Chapter 19 Flashcards
(51 cards)
Over the past 900,000 years what had experienced prolonged periods of global cooling and global warming?
The troposphere
How much did the Philippines explosion cool the average temperature by, and after how long would it return to normal?
It would cool the earth by .5 degrees Celsius and after 15 months
What is true about the temperatures over the past 1000 years?
Temperatures have remained fairly stable but began to rise during the last century.
What do scientists learn about the past from tiny air bubbles trapped in ice cores?
Troposphere composition, temperature trends, greenhouse gas concentrations, solar snowfall and forest fire activity.
In what year did an ice core show the co2 levels in the troposphere are the highest they have been in 650,000 years?
2005
What three major facts shape the earth’s climate?
1) the sun
a. greenhouse effect that warms the earths’s lower troposphere and surface because of the presence of GREENHOUSE GASES
2) oceans store co2 and heat, evaporate and receive water, move stored heat to other parts of the world
3) natural cooling process through water vapor in the troposphere (heat rises)
What are the major greenhouse gases in the lower atmosphere?
Water vapor, carbon dioxide, methane, and nitrous oxide
Facts about the major greenhouse gases in the lower atmosphere
- these gases have always been present in the earth’s troposphere in varying concentrations
- fluctuations in these gases plus changes in solar output are the major factors causing the changes in tropospheric temperature over the last 400,000 years
What are the causes mostly of the increases in the greenhouse gases in the troposphere between 1860 and 2004?
Fossil fuel burning, deforestation, and agriculture
What evidence shows that the earth’s troposphere warming is mostly because of humans?
- the past 20th century was the hottest century in the past 1000 years
- since 1900, the earth’s average tropospheric temperature has risen .6 degrees Celsius
- over the past 50 years, Arctic temperatures have risen almost twice as fast as those in the rest of the world
- glaciers and floating sea ice are melting and shrinking at increasing rates
Warmer temperatures in what states are melting permafrost and releasing more co2 and ch4 into the troposphere?
Alaska, Russia, and the arctic
During the last century, how much has the world’s sea level risen and what are the causes?
10-20 cm and mostly due to runoff from melting and land based ice and the expansion of ocean water as temperatures rise
What couple or combine the effects of the atmosphere and the oceans on climate?
Couples General Circulation Models (CGCMs)
FACTORS AFFECTING THE EARTH’S TEMPERATURE
- some factors can amplify (positive feedback) and some can dampen (negative feedback) projected global warming
- there is uncertainty about how much co2 and heat the oceans can remove from the troposphere and how long the heat and co2 might remain there
- warmer temperatures create more clouds that could warm or cool the troposphere
What can increased co2 in the troposphere cause?
- plant photosynthesis
- increase in plant photosynthesis would slow as the plants reach maturity
- carbon stored by the plants would be returned to the atmosphere as co2 when the plants die
- increased PS decreases the amount of carbon stored in the soil
- tree growth may temporarily slow co2 emissions in the Southern Hemisphere but is likely to increase co2 emissions in the northern hemisphere
Warmer air can release methane gas stored where?
Bogs, wetlands, tundra souls and will accelerate global warming
What nations would suffer the most in a warmer climate?
The tropics
Effect of global warming on ice?
Some of the worlds floating ice and land based glaciers are slowly melting and are helping warm the troposphere by reflecting less sunlight back into space
Between 1979 and 2005 how much has the arctic sea dropped by?
20%
Where are rising sea levels projected to flood?
Low-lying urban areas, coastal estuaries, wetlands, coral reefs and barrier islands and beaches
If sea levels rise by how much, what islands and their coral reefs will be flooded?
9-88 cm, Maldives islands
What effect could global warming have on ocean currents?
Alter ocean currents and cause both excessive warming and severe cooling
A warmer troposphere can?
Decrease the ability of the ocean to remove and store co2 by decreasing the nutrient supply for phytoplankton and increasing the acidity of water.
Global warming will lead to?
Prolonged heat waves and droughts in some areas and prolonged heavy rains and increased flooding in other areas
