Download Climate of the Earth: CO2 and Climate Change

The Climate of the Earth:
Climate Change – The
Science, the Future
Note: “climate change” was a term invented by
Republican pollster Frank Luntz, for the Bush
Administration in 2003, for political reasons.
I’ll just as often use the term “Global Warming” as it
doesn’t have the political spin.
The Greenhouse Effect
• The sun radiates mostly visible light since it is ~6,000K. It passes
through to the ground
• The warm Earth radiates in the long wave IR since it’s only ~300K.
• But long IR is absorbed to a significant extent by water vapor and
CO2 and any non-symmetric molecule
• This inhibits the cooling ability of the Earth, leading to higher temps
on the ground before radiation balance can be restored and we
radiate as much as we get from the sun
• Greenhouse gases: H2O, CO2, CH4, NO2 are the major ones.
Because of our watery world, H2O produces a bit more greenhouse
heating than CO2.
• Methane is 20-100 times more powerful than CO2, pound for pound,
depending on time. Over a century it is 20x, over a few years more
like 100x, since CH4 turns back into CO2 and H2O with half-life of
10 years.
• 99% of our atmosphere is made of symmetric diatomic molecules
N2 and O2, and atomic Argon. None of these are greenhouse
gases.
Is there a Scientific Controversy
about the Cause of Global
Warming?
• No. Climate scientists themselves are (and
have been, for over 20 years) convinced by
the evidence – global warming is humancaused, primarily by fossil fuel burning.
• AGW = Anthropogenic Global Warming, a
useful abbreviation
• Millions of dollars of oil money is financing an
ugly mis-information campaign to seed cynicism
towards legitimate science in the American
public and in politicians about the cause. See
my website page on the politics here.
Note How The More Closely You Understand
Climate Science, The More Convinced You are that
Global Warming is Human-Caused
Are Global Average Temperatures Rising
Significantly compared to Recent Geologic
History? Yes.
Longer Term: Over Several
Hundred Thousand Years - Ice
Ages
• Ice Ages show a strong correlation with small
changes in the Earth’s orbital ellipticity,
orientation, and angle of the Earth’s spin axis.
As these go through cycles – the Milankovitch
Cycles – the amount of heat delivered to the
Arctic Circle varies, showing a strong correlation
with inducing Ice Ages
• Reason: Ice is its own refrigerant. White ice
reflects incoming sunlight, radiates little IR. More
ice means more reflection, means more cooling,
means more ice… etc.
• Without Humans to add large amounts of greenhouse
gases (GHG’s) to the atmosphere, temperatures rose
and fell with very slow geological changes (or
occasionally, by a big comet/asteroid impact)
• Rising temperatures will slowly lower the amount of CO2
that can be dissolved in the oceans, pulling it out and
adding to GHG warming coming out of an Ice Age. This
mechanism explains why temperature rises preceeded
CO2 rises IN THE PREHISTORIC GEOLOGIC
RECORD.
• This is NOT relevant for today’s Global Warming, which
is caused by GHG’s, not slow Milankovitch cycles or
other slow natural changes.
• Note the Temperature Range: Roughly 6 degrees C.
That’s the same temperature changes climate
models say we can expect – not in ~100,000 years,
but this century.
• So – YES – today’s global warming is significant!
Temperatures are Rising Rapidly. Do we Know for Sure that CO2
is Rising and in a Significant Amount? YES.
The Rising Atmospheric CO2 is clearly in Agreement with
Rising CO2 emissions by Human Activity
Is there Other Evidence that Rising CO2
levels are Caused by Humans? Yes.
• Plants preferentially use C12, and since fossil fuels are
ancient plants, they have much lower C13/C12 ratios.
• Carbon isotope ratio C13/C12 in the atmosphere is
dropping, exactly as calculations say it should, as very
low C13/C12 carbon from oil and coal dilutes the higher
C13/C12 carbon which has existed in the atmosphere for
millions of years. Adding fossil fuel-generated carbon to
the atmosphere therefore should be lowering the
C13/C12 ratio, and in a quantitatively knowable way, since
we know the rate at which we’re burning carbon.
• Known production levels of CO2 from mining and oil
production fit with the rate of observed rising CO2 levels.
See following slides.
Global Temperatures vs Atmospheric CO2 vs CO2 Emissions by
Humans – Last 1000 Years
C13/C12 – Past thousand years. Dropping As we Burn Fossil Fuel
Since Photosynthetic Plants Enriched in C12
So, OK – Temperatures are
rising dramatically, and so are
CO2 levels, and so are human
generated CO2 Emissions. But,
couldn’t there be other causes
of global warming that might be
as significant or more so, than
human activities?
