World leaders are arriving in Copenhagen this week to forge the framework of a plan to limit the causes of global warming, seeking to prevent catastrophic changes to the climate.
Q: What would such a framework involve?
A: There are two key elements:
_Agreeing how much carbon dioxide and other greenhouse gases each industrialized country should be allowed to produce and how much such major developing countries as China and India should aim at restraining the growth in their emissions.
_Agreeing how much wealthy countries should pay poor nations to help them protect themselves from climate change and to shift away from burning coal or oil, which contribute to climate change. These nations also lack the money to build seawalls against rising oceans, to cope with unusual drought and to deal with other effects of climate change.
Q: How much would carbon dioxide emissions be limited?
A: That's one of the sticking points. This past week in preliminary talks, a key document suggests options that range from nearly eliminating global emissions to cutting them in half by 2050.
More specifically, it suggests rich countries like the U.S., by the year 2020, should cut emissions by 25 to 40 percent of the amount produced in 1990. So far, industrial nations' pledges to cut emissions have amounted to far less than the minimum. The U.S. proposal is for a 3 to 4 percent cut _ a sign of the vast chasm that must be bridged. The European Union is committed to a 20 percent cut.
Q: What about emerging countries like China and India?
A: These countries are moving rapidly to bring electricity and modern conveniences to their citizens. There is some consensus that they should not be required to follow draconian carbon reductions. But China recently surpassed the U.S. as the world's biggest producer of greenhouse gases, and the U.S. for one, wants much stricter limits than China will accept.
Q: How much money are wealthy nations likely to pay poor countries?
A: The U.N. has called for $10 billion annually in the next three years. The European Union has pledged $3.6 billion a year. It's still unknown how much other wealthy nations, such as the U.S. and Japan, will contribute. The U.N. says much higher amounts will be needed in 10 years.
Q: What would happen if no action, or too little action, is taken?
A: By some leading estimates, temperatures by 2060 could be at least 4 degrees Celsius (7 degrees Fahrenheit) higher than preindustrial levels. Oceans, already expanding from warmth and melting glaciers, would rise, increasing coastal flooding; a chain reaction of climate changes is projected to lead to harsher, more widespread droughts and more powerful storms.
U.S. intelligence and defense agencies say such environmental changes can lead to energy insecurity, water and food shortages, and social instability. That could mean more military involvement and massive disaster relief.
Q: Are the proposals on the table now enough to prevent climate upheaval?
A: Experts say the pledges in recent days would fall far short. That benchmark is anything more than 2 degrees Celsius (3.6 degrees Fahrenheit) above temperatures before the Industrial Revolution when man started widespread use of coal and other fossil fuels. If larger reductions are not set now, they will have to come later and be more painful, scientists say.
Q: Some people, including some in the U.S. Congress, don't trust the science predicting cataclysmic climate change. How do we know global warming is man-made and that it will lead to such cataclysmic upheaval?
A: The notion of warming comes from basic science: Carbon dioxide traps heat. CO2 has built up tremendously in the atmosphere, and temperatures are rising. The carbon buildup has occurred because of the explosion in fossil fuel use in our industrial age.
In 1988, U.N. agencies organized the Intergovernmental Panel on Climate Change, a network of 2,500 of the best scientists in climatology and related fields, who assess the huge volume of scientific studies on climate. In 2007, in their latest assessment, they found it "very likely" that most observed warming is due to greenhouse gases. Rapid change is already occurring, in the swift summer melt of Arctic sea ice, for example.