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 human-caused, 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 Man-

Made GHG’s are Included (Meehl et al. 2004)

But What About Subtle, Indirect Causes…

• 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…

•

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…• 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 ash-

covered 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?

• 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.