Scientific American - Climate Central
Analysis suggests climate change is on track to be much warmer
Global leaders are meeting in New York this week to sign the Paris
climate agreement. One of the expressed purposes of the document is to
limit warming to “well below 2°C above pre-industrial levels and
pursuing efforts to limit the temperature increase to 1.5°C.”
A Climate Central analysis shows that the world will have to
dramatically accelerate emissions reductions if it wants to meet that
goal. The average global temperature change for the first three months
of 2016 was 1.48°C, essentially equaling the 1.5°C warming threshold
agreed to by COP 21 negotiators in Paris last December.
February exceeded the 1.5°C target at 1.55°C, marking the first time
the global average temperature has surpassed the sobering milestone in
any month. March followed suit checking in at 1.5°C. January’s mark of
1.4°C, put the global average temperature change from early industrial
levels for the first three months of 2016 at 1.48°C.
Climate Central scientists and statisticians made these calculations
based on an average of global temperature data reported by NASA and the
National Oceanic and Atmospheric Administration (NOAA). But rather than
using the baselines those agencies employ, Climate Central compared
2016’s temperature anomalies to an 1881-1910 average temperature
baseline, the earliest date for which global temperature data are
considered reliable. NASA reports global temperature change in reference
to a 1951-1980 climate baseline, and NOAA reports the anomaly in
reference to a 20th century average temperature.
NASA’s data alone showed a February temperature anomaly of 1.63°C above early industrial levels with March at 1.54°C.
Calculating a baseline closer to the pre-industrial era provides a
useful measure of global temperature for policymakers and the public to
better track how successful the world’s efforts are in keeping global
warming below agreed-upon thresholds.
A similar adjustment can be applied to some of the temperature change projections in the most recent IPCC report.
The IPCC AR5 Working Group 1 Report contains projections of future
global surface temperature change according to several scenarios of
future socio-economic development, most of which are presented using a
baseline of 1986 to 2005. The IPCC chose this baseline in order to
provide its readers a more immediate base of comparison, the climate of
the present world, which people are familiar with. But these
representations may suggest that the Paris goals are easier to
reach than is true.
The IPCC’s presentation of these scenarios was not designed to inform
the discussion about warming limits (e.g., 1.5°C, 2°C goals of the
Paris COP21 agreements). But the Panel does provide a way to make its
projections of future warming consistent with discussions about targets.
IPCC estimates, using the best and longest record available, show
that the difference between the 1986-2005 global average temperature
value used in most of the Panel’s projections, and pre-industrial global
average temperature, is 0.61°C (0.55-0.67). Neglecting 0.61°C warming
is not trivial, and makes a significant difference for the assessment of
the goals established in Paris. In fact, 0.61°C amounts to about half
the warming already experienced thus far.
To capture this warming and display the IPCC warming time series
relative to the pre-industrial period, Climate Central adjusted a well
known IPCC projection (SPM7(a)) to reflect a 1880-1910 baseline. This
adjustment has a significant effect on the dates at which the 1.5 and
2°C thresholds are crossed, moving them up by about 15-20 years.
If current emissions trends continue (RCP8.5) we
could cross the 1.5°C threshold in 10 to 15 years, somewhere between the
years 2025-2030, compared to 2045-2050 when a 1985-2005 baseline is
used.
The dramatic global hot streak that kicked off 2016 doesn’t mean the
world has already failed to meet the goals in the Paris agreement. Three
months do not make a year, and it is unlikely that 2016 will exceed the
1881-1910 climate-normal by 1.5°C. This year is also in the wake of a
strong El Niño, when higher-than-average temperatures would be expected.
And of course, exceeding the 1.5°C threshold for even an entire year
would not mean that global temperatures had in fact risen to that point,
never (at least within our lifetime) to drop back below it as it’s too
short of a timeframe to make that determination.
But the hot start for 2016 is a notable symbolic milestone. The day
the world first crossed the 400 parts per million (ppm) threshold for
atmospheric carbon dioxide heralded a future of ever increasing carbon
dioxide. So too, do the first three months of 2016 send a clear signal
of where our world is headed and how fast we are headed there if drastic
actions to reduce carbon emissions are not taken immediately.
Background
On Dec.12, 2015, the 21st Conference of the Parties to the U.N.
