Download As a rule of thumb, those working for an organization which

Hot Topics, Questions and
Misconceptions about
Climate Change
Who do you trust…?
“As a rule of thumb, those working for an organization which conducts
primary research on climate science (e.g. NASA, NOAA, CSIRO or
Universities), and publishes this work in peer-reviewed scientific journals
(the industry gold standard), should have their theories taken seriously.
This is because they are following the scientific process – the same
process that underpins the massive literature reviews of the
Intergovernmental Panel on Climate Change (IPCC) assessment
reports, and indeed the same process that has taken man to the moon,
decoded the genome, and given you digital watches, laptop computers
and automobiles. In any research field there will, of course, be diverse
opinions about causes and effects – the positing, testing and overturning
of theory and hypotheses are at the very core of science. Provided such
arguments are bound by empirical or experimental evidence, and have
survived rigorous pre-publication scrutiny and review, then they should
be considered a valid viewpoint.”
Prof. Schneider, Professor for Interdisciplinary Environmental Studies, Professor of Biological Sciences, and Professor by Courtesy of Civil and
Environmental Engineering at Stanford University, Co-Director of the Center for Environmental Science and Policy in the Freeman-Spogli Institute and a
Senior Fellow in the Woods Institute for the Environment. He received his PhD in Mechanical Engineering and Plasma Physics from Columbia University,
USA, in 1971.
There is no “scientific consensus”
on global warming
This question (is there a consensus on
warming) can be addressed in a scientific
manner itself!
1. The earth is getting warmer (0.6 +/- 0.2 C
in the past century; 0.1 0.17 C/decade
over the last 30 years
2. People are causing this
3. If GHG emissions continue, the warming
will continue and indeed accelerate
48% of Americans think climate scientists do not
agree that the Earth has been warming
53% think climate scientists do not agree that
human activities are a major cause of that warming
Proceedings of the National Academy of Sciences
Anderegg et al. (2010)
http://www.pnas.org/content/early/2010/06/04/1003187107.abstract?sid=5ce5529a-3fb5-422c-9eab-acb264229858
Survey:
1372 climate researchers
Their publications and citation record
Results:
• 97–98% of the climate researchers actively
publishing in the field support the tenets of
anthropogenic climate change outlined by the
Intergovernmental Panel on Climate Change
• The relative climate expertise and scientific
prominence of the researchers unconvinced of
ACC are substantially below that of the
convinced researchers
What specifically are the “tenets of the IPCC”?
•Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities
since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years. The global increases in
carbon dioxide concentration are due primarily to fossil fuel use and land-use change, while those of methane and nitrous oxide are primarily
due to agriculture.
•The understanding of anthropogenic warming and cooling influences on climate has improved since the Third Assessment Report (TAR),
leading to very high confidence that the globally averaged net effect of human activities since 1750 has been one of warming, with a radiative
forcing of +1.6 [+0.6 to +2.4] W m2.
•Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean
temperatures, widespread melting of snow and ice, and rising global average sea level.
•At continental, regional, and ocean basin scales, numerous long-term changes in climate have been observed. These include changes in
Arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather
including droughts, heavy precipitation, heat waves and the intensity of tropical cyclones
•Paleoclimate information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1300 years.
The last time the polar regions were significantly warmer than present for an extended period (about 125,000 years ago), reductions in polar
ice volume led to 4 to 6 metres of sea level rise.
•Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in
anthropogenic greenhouse gas concentrations. This is an advance since the TAR’s conclusion that “most of the observed warming over the
last 50 years is likely to have been due to the increase in greenhouse gas concentrations”. Discernible human influences now extend to other
aspects of climate, including ocean warming, continental-average temperatures, temperature extremes and wind patterns.
•Analysis of climate models together with constraints from observations enables an assessed likely range to be given for climate sensitivity
for the first time and provides increased confidence in the understanding of the climate system response to radiative forcing.
•For the next two decades a warming of about 0.2°C per decade is projected for a range of SRES emission scenarios. Even if the
concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade
would be expected.
•Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global climate
system during the 21st century that would very likely be larger than those observed during the 20th century.
•There is now higher confidence in projected patterns of warming and other regional-scale features, including changes in wind patterns,
precipitation, and some aspects of extremes and of ice.
•Anthropogenic warming and sea level rise would continue for centuries due to the time scales associated with climate processes and
feedbacks, even if greenhouse gas concentrations were to be stabilized.
