evolved" (i.e. European) cultural artifacts like Beethoven's symphonies. The symphonies are overtaken in his head by imaginary bongo-like drumming. The African "jungle," this transformation implies, has invaded not only London, but the White protagonist's own psyche. Ballard portrays the transformation as titillating and horrifying.
As Kerans loses touch with European culture, Ballard imagines what he frames as an even greater horror: a hostile takeover of London's cultural institutions by immigrants. Strangman's treasure-hunting crew has no respect or appreciation for the cultural value of the treasures they have come to loot. They drain the lagoons only to dump sewage in the streets, polluting the city that was once considered the epicenter of White British culture and high society. The Admiral and Big Caesar are vicious stereotypes who speak in dialect that makes them sound unintelligent. Big Caesar even resembles the inhuman, man-eating Cyclops from Homer's Odyssey. Kerans ultimately concludes that London's cultural heritage is better off underwater than in the hands of these men. Ballard seems to be suggesting that the London of yore has been distorted and sullied beyond repair by the racial restructuring the British Empire has undergone. "Flooded" by immigrants, it is turning into a "jungle" that can no longer sustain White culture; Kerans's ultimate destruction of London and doomed flight South represent a fatalistic, racist surrender to the death of the empire.
In Chapter 3, after Kerans sees Bodkin treating Hardman for disturbing dreams, Bodkin explains his theory of the "archaeopsychic past." According to him, individual human development is an allegory for the evolutionary development of the human species:
The brief span of an individual life is misleading. Each one of us is as old as the entire biological kingdom, and our bloodstreams are tributaries of the great sea of its total memory. The uterine odyssey of the growing foetus recapitulates the entire evolutionary past, and its central nervous system is a coded time scale, each nexus of neurones and each spinal level marking a symbolic station, a unit of neuronic time.
Bodkin describes fetal development as a "uterine odyssey," emphasizing the massive timescale he believes every fetus traverses over the course of a mere nine months. Before a human is born, he argues, their body has undergone every evolutionary development that has led to the existence of modern humans. These developments are not left behind in the uterus. Rather, they form the building blocks of the human body (especially the spinal column). He explains to Kerans that the spinal cord is a linear timeline, stacking one stage of human development on top of the last. From the bottom to the top, it is organized from the simplest and most ancient stage up to the newest and most complex. Bodkin likens the circulatory system to a waterway; each person's "waterway" is continuous with the rest, "tributaries of the great sea" of "biological memory." Every human is a living record of human evolution.
Bodkin explains to Kerans that Hardman's dreams are coming from the "archaeopsychic past" he carries with him in his own body. The more the environment mimics the African environment where humans first evolved, the more Hardman's vestigial biological memories are stirred. Bodkin believes that the memories will eventually send Hardman back in time, turning him into a less developed version of a human; Bodkin cannot stop the transformation, but he is trying to ease it by exposing Hardman to higher temperatures under controlled conditions. This exposure therapy will hopefully allow Hardman to become accustomed to the feeling of biological memory so that it will not drive him utterly mad. Bodkin wants his therapy to allow his clients to become "jungle" creatures who remain civilized enough to "dress for dinner."
Ballard's futuristic science seems to have been heavily influenced by the discourse of scientific racism. While it is true that developing fetuses go through certain stages where they display vestigial traits, there is no scientific basis for the notion that a warm climate causes humans to devolve into an earlier stage of evolutionary development. Bodkin's theory uses pseudoscience to suggest that Black people are inherently less developed than White people. Furthermore, he insists that the relationship between the individual and species remains allegorical and not literal, even when someone like Hardman begins to regress back through the stages of development; Bodkin stops just short of reassuring Kerans that Hardman will remain distinguishable from an actual Black person when he undergoes this transformation. The book thus uses Blackness as an evolutionary threat to Whiteness while maintaining the problematic fiction that there are indelible biological differences between Black people and White people.