1
What is the difference between climate and weather? Why is a change of a few degrees in average global temperatures more concerning than day-to-day weather changes of a few degrees?
INFOGRAPHIC 21.1
Day-to-day changes in meteorological conditions are known as ____________, whereas long-term patterns of meteorological conditions are known as____________.
Weather; climate
True or False: A warmer climate should result in more heat extremes and in new record high temperatures.
TRUE
In the winter of 2010, the northeastern part of the United States had several large snowstorms that resulted in record high snowfall amounts. How does this weather fit in with the notion of global climate change?
Weather doesn’t equal climate. Isolated events such as snow storms cannot be taken as evidence either for or against climate change. Climate change models don’t predict that every location on Earth will be warmer, just that global averages will increase. Climate change is about changing climates, not just warming — shifts in the atmospheric jet streams or ocean currents that result from warmer temperatures may shift seasonal weather patterns resulting in colder or stormier weather in some places or simply more variable weather.
2
What is the physical and biological evidence that climate change is currently occurring?
INFOGRAPHICS 21.2 AND 21.9
Recent sea level rise is attributed to:
melting glaciers.
thermal expansion of water.
melting icebergs.
a and b.
a, b, and c.
D
Which of the following is least compelling line of evidence in that climate is indeed changing?
An increase in the number of hurricanes
An increase in global average temperature
Temperature-dependent shifts in the ranges of species
Sea level rise
A
Outline the evidence for climate change. Do you feel that this evidence supports the conclusion that climate is changing? Explain.
Evidence that climate is changing includes an increase in global average temperature since 1880, increased ice melt (from the warmer temperatures), a rise in sea level (from melting land ice and thermal expansion of water), changes in precipitation patterns consistent with warmer temperatures, changes in seasonal and daily temperature events (Fall is arriving later, Spring is coming sooner, nights are warmer than they used to be), and species responding as if the climate was changing (range shifts toward cooler regions, temperature dependent blooming and hatching is occurring sooner, some insects that would normally die back in the winter are staying alive and even going through additional breeding cycles). Whether students feel this evidence is sufficient to conclude that climate is changing will depend on their analysis of the data as well as what other factors they choose to consider.
3
What natural and anthropogenic factors affect climate, and which are implicated in the climate change we are experiencing now? How might positive feedback loops affect climate?
INFOGRAPHIC 21.3, INFOGRAPHIC 21.4, INFOGRAPHIC 21.5 AND INFOGRAPHIC 21.6
True or False: Current warming can be explained by the Milankovitch cycles.
FALSE
Which of the following has the greatest albedo?
A forest
A light-colored roof
A dark asphalt road
The surface of the ocean
B
Define greenhouse gases. What human actions have led to an increase in the amount of greenhouse gases in the atmosphere? What has been the result?
Greenhouse gases are gases found in the atmosphere that trap incoming solar radiation and reradiate it to Earth’s surface as heat, warming the planet. Without them, Earth would be too cold to sustain human (and most other) life. Humans have greatly added to the amount of greenhouse gases in the atmosphere, especially carbon dioxide (resulting from burning fossil fuels). The result has been a relatively rapid increase in average global temperatures leading to climate change around the world.
What is the difference between a positive feedback loop and a negative feedback loop? Give a climate-related example of each.
A positive feedback loop is one in which an initial event that causes a response then sets into motion future events which enhance that response (i.e. warming that melts land or sea ice decreases the albedo of the surface and would lead to more warming). A negative feedback loop is one in which an initial event causes a response that reverses the response (i.e. warming that increases the formation of clouds could lead to cooling).
4
How do scientists determine past and present temperatures and CO2 concentrations? What evidence suggests that climate change is due to human impact?
INFOGRAPHICS 21.7 AND 21.8
True or False: Current CO2 levels in the atmosphere can be measured, but there are no good methods for determining CO2 levels in the distant past.
FALSE
What relationship is seen between temperature and atmospheric CO2 levels?
They are positively correlated.
They are negatively correlated.
They are not correlated in any meaningful way.
A
Compare and contrast the major radiative forcers, including both those that are natural and those that are humanmade. Overall, which forcers are currently having the greatest effect on global climate? Are they natural or produced by human actions?
Radiative forcers include greenhouse gases, albedo, ozone, stratospheric water vapor, aerosols, cloud albedo, and solar irradiance. Negative forcers are those things that have a cooling effect (such as light colored surfaces and particles, and some types of clouds that reflect away incoming solar radiation) whereas positive forcers have a warming effect such as dark surfaces (asphalt) or particles (like soot) that absorb more of the incoming solar. Greenhouse gases such as CO2 and methane are positive forcers that trap solar radiation and re-radiate it as heat, warming the atmosphere. The positive forcers currently are having a greater effect on the climate than the negative forcers such that overall we are experiencing a net warming. By far, most positive forcers (around 95%) are human-caused and include CO2 release and tropospheric ozone production from fossil fuel use, methane release (from agriculture, waste and energy extraction), and synthesized halocarbons.
5
What are the current and potential future impacts of climate change? What actions can we take to respond to a world with a changing climate?
INFOGRAPHICS 21.10 AND 21.11
True or False: The amount of future warming that Earth will experience in the next 100 years depends on the choices we make now.
TRUE
Trying to decrease the extent or impact of future climate change is known as ___________, whereas taking steps to adjust to current or inevitable climate change is known as____________.
Mitigation, adaptation
According to the stabilization wedge strategy proposed by Pacala and Socolow we:
must reduce atmospheric CO2 concentrations below the 350ppm to avoid disastrous consequences.
can continue to burn fossil fuels for the next 50 years if we reduce greenhouse gas emissions in other ways.
can use a variety of currently available strategies to prevent atmospheric CO2 from exceeding 500 ppm.
should focus our efforts on adapting to inevitable climate change rather than mitigation
C
Describe the types of problems that global climate change causes for human health. Which do you feel is likely to cause the biggest problem? Why?
Some problems include increases in weather-related mortality, infectious diseases, and respiratory illnesses. The impacts on agriculture will include lower crop yields, biomes will change in both species composition and range leading to a loss of ecosystem function, water supply and quality will decline in many areas, coastal areas will be subject to increased erosion and flooding, and habitat loss will result in the loss of species. Student answers regarding the biggest problem will vary but should be supported with evidence that explains why they feel this is the biggest problem.
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