An Overview on Global Warming in North America
Uploaded by on Sep 23, 2007
GLOBAL WARMING IN NORTH AMERICA
The vast North American continent ranges from the lush sub-tropical climate of Florida to the frozen ice and tundra of the Arctic. Within these extremes are two wealthy industrialized countries with diverse ecosystems at risk. Yet the United States and Canada are two of the largest global emitters of the greenhouse gases that contribute to a warming climate. Examples of all 10 of the "hotspot" categories can be found in this region, including changes such as polar warming in Alaska, coral reef bleaching in Florida, animal range shifts in California, glaciers melting in Montana, and marsh loss in the Chesapeake Bay.
For North America we have many more hotspots than for some other regions of the world, although impact studies have been emerging in larger numbers in recent years from previously under-studied regions. This higher density of early warning signs in the US and Canada is due in part to the fact that these regions have more readily accessible climatic data and more comprehensive programs to monitor and study environmental change, in part to the disproportionate warming that has been observed over the mid-to-high-latitude continents compared to other regions during the last century, and in part to capture the attention of North Americans who need to take action now to reduce greenhouse gas emissions.
EVIDENCE
Scientist by far and large accept that Earth’s climate is changing because of the amount of so-called greenhouse gases humans are pouring into the atmosphere. Most of those gases come from fossil fuels, particularly carbon dioxide, or CO2.
And much of the scientific community thinks these gases are causing unnatural climatic warming that could have unimaginable effects on life.
The consensus agrees that Earth has warmed by 1 degree Fahrenheit over the last century. That doesn’t sound like much, but consider that during the last ice age Earth was just 5 to 9 degrees cooler.
And what may be most dramatic in the short run is the idea that changes in climate may also be leading to more severe weather.
THEORY, FACT AND EVIDENCE
In July 1997, President Bill Clinton launched a global warming awareness campaign, with headlines quoting him as saying it’s “no longer a theory, but now a fact.”
But his full sentence reveals an important caveat: “The overwhelming balance of evidence and scientific opinion is that it is no longer a theory but now a fact that global warming is...