The ONLY Known Mechanism which produces Heating of the
Lower Atmosphere AND Cooling of the Stratosphere – is:
Rising Greenhouse Gas Concentrations
…And Observations Show that Indeed, the
Stratosphere is Cooling
Another Key – Nighttime Temps Rising
faster than Daytime Temps
• This is expected only from rising
greenhouse gas concentrations, because
of the lag effect of temperature rise during
the day; hot ground at night can’t radiate
away its heat because of CO2 blanket
• If the sun were somehow causing rising
temps, you would expect day temps to be
rising faster than night temps. We see the
opposite…
DTR = Daily Temp Range: 2000 vs
1951.
But Couldn’t there still be something Else? Other
Influences Causing Global Warming, Not Us? No. The
green (greenhouse gas) Curve Dominates
Climate Modelling Has Improved Dramatically. Climate
Models Can ONLY Fit the Observational Data if ManMade GHG’s are Included (Meehl et al. 2004)
But What About Subtle, Indirect
Causes…
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1. Svensmark Hypothesis: Cosmic Rays causing cloud
condensation nucleation, and low clouds would cool the
surface, so maybe this amplifies the weak solar radiation
effect?
No – First, the theory doesn’t make sense. There’s plenty of
potential cloud nuclei (dust, aerosols, pollen…) in the troposphere
w/o having to make more from cosmic rays.
Second, the observations don’t show a believable correlation, and
Third and most important – the solar cycle shows no trend for the
past 60 years, precisely when global warming has been most severe
and accelerating.
While cosmic ray flux does correlate strongly with solar cycle, the
observed correlation between solar cycle and temperatures is
directly explained by the known (small) change in solar irradiance
with solar cycle, only coincidentally with cosmic ray influx.
Svensmark’s is the Only Idea I’ve
Seen which isn’t Outright Climate
Denialism at Work…. And Yet You See
That it Too is Wrong.
• The politics of climate is ugly. See my
website for details. Look especially at the
YouTube’s “Climate Crock of the Week”
series, which are faithful to good science,
and also entertaining. Linked near the top
of this page
Industry Science – If Your Science Hurts Profits, Don’t
Expect Objective Honesty! Example…
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Conclusion – Industry “science” is suspect.
Industry hires scientists to help it earn profits.
If there’s a conflict between the Truth, and
Profits….. You can guess which wins
• It may not always be the scientists themselves who
buckle under threat of losing their jobs – industry may
simply ignore or de-fund studies which to not serve their
profits
• Contrast with Academia, where support comes from the
NSF, NASA, and generally unbiased funding sources.
• Academic scientists publish in peer-reviewed journals
with a reputation for honesty to maintain. Industry
scientists often can’t make the grade in true journals,
and end up having to publish in “trade journals”, which
have a poor track record of truth and objectivity.
Positive Feedbacks Accelerate
CO2 Greenhouse Warming…
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Warmer air holds more water vapor, itself a greenhouse gas. Strong! 7%
higher humidity per 1 degree C
Warmer ocean holds less CO2, keeping more in the atmosphere to cause
more GH warming
Melting Arctic Ocean exposes dark waters, absorbing more heat, causing
further melting
Warming Arctic thaws permafrost, releasing vast methane from prior Ice Age, a
powerful greenhouse gas
Hotter planet damages ecology, trees die, more wildfires leading to ashcovered darker snow in Arctic, accelerating absorption of sunlight and melting,
further warming Earth
Partially melted snow has lower albedo, accelerating melt and exposing dark
ground for further solar heating.
Stronger heating of ground causes more convection “mixing out” low clouds,
which net/net cool climate
Stronger convection may also generate more more cirrus as anvil
cumulonimbus clouds flatten at tropopause – cirrus clouds heat climate
There are more
Rising Ocean Concentrations of CO2 and
Dropping pH (Acidification) Clearly Observed
Worldwide Retreat of Glaciers
What About the Future? IPCC 2007
Predictions are not “Alarmist” Enough – why?
• (1) The IPCC did not know how to model
melt-water effects on glacial base/rock
interface and so simply ignored it.
However, subsequent empirical modelling
shows much higher losses
• In fact, Greenland is losing ice much faster
than predicted as this base meltwater
accelerates glaciers into the ocean
Using Observed Greenland Ice Loss Rates – Sea level rise will be 3
times higher than even the IPCC 2007 AR4 Predicted
Second…
• The IPCC 2007 modelling did not include
the effects of Arctic broken ice migrating
out of the Arctic Ocean and into the
warmer Atlantic, which is clearly
accelerating Arctic Ocean ice loss.
