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Understanding Global Warming
Humanity will likely "survive" this century,
but in what state is up to us.
normal for local 'weather' to be hard to forecast, and change rapidly
(within a general range). But does the same apply to the holocene climate that threatens to heat up much faster than the prehistoric late paleocene, and with much more sea level rise? And what are the implications of accelerated warming during a mild interglacial populated by billions of people, many still thinking their contributions are a meaningless drop in the (overflowing) bucket?
Climatic "signal" vs. "noise" (fluctuation from ocean & solar cycles): Just the beginning (Updated here)
Ocean heat content anomaly, to 2000 meters
Not only do people wonder
why climate change is a problem when it "happened in the past" (see
below), but they question the existence of evidence. Yet it has
been accessible for many years (examples here
, and here
We have a rise in temperature averages in three major surface datasets
(affirmed by the tropospheric satellite record), nighttime temperatures
rising faster than daytime (consistent with the amplified greenhouse
effect, not enhanced solar activity), borehole analysis, ocean heat content
(erroneous claims of cooling aside), widespread glacier disintegration, rapid sea ice "rot"
(excepting Antarctica's special case), thousands of bio-markers,
increasing ratios of record high to record low temperatures, a rising
tropopause, increased water vapor as temperatures rise, greater
precipitation extremes, thawing permafrost... All combined with the
well-established infrared heat absorption properties of CO2/CH4, and
changes in the infrared energy emitted from, and re-radiated to, Earth
There's a distinct human fingerprint in the
climate of the last several decades, despite the temporary offsetting
effect of things like sulfur pollution and natural variability (such as
the cool phase of the Interdecadal Pacific Oscillation, accompanied by
the dominance of La Niña vs. El Niño sea surface patterns over the past
Science has moved beyond just strengthening the
attribution case, to refining projections based on physical processes
(linear and otherwise), paleoclimatology, and trends in human activity.
Uncertainty remains on a number of details, partly because there's no
exact prehistoric analog to our situation (a rapid, globally-distributed
forcing coupled with a black carbon influence, and mixed with the
short-lived cooling effect of sulfates). But the main conclusions are
solid, and the stakes are high for the most populous civilization to
exist on Earth. There is, though, a disconnect between the mainstream
scientific community and the controversy-driven media. That would
include claims that global warming doesn't affect weather (when over
time it can't help but do so), and of it "stopping" every time there's a
short down-tick in surface temperature, vs. a statistically significant
visible even on shorter timescales:
What the scientific community is saying (reflecting the consensus among actual published researchers):
strong, credible body of scientific evidence shows that climate change
is occurring, is caused largely by human activities, and poses
significant risks for a broad range of human and natural systems...
- National Academy of Sciences
bottom line is that CO2 is absolutely, positively, and without
question, the single most important greenhouse gas in the atmosphere. It
acts very much like a control knob that determines the overall strength
of the Earth?s greenhouse effect... - Dr. Andrew Lacis, NASA climatologist
To slow the rate of climate change, we can decrease the amount of carbon dioxide that we release into the atmosphere.
- National Center for Atmospheric Research
There is no single threshold above which climate change is dangerous
and below which it is safe. There is a spectrum of impacts. But some of
the largest impacts are effectively irreversible and the thresholds for
them are very near... In particular, the melting and breakdown of polar
ice sheets seems to be in the vicinity of a couple of degrees warming.
This expectation is based on current high rates of mass loss from the
ice sheets compared to relative stability through the Holocene (the past
10,000 years) and on past ice sheet response in periods such as the
Pliocene (a few million years ago) when the Earth was a couple of
degrees warmer than preindustrial times (and sea level up to 25m
higher)... - Dr. James Risbey, CSIRO Australia Recent
observations confirm that, given high rates of observed emissions, the
worst-case IPCC scenario trajectories (or even worse) are being
realized. For many key parameters,
the climate system is already moving beyond the patterns of natural
variability within which our society and economy have developed and
thrived. These parameters include global mean surface temperature,
sea-level rise, ocean and ice sheet dynamics, ocean acidification, and
extreme climatic events. There is a significant risk that many of the
trends will accelerate, leading to an increasing risk of abrupt or
irreversible climatic shifts.
- 2009 Copenhagen climate congress of 2,500 scientists
Earth's climate is now clearly out of balance and is warming. Many
components of the climate system?including the temperatures of the
atmosphere, land and ocean, the extent of sea ice and mountain glaciers,
the sea level, the distribution of precipitation, and the length of
seasons?are now changing at rates and in patterns that are not natural
and are best explained by the increased atmospheric abundances of
greenhouse gases and aerosols generated by human activity during the
20th century... - American Geophysical Union There
is no doubt that Greenland ice loss has not just increased above past
decades, but it has accelerated. The implication is that sea level rise
estimates will again need to be revised upward. - Dr. Jason Box, Glaciologist
not the right question to ask if this storm or that storm is due to
global warming, or is it natural variability. Nowadays, there?s always
an element of both.
- Dr. Kevin Trenberth, NCAR
As humans burn enormous amounts of fossil fuel
(containing carbon removed over eons from the prehistoric atmosphere),
gigatons of carbon dioxide are accumulating beyond the uptake capacity
of today's natural "carbon sinks". With this imbalance, atmospheric concentration
has increased 41% since industrialization, rivaling the smaller and
much slower oscillations of glacial cycles, and reaching it's highest in
at least 800,000 years. Other studies (Pagani et al., Pearson & Palmer, Hönisch et al.) suggest millions of years. And although there's some short-term fluctuation, the trend persists (accelerates).
This has changed the infrared transparency of Earth's atmosphere
similarly to the way a drop of ink changes the visible transparency of
water. So what's wrong with this change, and how can we improve the odds
of ecosystem integrity and human prosperity into the future? First, a
crash course on the basics.
A small percentage of the atmosphere,
CO2 is nevertheless the primary persistent "greenhouse gas",
re-radiating heat energy over an atmospheric lifetime of several years.
But a significant accumulation (total volume in the atmospheric column being key) exceeding the carbon cycle's quasi-equilibrium, can last centuries and subside over millennia. After all, CO2 molecules aren't just absorbed
in nature, they're also re-released. Carbon is constantly exchanged
between the oceans, atmosphere, and biosphere, so seemingly modest
atmospheric "residence times" are misleading. The net uptake resulting from a pressured carbon cycle would slowly
reduce the total "pool" once emissions fall (assuming no big feedbacks
beforehand). But like an overflowing bathtub with a slow drain, the
input must drop below the sink rate. Then, even with no biological sink
reduction, carbon transfer rates to the deep ocean are an absorption
"bottleneck". So barring fantastical future advancements in carbon
sequestration, today's buildup is a very long term commitment.
Carbon dioxide plays vital roles in climate and the biosphere, but there can be too much of a good thing. A buildup semi-permanently (in human vs. geologic terms) amplifies the greenhouse effect that keeps Earth's average temperature above zero, causing warming (2).
Research overwhelmingly indicates this is the main factor in a
climatically strong trend, with much of the extra heat accumulated and
distributed by the oceans (their thermal inertia produces a lagged
atmospheric response). This rise, subject to fluctuation from things
like ocean cycles (in the exchange of heat between the depths and the
surface) and sulfate "aerosol", is extensive but not uniform, and proxy
studies suggest it has already exceeded anything in at least 2,000
Heat is the ultimate driver of the climate system.
