November 3, 2014

Meanwhile, Outside...

Yes, I know there's a midterm election tomorrow.  Get your ass out there and vote!

But meanwhile, from the beeb:
The IPCC's Synthesis Report was published on Sunday in Copenhagen, after a week of intense debate between scientists and government officials.

It is intended to inform politicians engaged in attempts to deliver a new global treaty on climate by the end of 2015.

The report says that reducing emissions is crucial if global warming is to be limited to 2C - a target acknowledged in 2009 as the threshold of dangerous climate change.
Here's the report.

Some highlights:
Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.
And some details regarding the above:
Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. The period from 1983 to 2012 was very likely the warmest 30-year period of the last 800 years in the Northern Hemisphere, where such assessment is possible (high confidence) and likely the warmest 30-year period of the last 1400 years (medium confidence).

The globally averaged combined land and ocean surface temperature data as calculated by a linear trend, show a warming of 0.85 [0.65 to 1.06] °C1 over the period 1880 to 2012, for which multiple independently produced datasets exist. The total increase between the average of the 1850–1900 period and the 2003–2012 period is 0.78 [0.72 to 0.85] °C, based on the single longest dataset available. For the longest period when calculation of regional trends is sufficiently complete (1901 to 2012), almost the entire globe has experienced surface warming. [Italics in original]
But it hasn't warmed in 18 years right?  So that means all that above is bullshit, right?

Wrong:
In addition to robust multi-decadal warming, the globally averaged surface temperature exhibits substantial decadal and interannual variability. Due to this natural variability, trends based on short records are very sensitive to the beginning and end dates and do not in general reflect long-term climate trends. As one example, the rate of warming over the past 15 years (1998–2012; 0.05 [–0.05 to 0.15] °C per decade), which begins with a strong El Niño, is smaller than the rate calculated since 1951 (1951–2012; 0.12 [0.08 to 0.14] °C per decade).
So next time you hear someone say that the warming has stopped because it "hasn't changed" (or whatever) in 18 years or so, tell them that they're bringing up something the actual scientists already know about and they've already explained away and that coming to a conclusion based on a short term that's skewed by the dates picked is not very reliable scientifically.  No, not at all.

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