Indigenous collaborators are recording a Bornean hillside before Indonesia's new capital reaches it

The chosen ground is a plantation. Leah Varjacques, reporting for Scientific American's Science Quickly, describes the 256,000 hectares in the hills of Eastern Borneo as an industrial eucalyptus forest, sited far from the coast ^[5]. Host Rachel Feltman's introduction to the same episode describes construction beginning to transform one of the world's most biodiverse rainforest areas ^[3]. Both descriptions can hold at once if the footprint sits in a mosaic of plantation and older forest. The transcript gives no figure for primary forest inside or beside the site ^[24].

256,000 hectares is 2,560 square kilometres ^[20]. Varjacques puts that at about three times the size of New York City ^[4].

The instrument is modest. A white metal box marked Swift is strapped to a tree on Mount Tembinus, a caged microphone below it, a terrestrial passive acoustic recording unit of the cheap, sturdy, weatherproof kind used in research and conservation ^[8]. It has recorded continuously for 18 months ^[9], which is roughly 13,000 hours of audio from one point on one hillside ^[21]. A passive recorder captures what makes sound within its range, so it answers one question well: what called here, and when. Trends across 2,560 square kilometres are a different question, and they need more boxes.

Abidin, the guide in his late 40s who leads Varjacques up the slope, cuts a path to the box and swaps its batteries and SD card ^[10]. "This is the land of my ancestors from long ago," he said of the hillside ^[12]. Of the recorder, he said: "So with these wildlife recording devices, we are preserving the knowledge of our ancestors. Then from us, if possible, we'll pass it down to our children and, and grandchildren." ^[11]

The two archival clips the episode uses on Jakarta's future measure different areas. DW says 90 percent of North Jakarta could be permanently flooded by 2050 ^[16]. PBS News Hour says about 40 percent of Jakarta is below sea level and that nearly half the city could be inundated and uninhabitable by 2050 ^[17]. The first covers one district, the second the whole city. Sea-level rise made an existing problem worse, and Indonesia has been raising sea walls for years to buy time ^[15].

Widodo announced the relocation in 2019 ^[18]. "Indonesia as a great nation must dare to take steps," he said. "We must be brave to have a big agenda, and this is for the advancement of our country, for the progress of the nation." ^[19]

The comparison this archive can support is a before-and-after at the same tree on the same microphone. Eighteen months in, the earlier half of it exists ^[9].