Effects on evaporation, all forms of precipitation, reflective ice
cover, oceanic and atmospheric circulation, and storm intensity make
"global climate change" a more complete descriptor of the situation.
Although it's still early in the process, and there are variables
between climate change and disaster losses that so far make direct
attribution between them difficult, trends in heat waves and
precipitation are already clear. And along with fast responses like
increasing levels of water vapor
(a reactive greenhouse gas), protracted warming is also subject to
amplification by an interplay of longer-term feedbacks, like reduced
carbon storage (example1, 2, and 3), and the release of more greenhouse gas from warming oceans, forests, peatlands, and tundras. Higher wildfire incidence and increased CO2 and methane emission from thawing permafrost
(See sidebar) are examples. How fast carbon cycle effects will be is
uncertain, but even the substantial mid-range climate projections have
insufficiently assessed their potential, and with improved understanding
of amplifying feedbacks and their lasting dominance, concerns have only
Warming may not seem like an urgent problem
in most temperate regions, where so far it has been largely subtle and
mixed with significant variability. But it does have the potential to
cause lasting disruption, since many things in today's world are
vulnerable to rapid change. The rate of warming (and potentially carbonic ocean acidification)
will be a key to how ecosystems and large human populations will be
impacted. Many a scientist would say past climate change has helped
shape humanity (usually in transitions over thousands or
millions of years), but so has the relatively mild, stable holocene in
which intensive agriculture and modern civilization have developed,
allowing us to expand our horizons beyond the mere struggle for
Nature is not without resilience, but with cumulative pressures, biomes can weaken and change can snowball. Yet we can
limit it's progression and protect the biologically-rich interglacial
that has helped societies thrive. Markets are more globalized, so this
will take international efforts to reduce emissions from sources like
electric generation, animal agriculture, and transport (none of which
are likely to realize sufficient cuts alone). As well as technology to
handle changes already underway. And those in the middle and upper
classes, who've benefited most from a fossil-fueled system, are the ones
more likely to have the means to help foster newer technologies. Still,
certain ideological forces seek to cast doubt on strong science, or
downplay the negatives while emphasizing some regional benefit (from moderate warming). An industry of disinformation has arisen, similar to past efforts to deny the health effects of cigarettes, with some of the same players. And those PR operations have helped delay a stewardship-oriented approach.
Delay means locking in stronger impacts,
including on agriculture and resource reliability. This issue is about
rapid climate change, and its many effects on today's biosphere. If we
stop ourselves from pushing too far, we at least have the chance at
several thousand years of advancement; to become more resilient as a
civilization, not just as a species.
Addressing Some Common Questions & Arguments
1? "They can't even predict next week's weather"/"Models are useless" As Dr. William Connolley notes, weather and climate aren't the same thing, and "predicting
one isn't the same as the other. Consider (analogy: not perfect but not
bad) the shore of the ocean and the level of the sea: tides can be
predicted with great accuracy years in advance; waves can't be predicted
any better than weather." Although
ultimately affected by warming, weather events are also influenced by
short-term ocean-atmosphere dynamics, and are more about the movement
of heat and moisture within the system, while climate is more a
function of persistent, large-scale factors related to Earth's "energy
budget" (sunlight in vs. infrared out). Weather "noise" cancels out over
time, revealing the "signal" of a changing climate in the longer-term
Computer models of highly variable local weather are actually more error-prone than those of climate trends. Although
some people demonize models in general (a key tool in many areas of
science and medicine), what counts is how scientifically robust they
are. Modern general circulation
models are valuable for analyzing influences from greenhouse gases to
solar flux, and they produce large to medium scale simulations that
agree well with the real world. They're continuously validated (Example), and refined with the latest data and cutting-edge physics. Yet their indicated trends have persisted, and no
model can account for them without including human-generated greenhouse
gases. GCMs have done a good job of projecting average temperature
change, the magnitude of short-term volcanic cooling, the amplification
of Arctic warming, an increase in heat waves and drought, ocean warming,
and the stratospheric cooling effect (#24).
Still, as in any science we can't expect perfection. Detailed
projection (particularly of complex regional climates) is difficult. But
models needn't be exact to give an indication of a trend and it's major
effects. While there are uncertainties, recent research suggests models
may be inadequately assessing amplifying feedback potentials. Something
that would make at least the longer term projections too conservative.
Those who argue against climate concerns by pointing to uncertainties in
models tend to ignore the possibility that they won't turn out in our
The Physics of Climate Modeling
Realclimate: Short and simple arguments for why climate can be predicted
2? "So what's a few degrees?" Contrarians
take advantage of the public's weather-oriented perspective when
highlighting lower-end warming projections of "only" a few degrees. The
IPCC fourth assessment, representing reviewed and assessed research,
included a "best estimate" range of 1.8 - 4.0°C (3.24 - 7.2°F, Δ T) by
2100, with a potential range of 1.1 - 6.4°C (1.98 - 11.52°F). This is
based on several scenarios, with the low end assuming a world with
stabilized population and a quick transition from fossil fuels, and the
top numbers assuming high emissions. Subsequent studies based on
continuing emissions growth indicate a rise of 4-7 degrees C. One of the
latest from Hadley Centre (here) suggests that on today's path, we could see 4 degrees C as early as 2060.
climatologists view warming of about 2°C (3.6°F) this century as a
hazard point, beyond which broadly disruptive changes become much more
likely. This would be at least 40 times the estimated average warming rate of the
paleocene-eocene thermal maximum about 56 million years ago (which was
coming off a relatively warm-adapted biosphere, with little land-based
ice to contribute to sea level rise).
suggest a "climate sensitivity" of around 3°C (5.4°F) for a doubling of
pre-industrial CO2 (something that will easily occur without
mitigation). The AR4 notes that it's "likely to be in the
range 2 to 4.5°C with a best estimate of about 3°C, and is very
unlikely to be less than 1.5°C. Values substantially higher than 4.5°C
cannot be excluded, but agreement of models with observations is not
as good for those values
." More here.
For local weather, a single-digit change over decades may not seem like much, but a global average
temperature increase of a few degrees is large, translating to stronger
regional effects, including from concentrations of extra energy within
the system. To help put things into perspective, the anomaly associated with early 20th century warmth was less than 1°F. The global mean temperature during the last glacial period was about 9°F lower than today's, and much of that seems to have occurred more slowly. Since then, things have been relatively stable, aiding the development of agrarian societies.
Dr. Ray Pierrehumbert notes: "So
far we haven't quite gotten to 400ppm CO2, but we'll eventually go to
700 or more without controls. We haven't even seen the full warming
effects of that 400ppm yet, because it takes time for the ocean to warm
up. So, the striking thing is that it has already gotten to the point
that the recent warming stands out from the natural variability of the
past thousand years or more, despite the fact that so far we've only
experienced the barest beginnings of the warming. That's not just
striking. It ought to be alarming."
Dr. Tim Flannery: "Our
deep psychological resistance to thinking that "warm" might be bad
allows us to be deceived about the nature of climate change. Those who
have exploited this human blind spot have left many people - even the
well-educated - confused. This is the result of an unhealthy, in some
instances corrupt, relationship between government and industry."
People often do see warmth as "nice", until winter ends or the warmth
is accompanied by drought, ecological impacts, insect invasions, floods,
changing croplands, more severe weather, or high wildfire danger.