• IPCC 2007 expected the Arctic Ocean
would not be ice-free until 2100. We now
expect it’ll be more like 2030. (see graph
on next slide)
What Are the Effects of Global
Warming?
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Rapid melting of the Arctic. The long term “permanent” ice of the Arctic
Ocean (i.e. ice which survives summer) is already almost gone, and
predicted to vanish entirely before mid-century.
Greenland is losing ice at an accelerating rate
Rising sea levels. At 400ppm CO2, paleo data indicates ultimately 80 ft of
sea level rise before stability.
Desertification of the mid latitudes is accelerating
Migration of tropical diseases to mid latitudes. Malaria is already now being
found in south Texas, West Nile Virus as far north as Santa Cruz County
Massive dying of forests as pests which used to be held in check by cold
winters are now multiplying. This releases yet more CO2 via wildfires, which
darken Arctic ice causing further positive feedback melting.
Acidification of the ocean, destroying coral reefs and predicted before the
end of this century - all aragonite calcium carbonate shell-building animals,
a key base of the food chain on Earth.
We are in the midst of the 6th Great Extinction – the Anthropocene
Extinction.
Half or more of all species of life on Earth are expected to be extinct by the
end of this century. Caused by us, with Global Warming the single most
important cause.
Alarming and Poorly Constrained…
• Studies show an ice-free Arctic would cause thawing of
permafrost as far as 1500 km south of the Arctic
coastline. This region contains more than twice the entire
carbon content currently in the atmosphere.
• Worse, it contains 10 times the methane as is already in
the atmosphere, just in the frozen lakes alone. These
lakes are now melting. (methane is 25x stronger GHG
than CO2, averaged over ~20 year time spans)
• If all of this methane is released to the atmosphere, the
Greenhouse Effect heating goes up by 400%. Then add
in further heating due to higher humidity (water vapor is
a power greenhouse gas too), and the above CO2 in
peat, and climate change would be extreme and
significantly worse than the most pessimistic IPCC 2007
model scenario.
• See this video of the arctic lakes methane content
Will the Earth Return to Normal if
we Stop GHG Emissions?
• No.
• At best, even if all industrial society comes to a halt,
and even if somehow Arctic permafrost methane
thaw did not continue, still - temperatures would
not go back down, but would instead remain the
same for thousands of years.
• Why? The ocean has absorbed 93% of our
Greenhouse warming and that heat remains there.
• If we want to return to “normal” we’ll have to figure
out how to REMOVE the CO2 we put up there. Very
tough.
Global Warming is Only a Symptom of a Larger
Problem: Living Beyond the Carrying Capacity of the
Earth
• According to Stanford studies, with current technology,
our planet can support only 1.5-2 billion people
sustainably. We have 7 billion, heading up towards 10
billion by mid century.
• Topsoil can only be replaced on geological time scales.
Modern agriculture and land use is causing a loss of 1%
of our topsoil per year
• Our planet today can only sustainably support 7
billion people if they are reduced to a standard of
living equivalent to that in Ethiopia – a place of
widespread grinding poverty.
Finally…
• Only 36% of Americans believe that global warming is caused
by human activities, from a Pew poll in 2009 (AGW is far better
understood and accepted elsewhere)
• A poorly science-educated public is allowing the fossil fuel industry
and the politicians they influence to commit a great tragedy. Both on
the planet, and on our children and all future generations
• The 21st century will Very Likely be ugly, as this climate-crippled
diving food and water resources confronts rising population.
• Nolthenius’ First Law – People Learn the
Hard Way
• The scientific studies and journal papers backing up and
expanding on the content of this powerpoint can be found on
my website’s climate page: Click here. I urge you to read it.
• This is your future more than it is mine.
Astro 3 Climate Change: Key Points
• Know the how the Greenhouse Effect warms planets. Atmospheres
warm all planets
• 20th/21st Century climate change is being caused by fossil fuel
burning via Greenhouse warming
• If all human-generated greenhouse gas emissions stopped, future
temperatures would not go back down, but instead stay constant, for
many centuries
• Half or more of all species predicted to go extinct by 2100
• For every degree temperature rise, air can hold 7% more water
vapor before is rains out.
• Water vapor is a powerful greenhouse gas as well, and accounts for
a little more greenhouse warming of Earth than CO2
• 99% of Earth’s atmosphere is N2, O2 and Ar – none of which block
long wave IR and are therefore NOT greenhouse gases.