Post on 22-Dec-2015
Climate forcings: changes in some parts of the Earth’s energy budget that affects the temperature of the Earth
Look at the past, (models are changing to agree with the experimental data for past climate)
Predict the future
Is the Globe Warming?
Land and sea (different heat capacities) temperatures are recorded separately
“Urban heat island effect” cities are warmer by about 5 °C from sunlight absorbed by pavement (sensible heat), the heat is emitted at night
“Countryside” sunlight hits land, water evaporates and contains latent heat, latent heat releases as water condenses
Thermometer Records
Removing urban temperatures from the
models has only a small effect, the result – the planet is still warming
Model results:
Records changed in 1942 <1942, a wood or canvas bucket provided
some cooling, and were thrown at various depths.
>1942 the SST was measured in the engine room as cooling water entered the engine room.
The sea surface temperature agrees with the land, the Earth’s surface is warming
Surface Sea Temperature (SST)
The agreement between the land and the sea
temperatures warming are based on thousands of
locations globally, and not by “cherry picking” only
selected areas.
Results:
Measures oxygen molecules in the rotational mode, they emit microwave radiation, which is a longer and lower energy wave than infrared.
Temperature estimates from satellites used to disagree with the thermometer reading on the ground, but this was caused by errors in data processing that have now been fixed
Is this a problem?
Satellite measurements for temperature
Measurements are made from a series of satellites
They are all calibrated against each other
Raw data is corrected for things like changes in the orbit of the satellite
Satellites are ideal for global “snapshots”
Satellite measurements
Glaciers are melting, and they are routinely monitored and measured
Another confirmation that the Earth is warming
Visual Indicators
Climate forcings are different factors that can change the climate
The comparison is the effect on the Earth’s energy budget (W/m2)
The radiative forcing in W/m2 allows us to compare the causes of climate change on a roughly equal footing
Climate Forcings
The state variable is W/m2
These changes include:◦Solar variability◦Greenhouse gasses◦Anthropogenic aerosols◦Volcanic particulate emissions to the atmosphere
Changes in climate forcings
The energy imbalance immediately after the change happened, but before the
climate responds to the change
Chapter 4 – the climate sensitivity benchmark was the CO2 doubling, ΔT2X
Earths temperature rises in proportion the number of CO2 doublings, the estimate is 3°C
Radiative Forcing
Chapter 11 – the climate sensitivity parameter relates the equilibrium warming
to the radiative forcing
ΔTR ~ 0.75 / W/m2
~ 1.5 W / m2
New version
Have the climate forcings changed with time? Solar intensity:
◦ Measured by satellite◦ No atmospheric interference◦ Data collection since 1975◦ The sun has an eleven year sunspot cycle◦ <1975, observations in the sunspot cycle for about
400 years◦ Also measured in ice cores, checking the ratio of
cosmogenic isotopes Be-10, and C-14◦ Weaker sun, less cosmic ray deflection, more
isotopes
Climate forcings: Changes with time
Maunder Minimum, 1650 – 1700A period of no sunspotsColdest period in Europe in the last 1000 years
Climate anomalies
If the eruption is strong enough, it can send particulate into the stratosphere and cool the planet for several years
Mt. Pinatubo in the Philippines erupted in 1991
1900 – 1950, the temperature rose 1950 – 1970, the temperature declined 1970 – present time, the temperature is
rising
Volcanic Eruptions
Intergovernmental panel on climate change, had their meeting in Warsaw last month
The 2007 assessment report: 19 models were run twice using the same
scenarios They were run with human contributions,
and they were run without human contributions
With human contribution, the model simulates the temperature increase since 1970
United Nations - IPCC
The smoking gun for global warming is the rise in temperature since 1970
The models can’t reproduce the temperature change that has been measured without considering the human contribution of greenhouse gasses to the atmosphere
The Smoking Gun
1. There would have to be some other way to explain the recent warming since 1970
2. There would have to be a reason to throw out the greenhouse effect theory – or – explain why increasing CO2 would not block outgoing IR energy by absorbing the IR in its vibrational energy mode
What would it take for the Global Warming Forecast to be wrong?
