Hypothesese

James Lovelock 1979 -life and its non living environment on Earth form a self-regulating system that maintains the Earths climate and the composition of the atmosphere in a habitable state

Charles Darwin 1859 -more individuals of each species are born than can possibly survive, so there is a struggle for existence. individuals with any advantageous characteristics are more likely to survive and thus be naturally selected

almost always open systems, flows of mass and energy across the external boundaries of the system and internally, described was throughputs

DMS=dimethyl sulphate. DMS is produced by marine phytoplankton and is a major source of cloud condensation nuclei. increased CNN makes clouds whiter, leading to albedo and cooling of earth - negative feedback. but if temp gets too high then the supply of nutrients lessened and DMS production is limited - positive feedback

• Alfred Wegener: proposed the theory of continental fit. noticed some rocks matched, fossils were similar on both. supercontinent - Pangea. • Harry hess: led to Tharp and Heezens map of global geomorphology. Hess was win the navy and operated submarine sonar systems - collected data on depth of ocean and detected ocean ridges and trenches and mapped them • Fred Vine and Drummond Mathews: 1963. earths magnetic fields occasionally swap. 780,000years avows when it last reversed. can see evidence for this in the ocean crust as magma has mineral (iron) ions that flip and fossilise. • Dan mcKenzie: 1967. theory of plate tectonics, integration of seafloor spreading and continental drift - suggested convection currents.

external cold spell - oceans freeze - albedo cools earth further - co2 cycle in ocean stops and is outgassed by volcano build up - strong greenhouse effect melts snow - hothouse earth - co2 cycle restarts, pulling co2 into oceans and returning earth to normal

suggested earth had low co2 in atmosphere leading to a cold climate and glaciation

astronomical theory of ice ages. its the coldness of summers that’s important, snow lasts longer and eventually doesn’t melt - albedo - icesheets berger, a more recent scientist agrees

defined eccentricity (earths orbit), obliquity (axial tilt) and precession (spinning top)- linked it to climate and said the severity of winters led to ice ages

ocean tides result from the gravitational attraction of sun and moon. gravitational attraction of 2 bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between bodies. thus, the greater the mass of the objects and the closer they are to each other, the greater the gravitational attraction between them

seafloor spreading rate seafloor is spreading and subduction is rapidly occurring - volcanoes - co2 input into atmosphere. if there’s a reduction in the rate, less co2 is outgassed, atmospheric co2 drops and ice sheets form. external forcing is the cause of major climate change - critical threshold reached 34Ma, allowing ice sheets to grow

breakup of Gondwanaland, India broke off and collided with Asia, crumpling up (mountains) Orogenesis=production of mountains due to collision. intense convection, rising air - moistures, rises above mountains, cools, monsoon. long term carbon cycle - co2+h2o=carbonic acid. reacts with rocks/minerals in chemical weathering (silicate rocks) silicate weathering reduces co2 in atmosphere therefore, tectonic collision= less co2

drake passage opened 25-20Ma BP and allowed a strong circumpolar Antarctic current to flow unimpeded around Antarctica. tasman gateway(australia and Antarctica) opened 15Ma earlier -prevents water from N reaching Antarctica -thermally isolated we now know drake passage opened too recently for it to occur.

iron fertilisation by dust causes oceanic primary production and lowering of atmospheric co2 concentrations - glacial stages v dusty(50x more than interglacial) due to low sea level (exposed continental shelves), glacial outwash plains(sediment source) and weak thermohaline circulation. dust in ice cores is sodium ions from sea salt DUST FLUX INTO OCEAN > STIMULATES PRIMARY PRODUCTIONS > PHOTOSYNTHESIS. USES CO2 , FLUX OF CO2 DOWN IN OCEAN. , positive feedback, reducing temp

freezing sea ice acts as lid on ocean. air-sea exchanges of co2 result in equilibrium between surface ocean and atmosphere. ocean can’t replenish co2 as sea ice present. albedo

homosapiens evolved in E Africa around 200Ka and around the last interglacial (125Ka) spread throughout other countries, due to land bridges

global pandemics led to reduction in human activity/agricultue and so powered GHG emissions and increased afforestation