Matt Ridley's climate science based on weak foundations
Popular science writer Matt Ridley had a piece
in Tuesday's edition of the Times which likens climate change
to a nosebleed - and the proposed solutions to a tourniquet round
your neck. Ridley writes:
"if you are bleeding to death from a
severed limb, then a tourniquet may save your life, but if you have
a nosebleed, then a tourniquet round your neck will do more harm
So what is the basis for Ridley's argument?
With regard to the impacts of climate change, he makes three key
arguments - that sea level rise is a 'slight nosebleed', (i.e.
insignificant), that the impacts of 'most of the other symptoms of
climate change' are also slight, and that the rate of temperature
increase is 'not on track to do net harm… by the end of this
To support his first point, Ridley cites a
paper in the Journal of Coastal Research in November 2010,
recently published online and
profiled last week on prominent climate sceptic website Watts
Up With That.
The paper looked at tide gauges in North America to ascertain
whether sea-level is rising in the USA. It concluded that although
sea level rise is still occurring, it is occurring more slowly than
expected, and the rise is slowing down rather than speeding up. The
first part of the
"Without sea-level acceleration, the
20th-century sea-level trend of 1.7 mm/y would produce a rise of
only approximately 0.15 m from 2010 to 2100"
Ridley argues that:
"Sea level rise is the greatest
potential threat to civilisation posed by climate change because so
many of us live near the coast. Yet, at a foot a century and
slowing, it is a slight nosebleed."
In his article, Ridley does not however consider any other
research in this area. Other research on this subject disagrees
with its conclusion - a fact illustrated by comments made by
oceanographer and climate scientist John Church. Church, who
is writing the chapter on sea level rise for the IPCC's 2013
update, told Australia's
biannual climate science conference just earlier this week that
sea levels are rising at the upper end of projections by the IPCC -
meaning a rise of 60-80cm by 2100.
review of the subject published in January 2010 concluded
"Most recent developments indicate that
sea level is currently rising, slightly faster since the early
1990s than during the previous decades."
Why is there disagreement within the scientific literature? It
could be for a variety of reasons - including contradictions
between tide gauge data and the satellite data which is also used
to measure sea levels, the impact on tide gauge data of land
subsidence, and the fact that sea level rise varies regionally.
Another uncertainty arises from the impact of melting ice sheets
- a factor which the IPCC is known to have
underestimated in its
2007 report. Research
published earlier this year suggested ice sheet loss has
accelerated over the last 18 years, and that if this trend
continues ice sheets will be the dominant contributor to sea level
rise in the 21st century. At the upper end of the scale,
some scientists suggest that this could lead to a sea level
rise of up to 1.9 metres by 2100 (relative to 1990 levels).
The conclusions of the research Ridley cites are interesting.
They need to be tested against the rest of the scientific
literature as this is a complex area. It is also an area where the
risks in terms of impacts on human population are very significant.
Bearing this in mind, it would seem unwise to draw such definitive
conclusions from just one paper.
Ridley moves from this assessment of sea level rise to apply the
'slight nosebleed' comparison to
"most of the other symptoms of climate
change, such as Arctic sea ice retreat, in terms of their
No supporting scientific literature is given for this statement,
which is at odds with the views of the scientific community, to put
To briefly consider Arctic sea ice - loss of the ice leads to
further regional warming, as with the very reflective ice gone,
less of the sun's energy is reflected back into space.
A major gathering of
top climate scientists, who came together to review the scientific
data on climate change in March 2009 in the run-up to the
Copenhagen summit, concluded
"Recent observations show that
greenhouse gas emissions and many aspects of the climate are
changing near the upper boundary of the IPCC range of projections.
Many key climate indicators are already moving beyond the patterns
of natural variability within which contemporary society and
economy have developed and thrived. These indicators include global
mean surface temperature, sea-level rise, global ocean temperature,
Arctic sea ice extent, ocean acidiﬁcation, and extreme climatic
events. With unabated emissions, many trends in climate will likely
Ridley's article continues:
"The rate of increase of temperature
(0.6C [sic] in 50 years) is not on track to do net harm (which most
experts say is 2C [sic]) by the end of this century."
This statement is problematic, because it makes the assumption
that as temperatures rise, they will continue to do so at a stable
Again, Ridley is at odds with the scientific understanding of
IPCC's projections suggest that temperature will rise by 2°C
(relative to pre-industrial values) by the end of the
21st century, even under the most moderate emissions
scenarios, which we are currently exceeding. Under the highest
emissions scenarios, a temperature increase of 4°C is more
Ridley's suggestion that the temperature increase will not do
"net harm" contrasts with the conclusions of the IPCC - which
concludes for example that the health impacts of climate change
will be "
overwhelmingly negative" and that "
the resilience of many ecosystems is likely to be
Ridley's article is about the potential impacts of climate
change, and what we as a society should be doing to avoid those
impacts. Interesting as his argument is (also citing a paper on the
impact of biofuels), it is built on weak foundations. One paper on
sea level rise has not overturned the weight of evidence, and of
scientific opinion, on climate change.