A giant glacier remnant in Baffin Bay, northwest Greenland.
Your Questions on Climate Change
Starting May 1, NPR, in partnership with National Geographic, will take you on a year-long global voyage, exploring how the Earth's climate shapes people, and how people are shaping the Earth's climate. We'll follow the prime meridian and international date line — the meridians that circle the Earth at 0 and 180 degrees longitude — stopping along the way to see how changes in climate are affecting lives, landscapes and societies.
But first, we want to know your questions on climate change. What issues would you like us to explore? What are you confused about? And what are your observations on climate change?
The Earth is warming and humans are the cause. That's the conclusion of the first installment of the United Nations' Intergovernmental Panel on Climate Change 2007 report, released in February. Multiple lines of evidence confirm this, with measurements coming from ocean, land and air sensors, as well as satellites and ice cores that have preserved atmospheric information from up to 650,000 years ago.
Carbon dioxide emissions from burning coal and oil – the energy sources behind industrial revolutions – are the main culprit behind warming, but methane and nitrous oxide, byproducts of agriculture, also play a role.
Overall, the IPCC says we can expect a 4 or 5 degree Fahrenheit rise in global temperature over the next century – which is considerable. And what does that mean for humans? That's the subject of the next installment of the IPCC's Climate Change 2007 report. Here, a look at the key findings of the February report:
Greenhouse gases, such as carbon dioxide, methane and nitrous oxide, trap heat in the Earth's atmosphere. These gases occur naturally, but the marked increase seen in these gases over the past 50 years is the result of human activity, says the IPCC.
-- The amount of carbon dioxide in the atmosphere in 2005 "exceeds by far" the levels recorded in ice cores over the last 650,000 years.
-- The rate of increase of carbon dioxide in the atmosphere has been greater in the past 10 years than at any point since continuous measurements began in 1960.
-- There is a greater than 90 percent chance that the global warming seen in the last 50 years is the result of human activity.
-- Eleven of the last 12 years rank among the 12 warmest years in the instrumental record of global surface temperature, which dates back to 1850.
-- Observations since 1961 show that the average temperature of the global ocean has increased, down to depths of 3,000 meters (9,000 feet). The ocean has been absorbing more than 80 percent of the heat added to Earth's climate system. As seawater warms, it expands, contributing to the rise in sea levels.
-- Mountain glaciers and snow cover are on the decline, with the resulting meltwater contributing to rising sea levels.
-- Losses from the ice sheets in Greenland and Antarctic have very likely (a greater than 90 percent chance) contributed to sea level rise since 1993.
-- Average Arctic temperatures increased at almost twice the global average rate in the past 100 years.
-- Rainfall patterns are shifting away from the equator. A significant increase in rainfall has been recorded in eastern North and South America, northern Europe, and northern and central Asia.
-- An increase in drying and drought has been seen in the Sahel, the Mediterranean, southern Africa and parts of southern Asia.
-- More intense and longer droughts have been seen over wider areas since the 1970s, particularly in the tropics and subtropics.