Exam 2 Flashcards
Subtropical high pressure band: location and climate
Located around the 30 degree points. Little precipitation and dry climate. Deserts are almost always located around here
Polar jet stream: features, seasonal variation of its strength and location, impact of climate change on the polar jet stream and weather
Found between 50 and 60 degrees N at ~250 mb pressure. In the summer, position migrates poleward with slower speeds. In the winter, migrates equatorward with twice as fast speeds. The Arctic Amplification greatly reduces contrast between high and low temperature zones, thereby reducing speed. This changes formation of cyclones and anticyclones, which means that weather systems tend to linger and more extreme weather patterns occur
Oceanic conveyor belt mechanisms
Cold and salty water is the densest and tends to sink. As northern Atlantic ocean currents flow towards higher latitudes, the salinity of the ocean water gradually increases because of evaporation and ice formation. Cold, salty, dense water sinks to the ocean floor in the Arctic. Bottom waters head back south and enter cold Antarctic waters. They then flow into the Pacific, where they gradually warm and rise. Driven by winds, surface ocean currents flow west and complete the cycle
Ocean conveyor belt’s relationship with climate change
Arctic Amplification has resulted in significant reduction and melting of ice cover in the region, leading to an influx of freshwater into the region. Surface ocean water there has thus warmed and become less salty and less dense. So, sinking of ocean water will be reduced and belt will be weakened. If the belt slows, it has less of an ability to absorb CO2 and air temperatures will be higher. Winters in Europe will be prolonged and colder
Proxy and instrumental data
Instrumental data takes real time measurements of climate systems, ocean temperatures, etc. Includes thermometers, barometers, Argo floats, etc.
Proxy data reflects, but does not directly measure, data. Includes pollen, tree rings, sea sediments like ice cores and corals
In situ and remote sensing measurements
In situ measurements examine the phenomenon exactly in the place it occurs. Remote sensing examines it from a distance, often using satellite radars
18O and 16O isotopes
99.8% of Earth’s oxygen is 18O, which is heavier. Lighter water molecules (H2-16O) evaporate more readily. Heavier molecules condense more readily. Warm tropical areas are thus high in 18O and cold polar regions are depleted in 18O. Relative amount of 18O and 16O in a sample is a function of climate. The ratio of 18O and 16O is relatively low in rain and ice. It is high in ocean water.
How delta 18O in ocean water and ice sheets is related to temperature changes and why
It is related to temperature changes because the ratio of 18O/16O is affected by evaporation and precipitation, which are closely correlated to temperature Delta 18O is lower in rain and ice and is high in ocean water. Negative correlation between temperature and delta 18O in ocean water. Positive correlation between temperature and delta 18O in glaciers
Temperature change and the rate of change
From 1906 to 2005, average global surface temperatures have increased by 0.74 degrees Celsius, with most of this since 1980. Rate of increase has itself increased
Sea level change and the rate of change
Sea level has risen and rate of the sea level’s rise has also increased. Major reason for this is thermal expansion of seawater and melted ice from glaciers and land ice
Land and sea ice change and the rate of change
Arctic sea ice has dramatically decreased since 1980 with rate of decrease accelerating. Billions of metric tons of Greenlandic ice has melted. Greenland has had a much more signficant retreat in ice cover because of effect of Arctic amplification
Solar energy output changes and their effect on climate
11-22 year cycle of sunspots causes total solar irradiance to vary and affect Earth’s climate. More sunspots mean sun is brighter and there’s more solar radiation reaching Earth. Actual variation of energy is relatively small
Earth’s orbital cycles and their effect on climate
Milankovitch cycles (eccentricity, tilt, and precession) occur over thousands of years and climate systems may also take thousands of years to respond to them. Have a very small effect at any given point
Volcanic eruptions and their effect on climate
They produce less than 1% of human-produced CO2. Have a significant cooling effect on climate, but only for one year at most
Natural greenhouse effect and its effect on climate
Has a warming effect on climate, but the enhanced GHE has caused extra warming
Human causes of climate change and their effects on climate
Deforestation, which affects the ability of plants to absorb existing CO2. Burning fossil fuels produces an extra 6 gigatons of CO2 that oceans and plant respiration cannot absorb
Primary cause for modern climate change and how we know
Primary cause is human-produced changes. We know because of the proportion of 4C in the atmosphere, which all living things contain. Fossil fuels do not contain it. Proportion of 4C in the atmosphere has been decreasing because fossil fuels release none of it
Positive and negative feedback mechanisms and their relation to climate
Positive feedback mechanisms: initial change causes an additional change in same direction. Negative feedbacks: initial change causes additional change in opposite direction. Ice, oceanic conveyor belt, oceans, and water vapor are positive. Clouds are negative
How climate models are used to understand climate change
One application is to examine the impact that humans have had on climate. In this process, they model weather anomalies with just natural forcings as well as ones with both natural and anthropogenic forcings to see what was or was not human-caused
Projected future climate change: CO2, temperature, and sea level
CO2 emissions have outdone high-emission models. Several different concentration pathways detail different possible temperature increases. Sea ice has decreased far more than models predicted and sea level rise is at the very edge of high-rise model
Distinguish between renewable and nonrenewable energy sources and between fossil fuels and non-fossil fuels
Non renewables: Oil, coal natural gas (fossil fuels) derived from ancient organic materials. Nuclear energy, not a fossil fuel, is not renewable, but there is a very long supply of uranium left
Renewables: solar energy, wind power, geothermal energy, and hydroelectricity
Nuclear power vs coal
Nuclear power emits no CO2 or air polluants but there are concerns about its safety and the feasibility of building new plants. Produces no nuclear waste, which we don’t know what to do with
Natural gas vs coal
Natural gas has lowest CO2 emissions among 3 major fossil fuels (~half of coal) and is cleanest in terms of air pollutants. But still produces very large amounts of CO2, produces NOx (air pollutant responsible for acid rain), and is nonrenewable
Energy efficiency: its definition and importance to climate change
Formula: (useful word done / total energy consumed) * 100%
Certain sectors of energy consumption in US have very low energy efficiency, which means that more fuels are needed and thus more CO2 and air pollutants are released
