Do polar bears belong in garbage dumps?
Changes due to warmer temperatures are becoming more visible. The Arctic is covered with ice less of the year, so polar bears can't hunt and are raiding garbage dumps for food. Extreme weather events are becoming more common as weather becomes stranger. Sea level is rising, which is a problem during storms.
With more greenhouse gases trapping heat, average annual global temperatures are rising. This is known as global warming.
Global warming - How Humans are Affecting our Planet from NASA, discusses the basics of global warming science (4c): http://www.youtube.com/watch?feature=player_profilepage&v=VXvGPbHXxtc#! (7:58).
While temperatures have risen since the end of the Pleistocene, 10,000 years ago, this rate of increase has been more rapid in the past century, and has risen even faster since 1990. The 12 warmest years on record have all occurred since 2001, and the 20 warmest years have occurred since 1987 (through 2011) (Figure below). The 2000s were the warmest decade yet.
Recent temperature increases show how much temperature has risen since the Industrial Revolution began.
Annual variations aside, the average global temperature increased about 0.8oC (1.5oF) between 1880 and 2010, according to the Goddard Institute for Space Studies, NOAA. This number doesn’t seem very large. Why is it important? http://www.giss.nasa.gov/research/news/20100121/
Greenhouse Gas Emissions
The United States has long been the largest emitter of greenhouse gases, with about 20% of total emissions in 2004. As a result of China’s rapid economic growth, its emissions surpassed those of the United States in 2008. However, it’s also important to keep in mind that the United States has only about one-fifth the population of China. What’s the significance of this? The average United States citizen produces far more greenhouse gas emissions than the average Chinese person.
An animation of CO2 released by different fossil fuels is seen here: http://www.nature.nps.gov/GEOLOGY/usgsnps/oilgas/CO2BTU_3.MPG.
Changes Due to Warming Temperatures
(a) Breakup of the Larsen Ice Shelf in Antarctica in 2002 was related to climate warming in the region. (b) The Boulder Glacier has melted back tremendously since 1985. Other mountain glaciers around the world are also melting.
Permafrost is melting and its extent decreasing. There are now fewer summer lakes in Siberia.
(a) Melting ice caps add water to the oceans, so sea level is rising Remember that water slightly expands as it warms — this expansion is also causing sea level to rise. (b) Weather is becoming more variable with more severe storms and droughts. Snow blanketed the western United States in December 2009. (c) As surface seas warm, phytoplankton productivity has decreased. (d) Coral reefs are dying worldwide; corals that are stressed by high temperatures turn white. (e) Pine beetle infestations have killed trees in western North America The insects have expanded their ranges into areas that were once too cold.
The timing of events for species is changing. Mating and migrations take place earlier in the spring months. Species that can are moving their ranges uphill. Some regions that were already marginal for agriculture are no longer arable because they have become too warm or dry.
Modeled Climate-Induced Glacier Change in Glacier National Park, 1850-2100: http://www.nrmsc.usgs.gov/research/glacier_model.htm.
What are the two major effects being seen in this animation? Glaciers are melting and vegetation zones are moving uphill. If fossil fuel use exploded in the 1950s, why do these changes begin early in the animation? Does this mean that the climate change we are seeing is caused by natural processes and not by fossil fuel use?
A number of videos on the National Geographic site deal with global warming: http://video.nationalgeographic.com/video/environment/global-warming-environment.
- A no-nonsense look at global warming and what we can do about it is found in “A Way Forward: Facing Climate Change.”
- “Antarctic Ice” describes the changes that are already happening to Antarctica and what the consequences of future melting will be.
- “Glacier Melt” looks at melting in a large alpine glacier and the effects of glacier loss to Europe.
- In “Greenhouse Gases,” researchers look at the effects of additional greenhouse gases on future forests.
- Researchers look for changes in the range of a mountain-top dwelling mammal, the pika, in “Hamster-like Pika in Peril.”
- “State of Polar Bears” show how polar bears, in their specialized habitat in the Arctic, are among the species already affected by warming temperatures.
Warming temperatures are bringing changes to much of the planet, including California. Sea level is rising, snow pack is changing, and the ecology of the state is responding to these changes.
- Greenhouse gases trap heat in the atmosphere; burning fossil fuels and other human activities release greenhouse gases into the atmosphere; greenhouse gas levels in the atmosphere are increasing; and global temperatures are increasing.
- Average global temperature has been rising since the end of the ice ages but the rate of its rise has increased in recent decades.
- Changes due to increasing temperatures are seen around the globe but are most dramatic in the polar regions.
Use this resource to answer the questions that follow.
1. How much has the global temperature risen in the last few decades?
2. What contributes to global warming?
3. What is the greenhouse effect?
4. What is the evidence for global warming?
5. What was the warmest recorded year?
6. What gases have been recorded at their highest levels in history?
7. What do researchers predict will happen?
1. The first point in the summary above is a set of facts. Does it logically follow that human activities are causing global temperatures to rise? Is there a different explanation that fits with the facts?
2. Why is average global temperature the most important value when talking about climate change?
3. What are some of the effects of climate change that are already being seen?