Carbon dioxide and other greenhouse gases (GHGs) are responsible for global warming, the long-term worldwide average warming experienced since the industrial revolution. GHGs arise from human use of fossil fuels for energy. Major emitters of GHGs include both industrialized countries and, in recent decades, developing countries as well. Higher global temperatures cause the extremes of hot and cold, and wet and dry, weather of recent years. This blog examines global warming and its effects.
See the Tabbed Pages for links to video tutorials, and a linked list of post titles grouped by topic.
This blog is expressly directed to readers who do not have strong training or backgrounds in science, with the intent of helping them grasp the underpinnings of this important issue. I'm going to present an ongoing series of posts that will develop various aspects of the science of global warming, its causes and possible methods for minimizing its advance and overcoming at least partially its detrimental effects.
Each post will begin with a capsule summary. It will then proceed with captioned sections to amplify and justify the statements and conclusions of the summary. I'll present images and tables where helpful to develop a point, since "a picture is worth a thousand words".
and across wide regions of the globe, 2011 and 2012 have recorded heat waves
and droughts at or near record levels.These have severely impacted yields, and prices, of world staple grain
OXFAM has issued a
new report that projects impacts of global warming on staple grain crops and
prices up to 2030.As a baseline, it
shows that yields and prices will rise significantly as a lon-term trend over
this period.But more importantly the
effects of regional short-term extreme weather “shocks” must be added to the
long-term trends.These can produce
serious crop and nutritional deficiencies, especially in regions of poverty
around the world.OXFAM urges renewed
efforts to mitigate global warming, and investments by developed countries to
help poorer nations adapt to the effects of long-term warming and short-term
shocks on agricultural yields and nutritional status.
Introduction. Recent years have seen increases in the
occurrence and intensity of extreme weather and climate events to an extent
having no precedent in earlier decades or the previous century. Examples that
come easily to mind include, at various times and locations around the planet,
heavy rain and consequent flooding, prolonged heat waves accompanied by
drought, and a high frequency and extent of forest wildfires.
Intergovernmental Panel on Climate Change (IPCC), an organization of hundreds
of climate scientists from all around the world, operating under the auspices
of the United Nations, issued its Fourth Assessment Report (4AR) in 2007.4AR indicates that, as a result of man-made
increases in the concentration of atmospheric carbon dioxide (CO2)
and other greenhouse gases (GHGs), the long-term global average temperature has
increased since the industrial revolution began and will continue to do so.
Extreme weather events
are consistent with trends anticipated by the IPCC in 4AR and its 2011 report
on this subject (SREX; see Note 1). 4AR
and SREX foresee that this warming will lead to warmer daytime as well as
nighttime temperatures, increases in dryness and drought conditions in certain
regions of the world, and increases in intense rainfall and flooding in others.
provides examples of recent extreme weather events consistent with the
expectation of higher temperatures and rainfall or drought foreseen by the
as of July 2012, the U. S. has experienced its hottest 12-month period
in the UK, the heaviest rainfall on record fell
between April and June 2012, and it experienced the highest November temperatures
in 100 years in 2011; and
worldwide, June 2012 was the 328th
month in a row in which the global average temperature exceeded the average
temperature during the 20th century.
The Briefing points
out that single events cannot be categorically attributed to worsening warming
of the planet, but rather that long-term warming trends have a much higher
probability of occurring; it cites as examples the 2003 European heat wave
and the 2011 heat wave and drought in Texas, in the U. S.
The post “ExtremeWeather Events and Global Warming”
summarizes two current research papers confirming, by rigorous statistical
analysis, that recent heat waves are unprecedented in history. Hansen and
coworkers conclude there is a “high degree of confidence that events such as
the extreme summer heat in [Russia] in 2010 and Texas in 2011 were a consequence of global
warming”.Coumou and Rahmstorf conclude
“it is very likely that several of the unprecedented extremes of the past
decade would not have occurred without [man-made] global warming….the evidence
is strong that [man-made], unprecedented heat and rainfall extremes are here —
and are causing intense human suffering.”
Foresees Higher Crop Prices Because Of Warming.The
model used in the Briefing predicts long-term trends for commodity prices of
the staple foods maize (corn), wheat, and rice, for the period ending in
2030.To establish accuracy, the
modeling process was used to reproduce the effects of historical weather events
on crop yields from 1979-2009.It terms
this long-term trend its baseline modeling.
foresees significant worldwide increases in food staple prices by 2030,
approximately doubling by 2030 over the price levels of 2010.For example, baseline average world prices
for maize, by 177%, with almost half being due
to the effects of warming;
for wheat, by 120%, of which about one-third
is due to the effects of warming; and
for processed rice, by 107%, of which about
one-third is due to the effects of warming.
The predicted price
trends are the consequence of the long-term warming trend in the world’s
climate.For that portion of the world’s
population living in poverty, these price increases are expected to impose the greatest
hardship because the fraction of their personal incomes devoted to procuring
food is already high.Further price
increases would impose even greater stress on these people.
