Biology Reference
In-Depth Information
origin into the Earth's living envelope and for the evolutionary development
of many crown groups.
Looking at the collective evidence from pole to pole since 100 Ma, the con-
clusion is inescapable that environments and the biota have changed both
through long-term geological time, and on scales measured in decades or
years. Patterned changes caused by Milankovitch variations, the omnipres-
ence of variations in atmospheric CO
2
concentration, and changes in ocean
circulation have been augmented by a series of catastrophes, including as-
teroid impacts, sudden methane emissions, salinity crises, and jökulhlaups.
The detailed record of the more recent Neogene and Quaternary provides
especially clear analogs for the kind, extent, and future effect of alterations
taking place at present. These include burning—for example, the burning
of the tropical forests and the tundra (Qiu 2009)—lumbering and other
removal of the Earth's vegetation on an unprecedented scale, and the unre-
lenting release of greenhouse gases into the atmosphere from these activities
and through the use of fossil fuels. Technology is beginning to play a role
in documenting and raising awareness of illegal biome destruction through
satellite images posted on the Web that show these activities happening in
real time. For example, current incursion into tropical preserves set aside
through the efforts of the Amazonian chief Almir Surui, commemorated in
the epigraph to this topic, are now posted across the Web for the world to
see. The present state of affairs is unique for the past 65 million years in
its combination of magnitude and rapid pace. The simultaneous and global
destruction or severe damage across the Earth's entire living envelope, with
previously existing natural extinction rates now being augmented by ram-
pant exterminations through human activities, is unprecedented. This is
occurring within the context of an ever-expanding human population es-
timated to further increase from 6.5 billion to 9 billion people in the next
fi fty years.
Efforts to anticipate the consequences require a multiplicity of ap-
proaches, an arsenal of techniques, and perhaps most diffi cult of all to
achieve, the mind-set of an informed and activist majority unencumbered
by extreme self-interest and antiscience bias. Vegetation and environmen-
tal history provides one source of information for estimating the causes,
effects, and extent of past environmental change; and it can contribute to
modeling the future of an immensely complex, multifactored, and telecon-
nected global system. Recent fi ndings create a sense of urgency. For ex-
ample, it has become clear that forcing mechanisms need only be as slight
