Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: From cosmic explosions to terrestrial fires?   Multiple lines of evidence point to one or more moderately nearby supernovae,
with the strongest signal ~2.6 Ma. We build on previous work to argue for the
likelihood of cosmic ray ionization of the atmosphere and electron cascades
leading to more frequent lightning, and therefore an increase in nitrate
deposition and in wildfires. The potential exists for a large increase in the
pre-human nitrate flux onto the surface, which has previously been argued to
lead to CO2 drawdown and cooling of the climate. Evidence for increased
wildfires exists in an increase in soot and carbon deposits over the relevant
period. The wildfires would have contributed to the transition from forest to
savanna in northeast Africa, long argued to have been a factor in the evolution
of hominin bipedalism.

36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an