If you want to understand the dynamic that is going on, here is a clear example:

Part 1: leaked early version of next IPCC report (by fervent AGW supporter)

http://www.bbc.co.uk/news/science-environment-15698183

The draft, which has found its way into my possession, contains a lot more unknowns than knowns.

On the one hand, it says it is "very likely" that the incidence of cold days and nights has gone down and the incidence of warm days and nights has risen globally.

And the human and financial toll of extreme weather events has risen.

Human hand fingered?

But when you get down to specifics, the academic consensus is far less certain.

Enhanced glacier melt could speed up sea level rise in the coming decades

There is "low confidence" that tropical cyclones have become more frequent, "limited-to-medium evidence available" to assess whether climatic factors have changed the frequency of floods, and "low confidence" on a global scale even on whether the frequency has risen or fallen.
[Gore Fail]

In terms of attribution of trends to rising greenhouse gas concentrations, the uncertainties continue.

While it is "likely" that anthropogenic influences are behind the changes in cold days and warm days, there is only "medium confidence" that they are behind changes in extreme rainfall events, and "low confidence" in attributing any changes in tropical cyclone activity to greenhouse gas emissions or anything else humanity has done.


(These terms have specific meanings in IPCC-speak, with "very likely" meaning 90-100% and "likely" 66-100%, for example.)

And for the future, the draft gives even less succour to those seeking here a new mandate for urgent action on greenhouse gas emissions, declaring: "Uncertainty in the sign of projected changes in climate extremes over the coming two to three decades is relatively large because climate change signals are expected to be relatively small compared to natural climate variability".

It's also explicit in laying out that the rise in impacts we've seen from extreme weather events cannot be laid at the door of greenhouse gas emissions:

"Increasing exposure of people and economic assets is the major cause of the long-term changes in economic disaster losses (high confidence).


"Long-term trends in normalized economic disaster losses cannot be reliably attributed to natural or anthropogenic climate change."


The succour only lasts for so long, however.

If the century progresses without restraints on greenhouse gas emissions, their impacts will come to dominate, it forecasts:

  • "It is very likely that the length, frequency and/or intensity of warm spells, including heat waves, will continue to increase over most land areas...
  • "It is likely that the frequency of heavy precipitation or the proportion of total rainfall from heavy falls will increase in the 21st Century over many areas of the globe...
  • "Mean tropical cyclone maximum wind speed is likely to increase...
  • "There is medium confidence that droughts will intensify in the 21st Century in some seasons and areas...
  • "Low-probability high-impact changes associated with the crossing of poorly understood thresholds cannot be excluded, given the transient and complex nature of the climate system."

The draft report makes clear that lack of evidence or lack of confidence on a particular impact doesn't mean it won't occur; just that it's hard to tell.
Then, the actual press releases such as this one in the San Francisco Chronicle

http://www.sfgate.com/cgi-bin/articl...w024142S99.DTL

Top international climate scientists and disaster experts meeting in Africa had a sharp message Friday for the world's political leaders: Get ready for more dangerous and "unprecedented extreme weather" caused by global warming.

Making preparations, they say, will save lives and money.


These experts fear that without preparedness, crazy weather extremes may overwhelm some locations, making some places unlivable.


The Nobel Prize-winning Intergovernmental Panel on Climate Change issued a new special report on global warming and extreme weather after meeting in Kampala, Uganda. This is the first time the group of scientists has focused on the dangers of extreme weather events such as heat waves, floods, droughts and storms. Those are more dangerous than gradual increases in the world's average temperature.

"We need to be worried," said one of the study's lead authors, Maarten van Aalst, director of the International Red Cross/Red Crescent Climate Centre in the Netherlands. "And our response needs to anticipate disasters and reduce risk before they happen rather than wait until after they happen and clean up afterward. ... Risk has already increased dramatically."
[yet another NGO "scientist"]

The report said "a changing climate leads to changes in the frequency, intensity, spatial extent, duration, and timing of extreme weather and climate events, and can result in unprecedented extreme weather and climate events." And it said that some — but not all — of these extreme events are caused by the increase of man-made greenhouse gases in the atmosphere.

"We face many challenges in the future," another study lead author, Chris Field of Stanford University, said in a news conference. Those include floods, drought, storms, and heat waves. Field said scientists aren't quite sure which will be the biggest threat to the world because disasters are weather extremes interacting with economics and where people live. Society's vulnerability to natural disasters, aside from climate, has also increased, he said.

Field told The Associated Press in an interview that "it's clear that losses from disasters are increasing. And in terms of deaths, "more than 95 percent of fatalities from the 1970s to the present have been in developing countries," he said.

Losses are already high, running at as much as $200 billion a year, said Michael Oppenheimer of Princeton University, a study author.

"Global warming is increasing the risk of disaster and already makes dealing with several types of disaster, like heat waves, more difficult. The risk will become greater as the future gets hotter," he said.

Science has progressed so much in the last several years that scientists can now attribute the increase in many of these types of extreme weather events to global warming with increased confidence, said study author Thomas Stocker at the University of Bern.


Scientists were able to weigh their confidence of predictions of future climate disasters and heat waves were the most obvious. The report said it is "virtually certain" that heat waves are getting worse, longer and hotter, while cold spells are easing.

What that means is the nasty heat wave that used to happen once every 20 years by mid-century will be once every five years and by the end of the century will be an every other year scorcher, Field and Stocker said.

The report said there is at least a two-in-three chance that heavy downpours will increase, both in the tropics and northern regions, and from tropical cyclones.

The 29-page summary of the full special report — which will be completed in the coming months — says that extremes in some unnamed regions at some point in the future can get so bad that they may need to be abandoned.


...
The juxtaposition between observation, vs the actual scientists studying the details, vs. the IPCC 'Lead Authors', vs. the media - is what is extreme.