Global Environmental change pt 2

paleo-proxy
sources of climate information from natural or human archives used to estimate climate conditions prior to modern period.
When was the little ice age?
1600
How long is it between interglacial periods?
100,000 years. (125, 225, 325…)
ice age
extended period of cold climate including glacials and interglacials
glacials
times of ice accumulations, cold spells, 90,000 years
interglacials
times of ice retreat, brief warm spells, 10,000 yrs
hot house periods
times with no permanent ice on earth
when did the last glacial maximum ed?
10,000 years ago
4 climate change drivers
tectonics and ocean circulation, orbital ariations, solar variability, atmospheric factors (volcanoes, greenhouse gas fluctuations)
how do plate tectonics affect climate change?
land masses move, change ocean flow and landmass concentration.
how do ocean currents affect climate change?
sinking, cold, salty water from artic and antarctic goes south in atlantic, warm water goes north. change in directions changes climate.
eccentricity
100,000 years. earths orbit around sun varies from nearly circular to an elipse. circle = warmer
obliquity
41,000 yr cycle. earth’s axial tilt varies from 22 to 24 deg. if it’s tilted more, the poles get more sun.
precession
26,000 yr cycle. axis wobbles and changes the orientation of hemispheres toward the sun. eventually, aphelion is dec 4th instead of july 4th.
solar cycle variations
solar flares, sun spots, irradiance go up every 11 yrs. high 1991, 2001. low 1996.
atmospheric perturbations
natural and anthropogenic short term climate change. pinatubo, el nino, la nina.
greenhouse gases
water, NOx, CO2, Methane, CFCs
Greenhouse effect
gases transparent to shortwave, but absorb and reemit longwave radiation
What causes increase in CO2?
fossil fuel burning, fires, deforestation, cement making
What causes increase in Methane?
as ocean warms, thaws frozen Deep Sea Methane Hydrate. also, Rice, livestock, coal mining
What causes increase in N2O?
Internal combustion, fertilizer, manure
effects of greenhouse gases on energy budget
less heat escapes to space, more LW radiation emission of atmo to earth, increased LW absorbtion by atmo
Why is NOx worse than CO2?
Higher GWP, absorbs more LW, longer atmo lifetime.
What is the GWP of CO2?
25
What is the GWP of N2O?
298
What is the GWP of CFCs?
10900
Historical Data record length
since 221 BC in China, whole world since 1000.
What does Historical Data measure?
observations of weather phenomena, data through measurement and indirect observations (planting season length)
Pros of Historical Data
firsthand accounts, usually dated, from most inhabited places
cons of historical data
calendars might be off, language/handwriting, exaggeration, etc
What do tree rings measure?
temperature and moisture of growing seasons
How long is tree ring record?
9,000 years ago
Pros of tree rings
doesnt damage living tree, dead trees preserve well and can be compared to living, high resolution
con s of tree rings
they only record growing seasons (in temperate zones) so can’t see winter. tropical trees have no rings. only available where trees are.
what do ice cores measure?
atmo composition, wind speed, volcanoes, temperature
length of ice core record
400,000 years
pros of ice cores
found on 6 continents, can be cross-references, traps actual bubbles of atmo, accurate
cons of ice cores
expensive, melting can ruin layering, can be altered by wind or ice flow
What do ocean/lake sediments measure?
microorganisms, pollen, plankton for climate history
how long is ocean/lake sediment record?
65 million years
pros of ocean/lake sediments
show what plants grew, temp of earth, conditions in climate for these fossils to be abundant
cons of ocean/lake sediments
water currents can mix record, really hard to do
what do corals measure?
calcium carbonate skeletons’ growth rings. reflect conditions of oceans – nutrients, temperature, sea level, storms
how long is coral record?
200 years
pros of coral
fine resolution, easy to see year bands, record composiiton of ocean and temp
cons of coral
areas with little seasonability – no banding. no way to tell monthly from yearly in high seasonability
what is measured in caves?
precipitation record, seasonal length,
length of cave record
10,000-100,000 years
pros of caves
caves everywhere
cons of caves
influenced by geography, ground water chemistry
What does IPCC say causes global warming?
increase in anthropogenic greenhouse gases
what do climate models do?
day to day weather forecasts, analysing local severe weather, predicting future climates, modeling the atmos of different planets
what are global circulation models?
