Glossary and abbreviations - Climate Change: Biological and Human Aspects - page 535

Phanerozoic The eon since the beginning of the Cambrian (542

mya), with multicelled species ( see Appendix 2).

phenology The study of plant and animal development in response

to the seasons.

photoperiodism The response of an organism to the day/night cycle as

well as its changes in the course of the year.

photosynthesis The (sun) light-powered process by which plants

(including algae) synthesise carbohydrates from car-
bon dioxide and water.

Pliocene The epoch that occurred 5.3-1.8 mya ( see Appendix

2).

pluvial A geologically short time of high rainfall that is usually

associated with Milankovitch or other climatic cycles,
such as those related to Heinrich events.

production The biomass fixed over a period of time (usually a

year), expressed in terms of either mass or energy.
Primary production is the production due to photo-
synthesis (also called gross primary production). Net
primary production is the production due to photosyn-
thesis after respiration losses are taken into account.
Secondary production relates to the production of
species living on photosynthetic species. Productiv-
ity relates to production in a unit area over a period of
time (again, usually a year).

prokaryote A simple cell that has no internal membrane-bound

structures or nucleus. Bacteria and blue-green algae
have prokaryotic cells. See also eukaryote.

pyroclastic rocks Rocks formed by materials thrown out by explosive

volcanic eruptions.

Quaternary The period (in the geological sense) of time from

the present to 1.806 mya (as provisionally defined
by the International Commission on Stratigraphy in
2008) that saw a number of deep glacials and intergla-
cials ( see Appendix 2). (It may shortly be redefined to
2.588 mya.)

refugium An ecological area where species can survive sur-

rounding or nearby environmental change (plural:
refugia).

Sangamon See Eemian.

Snowball Earth The Earth covered with snow and ice, either nearly or

completely.

speciation The processes by which new species evolve.

stoma A minute opening on the leaf of a plant (usually on

the underside) through which gas and water exchange
takes place (plural: stomata).

stromatolite A fossilised mat of algae.