“I have this list of 40,000 signatures of scientists
that don’t believe in global warming…”
More “consensus” issues…
• “Consensus” isn’t science!
–
–
"Scientific knowledge is the intellectual and social consensus of affiliated experts based on
the weight of available empirical evidence, and evaluated according to accepted
methodologies. If we feel that a policy question deserves to be informed by scientific
knowledge, then we have no choice but to ask, what is the consensus of experts on this
matter." Historian of Science, Dr Oreskes, UC San Diego
Medical doctor example…
• What about Galileo? (or Darwin or Einstein?)
– Presented views well outside of the consensus view at the time
– These scientists were able to PROVE that they were correct and
that the consensus was wrong.
– One never hears about the thousands of scientists that went
against the consensus –and ended up being wrong.
– To date, not a single scientist has been able to demonstrate with
a reasonable certainty a natural cause of the modern warming
trend while also showing how human emissions of greenhouse
gases is a minor forcing mechanism
In the 1970s the scientific consensus was
on “global cooling”!
Bulletin of the American Meteorological Society:
•Comprehensive survey of all peer-reviewed articles on climate change
during the 1970s
•The survey identified only 7 articles indicating cooling compared
to 44 indicating warming. Those seven cooling articles garnered
just 12% of the citations.
“There was no scientific
consensus in the 1970s
that the Earth was
headed into an imminent
ice age. Indeed, the
possibility of
anthropogenic warming
dominated the peerreviewed literature even
then.”
Peterson, Connolley, and Fleck, 2008
“the number of papers classified as predicting,
implying, or providing supporting evidence for future
global cooling, warming, and neutral categories”:
National Research Council
1979 meeting: panel on climate change
National Academy of Sciences
National Academy of Engineering
Institute of Medicine
National Research Council
Office of News and Public Information
Office of Congressional and
Government Affairs
Produced a national report
The panel concluded that the potential damage
from greenhouse gases was real and should not be
ignored. The potential for cooling, the threat of
aerosols, or the possibility of an ice age shows up
nowhere in the report. Warming from doubled CO2
of 1.5°–4.5°C was possible, the panel reported.
What information makes its way into the media?
vs
If a national report in the 1970s advocates
urgent action to address global warming,
then the scientific consensus of the 1970s
was not global cooling.
“This is just a natural cycle”
• What is behind this cycle?
• Without a forcing, there is no change (trend)
• How does “natural cause” accommodate a 39%
increase in 2nd most effective GHG not affecting
global temperature
• Climate science: well-developed internally
consistent theory matched by obs. to expl. recent
warming
• No other forcing (i.e. Milankovitch, solar etc) that
expl. the very detailed information in ice cores etc
“Carbon dioxide is natural!”
http://www.youtube.com/watch?v=URGcs4WV1fY
CO2 is natural…
2007 IPCC
Carbon “budget” circa 1990: 190.2 GtC emitted,190 GtC absorbed
Red values anthropogenic, black values naturally occuring
CO2 is natural…
• Natural land and ocean CO2 sinks removed
57% (~5 Gigatons per year) of all
CO2 emitted from human activities during
the 1958-2008.
• During this period the size of the natural
sinks has grown but at slower pace than
emissions have grown, although year-to-year
variability is large.
• This implies a decline in the efficiency of the
sinks in removing atmospheric
CO2 over time (from 60% fifty years ago
down to 55% in recent years), a trend
expected to continue the future.
Water vapor is more important than
CO2!
• Difference between forcing
– i.e. CO2  if altered it will cause a change in
climate
• and feedback
– A mechanism by which the forced change is
amplified (+) or dampened (-)
• If introduce 5 extra Gt C to atmosphere it
will cause long term T increase
• If introduce 5 extra Gt H2O to atm., it will
rain out in a few days
BTW, water vapor is the most important feedback process…
http://www.youtube.com/watch?v=M_s-h8AkVSo
CO2 lags temperature change!
• At least three detailed
ice core studies have
shown that CO2 starts to
rise about 800 years
(600-1000 years) after
Antarctic temperature
(about the amount
of time required to flush
out the deep ocean
through natural ocean
currents, CO2 stored in
the deep ocean during
ice ages, and then gets
released when the
climate warms)
CO2 lags temperature change!
