Where will Earth’s climate go from here?
The pace of extreme weather events has remained remarkably high during 2011, giving rise to the question–is the “Global Weirding” of 2010 and 2011 the new normal? Has human-caused climate change destabilized the climate, bringing these extreme, unprecedented weather events? Any one of the extreme weather events of 2010 or 2011 could have occurred naturally sometime during the past 1,000 years. But it is highly improbable that the remarkable extreme weather events of 2010 and 2011 could have all happened in such a short period of time without some powerful climate-altering force at work. The best science we have right now maintains that human-caused emissions of heat-trapping gases like CO2 are the most likely cause of such a climate-altering force.
Human-caused climate change has fundamentally altered the atmosphere by adding more heat and moisture. Observations confirm that global atmospheric water vapor has increased by about 4% since 1970, which is what theory says should have happened given the observed 0.5°C (0.9°F) warming of the planet’s oceans during the same period. Shifts of this magnitude are capable of significantly affecting the path and strength of the jet stream, behavior of the planet’s monsoons, and paths of rain and snow-bearing weather systems. For example, the average position of the jet stream retreated poleward 270 miles (435 km) during a 22-year period ending in 2001, in line with predictions from climate models.
A naturally extreme year, when embedded in such a changed atmosphere, is capable of causing dramatic, unprecedented extremes like we observed during 2010 and 2011. That’s the best theory I have to explain the extreme weather events of 2010 and 2011…. [T]he ever-increasing amounts of heat-trapping gases humans are emitting into the air puts tremendous pressure on the climate system to shift to a new, radically different, warmer state, and the extreme weather of 2010 – 2011 suggests that the transition is already well underway. A warmer planet has more energy to power stronger storms, hotter heat waves, more intense droughts, heavier flooding rains, and record glacier melt that will drive accelerating sea level rise. I expect that by 20 – 30 years from now, extreme weather years like we witnessed in 2010 will become the new normal.
Finally, I’ll leave you with a quote from Dr. Ricky Rood’s climate change blog, in his recent post, Changing the Conversation: Extreme Weather and Climate: “Given that greenhouse gases are well known to hold energy close to the Earth, those who deny a human-caused impact on weather need to pose a viable mechanism of how the Earth can hold in more energy and the weather not be changed. Think about it.”
That’s from the conclusion of a comprehensive must-read analysis by uber-meteorologist and former Hurricane Hunter Dr. Jeff Masters. Masters has the most comprehensive review I’ve seen — with images and graphs — of the remarkable extreme weather of last year.
I am reposting the entire piece below.
Bear in mind as you read it that we have warmed only about 1°F in the past few decades. If we stay anywhere near our current emissions path, we face 10°F warming this century (see here). Who can even imagine what a 100-year or 500-year extreme event will be in the second half of the century? For some of the relevant scientific literature, see “Two seminal Nature papers join growing body of evidence that human emissions fuel extreme weather, flooding that harm humans and the environment.”