Framework Convention on Climate Change approved the Paris Agreement
committing 195 nations of the world to “holding the increase in the
global average temperature to well below 2°C above preindustrial levels
and pursuing efforts to limit the temperature increase to 1.5°C.” The
pact commits the world to adopt nationally determined policies to limit
greenhouse gas emissions in accord with those goals.
The 2°C goal represents a temperature increase from a pre-industrial
baseline that scientists believe will maintain the relatively stable
climate conditions that humans and other species have adapted to over
the previous 12,000 years. It will also minimize some of the worst
impacts of climate change: drought, heat waves, heavy rain and flooding,
and sea level rise. Limiting the global surface temperature increase to
1.5°C would lessen these impacts even further.
1.5 and 2°C are not hard and fast limits beyond which disaster is
imminent, but they are now the milestones by which the world measures
all progress toward slowing global warming. And yet it is surprisingly
difficult to find objective measures that answer the question, where are
we today on the path toward meeting the 1.5 or 2°C goals?
Every month NOAA and NASA update their global surface temperature
change analysis, using data from the Global Historical Climate Network,
and methods validated in the peer-reviewed literature (Hansen et al.
2010; NCDC). The monthly updates are posted on their websites, and made
available to the public along with the underlying data and assumptions
that go into their calculations.
These calculations are enormously useful for understanding the
magnitude and pace of global warming. In fact, they are the bedrock
measurements validating the fact that our planet is warming at all.
But none present their results in comparison to a pre-industrial climate normal.
Methods and Results
The NASA and NOAA monthly updates are presented as anomalies, or as
the deviation from a baseline climate normal, calculated as an average
of a 30-year reference period, or the 20th century average; they do not
represent an absolute temperature increase from a specific date. NASA
presents their results in reference to a 1951 to 1980 average
temperature, NOAA in reference to a 20th century average temperature.
The NASA results, calculated by Goddard Institute for Space Studies are published monthly on the NASA/GISS website (
GISTEMP). NOAA methods and monthly updates are published via the National Centers for Environmental Information
here.
Climate Central used data from NASA and NOAA to create an 1881 to
1910 climate normal for the months of January, February, and March. We
then compared the reported monthly 2016 anomaly for each of these months
to this “early-industrial” baseline reference period. These anomalies
were then averaged to produce a mean monthly NASA/NOAA anomaly for each
month. The results are presented below.
The NASA anomaly is considerably higher than the anomaly reported by
NOAA. This reflects the fact the NASA’s calculations are tuned to
account for temperature changes at the poles, where there are far fewer
monitoring stations. NOAA relies only on historical station data and
makes no adjustment to account for sparse records at the poles, where
warming has been more rapid relative to non-polar regions.
Links
!["For this series, I simply focused on two facts — [the] disappearing island and its inhabitants," Lee told Business Insider. "I found some symbolic landscape that explained the situation of the island and [I photographed] the inhabitants on this land to show their home is disappearing."](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_vfnD1d6JGVWrIrkVt5BbyJDUK2OB6uh_yxpcGm0BEYW3PEqWVr-utQ88FZLi56K30NcnGlYhOhhRBx-g2CVei1j1nXBsEjVZQ7_pE7Hbg3COqIg3Y2oh5y-m4f-jXoIDFKIpbn5QWTi9w0MMNUwp3irhsSITwpI_-mP4OxBLwcDul9BlcjsZmF32_NjG_jRaC3fw6kUyvF82abkPvmHKmSvS7e0CzAjBtDdRWRlhxxZvfFqK4p5sq7d7P5y6JnCfn7hiEvnzRQOZHR0dtV4AHBolD_9nE9SyKxOyVq3mBTpWD9LBZU-oyHjKzquNoE8fCk2wtLxVTwxUKw5I6HCO6QyEPZOAgX_aAy4C0y8bcUpLTvN306T56MFvSPHXUy1NLQIrkH569K1GWMT-86kXxuJljxxCyt2Lb0z-RS6JcnAilRXhvMdn8zpHz4uq5gbv10XRuWjJQjE66Tz4J-0Xr7E4Zx146_85Rn_Dh9Eo7gy5KIGLLgCZN5DGs4qtl2-ep9=s0-d)