• At least three detailed ice core studies have shown that CO2 starts to
rise about 800 years (600-1000 years) after Antarctic temperature
(about the amount of time required to flush out the deep ocean
through natural ocean currents, CO2 stored in the deep ocean
during ice ages, and then gets released when the climate warms)
• This process also causes CO2 to start rising, about 800 years later.
•
Release of CO2 causes Antarctica and the surrounding ocean to warm.
• Then CO2 further warms the whole planet, because of its heat-trapping
properties.
• This leads to even further CO2 release. So CO2 during ice ages should
be thought of as a “feedback”
• These warmings take about 5000 years to be complete…
Medieval Warm Period was warmer
than today!
Grapes in England!
Norse Ruins
Greenland colonized,
Called Green-land as it was so
warm!
Was MWP global…?
NOAA Paleoclimate page: "The idea of a
global or hemispheric "Medieval Warm
Period" that was warmer than today
however, has turned out to be incorrect."
“Medieval Climate Anomaly”
more accurate term…
North Atlantic  warmer
BCP White Mtns, CA wetter
Southwest US  drought
(disappearance of Anasazi),
increased fire frequency
Central tropical Pacific  cooler
IPCC Fourth Assessment Report, 2007
Antarctic icesheets are growing though!
There was much
uncertainty surrounding
the dynamics of the
Antarctic ice sheets –
even recetly
Satellite measurements
give us the best
estimate –thickness
(volume, mass) is a
better measure than
length.
Antarctic Ice Sheets Growing…?
Accelerated loss in
West Antarctic Ice
Sheet
Increased snowfall in
some areas
Ice mass lost on
Antarctica exceeded
prior IPCC predictions
Global Warming Ended in 1998!
UK Met. Office Hadley Centre
NASA Goddard Inst. For Space Studies
UK Met. Office Hadley Centre
•Excludes Arctic
•Based only on surface temperatures
•Excludes ocean temperatures
NASA Goddard Inst. For Space Studies
•Assumes warming follows nearest land
based stations
•No permanent weather stations in Arctic, where warming is greatest
•What is important is total warming of whole atmosphere
•Top of the atmosphere radiation budget- the radiation balance!
•90% excess heat into warming oceans, 3% into atmosphere
•If oceans absorb less, land /atm heats up more; if oceans absorb more,
decrease in atm/land temp
What happened in 1998 then, anyway?
A “global warming spurt”…?
1998 was a particulalry strong El
Nino
No cold water upwelling
Especially large area of Pacific
Ocean very warm
Increased heat transfer from ocean
to atmosphere
(in general, El Nino accompanied by
warmer temps
We had record snow on east coast during
winter 2009/2010 –how can you say
there’s global warming?
…or record cold in LA…
…or freezing in Argentina…
…or record rains in July in Mexico…
etc
The temperature of one place at one time is just weather,
and says nothing about climate, much less climate change,
much less again for global climate change…
You can’t trust the computer models…
Can we?
Based on:
•Well-established laws of physics
•Extensive observations
How well can they reproducePast climate changes (Glacial-interglacials)?
Current climate change?
You can’t trust the computer models…
You can’t trust the computer models…
2007 IPCC Fourth Assessment Report
•According to the IPCC 2007 WGI, Chapter 8 report by Randall, et al. (2007):
•There is considerable confidence that Atmosphere-Ocean General Circulation Models (AOGCMs) provide credible quantitative estimates of future climate change, particularly
at continental and larger scales.
•Models now being used in applications by major climate modeling groups better simulate seasonally varying patterns of precipitation, mean sea level pressure and surface air
temperature than the models relied on by these same groups at the time of the IPCC Third Assessment Repport (TAR).
•Model global temperature projections made over the last two decades have also been in overall agreement with subsequent observations over that period.
•Some AOGCMs can now simulate important aspects of the El Niño-Southern Oscillation (ENSO).
•The ability of AOGCMs to simulate extreme events, especially hot and cold spells, has improved.
•Atmosphere-Ocean General Circulation Models are able to simulate extreme warm temperatures, cold air outbreaks and frost days reasonably well.
•Models also reproduce other observed changes, such as the faster increase in nighttime than in daytime temperatures and the larger degree of warming in the Arctic known
as polar amplification.
•Models account for a very large fraction of the global temperature pattern: the correlation coefficient between the simulated and observed spatial patterns of annual mean
temperature is typically about 0.98 for individual models. This supports the view that major processes governing surface temperature climatology are represented with a
reasonable degree of fidelity by the models.
