What is Climate Change?
Climate change is the term used to describe changes in average weather over time periods ranging from decades to millions of years. These changes may be driven by external forces (i.e. predictable orbital variations or solar variation), result from processes internal to the Earth (i.e. plate tectonics or volcanic activity) or be caused by human activities (anthropogenic) such as global warming.
The current warming trend is of particular significance because most of it is very likely human-induced and proceeding at a rate that is unprecedented in the past 1,300 years.
To see how much the global temperature has risen since 1880, read here: https://www2.ucar.edu/climate/faq/how-much-has-global-temperature-risen-last-100-years
An increase in greenhouse gas levels (global warming) is one of the major impacts that humans have on climate. These include carbon dioxide, water vapour, nitrous oxide, methane, ozone and halocarbons. There is no question that increased levels of greenhouse gases must cause the Earth to warm in response.
Ice core samples drawn from Greenland, Antarctica, and tropical mountain glaciers show that the Earth’s climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks. This ancient evidence reveals that current warming is occurring roughly ten times faster than the average rate of ice-age-recovery warming.
To understand the greenhouse effect better, go here: https://theserangoonview.wordpress.com/2017/03/09/living-in-a-greenhouse-a-blanket-around-the-earth/
The evidence for rapid climate change is compelling
Sea level rise
Global sea level rose about 17 centimetres (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century.
Global temperature rise
All studies show that Earth has warmed since 1880. Most of the warming occurred in the past 35 years, with 15 of the 16 warmest years on record occurring since 2001. The year 2015 was the first time the global average temperatures were 1 degree Celsius or more above the 1880-1899 average. Even though the 2000s witnessed a solar output decline, surface temperatures continue to increase.
Globally Warming Oceans Are Killing Coral Reefs, like here in Samoa.
The oceans have absorbed much of this increased heat, with the top 700 meters (about 2,300 feet) of ocean showing warming of 0.302 degrees celsius since 1969.
Shrinking ice sheets
The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA shows Greenland lost 150 to 250 cubic kilometres of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometres of ice between 2002 and 2005.
Declining Arctic sea ice
Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades.
Glaciers are retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa.
The number of record high-temperature events in the United States has been increasing, while the number of record low-temperature events has been decreasing, since 1950. The U.S. has also witnessed increasing numbers of intense rainfall events.
Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30 percent. This increase is the result of humans emitting more carbon dioxide into the atmosphere and hence more being absorbed into the oceans. The amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by about 2 billion tonnes per year.
Decreased snow cover
Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and that the snow is melting earlier.
Did you know?
What do volcanic eruptions mean for the climate?
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