Geoscience Reference
In-Depth Information
plant source but from ancient plants. The only source of ancient plant carbon in the
quantities observed is fossil fuel combustion.
The next question is how much global temperatures have risen and whether the
increase can be attributed to the added CO
2
and the greenhouse effect. Accord-
ing to the Berkeley Earth Surface Temperature Study (BEST), since 1750 global
temperatures have risen 1.4°C (2.5°F). Over the past fifty years, the rise has been
about 0.9 °C (1.6°F), higher than the IPCC estimate. The BEST team says that the
Sun “does not appear to contribute to the observed global warming of the past 250
years; theentire changecanbemodeled byasumofvolcanism and[anthropogenic
carbon emissions].” As BEST's director Richard Muller put it, “humans are almost
entirely the cause” of recent global warming. “Berkeley Earth also has carefully
studied issues raised by skeptics,” they add, “such as possible biases from urban
heating, data selection, poor station quality, and data adjustment. We have demon-
strated that these do not unduly bias the results.”
16
Finally, the Berkeley group debunks the specious claim that “global warming
ended in 1998,” pointing out that it amounts to cherry-picking the start date of
the comparison. The El Niño weather pattern causes anomalously high temperat-
ures, and 1998 had one of the strongest El Niños in history. Pick 1997 or 1999 as
the start year of the comparison and you could not claim that global warming had
ended. Using a running twelve-month average of temperature, rather than the cal-
endar year, three temperature peaks since 1998 have been higher. The year 2010
had both the highest-running twelve-month average and the highest calendar year
temperature on record. Globally, 2012 was the eighth or ninth warmest, depending
on the data set used, and in the United States it was the warmest year on record.
Thuseverypartofthestatementistrue:
By burning fossil fuels, humans have ad-
ded ancient carbon to the atmosphere and, through the greenhouse effect, caused
global temperature to rise
.
Yet global warming deniers say the statement is false. What would it take for
them to be right? Two things: First, some invisible process must have offset the
greenhouse effect. Second, with the greenhouse effect diminished or absent, some
other invisible process must have caused the observed temperature rise. Thus the
choice is to accept known scientific facts or agree with the deniers and appeal to
two unknowns. That would be like ignoring your physician and trusting a witch
doctor's mumbo jumbo.
Moreover, if global warming is
not
occurring, then why are Antarctica, Green-
land, and the world's glaciers melting at unprecedented rates? Why is Arctic sea
ice at a record low? Why is the sea level higher and rising faster than at any time
in history? Why, as the insurance companies confirm, are there more instances of
