Saturday, October 18, 2014

Climate change?

Shortly after the last post (Winter's a' comin'10/1/14), the climate summary for Alaska came out. Not surprisingly, the average temperatures for September, like August, were well above normal statewide (http://climate.gi.alaska.edu/node/710).
What was surprising was an article that came out a little later: September Was Warmest on Record, NASA Data Show. "Like August before it, September 2014 was the warmest September on record, according to newly updated NASA data. The warm month makes it even more likely that 2014 will become the warmest year on record. Ocean temperatures have played a large role in 2014’s warmth, including the warmer-than-normal sea surface temperatures in the tropical Pacific Ocean that have accompanied an emerging El Niño, Kevin Trenberth, a climatologist with the National Center for Atmospheric Research, told Climate Central in an email. The ocean is where some 90 percent of the excess heat trapped by greenhouse gases is stored." (http://www.climatecentral.org/news/september-2014-warmest-on-record-18172). Proof of global warming?
Hold on. Here's another view: Why is the Northwest U.S. warming? Natural variations or mankind's greenhouse gases? "Originally there was a lot of talk (last spring) of the potential for a Super El Nino, with some of the global warming "advocate" sites talking about its effects on the global temperature record. El Ninos (ENSO) are associated with warmer than normal water in the tropical Pacific and that such anomalies can influence Northwest weather (less storms, warmer, less snow). However, the sea surface temperatures in the critical central Pacific is only modestly warmer than normal and the atmospheric circulation has not reacted in a way to reinforce the warming and push us towards a moderate or stronger El Nino. So we should not expect much more than a marginal El Nino during the upcoming fall and early winter months. And amplitude matters. Weak El Ninos have lesser impacts. The correlation of our weather with El Nino is not perfect to start with. And for weak El Nino years the relationship weakens further. But for weak El Nino years, the precipitation patterns are all over the place. The latest NWS Climate Forecast System forecasts for December-January-February is for warmer than average over much of the U.S. But there is another type of natural variability that has a huge impact on the weather/climate of the Pacific basin. The Pacific Decadal Oscillation (PDO) has a period of around 50 years, oscillating between warm and cold cycles. It was in a cool cycle between roughly 1950 and 1977, then a warm cycle until around 2005, and more recently looks to be in a cooler cycle. If you compare the variations of the PDO with the Northwest temperatures, it is very obvious that the variations of NW temps seems to closely follow the PDO changes, suggesting our temperatures are highly controlled by this mode of natural variability. Thus, when some local scientists say that the temperature changes experienced here in the Northwest are mainly due to greenhouse gas emissions they are certainly incorrect. We live in an area where the greenhouse gas signal is small and where natural variability (as forced by the PDO and ENSO) are quite large (and there are other modes of natural variability)." (http://cliffmass.blogspot.com/).
 So who's right? Perhaps a better indicator of climate change are systems that respond to longer term cycles, like ice caps and glaciers. Two articles that point towards longer climate change are: Strong Temperature Increase and Shrinking Sea Ice in Arctic Alaska, which discusses recent temperature rises and loss of sea ice cover in the Arctic ocean (http://climate.gi.alaska.edu). Are glaciers growing or retreating? "Globally, glaciers are losing ice at an extensive rate. There are still situations in which glaciers gain or lose ice more than typical for one region or another but the long term trends are all the same, and about 90% of glaciers are shrinking worldwide." (http://www.skepticalscience.com/himalayan-glaciers-growing.htm). So what's the answer? No matter how much data will point to a particular outcome, some skeptics will confound the issues by only picking individual anomalies or by ignoring long term trends. These diversions do not address the most important question: what is the real state of global climate change?  Politicians are the worst, often choosing a position solely to gain support from their base. And in election years, the climate change clown show will only escalate.

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