Some garbage never dies.
A comment on a recent post consisted solely of this link:
I responded thus:
[Response: I hope you can contribute something other than just a link to a rather amateurish bit of denialist garbage. This paper actually tries to claim that global warming stopped in 1998! This is not a blog to advertize (rather trashy) denialist propoganda.
This led to the following:
This paper actually tries to claim that global warming stopped in 1998!
actually no, the paper I cited gives a very balanced view of both PMOD and ACRIM solar cycle analysis
you on the other hand link to yourself
temps since 1998 have decreased, if solar cycles 24-25 continue the weakening trend then cooler temps are in our future
CO2 forcing is on the way out as a major factor
I responded by quoting directly from the paper:
OH YES, ONE MORE THING, THE EARTH STOPPED WARMING
As David Whitehouse noted in a response to the Lockwood/Frolich paper, that the temperatures of the world have leveled off the last decade after peaking in 1997/98.
The implication, or outright statement, that global warming stopped (or reversed itself) after 1998, is one of the all-time favorites of denialists. Let’s take a look at the most recent temperature data. I’ve often (and consistently) said that the “modern global warming era” starts in 1975. Here’s the global average temperature, according to NASA GISS and HadCRU, from 1975:
I’ve plotted the two data sets using different y-axes, because they’re on a different scale. That’s because NASA GISS computes anomalies compared to the 1951-1980 baseline while HadCRU uses the 1961-1990 baseline.
Clearly there’s a strong warming trend in both data sets, with GISTEMP data rising at 0.018 +/- 0.003 deg.C/yr, HadCRU at 0.019 +/- 0.003 deg.C/yr. We can also see some some sizeable ups and downs, like the cooling for a few years around 1992 caused by the Mt. Pinatubo explosion, and the strong warming in 1998 caused by el Nino. So we can tell, pretty much by looking, that a few years aren’t going to give us a reliable trend (we can tell by running the numbers as well). That’s why “climate normals” are generally defined using a 30-year timescale, and climate trends are best delineated in that way too.
The 1998 peak is very strong. For the GISTEMP data, 1998 isn’t the hottest year, 2005 is — but for the HadCRU data 1998 is the hottest year on record. Maybe global warming actually did stop in 1998? How would we tell reliably? Let’s look at just the data from 1998 on:
It turns out that even if we start at the 1998 peak, the trend is still warming. This is true for both GISTEMP and HadCRU data, and both results are statistically significant. There’s no getting around it: the planet has continued warming overall, since the 1998 el Nino event. The fact that one of two data sets indicates we haven’t broken the 1998 record, doesn’t alter the fact that the trend is still hotter.
We can even look at a very short time span, say, from 2000 onward:
Despite the brevity of the time span, there’s still a statistically significant warming trend in both data sets. GISTEMP indicates warming at a rate of 0.028 +/- 0.019 deg.C/yr, HadCRU indicates 0.018 +/- 0.016 deg.C/yr. Note that the time span is so short that these results are far less precise than the 30-year trend; for the trend from 1975 the error range was only 0.003 deg.C/yr, but for the trend from 2000 the error range is +/- 0.019 or 0.016 deg.C/yr. The brief time span of the most recent data, and the strong autocorrelation of temperature time series, combine to make the error range considerable. But even for the brief period since 2000, the trend is still positive, and the estimate is larger than the error range: it’s significant.
A note of caution for those who want to post links to further garbage. This is NOT a holding place for links to denialist propoganda. If you want to link to something that’s relevant to the topic of discussion, that’s great! If you just want to pepper this blog with links to junk, it’ll be treated like spam.
Yes, the claim that “global warming stopped in 1998″ is garbage. But some garbage goes on forever. Even after the 1998 record is broken in the HadCRU data, this garbage won’t disappear; I’m sure that ten years from now, in 2017, somebody somewhere will be declaring that global warming isn’t real — it stopped in 2014!