Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Case for a Hot Archean Climate and its Implications to the History
  of the Biosphere   The case for a much warmer climate on the early Earth than now is presented.
The oxygen isotope record in sedimentary chert and the compelling case for a
near constant isotopic oxygen composition of seawater over geologic time
support thermophilic surface temperatures prevailing in the Archean, with some
support for hot conditions lasting until about 1.5 billion years ago, aside
from lower temperatures including glacial episodes at 2.1-2.4 Ga and possibly
an earlier one at 2.9 Ga. Other evidence includes the following: 1) Melting
temperatures of proteins resurrected from sequences inferred from robust
molecular phylogenies give paleotemperatures at emergence consistent with a
very warm early climate. 2) High atmospheric pCO2 levels in the Archean are
consistent with high climatic temperatures near the triple point of primary
iron minerals in banded iron formations, the formation of Mn-bicarbonate
clusters leading to oxygenic photosynthesis and generally higher weathering
intensities on land. These higher weathering intensities would not have
occurred if seafloor weathering dominated the carbon sink, pulling down the
temperature, hence this empirical evidence supports a hot climate and high
carbon dioxide levels. 3) The inferred viscosity of seawater at 2.7 Ga is
consistent with a hot Archean climate. 5) A cold Archean is hard to explain
taking into account the higher outgassing rates of carbon dioxide,
significantly smaller land areas and weaker biotic enhancement of weathering
than present in the context of the long-term carbon cycle, taking into account
the fainter Archean sun in climate modeling. This evidence points to an
important conclusion regarding biological evolution, namely to the critical
role of a temperature constraint holding back the emergence of major organismal
groups, starting with phototrophs, culminating with metazoans in the latest
Precambrian.

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The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
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The categories of this paper are: plasm-ph
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The categories of this paper are: econ
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The categories of this paper are: stat
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: supr-con