Lecture 11 - Climate Change Part 2

cherry blossom phenology example

not a huge amount of directional change and the timing of peak cherry blossoms seems to be happening sooner in the year

phenology

study of cyclic and and seasonal natural phenomena, the timing of events by using climate effect and temperature into their effects on organisms

phenology examples

• ice thawing in canadian lakes

• bud bursts in european trees

• date of the first flowers in british wildflowers

• trophic cascade in caterpillars and their predators

• walden pond

budburst

emergence of new leaves or stems at the start of the growing season

bud burst in european birch and oaks

budburst coming earlier between 1984 and 1999

british plants flowering study

compared when plants flower in two different time periods and found that on average spring/flowering is sooner compared to the 1980s and 90s in the UK

Henry David Thoreau

american essayist, philosopher, naturalist, poet best know for walden and also a leading transcendalist

• natural historian: concerned with ecology, environmentalism and change

• abolitionist

Thoreau and the Walden pond

he studied the Walden Pond area by going of daily 4hr walks and recorded the flowering and leaf out of 43 species in his journals

transcendalist

belief in the inherent goodness of people and nature that is corrupted by society and its institutions

species lost and phylogenetic distribution

found that 27% of species recorded by Thoreau were lost and 36% abundances are so low that extirpation is imminent due to demographic stochasticity and deterministic forces

what findings are consistent with the notion that warming is caused by solar activity increase?

the fact that poles are warming faster than mid latitudes and that winter temperatures are rising faster than summer

what findings are consistent with the notion that the cause of warming is greenhouse effects

• poles warming faster than mid latitudes

• winter temps are rising faster than summer

• nighttime temps are rising faster than daytime

• troposphere heating and stratosphere cooling

what findings are inconsistent with the notion that warming is caused by solar activity?

• nighttime temps are rising faster than daytime

• troposphere heating and stratosphere cooling

what is the best way to model surface temperature?

to consider solar and volcanic activity as well as greenhouse gases

Koch brothers

climate change skeptics who played a huge role in funding climate change denial groups and republicans

volcanic eruptions + CO2

caused set back in global warming because all ash was in the atmosphere preventing warming

clathrate gun hypothesis

melting of frozen methane (clathrate) in the oceans, greenhouse gases so warming causes more CH4 in the atmosphere that warms the earth causing more CH4 in the atmosphere creating a positive feedback loop

PETM (Paleocene-Eocene thermal maximum) case study

56 million yrs ago there was a sudden spike in temperature and CO2 in Earth when it was much hotter than it was before, rise of 6C over 20k yrs, lasted 170k yrs

PETM events

• mass extinction of oceanic foraminifera

• ocean acidified from CO2 so animals couldn’t make carbonate shells

• migration of species and biomes

• dwarfing of mammals

• leaves shrank but more insect herbivory causing damage to fossilized leaves

oceanic foraminifera

organisms that need calcium carbonate

why couldn’t animals make carbonate shells?

acidification of the ocean by addition of atmospheric CO2 makes carbonic acid diluted dissolving calcium carbonate in shells

Bergmann’s rule

in cold climates, large body mass increase the ratio of volume to surface area and provides for maximum metabolic retention in mammals and birds

why did leaves shrink?

because of the increase in atmospheric CO2 cause they extract CO2 into the atmosphere , smaller leaves leads to less CO2 making climate warmer (feedback loop)