3? "But the weather is downright chilly in ________/We hit a record low!"
warming refers to global average temperature change over time (an
indicator of Earth's "energy budget": Energy in vs. energy radiated to
space). It doesn't mean constant,
regionally synchronous change or the end of cold snaps. Despite the
trend, fluctuations continue in a fluid-dynamic system, particularly
from the variability in ocean heat exchange and heat distribution. These maps give some idea of how anomalies can vary on short timescales, especially regionally:
Vs. average anomaly for the past decade (despite an overall surface
cooling influence associated with ocean-atmosphere heat exchange
Record highs will also occur more frequently with global warming
(already observed, with record highs occurring about twice as often as
record lows over the past decade), but local extremes alone are not
necessarily global indicators. It can be interesting, though, to
consider the circumstances under which records are set. Frequently
anomalous warmth despite the cooling influence of la niña,
increased Asian emissions of sulfur particulates, and a deep solar
minimum could be viewed differently from past warm spells under the
opposite conditions. An example of a trend in record temperature ratios, expected to accelerate:
And when we look at the global averages, most of the warmest years are in the past decade:
Still, the weather
we observe is a confluence of both natural variability (such as from
ocean cycles) and the cumulative human influence. And perceptions can
mislead. People don't think of global mean temperature being on the rise
when they're in the middle of a winter storm. Many regions experience
frosty spring weather, and lingering snowfall can give a strong
impression of cold even when temperatures aren't unusually low. And
under favorable conditions, water vapor feedback from a warming planet
can make regional snow & ice events more intense, via the mixing of
4? "Climate change is normal/has happened throughout Earth's history"/"CO2 has been higher before" Past
events do nothing to support the idea that today's ongoing process is
mostly natural, or irrelevant to Earth's present ecology. Although
there are generally modest holocene fluctuations from things like
sulfates, solar cycles, and El Niño/La Niña oscillations, warming from
the carbon imbalance is on top of those. Significant global-scale
changes in the past have generally occurred over millennia (instability
related to glacial period termination being an exception), allowing
life to adapt or migrate. Warming from unabated emissions will likely be
much stronger, more widespread and more persistent than anything seen
by civilization. Without this, Earth may well have thousands of years more of mostly stable, mild climate (see below).
As for CO2, there have been periods in pre-history with higher
concentrations, but other aspects of the Earth system were starkly
different (and a big issue today is the rate
of change, from a relatively moderate baseline). There were even periods of relatively high CO2 when
temperatures weren't as warm as one would expect. That's due to climate
factors like solar irradiance, which was lower and has slowly risen over
millions of years (some fascinating detail here).
If we could go back in time and double Earth's CO2 concentrations
(which we're poised to do without serious mitigation), that would have
consequences. But not the exact same consequences as ratcheting up CO2
levels in what is now considered roughly the middle of the holocene.
most of the warming occurred before 1940"/"What about past events like
the medieval warm period?", and "Isn't Earth just recovering from the
'Little Ice Age'?"
The first point is misleading and incorrect.
NASA notes that "More specifically, there was slow global warming, with
large fluctuations, over the century up to 1975 and subsequent rapid
warming of almost 0.2°C per decade." Despite some regionally
concentrated heat, events of the 1930's were much less significant
globally than the recent trend (example: 1930's vs. the 1990's & beyond), and were likely related to a period of moderately higher solar activity, with oceanic heat distribution helping determine local effects.
Greenland (so-named to attract colonists, when most of it wasn't green)
hasn't always been representative of major global trends, but change
there had been limited in scope during recorded history. And today's
situation is still progressing. Dr. Raymond Bradley of the UMASS Climate
System Research Center notes that "human activity is pushing warming at a much faster rate than in the past",
and NASA's Evelyne Yohe notes that the Arctic warmth of the early
1930's was the result of three decades of gradual warming. Even the
change of the past decade or so has exceeded that.
Research indicates that the "Medieval Warm Period" (and the moderate
cooling dubbed the "Little Ice Age") was comprised of non-synchronous
regional changes, and had relatively little impact on the global averages. It also occurred over centuries (more detail on it here).
The 2007 AR4 references proxy studies, independent of the "hockey
stick" (links bar), affirming that the global magnitude of medieval
warmth was weaker than that of today. Dr. Michael Mann also addresses
(and for an example of a contrarian trick that makes it appear
otherwise, or that the current trend is part of a natural cycle, see
sidebar). The "mid-holocene warm period", about 6000 years ago, is a similar story, with high-latitude seasonal warmth. It has even been suggested that the trend is part of a recovery from the "little ice age". Not only does evidence suggest it wasn't a globally synchronous event either, but a trend can't be called a recovery if natural mechanisms can't account for it (see below).
6? "The temperature record is too short to suggest human influence"
determination of anomalous global change, and the expectation that it
will worsen under "business as usual", doesn't depend solely on human
temperature records. We also have observations of radiation imbalance,
studies on climate sensitivity, the physics of the greenhouse effect (infrared re-radiation), observed
ocean warming that fits with the amplified greenhouse effect,
independent proxy datasets, and other evidence for ongoing change in the
averages, in the absence of an associated natural forcing.
7? "Isn't 'black carbon' from developing nations the problem?" Black
carbon (AKA soot) is viewed as a secondary contributor to climate
changes, with significant regional effects. The melting of some glaciers
may be attributed in part to soot, from things like dirty coal-fired
power plants, unregulated diesel engines, and developing nation stoves.
Soot is an easy target that could be relatively cheap to address, and
with more immediate effect, but research is ongoing as to the likely net
result of such targeted efforts. To some, this represents an
opportunity to shift attention from CO2 (even briefly),
despite it being a much larger long-term threat that will take more
work to mitigate. It's worth noting, though, that CO2 reduction and soot
reduction can to some degree go hand-in-hand.
8? "What about claims of impending cooling/ice age aversion?"
W. Felix, a former architect, received some publicity for his book and
website claiming that we're actually entering an ice age, and that
glaciers are growing (more below). These claims were repeated by
botanist David Bellamy, and posted on "skeptic" sites like Steve Milloy's "junkscience.com" (more). The assertions were traced to figures published by Fred Singer (who, like Milloy, was connected with TASSC, and also with dubious petition projects, below). Singer stated his source as "A paper published in 'Science' in 1989"
- nowhere to be found. This and other papers (most outside of
peer-reviewed climate journals) suggesting we're entering a long-term
cooling phase have been roundly discredited. It has also been suggested that we're averting another ice age by tipping the climate scale with greenhouse gas
emissions. Although we've probably already tipped that scale enough to
significantly delay a Milankovitch-type glaciation, indications are that
Earth is nowhere near due
for another glacial period anyway. Humanity has been blessed with one
of the longer interglacials. Still, there are those who have used the
ice age aversion argument as positive spin. They're essentially implying
that rapid holocene warming is fine because we'll avert the subtle
multi-millennial cooling (or very rare, 'well-timed' supervolcanic
eruption) leading to the next big freeze. But if we're still around, we
can consider measured greenhouse gas emission/other geo-engineering to
avoid glaciation. For now, humans are in a period of development that
may eventually make us less vulnerable to disaster. It's in our interest
to value and prolong the time we have.
On a related issue, there's a common myth that climatologists predicted
an imminent ice age in the 1970's, despite the infancy of the science
& technology, and acknowledged uncertainty on the future trajectory
of climate forcings. While there was some speculation (along with
caveats) and some overzealous media coverage, there's more to the story than today's naysayers admit. Update: A more recent review paper affirms what the scientific literature was actually saying.
