Popn has declined 50 in recent years due to

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Pop’n has declined 50% in recent years due to displacement of native ants Current threats to biodiversity: Invasive species and climate change / Argentine ant
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Range changes of the Argentine ant, 2050 Blue areas will become less suitable Red areas will become more suitable Current threats to biodiversity: Invasive species and climate change / Argentine ant
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Amphibian decline: Globally, ~ 50% of species are in decline In Americas and Australia: introduced African fungus Batrachochytrium dendrobatidis has destroyed many populations. Warm temperatures increase virulence of fungus Threats to biodiversity: Invasive species and climate change
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Golden toad Alpine “cloud forests” of Costa Rica 1987 dense breeding congregations still a tourist attraction 1989: species extinct One of the first extinctions to be linked to climate change Threats to biodiversity: Invasive species and climate change / amphibian decline
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African clawed frog 1950s-60s: used in pregnancy tests resistant to the fungus but carries it on its skin many were released from medical labs into the wild Current threats to biodiversity: Invasive species and climate change / amphibian decline Where did the fungus come from?
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Climate change: an emerging threat Recall: Current geological period = Quaternary ; 2.4 mya-present Distinguishing feature: cycles of alternating glaciations (~ 100,000 yrs) and warm interglacial periods (~ 10,000-15,000 yrs). 20,000 yrs ago
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Recall: Holocene Epoch (0.01 mya - present) = the current interglacial period Began ~ 11,000 yrs ago as ice sheets rapidly melted Stable, warm climate allowed agricultural revolution, development of human civilization Maximum warmth: 10,000 - 5,500 years ago 5,000 years ago: conditions generally becoming colder, dryer Climate change
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Climate change Recent History: The “Hockey Stick” Graph Due to a natural cycle? Normal interglacial trend: temp peaks within first 5,000 years, followed by gradual decline over 100,000 yrs Present warming contrasts with expectation ? Medieval warm period Little ice age
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What’s causing current warming? Main contributor: burning of fossil fuels Include coal, natural gas, and petroleum (oil) Made from the fossilized remains of prehistoric plants (= carbon trapped in an abiotic reservoir ) Burning releases CO 2 : 2 C 8 H 18 + 25 O 2 --> 18 H 2 O + 16 CO 2 octane
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CO 2 in the atmosphere CO 2 dissolved in the ocean H 2 CO 3 (carbonic acid) plants and algae photosynthesis herbivores carnivores respiration detritus (dead material) decomposers (microbes, invertebrates, scavengers) limestone and fossil fuels (coal, oil, natural gas) mining and natural weathering volcanoes anoxic conditions
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CO 2 and temperature CO 2 is a greenhouse gas (GHG) it traps infrared radiation emitted from the earth’s surface --> warms the atmosphere = the greenhouse effect
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With rising CO 2 , average global temperatures have increased by 0.8 o C in the last 150 years CO 2 and temperature Winter (low photosynth.) Summer (high photosynth.)
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The effects of global climate change have been most pronounced at the poles (+2 to +4°C). Some models predict a mean global temperature increase of 2 o C would correspond with a 15 o C increase at the north pole.
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