But the Briefing
presents even more stark predictions of the effects of single, short-term
extreme weather events affecting crop yields, which it calls “shocks”.Details of the effects of shocks depend, in
its view, on whether the affected region is exposed to pricing from world
commodity markets or is sufficiently isolated that it depends largely on local
and regional farming to establish availability and pricing of staple foods.
shocks can have a major impact on the nutritional health of affected
populations in two ways.First,
obviously, the price paid for a food staple will spike abruptly from an extreme
weather shock, adding to any price elevation arising from the long-term trend.But additionally, the effects of the shock
commonly reduce the resources available to affected populations that can be
used to purchase the commodity or staple at the spiked price.The Briefing presents the following graphic
as an example of the effects on world prices of wheat and maize from a climate
shock in North
Green, Price increase from
2010 to 2030 due to baseline climate projection; Pale Green,
additional price increase beyond the baseline projection due to a modeled short-term
climate shock.From context, the author
presumes that the upper bar should be labeled “WHEAT”.
graphic in the Briefing, other examples of the effects on prices expected in
2030 from a shock from an extreme weather event include:
East Africa, for a drought comparable to that in 1992, an
increase in maize price by about 50%;
Southern Africa, for a drought and flooding
comparable to that in 1995, an increase in maize price by about 120%; and
India and South Asia, for poor harvests generally, an increase
in processed rice price by about 25%.
sub-Saharan Africa are likely to be very large because this is
an example of a region not tied commercially to global commodity markets.The Briefing notes that by 2030 95% of the
maize and other coarse grains consumed is likely to be produced
regionally.Therefore a short-term
climate shock could reduce amounts available for consumption by as much as 54%,
while consumption of processed foods would fall by only 4%.
Its Projections To Be Conservative.Additional factors worsening the effects on
commodity prices were not incorporated into the model.These include competition for cropland and
crops produced by diversion into biofuel production, and impacts of low food
stocks at any time; actual intensities of climate shocks experienced by 2030
may be greater than those used in the model drawn from the baseline years
1979-2009; and cumulative effects of simultaneous or consecutive shock events.
concludes that a warming world requires strong action to help vulnerable
regions of the world survive long-term and shock effects of the climate on
availability of nutrition.It summarizes
adaptation mechanisms that need to be taken to make agriculture in developing
countries more robust, and more capable of accommodating the added stresses of
population growth.It notes that
investment in local agriculture, sustainable methods and resilient crops has
been lacking in recent decades, and should be increased.
It calls on
developed countries to live up to earlier commitments to adequately fund
adaptation mechanisms, such as the Green Climate Fund.This call to action is all the more important
because, as the Briefing notes, it is expected that greenhouse gas emissions
will continue to rise, leading to higher accumulated concentrations in the
atmosphere as time passes.This higher
concentration is foreseen to lead to an average warming of 2.5-5ºC (4.5-9ºF)
during this century.If this trajectory
of increased emissions and higher temperatures remains unabated, the Briefing
foresees serious consequences in the availability of food resources, affecting
especially the most vulnerable and poorest populations of the world.
Severe droughts in
the agricultural midsection of the U. S., and in Russia, during the summer of 2012 have led to
decreased grain harvests (posted online in the Huffington Post
(accessed Sept. 12, 2012)).It
states that, according to the U. S. Department of Agriculture (USDA), as of mid-September
2012, the U.
corn crop will be the worst in six years and the soybean crop will be the
lowest in nine years.USDA also reports
that the wheat crop in Russia and neighboring regions is 9% lower than an
estimate from August 2012, and that the world wheat crop is 5% lower than one
year ago. The decreased yield of wheat
in Russia arose presumably from excessive heat over the January-August 2012
interval, contributing, with the record heat in the U. S., to making worldwide
land surface temperatures over this interval be the sixth warmest on record (U.
S. National Oceanographic and Atmospheric Administration).These extremes are due at least in part to
global warming, according to an Op-Ed article by Mark Hertsgaard in the New York Times, Sept. 13, 2012.
In a retrospective study, Lobell and coworkers found (see “Decreased Worldwide Crop Yields Are Tied to Global Warming”)
that the worldwide yields for maize and wheat declined by 3.8% and 5.5%,
respectively, between 1980 and 2008 (yields for soybeans and rice showed no
clear trend over this period).
Here, the Briefing
by OXFAM GB projects future effects of long-term warming of the planet, and of
short-term extreme weather shocks, on crop yields and commodity prices for
staple foods around the world.The
warming and shock events are projected to adversely affect yields and lead to
lower availability and higher prices.These will impact the poorest populations of the world the most, causing
great suffering, and producing a need for emergency interventions for
is important for the developed countries of the world to invest both in abating
emissions of greenhouse gases so that the temperature of the world ultimately
stabilizes.Additionally they should
maintain their commitments, expressed in international meetings, toward those
less well off, by helping poorer countries accommodate to the increased
stresses on food availability.
Note 1. IPCC, 2011: Summary for
Policymakers. In: Intergovernmental Panel on Climate Change Special Report on
Managing the Risks of Extreme Events and Disasters to Advance Climate Change
Adaptation [Field, C. B., Barros, V., Stocker, T.F., Qin, D., Dokken, D., Ebi,
K.L., Mastrandrea, M. D., Mach, K. J., Plattner, G.-K., Allen, S. K., Tignor,
M. and P. M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA; http://ipcc-wg2.gov/SREX/images/uploads/SREX-SPM_Approved-HiRes_opt.pdf