Glossary and abbreviations - Climate Change: Biological and Human Aspects - page 536

sympatric Species occupying the same, or overlapping, geo-

graphical areas ( see also allopatric).

tundra The treeless polar regions with permanently frozen

subsoil (although surface soil may be thawed for some
parts of the year).

Younger Dryas A short, cool period at the end of the last glacial,

12 900-11 600 years ago, before the start of our current
(Holocene) interglacial.

zonation The occurrence of distinct bands of species across an

environmental gradient such as a seashore or moun-
tainside.

Abbreviations

ACC Antarctic Circumpolar Current

ACR Antarctic cold reversal

BAP Biodiversity Action Plan

B-a-U Business-as-Usual scenario

Bering, a unit of water volume (equivalent to 10 3 km 3 ). See also Sv
(water flow). Not to be confused with Be, the symbol for the element
beryllium.

Be

bya billion years ago

C carbon

12 C

Most common isotope of carbon with an atomic weight of 12. Pre-
ferred by the enzymes involved in photosynthesis.

13 C

Rare isotope of carbon, discriminated against by photosynthetic
enzymes.

14 C

Rare unstable (radioactive) form of carbon with a half-life of 5715
years. Used in carbon dating.

C 3 (plants) Plants that use the older photosynthetic pathway with three carbon

atoms in the first product during carbon dioxide assimilation.

C 4 (plants) Plants that use the more recently evolved photosynthetic pathway

capable in intense sunlight (hence low latitudes) of taking more carbon
dioxide out of the atmosphere than C 3 photosynthesis.

Ca calcium

CBD UN Convention on Biological Diversity (1992)

CCD calcite compensation depth

CCM carbon-concentrating mechanism

CCS carbon capture and storage

CDC US Centers for Disease Control and Prevention

CDM Clean Development Mechanism

CEH UK Centre for Ecology and Hydrology (formerly ITE and the NERC

River Laboratory)

CET record Central England Temperature record