No thermometers for most of the period, must be determined by proxy measurement
Look at the thickness of annual tree ring layers in the wood
Bore holes for surface temperature proxy measurements
Condition of ice sheets and mountain glaciers
Climate of the last millennium
There was a warm period from 800 – 1200, called the Medieval Climate Anomaly
There was a cold period from 1350 – 1800, called the Little Ice Age
The Little Ice Age corresponded to the Maunder Minimum, a period of no sunspots
Result – Natural Variability
Last Glacial Maximum was 18,000 years ago Continents were covered in massive ice
sheets There was a polar amplification, high
latitudes felt more of an effect than the tropics
The atmosphere had less CO2 and CH4
Ice, ice sheets, sea ice and snow changed Earth’s albedo
Further back:
55 million years ago, Paleocene, Eocene Thermal Maximum
The ratio of C-12 / C-13 in deep ocean CaCO3 sediments indicated that there was a sizeable release of C to the atmosphere or the ocean
The early release is an analogy to the fossil fuel CO2 release
And from the deep past
As with the Last Glacial Maximum, it will be many thousands of years for temperatures to recover to their natural baseline values
after a sizeable CO2 release
But what is the natural baseline temperature value?
Result?
The past few years have been warmer than the thermometer records of the past 140 years and warmer than reconstructed records over the past 1,000 years
Climate change is driven by natural and human-induced changes in radiative forcing, including volcanic eruptions, solar variability, greenhouse gases, and human released aerosols.
Take home points, Chapter 11
Models cannot explain the rise in global temperatures since about 1970 without including anthropogenic forcing. This is the smoking gun for a human impact on climate.
Continued…
GRACE – Gravity Recovery and Climate Experiment (March 2002, failed in 2011)
NASA's gravity field satellite mission GRACE has provided nine years worth of data about changes in Earth's gravity field. The analysis of the data from the two satellites on the mission was published in the Nature Geoscience Journal, which looks at the melting of our Earth's ice sheets.
Twin dedicated satellites
ICESat – Ice, Cloud and Land Evaluation Satellite (January 12, 2003, 3rd laser failed 2010)
ICESat, part of NASA's Earth Observing System, was a satellite mission for measuring ice sheet mass balance, cloud and aerosol heights, as well as land topography and vegetation characteristics. Wikipedia
After seven years in orbit and 18 laser-operations campaigns, the ICESat's science mission ended due to the failure of its primary instrument. http://nsidc.org/data/icesat/
Another satellite
Warmer temperatures are not going to be the most important thing to affect people.
There will be more impact from:◦ Drought◦ Storms◦ Regional rather than global effects
The Warming Itself
Temperature rise from 1 – 6 °C
Big range, why the uncertainty? Two reasons:
1. What is the temperature response to additional CO2?
2. How much CO2 will be released?
IPCC predicts
Changes in rainfall patterns and amounts Changes in a few degrees changes the
landscape Comparison to the last ice-age, global
temperatures were 5-6 ° cooler – huge impact!
Europe and North America were covered in huge ice sheets
Pollen data shows huge changes in vegetation
Main Impact
Changing climate caused the demise of two classical civilizations
The Mayan and the Anasazi civilizations collapsed in several stages that correlated with strong, decades long droughts.
History shows the impacts
High latitudes are warming fasterPermafrost melts, collapsing the soil
Houses and trees tiltLakes disappear
Global warming is not globally uniform
1995 Chicago 1999 Mid Atlantic area Europe 2003 (France) 100 year event? Happened again in 2006 2010 Russia 2011 Texas 2012 “summer in March” in the US Midwest Many more, causing very high heat related
morality rates
Extreme heat events
CDC document on heat events
Extreme heat events
Heat is the most lethal type of weather phenomenon
High mortality Psychological stress (higher crime rates) Power outages Wildfires Physical damage
◦ Softening pavement◦ Buckling railroad tracks◦ Burst water lines◦ Power transformers detonating
Health Effects
Changing climate rearranges weather patterns and water supplies that are difficult to forecast
Hadley circulation – expected to increase in a warmer climate, intensifying rainfall at the equator and causing further drying in the desert regions.
Projection for monsoons in South China and India to become stronger and stormier
Emergent Effects
Droughts driven by a change in the water pattern are expected to increase, particularly in:◦ American Southwest◦ Mediterranean◦ Australia
The loss of plants amplifies the drought and also makes it harder to break out of a drought.
The carrying capacity of the land depends on rainfall.
More effects…
But not uniformly! The tropical cyclones are predicted to be
stronger and more frequent The storm seasons have not validated this
prediction In fact, the hurricane season that ended last
weekend was the mildest storm season since 1982
Warmer = Wetter
Rising sea level – the change is slow, and seas will continue to rise for centuries, for two reasons:
1. Thermal expansion of water (0.5-2.0 m)
2. Melting ice on land, glaciers and ice sheets
Ice and Sea Levels
Floating ice, sea ice, and ice shelves do not increase sea level when it melts because the ice already displaces its own weight in water
Archimedes Principle – when floating ice melts, its water exactly fills the hole that the ice had previously occupied.