simulation of atmospheric circulations and interannual oscillations. used to forecast climate trends
Worst case Scenario
A2 (a divided world, independent nations, uncontrolled pop growth, slow tech changes, regionally oriented)
best case Scenario
B1 (integrated, ecofriendly. rapid econ growth, slow pop growth, clean, efficient tech)
what is the high forecast for temp change?
11.5F
what is the low forceast for temp change?
2F
what is the middle forecast for temp change?
3-7F
consequences of global warming
more frequent heat waves, more intense and longer droughts, shifting crop patterns, extended wildfire season, more intense storms, melting glaciers, changing sea level, increase in water vapor, expansion of malaria
what and when is kyoto protocol?
1997. 159 country signatories, 38 mandated to reduce emissions, voluntary limits on developing countries (China!) aims for reduction of 5.2% below 1990 levels by 2012
What is COP15?
in Copenhagen, 2009, global agreement on climate change
What to do ourselves?
CFLs, (90bil lbs of CO2) Moving thermostat 2F (2,000lbs/fam) recycling (2400lbs/fam), inflate tires, eat less meat, farmers markets
what is the control for diurnal energy cycles?
insolation, earth’s rotation
equation for net radiation
SWin-SWout + LWin-LWout
what determines daily cycle of temperature?
daily cycle of net radiation
what happens to increase temperature?
positive net radiation
what happens to decrease temp?
net radiation goes negative
what happens to radiation at night?
terrestrial radiation emitted surpasses terrestrial radiation emitted to surface by atmo
what does net radiation graph look like?
like temp graph, but shifted down and to left
what happens at sunrise to net rad and temp?
some solar radiation appears, but it is still negative for awhile, so temp still decreases, coldest about 2 hrs after sunrise
What happens when net radiation = 0 in morning?
minimum temp, then increase
what makes the net radiation go positive in morning?
as sun moves higher in sky, more solar radiation reaches surface, net rad = positive
when does solar radiation peak? what’s going on with temp?
peaks at noon, when sun is highest in sky. maximum net radiation of the day. temp still increasing
what happens in late afternoon?
the sun moves lower in the sky, net radiation decreases to 0, at 0, maximum temperature (3pm)
what happens in evening to net radiation?
net radiation goes negative again, temp starts to decrease.
what do clouds do to net radiation?
decrease daytime temp by lowering insolation and increase night time temp by rereflecting LW
what month is net rad highest?
june
what month is temp highest?
july
what month is the min of net radiation?
december
which month is coldest?
january
what are controls of latitudinal variations in energy?
daylength and solar altitude angle
what happens to net radiation at poles during winter?
net radiation goes negative for whole time
what is specific heat?
the heat required to raise 1g of water by 1C
What has a low Specific heat?
water
what has a high specific heat?
land
what does water do to temp variability
it dampens it (HAHA)
why doesnt land retain temperature?
no mixing of surface and inner soil, the surface is opaque and there is no evaporation
why does water retain temperature?
surface transparent, greater mixing, greater evaporation
system
an ordered, interrelated set of things and their attributes. distinct from surrounding environment, linked by energy flow.
open system
energy and matter flow freely in and out of system
closed system
shut off from the environment, self contained
positive feedback
amplifies or encourages response (snowball)
negative feedback
dampens the resonpse
arctic feedback if warming continues
+, warming melts ice which reduces aledo which reduces refelction
-, more evap=more snow=increased albedo
Carbon feedbacks if warming continues
+, CO2 dissolves in cold water = water sinks = resurfaces and escapes in warmer water

-, phytoplankton take up CO2, more phyto when warm

Ocean feedbacks to warming
+, warming releases CO2bubbles
-, more evaporation/clouds, more albedo, more phyto to eat CO2
CO2 on land feedback
+, warmer = more rain = rocks weathered into atmo and ocean
-, warmer = more plants = less CO2,
steady state equilibrium
balanced
dynamic equilibrium
changing trend over time
threshold (tipping point)
when a system can no longer resist changeee
climate forcing
any ongoing process or discrete event that alters the energy of the system
why is arctic sea ice at tipping point?
permanent blue ice melting, cant be recovered in annual cycle, still reaching an ice minimum even with cold 08 winter. feedback leads to more ocean warming, methane burps from melting ice, more warming.