Human impact

• Largest cause of deforestation in Brazil is cattle ranching (65-70%)
• about 1/2 (55%) of the world's temperate rainforests have been cut• Washington’s, Oregon’s and California’s 95% ancient rainforests gone• BC has about 1/4 of the world's remaining coastal temperate rainforest
• Edge effect leads to reduced fragment sizeReduced fragment size- leads to reduced size ofpopulations and reduced number of species
• Fossil fuels (coal, oil)were formed about 300million years ago from theforests and swamps ofthe Paleozoic
• ‘Black carbon is responsible for 50 percent of the total temperature increases in the Arctic from 1890 to 2007.
• Atmospheric contaminants: Carbon dioxide, black carbon, methane, Nitrogen trifluoride, chlorofluorocarbons, Sulphur dioxide, radioactivity
• one molecule of methane has ~80 times theeffect on global warming as one molecule of carbon dioxide
• Sources of methane 30% natural 70% anthropogenic (mainly agriculture and fossil fuels)
• Nitrogen trifluoride is an Industrial gas used in semiconductor manufacture
• Nitrogen trifluoride has radiative efficiency and global warmingpotential relative to a molecule of carbondioxide= 17,200 times
• Ultraviolet-ionizing radiation UV-C (<290 nm)UV-B(290-320 nm)UV-A(320-400 nm)
• ozone (O3)- natural atmospheric gas-formed in stratosphere 20 km elevation absorbs ultra-violet radiation from the sun
• Chlorofluorocarbon (CFC)- freon-’inert’ non-reactive solvent,-refrigerant, aerosol-rises high in the atmosphere
• chlorofluorocarbons results in loss of atmospheric ozone as ultraviolet radiation strikes the CFC molecules and causes a chlorine molecule to break away which then collides with ozone and steals an oxygen. Then another oxygen atom collides freeing chlorine to destroy more ozone.
• ozone hole allows greatly increasedpenetration of UV toearth’s surface
• Burning of fossil fuels rich in sulphur results in increased acidity of precipitation
• Acid rain results in major loss of forests and death aquatic ecosystems in lakes of northern hemisphere
• Nuclear Power plants-uranium or plutonium for fuel-global electrical production ~10% in 2022~440 nuclear power plants in the world+++ high efficiency and require little fuel+++ few greenhouse gases -potential solution to continued use of fossil fuels----- however, high environmental, human and financial costs with failure
• Top 3 uranium producers: Kazakhstan, Canada , and Australia.
• “Silent Spring”-1962Rachel Carson-led to ban of DDT in US in 1972-world ban of DDT in 2002 (Stockholm Convention-still used to control insects in some tropical countries-major search for alternative control of insect pests
• DDT has been linked to thinning eggshells in birds, which can lead to population declines and extinctions. It also accumulates in the food chain, leading to bioaccumulation and biomagnification.
• Hunting is a major driver of biodiversity loss,
• Major Exporters(alphabetical)• Argentina, Australia, Bolivia, Brazil, Canada, China,Columbia, Congo, Honduras, India, Indonesia, Nepal,Philippines, South Korea, Taiwan, Thailand, US
• Major Importers (ranked from most to least)• European Union, UK, US, United Arab Emirates,Canada, China, HongKong, Japan, Korea, Singapore,Taiwan, Yemen
• Peru: 15,000 dolphins/y
• Dolphins are used as shark bait
• Canada: Newfoundland 100,000-400,000 seals killed per year (legal)App: $30 million revenue
• Black Bear Current rates in BC--conservation officers kill 500-1000/y-10,000 Black bears/y killed legally (recreational),6000 bear killed illegally(gall bladders)
• Major threats to integrity of earths ecosystems: 1) habitat modification, 2) Overfishing/overhunting, 3) introduction of exotic (non-native) species.
• on average, a species persists for about 1 million y in the fossil record before disappearing
• characteristic of natural extinction of a species is that it is replaced (usually outcompeted) by a different species(typically genetically related and in a similar niche)
• Oceanic islands: ~25km2....extinction rate is ~10%/100 yrs~1km2...... extinction rate is ~50%/100 yrs
• 40% of amphibians, 33% of coral reefs, 34% of conifers, 31% of sharks and rays, 27% selected crustaceans, 25% mammals, and 14% of birds are at risk of extinction.
• Earth is well outside of the safe operating space for humanity
• Suess effect: burning fossil fuels releases CO2 without C14
• Biomagnification - when top predators have the highest levels of toxins.
• Research began towards identifying non-destructive biocides, leading to the discovery of of neonicotinoids. A natural insecticide related to nicotine, a common anti-browsing compound produced by plants.
• Major loss of bee populations due to noenicitinoids. led to widespread colony collapse disorder (CDC).