Archimedes Principle
The ice sheets in Greenland and Antarctica are the slow giants contributing to the rise in sea level.
Together they could raise sea level by 70 m 70 m = 230 feet The elevation of St. Leo is 167 feet Sea level could rise as high as a mid-rise, 14
story hotel on Miami Beach Florida’s highest elevation is 345 feet
Giant Ice Sheets
Ice shelves collapse abruptly, no way to add this into the models
In 2002, Larsen Ice Shelf took a few months for an area the size of Rhode Island to collapse into ice bergs
When the ice collapses, or melts, the land usually rises! The weight of the ice is gone and the crust lifts slightly higher in elevation
IPCC forecast for 0.5-1.0 m increase is totally unrealistic
Ice Shelves
Occasionally there is a flip-flop of climate Change occurs over a few years, but may
last for centuries Presently, the Holocene Period, the climate
has been stable for the last 10,000 years 20,000 – 80,000 years ago there were 1,000
year temperature swings called Dansgaard-Oeschger Events
Sudden warming of 10-15°C in a few years followed by gradual cooling
Most intense in the high Northern latitudes
Abrupt Climate Change
The land surface depends on the local climate
Includes temperature, precipitation, and the human footprint (agriculture, decorative lawns, and pavement)
Insects move easily; trees do not
Biological Impacts of climate change
The Arctic, polar bear habitat may be restricted to the northern parts of Greenland
The tropical oceans, coral reefs are particularly sensitive to pollution in runoff and changes in temperature
Corals respond to stress by “coral bleaching”
Symbiotic algae are ejected, and coral reefs soon die
Largest impact?
The climate change will amplify the extinction trends by demanding that natural
ecosystems get up and move, just when they are restricted by human land use and least
able to do so.
Species are declining
Changes in water availability
Melting mountain glaciers and snowpack are a summertime source of drinking water in:
Himalayas, for India, Pakistan, Uzbekistan Andes, for Lima, La Pas, Quito North America, in the Pacific Northwest
Human Impacts
The growers may have to change crops to meet the changing conditions
Presently, the world food production is greater that consumption – can it continue?
Agriculture
There is a concern about tropical diseases spreading with the warmer climate
Impacts will be stronger in the tropics and developing nations where there is less wealth to buffer setbacks from the weather and less infrastructure to deal with the aftermath.
Health Impacts
Climate models that simulate the past predict huge climate changes in the future, relative to what civilized humanity has ever seen before.
Drought is one of the most dangerous aspects of climate change, as continental interiors warm and dry out, despite a global increase in the amount of rainfall overall.
Extreme weather events are already getting stronger and this trend is expected to continue.
Take home points, Chapter 12
Sea level will continue to rise for centuries from thermal expansion and melting land ice.
Continued…
Tragedy of the Commons, the moral is that everyone would be better off if they co-operated!
A cost that is not paid by the decision maker is called an external cost.
The cost of climate change is not only paid by people who are responsible but by everyone, soon, and far into the future.
Global Warming is a Large Scale Problem
A regulatory agency allocates permits for emission of climate forcing agents such as CO2
The total number of permits they issue is a lower overall rate of emission
If a company has lower emissions than the permit allows, it can sell its allocation as carbon offsets
Companies already exist whose function is to sell carbon offsets, using the money to find ways of cutting carbon dioxide emissions
Cap and Trade Scheme
Carbon tax and cap and trade accomplish the same things in the end
The tax specifies the price and allows the market to choose the emission, whereas the cap and trade sets emissions and lets the market choose the price
Local issues, easy to solve Regional issues tend to be us vs. them Global warming is the most global of issues
and the most complicated type to solve
Carbon tax solution
1988, agencies of the U.N. formed the IPCC
Their role is to assess “the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation.”
Purpose is to publish reports summarizing the scientific literature
Negotiations
WGI – deals with the scientific basis for the climate change forecast
WGII – deals with the impacts of climate change on the natural and human world
WGIII – assess options for limiting greenhouse gas emissions or otherwise avoiding climate change
Three working groups
Consist of chapters and various levels of summaries
1990, the first IPPC report was that it was not yet possible to detect human-induced global warming (models left out human induced aerosols and changes in solar intensity)
1995, the second report fixed the models, and issued the now famous statement that “the balance of evidence suggests a discernable human influence on global climate.”
The Reports -
As a result, a 1997 meeting in Kyoto, Japan drafted the Kyoto Protocol which attempted to limit global CO2 emissions to about 6% below 1990 emission levels by the year 2010
The treaty cam into force when countries accounting for 55% of the emissions agreed to the terms
U.S. withdrew under the Bush administration in 2001
Russia agreed in 2005, putting the agreement into force without the U.S.