9? "Natural processes will fix the imbalance"
is essentially true, but it leaves out two important factors: The
timescales involved and the damage done in the meantime. Once the source
diminishes, an imbalance tends to self-correct, but not necessarily in a
quick and convenient manner. During the paleocene-eocene thermal
maximum, carbon accumulation occurred over 10,000 years, and recovery
took about 100,000. At this point, things are a bit different, but not
in a way that allows us to continue as usual. In fact, evidence suggests
humans are releasing carbon at a much higher rate than the natural emissions leading into the PETM (which appears to have occurred with less than a doubling
of carbon), and that climate change in today's less warm-adjusted world
has the potential to occur faster. If this compromises Earth's carbon
sinks, a multi-millennial recovery wouldn't be out of the question.
10? "Won't life just adapt?"
Rapid warming is a multi-faceted problem, with ecosystem impacts being
one result. Some organisms may readily adapt (many of them at the
expense of their populations), while others can't simply adjust in a
matter of decades or centuries. Thousands of species, including some
that play vital roles in complex ecosystems, are at risk (see link
section). More discussion here.
11? "What about religious views of global warming?"
those with a Bible-based perspective, the question becomes whether
there's direct divine control over Earth's life-supporting systems (thus
we can freely trash them), or whether a sustained quasi-equilibrium has
been set up that allows our
actions (born out of free will) to demonstrate either stewardship or
disregard. And which seems more responsible: To assume the former
because it's easy and convenient, or the latter because it's not worth
gambling with the future (a future that could be millennia, despite
ever-present predictions of apocalypse)? Several religious groups have
decided it's better to err on the side of caution and accept some
responsibility for the environment that sustains us. Others selectively
interpret the Bible as supporting careless plunder, while disregarding
passages that suggest such things as humanity's self-determination.
12? "More solar activity is responsible, and Mars/Pluto prove it.
Some highlight the sun as the primary cause of global warming (often selectively citing snippets from Solanki et al. 2004),
but the science doesn't support this. Although the sun goes through
11-year activity cycles, and contributed to moderate (but regionally
significant) warming in the early 20th century, it doesn't account for
the strong 'trend' of recent decades. A 2006 NCAR study (Foukal
et al.) affirmed with satellite and proxy data that solar flux has made a
negligible contribution to accelerated warming over at least the past
30 years, and that luminosity changes had a moderate influence over the
past thousand years or more. Lockwood & Frolich note in another
study that "over the past 20 years, all the trends in the Sun that
could have had an influence on the Earth's climate have been in the
opposite direction to that required to explain the observed rise in
global mean temperatures". Other solar-related claims have also taken it on the chin. Additionally,
the stratosphere has been cooling (#24), consistent with an amplified
greenhouse effect but not with a significant increase in average solar
The latest standing scientific papers agree that the sun isn't driving the ongoing trend (more here).
A trend that remained robust despite a deeper than average solar
minimum, the temporarily offsetting effect of natural and manmade
sulfates, and at least two ocean heat exchange cycles being in their
cool phases. In any case, elevated levels of greenhouse gas trap additional solar energy whatever it's intensity. The fact that the greenhouse effect strongly influences Earth's climate makes it an important part of the equation.
If it were allowed to snowball, and a period of substantial solar
warming were to occur in the future, one has to wonder about the
results. Re: Mars and other planets - Even if there were a global warming trend on Mars (vs. a changed polar ice cap over a few Martian seasons),
there are no oceans there, much of the ice isn't composed of water, and
the atmosphere is much thinner. So temperatures are bound to be more
sensitive to even small solar changes. But as noted by astrophysicist
Steinn Sigurdsson, there are other factors at work on Mars unrelated to
the sun's output (which, overall, had been declining slightly as it
moved towards solar minimum). The much greater influence of orbital
eccentricity, strong seasonal variation, and the strength & duration
of hemispheric dust storms are also involved. And of course that's a
change on of Mars over several years, vs. a trend over decades on Earth.
For Pluto, warming has been inferred from a change in atmospheric
thickness over less than one Plutonian season, following a close
approach to the sun. Other bodies in the solar system also have very
long seasons and orbital periods (even centuries), or surface conditions
driven mostly by internal energy sources, so they can't be used as
solar indicators either.
More here on the climates of other planets.
13? "The CO2 increase is natural"/"Ocean warming is responsible for the rise in CO2."
question is, what's causing that ocean warming if solar activity can't
account for most of it? A few "skeptics" have suggested undersea
volcanoes, but a major activity increase (for which there's no evidence)
would be required to globally heat the oceans a fraction of a degree,
and they're also warming from the surface down. Earth's average geothermal heat flow
is negligible compared to the energy received from the sun or retained
by the greenhouse effect. A recent Scripps study (see sidebar) affirms
that patterns of oceanic warming are consistent with CO2 forcing (as are
other changes). And in terms of CO2 exchange, the oceans still represent an absorption
of about 2 GtC (subject to decline as temperatures rise and ocean
chemistry changes). Even fossil fuel accounting, and the fact that part
of our carbon output doesn't remain in the atmosphere, indicates that
nature remains (at least for now), a net carbon sink, not a source. Scientists can also measure how much CO2 is from fossil fuels: How do we know that recent CO² increases are due to human activities?
14? "But ice core data shows that warming boosts CO2, not vice versa."
claim not only ignores the traceable origins of the current
accumulation (above), but it leaves out some important details. During
glacial period terminations, recovery of atmospheric CO2 acted as a
feedback to amplify warming triggered by Milankovitch orbital forcing.
This doesn't mean CO2 can't itself be a significant climate forcing (a cause of change rather than just a response). It just never has (until now) over the entire 800,000 year ice core record. More from Realclimate. Jeff Severinghaus, Professor of Geosciences at Scripps notes: "All that the lag shows is that CO²
did not cause the first 800 years of warming, out of the 5000 year
trend. The other 4200 years of warming could in fact have been caused by
CO², as far as we can tell from this ice core data". According to Caillon et al, 2003, "the CO² increase clearly precedes the Northern Hemisphere deglaciation"... And referring again to our 650 kiloyear CO2 chart, we can see the other difference between then and now:
15? "Aren't the oceans actually cooling?"
study by Lyman et al showed a decrease in oceanic heat content from
2003-2005. Such variability wouldn't necessarily indicate a new
trend. But there also seems to be an inconsistency in this study:
Sea level should have dropped along with temperature, unless there's
been a sharp increase in ice melt. Ocean circulation changes and
variability in heat exchange with the deeper ocean are variability
factors. While the study is still under review, short-term inconsistency
in warming wouldn't be surprising. Update:
Peer review at work. Lyman study seems to have a data problem, cooling
has disappeared in latest analysis. And some discussion here and here of trends and updates since.
16? "What about methane?"
it's emissions and concentrations are much lower than those of CO2,
methane is a more powerful greenhouse gas, and has the potential to play
a significant role in future warming. Along with the again rising
levels of directly human-induced emission, feedbacks are likely to
release more methane as warming progresses. One scenario, modeled by an
NCAR supercomputer, involves warmer water releasing methane currently
frozen under the sea floor (see sidebar). Thawing permafrost, though,
may have more feedback potential over the next several decades.
17? "Volcanic/other natural emissions far exceed those of humans."
Another volcanic gas, sulfur dioxide (SO²), can have a temporary cooling effect. But the real issue is a significant change in CO2 concentration. Overall, natural CO²
emissions have been balanced by absorption. A simplified example: The
trees that burn in a forest fire contain carbon that was previously
removed from the atmosphere. As the forest regenerates, CO²
is re-absorbed. With continued warming, though, wildfires are expected
to become more frequent and severe, further disrupting the carbon cycle.
