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Understanding Global Warming
Humanity will likely "survive" this century,
but in what state is up to us.
normal for regional '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 more sea level rise?
What are the implications of accelerated warming in a mild interglacial
world 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, here, and here).
We have a rise in surface temperature averages in three major datasets
(affirmed by the tropospheric satellite record), nighttime temperatures
rising faster than daytime (consistent with the amplified greenhouse
effect, not enhanced solar influence), 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
distinct human fingerprint in the climate of the last several decades,
despite the temporary offsetting effect of things like sulfate pollution
and natural variability (such as the cool phase of the Interdecadal
Pacific Oscillation, accompanied by the dominance of La Niña sea surface
patterns over the past decade plus).
Science has moved beyond just strengthening the attribution case, to
refining projections based on physical processes (linear and otherwise),
paleoclimatology, and 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. But there is 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" with every down-tick in surface temperature, vs. a
statistically significant trend 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
- Dr. James Risbey, CSIRO Australia
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
- American Geophysical Union
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 (in which CO2 concentration
follows temperature, as a feedback), 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 continues to accelerate.
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 from a pressured carbon cycle would slowly
reduce the total "pool" once emissions fall (assuming no big
feedbacks). 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. An accumulation semi-permanently 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 precipitation types, reflective ice cover,
oceanic and atmospheric circulation, and storm behavior would make
"global climate change" a more complete descriptor of the situation.
Although it's early in the process, and there are variables between
climate change and disaster losses that have made 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. Greater 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 concerns have grown with an improved understanding of
their lasting influence, and even the substantial mid-range climate
projections have insufficiently assessed their potential.
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 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 survival.
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
the risk of rapid climate change, and it's many effects on today's ecosystems and societies. 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
from solar activity to the scientific consensus
Skeptical Science on Climate Misinformers: What they say vs. what the science actually says
RealClimate.org, by real climate scientists
Climate Denial Crock of the Week
News, More Information, and Making a Difference
Winter cold air outbreaks linked to stratospheric phenomenon
preliminary research suggests a possible link with a warming
Arctic, it's still regional weather fluctuation (related to heat
'distribution' not just Earth's "energy budget"
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)
What ocean heating reveals about global warming
heat content of the oceans is growing and growing. That means that the
greenhouse effect has not taken a pause and the cold sun is not
noticeably slowing global warming".
A Ship Stuck in Antarctic Sea Ice Contradicts Global Warming?
(more on Antarctica's unique climate and cryology)
Antarctica's Ice Loss On the Rise
West Antarctic Ice Sheet losing "considerably more than when last surveyed
Arctic Sea Ice: "Recovery", or Another short-term uptick
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?
Study affirms meltwater impact on accelerated glacier flow
"Rising Temps, Shrinking Snowpack" contribute to Western wildfires
Congressional Budget Office: A price on carbon emissions is needed
Scientists suggest cyclical increase in ocean heat uptake slowed surface warming
Earth is Still Warming: A LOT
What could be causing it?
State Department downplays impact of Keystone XL pipeline
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
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.
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?
Increased weather instability: A new amplifying feedback?
Study: Ocean Less Able to Mitigate Climate Change
Capacity to take up the carbon humans put in the atmosphere is waning?
'Bombshell' # xx: Global Warming Debunked Again?
Nope. Roy Spencer 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 shifts to a new climate pattern
Can warming cause more winter Arctic air outbreaks in lower latitudes? (more)
Support for the higher end of Climate sensitivity estimates
Two new studies on cloud feedback
Extreme Events Linked to Global Warming?
The better way to think of it
Cap & trade
The conservative argument for not demonizing it
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
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
"Global cooling" again: Another lesson needed on climatic averages and how the trend is superimposed over short-term fluctuation
"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
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
Carbon capture schemes an expensive step into the unknown
Climate change and famine: Will agriculture simply shift North?
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
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'
Doonesbury: Science & Controversy
Study: Warming Could Doom Million Species by 2050
Ocean acidification: "The Other Problem..."
Corals, CO2-absorbing phytoplankton affected