Can you tell us if the purported rise is in degrees Fahrenheit or Celsius?
Some scientists have expressed the view that if we don't cut emissions, the temperature could rise to anything up to plus 7 degrees Celsius or so this century (above pre-industrial) - which would be nearly one degree Fahrenheit a decade and certainly more than half a degree Fahrenheit a decade.
The new projections, published this month in the American Meteorological Society's Journal of Climate, indicate a median probability of surface warming of 5.2 degrees Celsius by 2100, with a 90% probability range of 3.5 to 7.4 degrees. This can be compared to a median projected increase in the 2003 study of just 2.4 degrees. The difference is caused by several factors rather than any single big change. Among these are improved economic modeling and newer economic data showing less chance of low emissions than had been projected in the earlier scenarios. Other changes include accounting for the past masking of underlying warming by the cooling induced by 20th century volcanoes, and for emissions of soot, which can add to the warming effect. In addition, measurements of deep ocean temperature rises, which enable estimates of how fast heat and carbon dioxide are removed from the atmosphere and transferred to the ocean depths, imply lower transfer rates than previously estimated.
It depends on how much more greenhouse gas we emit and what other effects might be precipitated as the earth warms (eg how quickly the sea ice melts in summer; whether there will be a sudden eruption of methane etc.)
I doubt we'll let it get that bad, but who knows. Some people don't even understand yet what we're doing to the climate, so anything could happen I suppose.
