“We can now see the ;ngerprint of man in the past temperature
record. That’s a pretty radical change.” — TOM WIGLEY, 1995
ozone-destroying chloro-
fluorocarbons gets enough
signatures; it goes into effect
January 1, 1989 (9/26/87,
p. 196; 11/19/88, p. 333).
1990 | Hubble
NASA launches the
Hubble Space Telescope
(1/6/90, p. 8; 5/5/90,
p. 276; 6/30/90, p. 407).
1990s
1987 | Dino wipeout
Grains of shocked quartz
from around the world offer
further evidence that a
meteorite or asteroid struck
the Earth more than 65 mil-
lion years ago, causing mass
extinctions of life — includ-
ing dinosaurs (5/16/87,
p. 309).
Climate in flux
More than half a century ago, temperature records from
Antarctica and the Arctic showed data “consistent with
the theory that the entire world is slowly getting warmer,”
Science News Letter reported. This low-grade fever began
around 1900 and was believed “to amount to some two
or three degrees each century” (2/28/59, p. 131). But
not until the 1990s would climate experts from around
the world begin issuing consensus statements through
the Intergovernmental Panel on Climate Change warning
of catastrophic climate perturbations if humankind didn’t
put the brakes on releases of carbon dioxide and other
greenhouse gases (6/23/90, p. 391)— preferably immediately (11/4/95, p. 293). As international agreements
such as the 1997 Kyoto Protocol have largely failed in
that task, scientists have expanded efforts to chronicle
the world’s shifting climate (above, 2008 temperatures
compared with 1950–1980 baseline period) and ecosystems (SN Online: 12/2/11). —Janet Raloff
2008 surface temperature anomaly (ºC)
- 3. 5 - 2. 5 - 1. 5 - 1.0 -0.6 -0.2 0.2 0.6 1.0 1. 5 2. 5 3. 5
1991 | H. pylori
A series of research efforts
compellingly link stomach
ulcers to the H. pylori bacterium (12/14/91, p. 399). N
1989 | Exxon Valdez
A tanker accident dumps
more than 11 million gallons
of crude oil (slick below)
in Alaska’s Prince William
Sound (6/17/89, p. 383;
7/15/89, p. 38).
1992 | Big Bang signature
Cosmologists detect temper-
ature fluctuations in the cos-
mic microwave background,
variations that correspond
to ripples in the density
of matter shortly after the
Big Bang (5/2/92, p. 292;
12/19–26/92, p. 420). N
CLOCKWISE FROM LEFT: FLIP NICKLIN/GETTY IMAGES; © NASA/CORBIS; GETTY IMAGES
1992 | New brain cells
Neuroscientists discover
that a protein can prompt
mature nerve cells in adult
mice to divide, dispelling the
belief that adult mammals’
brain cells cannot reproduce
(4/4/92, p. 212).
1993 | Dark Milky Way
Astronomers report evidence of Massive Compact
Halo Objects at the outskirts
of the Milky Way (9/25/93,
p. 199). These MACHOs
account for part of the universe’s missing mass.
M87, 50 million light-years
from Earth (6/4/94, p. 356).
1995 | Climate changing
The Intergovernmental
Panel on Climate Change
finds evidence of a discernible human influence on
climate ( 11/4/95, p. 293).
1989 | Cold fusion
Martin Fleischmann and
B. Stanley Pons report on
benchtop nuclear reactions
that they describe as “cold
fusion” but that are never
confirmed (4/1/89, p. 196;
4/8/89, p. 212; 4/15/89,
p. 229; 4/22/89, p. 244).
1994 | Breast cancer genes
A pair of genes, BRCA1 and
BRCA2, appear to play a role
in some inherited breast
cancers (9/24/94, p. 197;
12/3/94, p. 372).
1993 | Human cloning
Scientists for the first time
clone human embryos, raising a host of ethical questions ( 10/30/93, p. 276).
1994 | Black hole
Astronomers report the
most compelling evidence
for the existence of a black
hole at the center of galaxy
1996 | Oldest life
Carbon isotope measure-
ments from Greenland rocks
push back the history of life
on Earth to 3.85 billion
years ago (11/9/96, p. 292).
l
1996 | Dolly the Sheep
A sheep named Dolly (left)
becomes the first mammal
cloned from the DNA of an
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March 24, 2012 | SCIENCE NEWS | 31