•The models, as a group, clearly capture the differences between marine and continental environments and the larger magnitude of the annual cycle found at higher latitudes,
but there is a general tendency to underestimate the annual temperature range over eastern Siberia. In general, the largest fractional errors are found over the oceans (e.g.,
over much of tropical South America and off the east coasts of North America and Asia). These exceptions to the overall good agreement illustrate a general characteristic of
current climate models: the largest-scale features of climate are simulated more accurately than regional- and smaller-scale features.
•Models predict the small, short-term global cooling (and subsequent recovery) which has followed major volcanic eruptions, such as that of Mt. Pinatubo in 1991
•Simulation of extratropical cyclones has improved. Some models used for projections of tropical cyclone changes can simulate successfully the observed frequency and
distribution of tropical cyclones.
•The models capture the dominant extratropical patterns of variability including the Northern and Southern Annular Modes, the Pacific Decadal Oscillation, the Pacific-North
American and Cold Ocean-Warm Land Patterns.
•With a few exceptions, the models can simulate the observed zonal mean of the annual mean outgoing LW within 10 W/m2 (an error of around 5%) The models reproduce the
relative minimum in this field near the equator where the relatively high humidity and extensive cloud cover in the tropics raises the effective height (and lowers the effective
temperature) at which LW radiation emanates to space.
•The seasonal cycle of the outgoing LW radiation pattern is also reasonably well simulated by models.
•The models capture the large-scale zonal mean precipitation differences, suggesting that they can adequately represent these features of atmospheric circulation. Moreover,
there is some evidence that models have improved over the last several years in simulating the annual cycle of the precipitation patterns.
•Models also simulate some of the major regional characteristics of the precipitation field, including the major convergence zones and the maxima over tropical rain forests,
although there is a tendency to underestimate rainfall over the Amazon.
•Confidence has also increased in the ability of GCMs to represent upper-tropospheric humidity and its variations, both free and forced. Together, upper-tropospheric
observational and modeling evidence provide strong support for a combined water vapor/lapse rate feedback of around the strength found in GCMs (approximately 1 W/m2 oC1, corresponding to around a 50% amplification of global mean warming).
Remember- scientists publish peer-reviewed
journal articles…
They don’t usually have time for easy to
understand blogs… or news shows
Sounds daunting:
How can an average citizen stay informed?
NATS 101 students way more informed than
Joe Public… but had to suffer through albedo,
radiation budgets, and latent heat to make it
this far…
Who do you trust…?
“As a rule of thumb, those working for an organization which conducts
primary research on climate science (e.g. NASA, NOAA, CSIRO or
Universities), and publishes this work in peer-reviewed scientific journals
(the industry gold standard), should have their theories taken seriously.
This is because they are following the scientific process – the same
process that underpins the massive literature reviews of the
Intergovernmental Panel on Climate Change (IPCC) assessment
reports, and indeed the same process that has taken man to the moon,
decoded the genome, and given you digital watches, laptop computers
and automobiles. In any research field there will, of course, be diverse
opinions about causes and effects – the positing, testing and overturning
of theory and hypotheses are at the very core of science. Provided such
arguments are bound by empirical or experimental evidence, and have
survived rigorous pre-publication scrutiny and review, then they should
be considered a valid viewpoint.”
Prof. Schneider, Professor for Interdisciplinary Environmental Studies, Professor of Biological Sciences, and Professor by Courtesy of Civil and
Environmental Engineering at Stanford University, Co-Director of the Center for Environmental Science and Policy in the Freeman-Spogli Institute and a
Senior Fellow in the Woods Institute for the Environment. He received his PhD in Mechanical Engineering and Plasma Physics from Columbia University,
USA, in 1971.
NASA/Goddard Institute for Space Science
http://www.nasa.gov/worldbook/global_warming_worldbook.html
NOAA (National Oceanic and Atmospheric Administration
http://www.ncdc.noaa.gov/oa/climate/globalwarming.html
National Academy of Science (NAS)
http://dels.nas.edu/climatechange/
NCAR (National Center for Atmospheric Research
http://www.ncar.ucar.edu/researrch/climate/now.php
American Meteorological Society (AMS)
http://www.ametsoc.org/POLICY/2007climatechange.html
EPA (Environmental Protection Agency)
http://www.epa.gov/climatechange/
National Academy of Engineering
National Weather Service
World Glacier Monitoring Service
Lawrence Livermore National Laboratory
Department of Energy
American Geophysical Union