[MCN] 2-What did climate science know, and when did it know it?
lance at wildrockies.org
Thu Feb 4 14:51:55 EST 2016
1st of 2: NATURE Vol 448 August 30, 2007
Fires and climate linked in nineteenth century
SIR - 'Atmospheric brown clouds', resulting from
the burning of fossil fuels and biomass, have
recently been reported to have a large effect on
climate by altering the atmosphere's absorption
of solar radiation (V. Ramanathan et al. Nature
448, 575-578; 2007).
Interestingly, even in the nineteenth century,
some scientists held the view that tiny
particles, or aerosols, produced from burning
affect solar radiation, clouds and precipitation
on a large scale - all factors that play into
climate. One of them, German geographer
Alexander Freiherr von Danckelman, wrote an
insightful but little-noticed paper on the topic
(A. von Danckelman Z. österr. Ges. Met.
(Meteorol. Z.) 19, 301-311; 1884).
After observing huge savannah fires in Africa
during the 1880s, von Danckelman reported that
fires were accompanied by cumulus clouds, which
subsequently spread and thinned, forming a
brownish or blueish haze that persisted for days
to weeks. He argued against the view that fires
were an immediate cause of rain showers, and
proposed instead that they affected cloudiness
and precipitation in an "indirect way". He
realized that by providing cloud condensation
nuclei, fires might contribute to the fog and
drizzle typical of the dry season. Estimating the
amount of biomass burned in Africa each year, he
concluded that savannah fires must have a major
influence on large-scale climate.
Von Danckelman's descriptions of haze produced
from burning biomass and its effects on climate
are surprisingly accurate. Although not every
detail is correct, his theories anticipated many
aspects of the current discussion on biomass
burning and the effects of aerosols. Sadly his
work, published in French and German, is almost
forgotten today and references to his papers are
absent in current studies.
Institute for Atmospheric and Climate Science,
ETH Zurich, Universitätsstraße 16,
CH-8092 Zürich, Switzerland
2nd of 2: NATURE Vol 448 August 30, 2007
Climate: Sawyer predicted rate of warming in 1972
SIR - Thirty-five years ago this week, Nature
published a paper titled 'Man-made carbon dioxide
and the "greenhouse" effect' by the eminent
atmospheric scientist J. S. Sawyer (Nature 239,
23-26; 1972). In four pages Sawyer summarized
what was known about the role of carbon dioxide
in enhancing the natural greenhouse effect, and
made a remarkable prediction of the warming
expected at the end of the twentieth century. He
concluded that the 25% increase in atmospheric
carbon dioxide predicted to occur by 2000
corresponded to an increase of 0.6 °C in world
In fact the global surface temperature rose about
0.5 °C between the early 1970s and 2000.
Considering that global temperatures had, if
anything, been falling in the decades leading up
to the early 1970s, Sawyer's prediction of a
reversal of this trend, and of the correct
magnitude of the warming, is perhaps the most
remarkable long-range forecast ever made.
Sawyer's review built on the work of many other
scientists, including John Tyndall's in the
nineteenth century (see, for example, J. Tyndall
Philos. Mag. 22, 169-194 and 273-285; 1861) and
Guy Callender's in the mid-twentieth (for
example, G. S. Callendar, Weather 4, 310-314;
1949). But the anniversary of his paper is a
reminder that, far from being a modern
preoccupation, the effects of carbon dioxide on
the global climate have been recognized for many
Today, improved data, models and analyses allow
discussion of possible changes in numerous
meteorological variables aside from those Sawyer
described. Hosting such discussions, the four
volumes of the Intergovernmental Panel on Climate
Change 2007 assessment run to several thousand
pages, with more than 400 authors and about 2,500
reviewers. Despite huge efforts, and advances in
the science, the scientific consensus on the
amount of global warming expected from increasing
atmospheric carbon dioxide concentrations has
changed little from that in Sawyer's time.
School of Geography and Environmental Science,
Monash University, Victoria 3800, Australia
"As an endangered species and an endangering one, we need, collectively,
all the self-understanding and self-direction that we can muster."
M. Brewster Smith. "Perspectives on Selfhood."
American Psychologist, December 1978
"Localized ecological systems are known to shift
abruptly and irreversibly from one state to
another when they are forced across critical
thresholds. Here we review evidence that the
global ecosystem as a whole can react in the same
way and is approaching a planetary-scale critical
transition as a result of human influence."
Barnovsky et al. "Approaching a state shift in Earth's biosphere."
Nature. 07 June 2012,Volume 486, Pages:52-58
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