Update: Rise in wildfires linked to climate change.
18? "CO2 trend data from Mauna Loa is biased by the volcano"
are taken upwind from volcanic vents, out-gassing is monitored, and any
short-term spikes are flagged for removal, but even if the Mauna Loa
figures were tainted, the volcano can't explain a long-term upward
trend. There are also multiple isolated measurements around the world,
including in Antarctica, that agree well. More here on the choice of Mauna Loa, and here on measurement reliability/verification.
19? "Is deforestation affecting climate?"
fossil fuel combustion is the primary factor, deforestation results in
the release of about 1.6 gigatons of carbon annually. The impact is
highest in the tropics, in part because those forests (which tend to be
ecologically sensitive) are often burned for pasture, and changes are
often permanent or very long-term. Forest loss can reduce the land-based
carbon sink, and re-forestation can help offset carbon cycle impacts,
but net absorption rates are influenced by multiple factors, including
forest type and regional climate. Although tropical forests are often
called the "lungs of the Earth" (and they are large carbon reservoirs), they are in fact less of a sink than the world's oceans.
20? "Extra CO2 will be beneficial/Plant growth will correct the imbalance."
It has been argued by certain fossil fuel interests that higher
CO² levels will enhance plant growth and benefit agriculture. This is
true to a point, under the right conditions. But in the real world,
plant growth and productivity are more limited by factors other than CO2
concentration (which is already quite sufficient to support healthy
growth rates). Growing conditions are likely to change (insect populations, water availability, extreme weather events...), and a comprehensive Stanford University study
found that elevated CO² only stimulated growth when nitrogen, water and
temperature were at normal levels. It was also suggested that excess
soil carbon or initially accelerated growth may limit the availability
of nutrients. Some "weedy" plants may benefit disproportionately from
extra CO2, but they would need to somehow overcome present-day
geographic limitations and more than triple the net terrestrial carbon
sink to counter most of our current emissions. Any enhancement of a sink helps, but the accumulation already in progress is exceeding sequestration by plants, and oceanic dissolution. For more detail on considerations in agriculture, see the consequences page.
21? "What about the role of clouds and precipitation?"
contrarians have suggested that extra cloud cover might offset warming.
John Christy of UAH speculated on this, and also stated (to digress for
a moment) that "Whatever happens, we'll adapt". The question is how many
of Earth's billions of people (ecology aside) might adapt, at what
cost, and with what quality of life? Regarding clouds, though: Although
storm intensity may increase, rising temperatures also mean more water
can remain uncondensed in the troposphere. The likelihood of significant
cooling from thick, low-level cloud cover appears questionable. Additionally,
proponents of the cloud-cooling theory don't seem to indicate why
negative feedback had trouble keeping up with the last carbon
accumulation event in prehistory, or even how Earth has come out of
glacial periods despite a supposedly strong negative feedback. Betting
on altered cloud cover is probably unwise.
Depending on their type, clouds can on balance reflect energy from
Earth or trap it in the atmosphere. They can reduce daytime warmth, but
also keep overnight temperatures higher and provide a head-start for
daytime heating. An overall increase in winter lower-level cloud cover
and a reduction in the summer would have a warming influence. The net
effect is an area of intensive study. All climate models project
significant warming, but cloud behavior may help determine whether it
will be closer to the high end or the low end of the range. Update: New research suggests the higher end. Spencer & Christy,
previously known for promoting a flawed satellite temperature
record, released a paper suggesting that an inter-annual cooling
effect in the tropics may have implications for the projection of global
warming. See How to cook a graph in three easy lessons.
22? "What about 'aerosols', contrails, and 'global dimming'?" Global
dimming refers to a reduction of solar energy at Earth's surface caused
by particulate/"aerosol" pollution and it's interaction with clouds.
Aircraft contrails also have a small (on average) effect, but this ends
up as a slight warming from infrared re-radiation. The cooling effect of
aerosols has partially masked global warming and presents what seems like a pollution control conundrum.
In the 1990's, this effect showed signs of declining, making CO2
emission reduction that much more important. Currently, particulates and
sulfur dioxide (source of sulfate aerosol) are reduced for the sake of
cleaner air. CO2 output often goes unchecked.
of these pollutants seems to be the intensification of winter storms in
the northern Pacific (and disruption of vital Asian monsoons), and their
circulation of warmer air to the Arctic (Zhang et al, 2007). In other
words, such pollution may worsen warming-induced changes in some
23? "Don't El Niño and La niña influence climate?"
are an oscillation related to the circulation of tropical Pacific heat.
The global average temperature impact of a strong El Niño is about 0.2
degrees C. Although a significant natural influence on weather patterns
and contributor to inter-annual fluctuation (see graph at the top of
this page), the temperature effects of the natural cycle smooth out over
years, and aren't a cause of the overall trend. However, the
effects of El Niño may be "enhanced" by global warming, since the
oscillation essentially pools oceanic heat and alters moisture flow.
Recent NASA and NOAA research suggests that much of the increase in
Pacific sea surface temperatures in recent decades has so far manifested
itself in the form of stronger central Pacific El
Niños, but macro-level circulation patterns like the Interdecadal
Pacific Oscillation influence which decades are more dominated by El Niño vs. La Niña. Discussions of how the average magnitude and persistence of El Nino may be affected here and here. Related: Natural ENSO responsible for warming trend? "Atrocious" paper makes it into JGR
24? "What about ozone, stratospheric cooling, and CO2 band saturation?"
sometimes confused in the media, stratospheric ozone depletion and
global warming are largely separate concerns. The main problem with
ozone depletion is higher levels of damaging ultraviolet radiation. This
is already being successfully tackled (see here
for more, including footnotes) with an international phase-out of
ChloroFluoroCarbons, while global warming needs to be addressed via
reduced emission of greenhouse gases ("GHGs") like carbon dioxide. The
two issues, though, are somewhat interconnected. CFCs (and some of their substitutes) and tropospheric ozone are also greenhouse gases (relatively minor
ones compared to CO2). And, as counter-intuitive as it may seem, the
amplified greenhouse effect causes stratospheric cooling (simplifying,
more GHG in the troposphere reduces infrared re-radiation to the
stratosphere). Ozone depletion itself contributes modestly to such cooling. The claim that band saturation severely limits CO2 as a climate forcing is a myth (more here and here, and this on the claims of ),
derived from a concept widely considered flawed since the 1950's. The
upper atmosphere and the "wings" of the CO2 absorption band are rather
important, and models already represent CO2 forcing as the natural log
of it's change in concentration (leaving plenty of climate-shifting
25? "Aren't glaciers growing?/Isn't Antarctica cooling/Sea ice growing"
are popular half-truths that mislead. Partly due to heat uptake by the
southern ocean and lower surface melt, ice sheets in East Antarctica
have remained relatively stable (consistent with model projections), and
appear to have received some extra snowfall. Some snowpack thickening
has also been observed in Greenland at high elevations. This is related
to the regional precipitation of extra moisture, and is not inconsistent
with a warming world. Despite this, and a slight cooling in parts of Antarctica, most of the world's glaciers have been receding as part of an inter-decadal trend, and ice loss has accelerated in Greenland (resulting in a large net mass reduction).
Above is one example of feedback: A moulin (vertical shaft) carries
meltwater to the ice sheet base, where it can (depending on sub-glacial
characteristics) act as a movement-accelerating lubricant.