Kyoto Protocol
The agreement has no “teeth” The rate of CO2 emission has grown rather
than decline Kyoto Protocol due to expire in 2012 “Only two things are clear after the climate
meeting in Doha, Qatar: a weak Kyoto Protocol will remain in place for a few more years and more negotiations are needed”
http://www.scientificamerican.com/article.cfm?id=climate-conference-renews-kyoto-protocol-but-looks-to-successor
In Practice?
The Montreal Protocol on Substances that Deplete the Ozone Layer was adopted in 1987 as an international treaty to eliminate the production and consumption of ozone-depleting chemicals.(www.worldbank.org)
The agreement to limit CFC emission to the atmosphere to save the ozone in the stratosphere has done more to slow global warming than the Kyoto Protocol
Interesting fact
The economy is much harder to forecast than the weather, otherwise we would all be wealthy
More and cheaper CO2 emission cuts are possible in the next few decades from improvement in energy efficiency that from new alternative energy sources
Costs of avoiding climate change would be comparable to the costs of deciding to go to war - significant, but not prohibitive
Economics
Goal of IPCC, “to prevent dangerous anthropogenic interference with the climate system” (lacks definition)
Accepted benchmark target is 2°C Earth has been warmer – probably 400,000
years ago when the Earth resembled today, a time called Stage 11 (look at fig.8-4)
>2°C isn’t really a danger limit, but surpassing it makes the projected damages go up rather drastically
Dangerous Anthropogenic Interference
How fast is the climate going to change? IPCC says that the warming should be slow
enough for ecosystems to adapt naturally, with no threat to food production, and to enable economic development to proceed in a sustainable manner
In other words – the transition to a new climate regime should be slow enough for
natural and human systems to adapt.
Another issue…
The greatest short term solution is conservation
Most of the cheapest solutions involve energy efficiency rather than new energy sources.
Nuclear energy generates no carbon, and we know it works, but the Uranium is in short supply
Converting U to Pu, increasing the yield 50x Downside, Pu is also a weapons-grade
radioactive element-not everyone wants
Alternatives
Windmills
Very clean alternative, and not so unattractive!
They supply 7% of Denmark's power, and 0.3% of the global energy.
It’s growing by 30% a year, scaling up the production by 50x would generate about 2 TW of energy.
Solar thermal, lower tech, concentrate sunlight with mirrors to heat water, generate steam, turn a turbine and generate electricity
Photovoltaic uses semi-conductor technology, it’s very expensive, but doable.
Generally, no one solution exists, it will need to be a combined effort, or a new technology that doesn’t exist yet.
Solar
It’s very easy to produce hydrogen from water, but it requires electricity
Hydrogen can be produced from the gasification of coal – probably messy
Requires a pressurized container
Extremely flammable
Hydrogen
Most countries are not capturing carbon dioxide emissions and storing them underground, because the process is expensive.
A closed-loop system that injects CO2 into hot brine brought to the surface from deep underground could make CO2 storage economical by providing geothermal energy and methane for fuel. The CO2-laden brine would be sent back down for permanent storage.
Calculations show that enough deep brine exists along the U.S. Gulf Coast to store one sixth of the country's CO2 emissions and to meet one sixth of its demand for natural gas annually.
In Brief:
When oceanographers add iron to the Southern Ocean, the plankton bloom – they are primary producers
The idea is that the plankton would grow, die, and sink to the deep ocean, taking the carbon with them
Ocean Fertilization
Generate a haze in the stratosphere by releasing sulfur of some other chemical
Aerosols cool the Earth by scattering sunlight
Putting particles in the stratosphere is that no rain originates there, so the injected aerosols would remain for several years
Shoot sulfur in canisters from large cannons Or just put sulfur in jet fuel and let the air
traffic do the job
Geoengineering
Human-induced climate change is an example of the tragedy of the commons. Economists refer to climate change as an external cost, which can cause the market to make poor decisions. Economic forces also keep the market focused on short-term profit and cost, disregarding costs that come far in the future.
International negotiations under the auspices of the United Nations have not made much progress so far in actually reducing GHG emissions.
Take home points, Chapter 13
The ultimate goal of negotiations is to prevent “dangerous interference” with the climate system. Danger, in this context, might be benchmarked in terms of global temperature, rate of warming, sea-level rise, peak atmospheric CO2 concentration, or the total amount of CO2 ever released.
The sooner we begin changing the energy infrastructure, the cheaper it will be to avoid dangerous climate change.
Continued…