Climate Change Flashcards
What is dendroclimatology?
Using tree rings to nterpret how climate was in the past
How can dendroclimatology help give insight into past climate and conditions?
-Each year that tree grows, it forms a new ring
The width, density and isotopic composition are influenced by climate so samples can be taken
-But different conditions of tree environment must be taken into account eg altitude (much slower at higher altitude than lower warmer, less extreme weather), soil acidity, species, age of tree etc
How can corals be an indicator of climate change?
-Corals grow and build extra layer of calcium carbonate on the ends of their tentacles each year
-Corals can provide high resolution data, so weekly records possible rather than annual like trees
-Oxygen isotopes giving insight into temp and salinity of water they lived in
-Strontium-Calcium concentration ratio are strong indicator of surface temp at time of growth
Uranium- calcium concentration ratio can give temp and pH of water
-Absence of corals when there used to be presence is also an indicator– water become too warm? Too deep (eg because of rising sea levels?) Too turbulent etc
What are ice cores?
Snowfall builds layer upon layer, and compresses snow into hard ice, which forms temporal profile that dates back
These layers traps air within it which serves as gas record to show atmospheric compositions at the time
Major ice sheets can be found in Greenland and Antarctica
How do Ice cores give an indication of past climates?
Gas composition: gas gets trapped in pockets of snow that ends up being bubbles in ice. We can compare CO2 and CH4 concentrations relative to todays concentrations
Oxygen isotope profile: tell us about temp at point when snow was laid on surface of ice.
Stable isotopes of Oxygen are 16,17 and 18
16 is the most abundant and light, which means it requires the least energy to be lifted and evaporated
Kinetic Fractionation (O16 and O18)
O16 easier to evaporate, which leaves O18 in water. Atmosphere becomes more concentrated in O16 while terrestrial and aquatic environments contain more O18, this is because O18 rains out much more easily (its heavier) and finds its way back to land
Ice and snow will then generally be enriched in O16
1 part per million decrease of O18 in ice signifies a 1.5°C decrease in air temp
O18 richer in equator, north and south more depleted in O18.
Negative value means depleting O18 relative to O16
Colder temp–> less evaporation–> precipitation and glacial ice more enriched in O16 because colder= less E available to mobilize O18, so even more 018 in ocean.
This can be reflected in shells too because they require oxygen from water to build the CaCO3 shell
Ice Core Impurities
Components/material gets trapped in ice
e.g dust from desert, ash and acids from volcanic activity, ammonium from biomass burning and forest fires …
Lead, phosphate, nitrate from human induced pollution
Beryllium from space
Lithological Information: Depositional Environment
Eg white cliffs of dover
-submerged
-tropical/lagoon environment
-whiteness of cliff is result of carbonate, which comes fromsheels and sekeltons of orhganisms that lived in watrm
-cretaceous period
Lithological Information: Fossils
Seeing fossils of animals/plants that lived there and in what environemnts they belong to we can drawe conclusions as to what the envornment/climate used to be like
Lithological Information: Physical properties
What was the salinity, temp and O2 levels like?
Suitable biology for life– enough O2? Nutrients?
Were sediments formed there or were they washed into this area?
Influenced by volcanic activity (presence of banding)
Still or turbulent (crashing waves) environment based on how coarse or fine material/sediment is
Direction of wind, waves?
Form and compositions of sediment
Material within Sediments: Pollen
Know climate that must’ve existed for this vegetation to be present/grow
Cold, dry= herbs grass and pollen
Warmer= tree pollen
Material within Sediments: Plant Macrofossils
Leaves, flowers, cones and other fragments within sediment are indicator of past climate and environment
Material within Sediments: Planktonic remains
Planktons are either composed of calcium carbonate or silica dioxide
Use O18 isotopes for body/skeleton
1part per million increase of O18 in plankton is equivalent to 4.2°C increase of temperature
Foraminifera and ocean productivity
C12
Planktons prefer to take up C12 (in form of CO2) this allows C13 to be left in ocean and accumulate
Higher photosynthesis = higher C12 taken up by planktons and higher C13 accumulating in water body for foraminifers to take up
Landscape evidence of climate past
-Glacial retreat (see max points glaciers moved/ grew to before they retreated)
-Raised beach
-Volcanic past
-Fossilized remains
Climate vs Weather
Climate change
Long term shifts in average climatic conditions across vast areas
Anthropocene unprecedented climate change: relationship between global temeprature and CO2 emissions –> both shoot up at same time
Weather:
short term changes in localized areas
hours, days, weeks, months, years
The longer the time span and larger the area that we consider, the easier it is to see robustt and reliable changes in climate
How do we know climate change is really happening?:
Surface air temperature
Rate in warming has not been seen in in the last 200,000 years
Arctic warming far more than other areas
How do we know climate change is really happening?: Ocean temperature
Not happening equally over ocean
Greatest warming at surface of ocean
Atlantic more warming that Indian and Pacific in deep waters
Such huge bodies of water absorb a lot of energy
Upper ocean v responsible for sucking in energy accumulation
How do we know climate change is really happening?:
Changes in CO2
These levels of CO2 have not been seen In last 200,000 years
How do we know climate change is really happening?:
Sea level rise
250mm rise since 1880 as a result of thermal expansion of water and also input of water from glaciers (82% melted ice coming from arctic)
Some areas are losing sea level, some gaining–> its not evenly distributed. Ocean systems are quite complex
How do we know climate change is really happening?:
Sea ice extent and thickness
Coverage of ice, not extending as far as it used to
Thicker ice is, lower chance of it melting/ will be more robust against heat
How do we know climate change is really happening?:
Ice sheet loss
Over last 20yrs, Greenland has lost 3800Gt of ice
Antactica hold far more ice than greenland though, so when that really starts to melt we will be in a lot of trouble with rising sea levels
How do we know climate change is really happening?:
Snow depth/cover
Albedo effect of snow important to keep planet cool
reflecting solar energy that is hitting the Earth
Also protects ground from UV radiation and preventing moisture loss through evaporation, protecting vegetation
How do we know climate change is really happening?:
Precipitation
Some areas getting wetter- heavy precipitation events– flooding, crop, loss soil damage.
Areas getting dryer (more areas equator)– droughts
Occurring because ocean are warmer, warm water can hold more moisture, more water vapor in atmosphere and this comes out as heavy rain events
How do we know climate change is really happening?:
Extreme weather events
Earthquake, Tsunami, flooding, snow, forest fires etc
Almost 2x the amount events between now and 1980s
How do we know climate change is really happening?:
Biological indicators
Very many so hard to go into details
Ocean acidification– causing thinning of CaCo3 shells
changes in growth season– grassland, forests
animal health
migratory patterns
how environments and ecosystems are changing and adapting to changes in climate