26? "Is there a link between warming and hurricanes?"
connection between recent hurricane strength and early-stage global
warming has been an area of some debate. The link with hurricane
frequency is even more so. It's typically difficult to prove a direct
causal link with a particular event, since such events are a confluence
of regional dynamics and the overall trends related to Earth's energy
balance. Ocean warming simply makes more energy and moisture available
for potential concentration, thereby increasing the odds of a severe
event. Research (such as Emanuel, Knutson, Webster et al.) indicates an
intensity trend influenced by warming. As warmer temperatures spread
north, tropical cyclones can also stay intact longer.
Even a seemingly small rise in sea surface temperature means extra
water vapor and energy for a storm to pick up (while el niño or Saharan
air layer conditions can periodically suppress hurricanes in the
Atlantic). There is also the element of rising sea levels
and their contribution to storm surge. Although the IPCC estimates are
often cited, those carried substantial caveats regarding dynamic ice
sheet disintegration, and the lack of thoroughly reviewed projections
for it as of the AR4. More recent research suggests we could see a foot
of sea level rise (on average) by 2050 and 4-6 feet by 2100. And some of
the newest, preliminary research is exploring the possibility that high
pressure blocking ridges in a warming Arctic can influence the path of a storm like Sandy, so it's less likely to drift out to sea.
Still, certain TV meteorologists and media outlets have quickly
dismissed any climate change connection, ignoring the ongoing scientific
inquiry, often focusing on frequency rather than intensity, and
chalking everything up to a natural Atlantic cycle (controversy followed). The research, though, found an intensity trend in Pacific and Indian ocean storms as well. This earlier article addresses the issue further.
New Research Shows Humans Causing More Strong Hurricanes
Gray and Muddy Thinking about Global Warming
A look at William Gray's contrarian arguments
Clarity Emerging on Hurricanes?
Skeptical Science: What is the link between hurricanes and global warming?
27? "Is there some level of consensus among climatologists?"
consensus isn't the point of science, and some might mock it, there
have been relatively few cases of established scientific tenets being
fundamentally overturned in modern Earth science. For every Galileo-type
challenge that succeeds in establishing an alternative theory, there
are many others that fail. In climatology, the peer-reviewed literature
and periodic assessments, and major scientific organizations indicate
wide agreement on several main points, including that there's a
significant human influence on climate: Skeptical Science on the consensus The Wall Street Journal vs. The Scientific Consensus
28? "Climatologists exaggerate/perpetuate the concept of human influence for funding."
Ray Pierrehumbert put it: "Money and perks! Hahahaha. How in the world
did I miss out on those when I was a lead author for the Third
Assessment report? Working on IPCC is a major drain on ones' time, and
probably detracts from getting out papers that would help to get grants
(not that we make money off of grants either, since those of us at
national labs and universities are not paid salary out of grants for the
most part). We do it because it's work that has to be done. It's
grueling and demanding, and not that much fun, and I can assure
everybody that there is no remuneration involved..." And "...scientists
are probing theories and conceptions all the time, trying to break them.
The best way to become famous is to overturn established wisdom, so
scientists look hard all the time for opportunities to do this."
Further, much attention is applied to areas of uncertainty - something
climatologists concerned mainly about money would over-emphasize, rather
than affirming the primary role of human activity. We also have the
reality that many climate researchers are tenured/conduct research as
they see fit, and that funding goes into cutting edge research and
expensive equipment. Can the same be said of funds disbursed to
contrarians by the fossil fuel industry? Even the finding of a significant natural factor would attract research grants. And
there have been decades of opportunity for any number of skeptical
scientists to overturn the case for anthropogenic influence. Instead it
has grown stronger.
29? "So what can be done?" Climate
change and our energy situation are big problems that require a
combination of solutions across multiple sectors. We need to start now
rather than simply betting on technologies that may not be viable in
time to avoid locking in dangerous effects. Dr. Romm lays out one reasonable plan here, while discussing the "breakthrough technology illusion" here. Alternative
energy sources that result in little or no net CO2 emission (from
production or consumption) will play a role, but there must be a focus
on reducing waste/improving fuel efficiency as well. The best way to
spur such changes, and recognize the externalized costs of fossil fuels,
may be through a cap & trade system that reduces their persistent
cost advantage, and provides rebates or incentives to consumers. Similar
systems have been supported in the past by even Republican
administrations to phase lead out of gasoline and moderate sulfur
emissions (see sidebar). If that isn't doable on the scale necessary to
cut carbon output, we at least need a concerted effort to redirect
fossil fuel subsidies (direct and indirect) to efficiency and
alternative energy. In any case, the longer society waits to quicken the
transition, the more difficult and expensive the future is likely to
For some basic things we can do now to address the issue of global climate change, see sidebar.
30? "Is 'clean coal' an option?" Newer
coal technologies have the potential to reduce CO2 emission, but
significant cuts will only be made by gasification plants that implement
carbon capture and storage/sequestration (CCS). IGCC plants can make separation
economical, but the CO2 must then be compressed, transported, and
sequestered. Except where it can be sold for enhancing oil extraction,
this represents an expense unlikely to be widely accepted without
ongoing subsidy and/or CO2 regulation. This and other problems with the technology (here) make large scale deployment unlikely in the foreseeable future.
As of this writing, there are no commercial CCS operations planned, but
this doesn't stop coal interests from advertising the technology as if
it were right around the corner. Additionally, "coal to liquid" fuels
represent a double CO2 pollution load unless CCS is employed. Even then,
there would be no difference between the impact of coal fuels and
31? "Improving efficiency and cutting emissions will ruin our economy."
political organizations have released reports on the costs of acting
that provide little detail and ignore or underestimate the benefits.
Further delay is more likely to ruin our economy, both in terms of the
lasting effects of climate change, and rising fuel prices as demand
outpaces cheap extraction. Higher prices may be good for oil companies
with the most robust reserves, but they will impact everything produced
and/or transported with oil, including plastics, building materials, and
even food (think agricultural chemicals and diesel). The costs of
climate change alone are likely to be very steep compared to the costs
of acting to limit global warming. Economic implications and claims of
economic ruin are further discussed here (including the relevant link at the end) and here.
32? "But doesn't mean consumption/'cow emission' have more impact than fossil fuels?" This
might seem like an odd one, but a 2006 UN report suggested that
livestock production results in (modestly) more greenhouse gas emission,
in CO2 equivalent, than the transportation sector. The 18% figure
includes methane (6%) and nitrous oxide (3%) output, and also CO2 from
forest burning & fossil fuel inputs (9%). Nitrous oxide forcing has
been growing moderately (recently 0.16 W/m2 vs. 1.66 for CO2) and methane is so far lingering around 0.5 W/m2.
Another study suggested that up to 51% of human greenhouse gas forcing
can be attributed, directly or indirectly, to animal agriculture, but
controversy abounds given the difficulty of what they authors attempted
to do: Count respiration emissions that are typically considered
carbon-neutral. The jury is still out on the robustness of the numbers,
but suffice it to say that modern cattle production is a significant
contributor, and moderating meat consumption could be a larger part of
mitigating accelerated climate change. Meanwhile, though, CO2 emission
from transit and power generation continues to grow rapidly, and may
take more time to mitigate (since associated supply systems are
decade-scale investments). Therefore, it's important to address all significant sources, agricultural and otherwise.
