ESS 7.2
national economies
NEGATIVE: Some would suffer if water supplies decrease or drought occurs. POSITIVE: Others would gain if it became easier to exploit mineral reserves that would have been frozen in the permafrost or under ice sheets. Agricultural production may rise in higher latitudes but fall in the tropics.
food production
NEGATIVE: Warmer temperatures should increase the rate of biochemical reactions so photosynthesis should increase. But respiration will increase too so there may be no increase in NPP. POSITIVE: Crop growing season expanded in Europe
human health
NEGATIVE: heatwaves may increase. Insect disease vectors will spread to more regions as the less cold winters means they will not be killed off. Tropical diseases (Malaria, yellow fever and dengue fever) could spread to higher latitudes.
oceans and sea levels
NEGATIVE: water expands as it heats up and ice melting on land slips off the land and into the sea increasing the volume of sea water--> inundations POSITIVE: As oceans warm, more clouds and snowfall and higher albedo (negative feedback loop)
GHGs
atmospheric gases that absorb infrared radiation, causing global temperatures to be higher than they would otherwise be.
identify a variety of human activities that contribute to GHG emissions
-CO2: deforestation, land clearing for agriculture, degradation of soils, industry, automobiles (burning fossil fuels) -Methane: Agricultural activities (cow farming), landfills where organic material breaks down, and biomass burning -Tropospheric Ozone: cars, power plants, industrial boilers, refineries, chemical plants--> (burning fossil fuels) -Nitrous Ozide: Agricultural activities such as fertilizer use, Fossil fuel combustion -CFCs: propellants in aerosols, expanders of gas-blown plastics, pesticides, flame retardants, and refrigerants
impacts of climate change summary
-changes in water availability -coastal inundation -ocean acidification -changes in distribution of biomes and crop growing areas (towards the poles) -loss of biodiversity and ecosystem services due to extinction of species in wild -damage to human health by the spreading of tropical diseases
What are weather and climate affected by?
-ocean: acts as a massive, heat-retaining solar panel, transports heat through convection cells. -atmosphere: helps to retain heat that would otherwise quickly radiate into space after sunset. -Clouds: may trap heat underneath them or reflect sunlight away from Earth above them. -Forest fires: release carbon dioxide, a GHG, but regrowth traps it again in carbon stores. -Volcanic eruptions: release huge quantities of ash which circulate in the atmosphere, cooling the Earth. -Human activities: we burn fossil fuels and keep livestock, both of which release GHGs.
outline of debate on climate change
-whether millions or billions will suffer, whether there will be losers and winners if climate shifts to a new equilibrium and whether the power bases of different nations will be affected -There is not total agreement about the cause of the rise in temperature nor over what we should be doing about it. (prevention or cure or no action) -The vast majority of scientists working in this field accept the correlation between increased GHG emissions and increased temperature, causing climate change. But there is a minority who question the cause and effect, some citing the earth's rotational wobble, sunspot activity or that increased temperature is causing increased GHG, not the other way round. And there are climate change deniers.
Evaluate contrasting viewpoints on the issue of climate change: reliability of ice core data on past atmospheric composition
1. Ice core data is unreliable SKEPTICS: Ice core data from Siple in the Arctic shows that CO2 in the atmosphere reached elevated levels in the late 19th century, even though scientists claimed this levels wasn't reached until the late 20th century (a century after). To fix this, scientists moved the graph to the right to make the data exactly fit. 2. Ice core data is reliable CONSENSUS: No other ice core data in the world shows CO2 reaching these levels in the past 650,000 years, at least not consistently. Ice at Siple is very porous so new air was able to circulate there and affect the record. Nevertheless, scientists detected this discrepancy and compensated for it, which is why the record was shifted.
Evaluate contrasting viewpoints on the issue of climate change: past relationship between C02 levels and temperatures
1. SKEPTICS: In the past, CO2 rises have occurred after temperature rises C02 levels rise 800 years after the temperature does. This massive lag proves that CO2 can't cause global warming. 2. CONSENSUS: Consensus view does not claim CO2 caused temperature rises in the past. However, because of its natural greenhouse effect, CO2 makes natural temperature rises much worse. Global warming cycles last 5000 years, so the 800 year lag only shows that CO2 did not cause the first 16% of warming. The other 4200 years of warming, however, were caused by a CO2 greenhouse effect.
Evaluate contrasting viewpoints on the issue of climate change: relationship between C02 levels and temperatures
1. SKEPTICS: Rising C02 levels are not always linked with rising temperatures Arctic temperature, the best indicator of global climate due to its extreme nature, does not match human CO2 emissions. 2. CONSENSUS: A single graph for a single, small area is not enough evidence. Although we don't know what caused the warming of the Arctic in the 1930s (which did not match the rest of the world), you can't draw conclusions about the warming of the entire planet based on a small area.
