ECOL 182R 1st Edition Lecture 17 Outline of Last Lecture I The present A Malthus II Growth patterns A Exponential growth III Estimates A Population growth B Stable age distribution IV Fertility rates A Demographic transition pattern Outline of Current Lecture I Black carbon tropospheric ozone II Politically controversial III IPCC reports A Positive negative IV Coral reefs V Predicted impacts VI Prediction rates compared to the past A Major extinction Current Lecture Global Climate Change The Elephant in the Room It s hard to ignore Warming is too much of a good thing Greenhouse gases trap heat that would otherwise go to space Carbon dioxide is the most abundant because it s tremendously stable Methane nitrous oxide have more warming potential but break down more quickly Recent UN report the important role of black carbon soot and tropospheric ozone on global warming Soot Small flecks get caught up in atmosphere and get deposited on glaciers where they absorb sunlight and accelerate warming The dirty snow concept Cookstoves in developing countries diesel exhaust wood burning where it comes from Existing technology can reduce black carbon and it would reduce it dramatically and it would help human health Tropospheric ozone The good ozone is the ozone in the stratosphere The bad is in the troposphere 0 10 km above Earth s surface The good ozone protects us from ultraviolet radiation The bad damages crops and isn t good for people either and it contributes to climate change Reducing bad ozone Methane is a major precursor So reduce methane production and increase methane recovery in animal production fuel production landfills wastewater treatment Methane is a product of archaea Controlling black carbon and methane with delay warming but longer term we need to control these two AND CO2 production Global temps and CO2 concentrations are very tightly correlated for the last 400k years As glaciers melt and warming ocean water expands sea levels have risen expected to continue to increase So far the rising sea level is mostly from the expansion of the oceans as they get warmer not because of melting glaciers The root causes of climate change include human population Climate change discussions are politically changed and controversial Why The magnitude of the problem An apparent challenged to our current way of life Costs associated with doing things to reduce effects The cautious language of science Scientists don t prove theory but support it By their nature climate models are predictive probabilistic and complex Predictions change with more data better modeling Lay people or all people would prefer certainty Effects on business Global issue Different countries won t agree with each other Skeptical about the because of climate change being human caused Promote energy savings renewable energy to promote US energy independence save money protect the environment improve the economy The vast majority of climate scientists are in consensus IPCC World Meteorological Organization and the UN Environment Panel UNEP with 195 countries participating Four reports released in 2007 The basis impacts mitigation and synthesis of climate change IPCC reports Conclude warming is occurring because of greenhouse gas buildup as a result of human activity Positive reports It s an accelerating process Polar ice reflects solar radiation Water absorbs it When ice melts more water leads to more melting leads to more water leads to more melting an accelerating process Arctic sea ice volume is receding The release of methane huge reserves trapped in underground arctic seabed Methane has 23x the warming potential of CO2 Warming releases methane leads to more warming leads to more release of methane accelerating process Negative reports A regulated process Fertilization effect Plants can respond positively to increase CO2 Increased growth increased uptake of CO2 less warming The problem is that it isn t that clear not a consensus about this may depend on kinds of plants and soil fertility Positive negative make predictions challenging However climate models have been shown to be pretty accurate when they are used to predict past temperature trends Worryingly many models have been shown to be conservative Current impacts on biodiversity Glaciers melt increase glacier lakes Increases ground instability Changes in arctic and antarctic biomes including top predators Sea level ride contributes to loss of coastal wetland and mangrove forests Coral reefs have declined by 25 since 1980s Why Warming oceans causes coral bleaching expulsion of symbiotic photosynthetic protists Without symbionts corals lose their main source of energy Sometimes recover sometimes don t CO2 makes oceans more acidic when oceans absorb the CO2 Reduces the availability of carbonate ion to make their shells More than 25 of all fish are associated with coral reefs Cradle of diversification where greatest proportion of marine species evolve Highest biodiversity of ocean habitats The rainforests of the oceans Other impacts of climate change include dangerous interactions 2 3 of 110 species of harlequin frog became extinct in 90s because of a deadly fungus where outbreaks happen in record warm years Western forests bark beetles fire Tree deaths doubled in years from 55 94 Drought reduced snowpack causes stress Bark beetles are able to attack stressed trees and kill them Dead trees more likely to burn release CO2 soot increased warming more stress on trees another positive feedback accelerating process Predicted impacts Water supplies in glaciers and snow cover will decline Competition for over allocated water resources 20 30 of plant and animal species are at increased risk of extinction if increase in global temp exceed 1 5 2 4 degrees celsius How do current and predicted extinction rates compare with the past Five major extinctions in fossil record Cretaceous Tertiary Most recent 50 of species died due to asteroid Cooling was the result So is this the 6th great extinction Well we can assume that all species go extinct eventually it s life The background rate is 0 01 0 001 of all species The current rates in the past century is 1 Even though that s low we re between 100 1000x the background rate Mass extinction is not inevitable what we do next really matters The US produces 20 of the world s greenhouse gases And we re 4 5 of the world s population It ll be 43 5 if we keep this up Which produces more CO2 All cars on the road Or cattle CATTLE They produce