33? "Aren't automakers improving efficiency/developing alternatives?" Following
the improvements of past decades spurred by clean air regulation, most
manufacturers resisted applying efficiency technologies in a significant
way, releasing limited lines of enhanced vehicles (including flex fuel
that can take advantage of the modest net benefit of ethanol), and then
developed ad campaigns appealing to concerns about fuel prices. Recent
increases in fuel economy standards should finally spur some real
change, and may eventually produce a moderate sustained emissions
reduction. That is, assuming that potential loopholes in the law don't
result in lower than advertised increases.
For vehicles that
burn ethanol, availability remains an issue in many regions, and without
further efficiency improvements (in both production and combustion) the
net benefit is very limited. As production methods advance and
agricultural wastes are utilized, ethanol could be a valuable
supplement, since the plants used to produce it are part of the
present-day carbon cycle (they absorb atmospheric CO2 in order to
produce the carbohydrates the fuel is derived from). But the liquid
transportation fuels with the most promise for having a small carbon
footprint (cellulosic ethanol, biobutanol, and algal biodiesel) are not
currently scalable or commercially viable, and at present consumption
levels they may have a hard time gaining a foothold. This makes
conservation more important than ever.
There's also been a lot of hype over hydrogen as a fuel.
Although it may have potential as the energy situation improves,
widespread use would be decades away at best. The key issues are the
lack of necessary infrastructure, the low energy density of hydrogen
compared with hydrocarbons, and the fact that hydrogen isn't an energy source.
It must be generated from water or fossil fuels, and takes more energy
to produce, store, and distribute than it yields in combustion. Fuel
cells may eventually offer
enough output and overall efficiency at reasonable pre-subsidy cost, but
probably not anytime soon. Hydrogen hype may be beneficial to oil &
gas companies likely to build infrastructure and provide potential
fossil feedstocks, and it may leave the impression that they're making
an effort to ease our petro-addiction. In reality, focusing on hydrogen
could delay the transition from fossil fuels, and require additional
energy supply and higher efficiency to satisfy demand.
34? "What about China?" It's
a common argument, often used to deflect responsibility, that China is
surpassing the U.S. in CO2 emission, but isn't required to improve
(therefore, the U.S. shouldn't bother). First, China is now investing
more than the U.S. in energy solutions (although they also have a bigger
challenge to tackle). Second, the West has been emitting large amounts
of CO2 longer, and still easily outpaces China in per-capita
emission. There are over a billion people in China, yet their total
output is nearly the same as ours. The fact that there are still heavy
growth pressures in China makes it less likely that they'll adopt a
nationwide carbon tax before seeing some real commitments from the West.
Some argue that efficiency (at least industrial efficiency) is higher
in the U.S./CO2 emission is lower per unit of GDP. Differences in
purchasing power aside, the U.S. has also shifted much of it's energy
intensive manufacturing overseas and become more of a "service economy".
As a result, we're indirectly responsible for part of China's carbon
footprint. We're all in this together. Most countries can do better, but
the U.S. is in a position to help foster technologies globally.
35? "Hasn't the climate been cooling for years?" This is an oldie that began with people like Pat Michaels (#2 above) and Geologist & prolific contrarian Bob Carter (here, here, and here). This claim takes advantage of annual to decadal fluctuation in atmospheric temperatures,
and is made by selecting a short, exceptionally warm period as a basis
for comparison. For example, the strongest el niño of the 20th century
helped make 1998 a record year in the CRU surface dataset, with 2005
being a close second (the NASA and NOAA data, which unlike CRU
represents the fast-warming Arctic, pegs 2005 and 2010 as the warmest
years on record). So choosing 1998 as a starting point is a classic
cherry pick. Since climate
change is based on trends of greater than a decade, relative to a
long-term average, it's invalid to make claims based on individual
later years (particularly those affected by la niña) being a bit cooler,
the averages remain anomalous in the longer-term context, and 9 out of
the ten warmest years on record all occurred in the past decade. And because the exchange of heat between the oceans and the atmosphere can vary, some modest near-term cooling of the atmosphere wouldn't necessarily mean Earth is actually losing more heat. See here for more.
petitions like these, some pertinent questions are: What does the
petition actually say, how was it presented, how many signatories were really scientists, and active in research climatology (vs. something like regional meteorology or petroleum geology)?
Flawed petitions used in attempts to debunk anthropogenic global warming
Re: Denier petition #1: OISM/Oregon Petition
, and here
(Update: Another sad attempt from OISM
). Re: Petition 2: Leipzig Declaration
, and here
. Re: Petition 3: Heidelberg Appeal "...the
Heidelberg Appeal itself makes no mention whatsoever of global
warming...", but like the OISM petition it was apparently still a
suitable vehicle for Singer and Seitz.
would be fools to risk so much to delay a transition that may initially
be a challenge, but also offers a myriad of environmental, economic,
and national security benefits.
- Andy C Newburg
1. Adaptation responds to current losses.
2. Mitigation responds to future losses.
3. Adaptation plus future costs is more expensive than mitigation.
4. Adaptation without mitigation drives procrastination penalties to infinity.
- J. Willard Rabett
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News, More Information, and Making a Difference
A Looming Climate Shift: Will Ocean Heat Come Back to Haunt us?
A rundown of the latest on oceanic modulation of global surface warming (for some, a source of doubt and complacency)
Solar radiation study offers clues on 20th century warming wobbles
"neither the rapid increase in temperature from the 1970s through the
1990s nor the slowdown of warming in the early 21st century appear to be
significantly related to changes of Rs (solar radiation reaching the
NASA: Is a Sleeping Climate Giant Stirring in the Arctic?
Climate change 10,000 times faster than evolution?
Which lifeforms will successfully adapt?
New study affirms strong impact of meltwater on accelerated glacier flow
"Rising Temps, Shrinking Snowpack" contribute to Western wildfires
Climate Change May Radically Transform Desert Bacteria
Possible consequences for ecosystems and dust storm severity
Congressional Budget Office: A price on carbon emissions is needed
Scientists suggest cyclical increase in ocean heat uptake slowed global warming in recent years
Earth is Still Warming: A LOT
What could be causing it?
State Department downplays impact of Keystone XL pipeline
"State?s Keystone Report Is The Tar Sands Pits"
IPCC, Assessing Climate Risks, Consistently Underestimates
Process is "inherently conservative". And how it relates to the Arctic meltdown.
How the Arctic "death spiral" favors persistent, extreme weather patterns
Related: Dr. Jeff Masters discusses research on the Arctic influence.
NCAR study: Future warming likely to be on the high side of projections
Related: MIT Analysis suggests climate change odds much worse than thought
"without rapid and massive action"
How hurricane Sandy may have been influenced (not necessarily "caused") by warming
More Re: hurricanes below
Is extreme weather caused by global warming?
Bad Science: Long-term CO2 rise natural/related to El Nino?
Paper ignores past findings, lacks logic and is biased by modest short-term fluctuations. It's humlum again.
Arctic sea ice minimum extent hits another record low
And Volume (2) follows
Vanishing Arctic Sea Ice: Going up the down escalator
How the Arctic "death spiral" can affect mid-latitude weather
Drop In U.S. CO2 Emissions: Real ?Weight? Loss, Or Just A Fad Diet?
As global emissions rise, U.S. emissions fall (with help from natural gas, a sluggish economy, and off-shored manufacturing). What about the longer-term CO2 & methane picture?
WMO: Preliminary data indicate 2011 warmest La Niña year on record
Despite some mid-latitude cold air outbreaks, potentially worsened by circulation changes in a warming Arctic.