Evaluate contrasting viewpoints on the issue of climate change: reliability of temperature records
1. We don't have accurate temperature records 90% of temperature recording stations are on land even though 70% of the Earth's surface is ocean. Cities and towns heat the atmosphere around land-based weather stations enough to distort recordings (urban heat island effect). 2. We do have accurate temperature records The urban heat island effect is controlled through detailed filters that remove the effect from records.
weather patterns
NEGATIVE: More heat means more energy in the climate and so the weather will be more violent and sporadic with bigger storms and more severe droughts. Global precipitation may increase by up to 15%. This will cause more soil erosion and lack of water will mean more irrigation and consequent salinization.
climate vs. weather
Climate describes how the atmosphere behaves over relatively long periods of time, whereas weather describes the conditions in the atmosphere over a short period of time.
application of tipping point concept to climate change
Greenhouse gases reduce heat loss from the atmosphere. If there are more greenhouse gases, less heat is lost. The atmospheric system changes in a dynamic equilibrium which may stabilize or reach a new equilibrium if a tipping point is passed. Climate may reach a tipping point if we do not respond to the threats of CC--> after the tp is passed climate will change rapidly until a new, much higher equilibrium is reached
biodiversity and ecosystems
NEGATIVE: Melting of the tundra permafrost would also release methane which is trapped in the frozen soils. -Animals can move to cooler regions but plants cannot. -Species in alpine or tundra regions have nowhere to go, neither higher up nor towards higher latitudes. Polar species could become extinct in the wild. POSITIVE: Birds and butterfies have already shifted their ranges to higher latitudes. Plants are breaking their winter dormancy earlier.
human migration
NEGATIVE: If people cannot grow food or fInd water, they will move to regions where they can. Global migration of millions of environmental refugees is quite possible and this would have implications for nation states, services and economic and security policies
water supplies
NEGATIVE: Increased evaporation rates may cause some rivers and lakes to dry up. Without a water supply, populations would have to move away.
glaciers
NEGATIVE: Loss of glacier ice leads to flooding and landslides. POSITIVE: Glacier summer melt provides a fresh water supply to people living below the glacier.
polar ice caps
NEGATIVE: Melting of land ice in Antarctica and Greenland will cause sea levels to rise as it flows into the oceans. POSITIVE: Melting in the Arctic could open up trade routes, make travel in the region easier and allow exploitation of undersea minerals and fossil fuel reserves.
Global climate models
complex and there is a degree of uncertainty regarding the accuracy of their predictions.
distinguish between the natural and the enhanced greenhouse effect
natural: necessary for life, otherwise we would freeze to death and Earth would be too cold to support life enhanced: caused by human activities and leads to unnatural global warming
climate change negative feedback mechanism
increased evaporation in tropical latitudes leads to increased snowfall on the polar ice caps, which reduces the mean global temperature.
climate change positive feedback mechanism
increased thawing of permafrost leading to an increase in methane levels, which increases the mean global temperature.
impact of human activities
increasing levels of greenhouse gases (GHGs, such as carbon dioxide, methane and water vapor) in the atmosphere, which leads to: - the potential for long-term changes in climate and weather patterns - an increase in the mean global temperature - increased frequency and intensity of extreme weather events - rise in sea level.
nature of impacts of climate change
may vary from one location to another and may be perceived as either adverse or beneficial.
global warming consensus viewpoint
the Earth's climate is rapidly warming due to a thickening layer of CO2 pollution caused by human activities. This layer traps heat in the atmosphere creating a "greenhouse effect" which heats the Earth. A rise in global temperatures of 3 to 9 degrees C will cause devastation. Greenhouse gasses are not the major cause of the ice ages and warming cycles. What drives climate change has long been believed to be the variation of the earth's orbit around the sun over thousands of years. In normal warming cycles (caused by variations in orbit), the sun heats the earth, the earth gets hotter and the ocean warms up, releasing CO2 and creating a greenhouse effect that makes warming intense. Our behaviour is so perilous because it is out of touch with the natural cycle and we haven't even gotten at the stage of ocean heating yet.
global warming skeptic viewpoint
there is no credible evidence that mankind's activities are the cause of global warming (if it's even happening at all.) There's only circumstantial evidence of a link between CO2 levels and global temperatures. Whatever affects global temperatures and causes global warming is not CO2. Whatever the cause, it works by affecting the climate balance, causing the temperature to change accordingly. The oceans then adjust over a long period of decades and centuries. Then the balance of CO2 in the atmosphere increases. The global panic about global warming is baseless and fear-mongering. The UN's reports on the matter are biased, unscientific, and alarmist.