Deja vu: Climate sensitivity to CO2 "overestimated"?
Not quite. Additional discussion here.
Increased weather instability: A new amplifying feedback?
Biggest Jump Ever Seen in Global Warming Gases
Global emissions higher than the worst case projections.
The "supply chain" of fossil CO2
Producers and consumers share responsibility, regardless of emitting nation.
Natural gas may be a valuable bridge fuel, but is it's relative climate benefit overstated?
Update: New study affirms limited climate benefit, with initially faster warming from aerosol reduction.
Related: How plentiful is natural gas, really?
Examining the lofty claims
Study: Much 'Missing Heat' is in the oceans
Global warming can be partially masked by deep ocean heat storage, then accelerate.
Study: Ocean Less Able to Mitigate Climate Change
Capacity to take up the carbon humans put in the atmosphere is waning.
Warming could deliver a jolt to coffee lovers
(and chocolate lovers, and peanut lovers, etc.).
'Bombshell' # xx: Global Warming Debunked Again?
Nope. Roy Spener at it again
Update: Journal editor apologizes, resigns, and slams Spencer's exaggerations.
Possible 'grand solar minimum'
= "mini ice age"?
Fox News types say yes, scientists say hardly (more)
Climate change denial becomes harder to justify
The Real Cost of Conventional Nuclear
Why there is no "renaissance"
"Climategate": A review of reality
"Climategate": What we have and haven't learned
Natural gas fracking carries risks, needs oversight
Fewer Polar Bear Births Tied to Less Sea Ice
Tornadoes and climate change?
More findings of anomalous warming
Complimentary to supposedly dead "hockey stick"
Second "100 year" Amazon drought in five years
"Current emissions pathways risk playing Russian roulette with the world's largest rainforest" (and it's carbon pool).
Arctic air flows into the Eastern U.S., Canada sees "freakishly mild" conditions, planet sets record pressure reading
Arctic shifts to a new climate pattern
Can warming cause a stronger NAO, and more winter Arctic air incursion into lower latitudes? (more)
Updates on rate of change and impact research
Support for the higher end of Climate sensitivity estimates
Two new studies on cloud feedback
Sub-Arctic wildfire intensity increasing
Another amplifying feedback
Extreme Events Linked to Global Warming?
The better way to think of it
Cap & trade
The conservative argument for not demonizing it
The Montford Delusion
Hockey sticks part deux, and heated discussion from frustrated scientists
Newspapers belatedly retract claims of "ClimateGate"
"SealevelGate" & "AmazonGate" II
"Update: AmazonGate bites the dust even harder
Subsea permafrost destabilizing as climate warms, future of greenhouse gas deposits uncertain
Climate Denial Crock of the Week
Concise video explanations for the lay person
Did Phil Jones say no warming since 1995? No.
"Statistically significant" warming in climatology is for periods greater than 15 years
Global warming: "Our best guess is likely wrong", or "Our best guess is likely too small"?
Study suggests that recent models may not adequately simulate long-term feedback amplification. Deniers spin away.
Sea Level Update: Civilization should do what it can to prepare for 7 feet this century
Atmospheric CO2 fraction unchanged in 160 years?
No, another botched story.
Dealing with the media and anti-science disinformers
"Climategate" provides lesson for scientists
If it walks like a duck ...
An allegory for climate "debate".
Scientific Malfeasance and Conspiracy?
From the CRU email hack to attacks on the IPCC, sometimes context is everything
Despite cooling claims, record highs far outpace record lows nationally
IEA: Each extra year of climate inaction adds $500 billion to final cost
It's all about methane?
Gore's comments, and political blog interpretations, in perspective. Hint: CO2 is far from off the hook
"Global cooling" again: Another lesson needed on climatic averages and how the trend is superimposed over short-term fluctuation
The Supposed Cosmic Ray Connection: "Why the Continued Interest"?
"It's the Oceans, Stupid!": The other part of the global warming equation
Ocean Temperatures Highest on Record
10 to 20 Years of "cooling" predicted? No.
Exxon Works Up New Recipe for Frying the Planet
Beetles & Wildfire: double threat in warming world
Antarctic glacier 'thinning fast'
four times faster than it was 10 years ago
George Will's "cooling" Earth nonsense
More on this topic in #40 below
Permafrost Could Be Climate's Ticking Time Bomb
Natural ENSO responsible for warming trend?
"Atrocious" paper makes it into JGR
"Suppressed" dissent from EPA's endangerment finding?
Carbon capture schemes an expensive step into the unknown
New study confirms solar/cosmic ray flux not driving climate trend
Should you believe anything Christy or Spencer say?
Climate change and famine: Will agriculture simply shift North?
AAAS President Urges Action on Climate Change/Energy
National Science Academies Do the Same
Study: Antarctic glaciers slipping swiftly seaward
Roger Pielke in the NY Times: "impartial expert" and ?honest broker??
Low Climate Sensitivity?
and more solar shenanigans
Estimates of sea level rise refined
Study suggests an upper bound for this century, and a range greater than that of the IPCC. Some media outlets misinterpret.
How Do We Really Know?...
A brief look at the case for human influence
National Post and IBD: Misrepresenting scientist's views on solar activity and potential cooling?
Sun showing signs of recovery from decadal minimum
Causes of rapid Arctic warming
More media misinterpretation: Contribution of heat transport presumed to be all natural
Inhofe & Morano at it again
400 "prominent scientists" dispute global warming?
(And again, even puffier)
More on the Inhofe & Morano denial and misinformation campaign
Direct tinkering with climate: Questions and caveats
Journalists misinterpret UK decision on "Inconvenient Truth"
Judge also made some errors in assessment
Western countries "outsource " emissions to China
Total emissions rise from carbon-intensive manufacturing
How to make the trend look normal
IPCC 4th assessment mis-represented
Contrarians claim it cuts two key estimates
Related: Did the IPCC underestimate sea level rise?
Peer Review: A Necessary but Not Sufficient Condition
Weeding out bad science
G.W. Swindle ?
Scientists feel swindled by TV documentary
Record Temperature Anomaly for 2005
(this is with solar activity "declining slightly" and no El Niño influence on the global average)
Supercomputer displays future warming, consequences of methane feedback
Coal-burning utility fights the science
Patrick Michaels receives $100,000
Global Temperature Highest in Millennia
Human activity-and very little else-is warming the world's oceans (Complete Scripps report here)
A "dazzling debunking of climate change science"
Actually, another lesson in contrarian disinformation
Antarctic's ice 'melting faster'
Greenland Glaciers 'Moving Faster'
Worst weather-related economic losses in history spur discussion of the future
Doonesbury: Science & Controversy
Study: Warming Could Doom Million Species by 2050
Ocean acidification: "The Other Problem..."
Corals, CO2-absorbing phytoplankton affected
Climate Research Distorted and Suppressed
British Defense Secretary sees rising conflict from warming and resource competition
Atmospheric Layers & the Satellite Record
Discrepancy in the temperature record explained
Study: Climate Warming to Shrink Key Water Supplies
Biologically-rich coral reefs at risk
Global Warming "Skeptic" Bingo!
Global Warming 101
The controversial "hockey stick" historical temperature graph: Broken? and ...
Vindication: "New Analysis Reproduces Graph of Late 20th Century Temperature Rise?
And another confirmation
2013: Extended "hockey stick" confirmd again by new comprehensive multi-proxy study