NASA & NOAA: January 2013 Was 6th, 9th Warmest Globally On Record

According to data released by NASA and NOAA last week, January was the 6th and 9th warmest January’s (respectively) globally on record.  Here are the data for  NASA’s analysis; here are NOAA data and report.  The two agencies have slightly different analysis techniques, which in this case resulted in not only different temperature anomaly values but somewhat different rankings as well.  The two techniques provide a check on one another and confidence for us.

The details:

January’s global average temperatures were 0.61°C (1.098°F) above normal (1951-1980), according to NASA, as the following graphic shows.  The warmest regions on Earth coincide with the locations where climate models have been projecting the most warmth will occur: high latitudes (especially within the Arctic Circle).  The past three months have a +0.58°C temperature anomaly.  And the latest 12-month period (Feb 2012 – Jan 2013) had a +0.58°C temperature anomaly.  The time series graph in the lower-right quadrant shows NASA’s 12-month running mean temperature index.  The recent downturn (2010-2012) is largely due to the latest La Niña event (see below for more) that ended early last summer.  Since then, ENSO conditions returned to a neutral state (neither La Niña nor El Niñ0).  Therefore, as previous anomalously cool months fall off the back of the running mean, and barring another La Niña, the 12-month temperature trace should track upward again in 2013.

Figure 1. Global mean surface temperature anomaly maps and 12-month running mean time series through January 2013 from NASA.

According to NOAA, January’s global average temperatures were 0.54°C (0.97°F) above the 20th century mean of 14.0°C (57.2°F).  NOAA’s global temperature anomaly map for January (duplicated below) shows where conditions were warmer than average during the month.

Figure 2. Global temperature anomaly map for January 2013 from NOAA.

The two different analyses’ importance is also shown by the preceding two figures.  Despite differences in specific global temperature anomalies, both analyses picked up on the same temperature patterns and their relative strength.

The very warm conditions found over Greenland and Alaska are a concern.  These areas were warmer than average during more months in recent history than not.  Additionally, Australia was much warmer than usual.  Indeed, Australia’s January average temperature was the highest on record: +2.28°C (4.10°F!) above the 1961–1990 average, besting the previous record set in 1932 by 0.11°C (0.20°F).  In contrast to 2012, Siberian temperatures were cooler than normal.  This is likely a temporary, seasonal effect.  Long-term temperatures over northern Siberia continue to rise at among the fastest rate for any region on Earth.

These observations are also worrisome for the following reason: the globe came out of a moderate La Niña event in the first half of the year.  During the second half of the year, we remained in a ENSO-neutral state (neither El Niño nor La Niña):

Figure 3. Time series of weekly SST data from NCEP (NOAA).  The highest interest region for El Niño/La Niña is NINO 3.4 (2nd time series from top).

The last La Niña event hit its highest (most negative) magnitude more than once between November 2011 and February 2012.  Since then, tropical Pacific sea-surface temperatures peaked at +0.8 (y-axis) in September 2012.  You can see the effect on global temperatures that the last La Niña had via this NASA time series.  Both the sea surface temperature and land surface temperature time series decreased from 2010 (when the globe reached record warmth) to 2012.  So a natural, low-frequency climate oscillation affected the globe’s temperatures during the past couple of years.  Underlying that oscillation is the background warming caused by humans.  And yet temperatures were still in the top-10 warmest for a calendar year (2012) and individual months, including January 2013, in recorded history.

Skeptics have pointed out that warming has “stopped” or “slowed considerably” in recent years, which they hope will introduce confusion to the public on this topic.  What is likely going on is quite different: since an energy imbalance exists (less outgoing energy than incoming energy) and the surface temperature rise has seemingly stalled, the excess energy is going somewhere.  That somewhere is likely the oceans, and specifically the deep ocean.  Before we all cheer about this (since few people want surface temperatures to continue to rise quickly), consider the implications.  If you add heat to a material, it expands.  The ocean is no different; sea-levels are rising because of heat added to it in the past.  The heat that has entered in recent years won’t manifest as sea-level rise for some time, but it will happen.  Moreover, when the heated ocean comes back up to the surface, that heat will then be released to the atmosphere, which will raise surface temperatures as well as additional water vapor.  Thus, the immediate warming rate might have slowed down, but we have locked in future warming (higher future warming rate).

In a previous post on global temperatures, I pointed a few things out and asked some questions.  The Conference of Parties summit produced no meaningful climate action (November 2012).  Countries agreed to have something on paper by 2015 and enacted by 2020.  If everything goes as planned (a huge assumption given the lack of historical progress), significant carbon reductions wouldn’t occur until later in the 2020s – too late to ensure <2°C warming by 2100.  If, as is much more likely, everything doesn’t go as planned, reductions wouldn’t occur until later than the 2020s.  Additional meetings are scheduled for this year, but I maintain my expectation that nothing meaningful will come from them.  The international process is ill-equipped to handle all the legitimate interest groups in one fell swoop.

Instead, actions that start locally and grow with time are more likely to address emissions and eventual warming and other climate change effects.  People started small-scale activities in cities around the world in recent years.  There are also regional and international carbon markets.  While most markets were poorly designed, lessons learned from the first generation can be used to make future generation markets more effective.  As these small-scale efforts grow and their effects combine, larger bodies will need to address differences between them so that they work for larger populations and markets.

Paying for recovery from seemingly localized severe weather and climate events is and always will be more expensive than paying to increase resilience from those events.  As drought continues to impact US agriculture, as Arctic ice continues to melt to new record lows, as storms come ashore and impacts communities that are not prepared for today’s high-risk events (due mostly to poor zoning and destruction of natural protections), economic costs will accumulate in this and in future decades.  It is up to us how many costs we subject ourselves to.  As President Obama begins his second term with climate change “a priority”, he tosses aside the most effective tool available and most recommended by economists: a carbon tax.  Every other policy tool will be less effective than a Pigouvian tax at minimizing the actions that cause future economic harm.  It is up to the citizens of this country, and others, to take the lead on this topic.  We have to demand common sense actions that will actually make a difference.  But be forewarned: even if we take action today, we will still see more warmest La Niña years, more warmest El Niño years, more drought, higher sea levels, increased ocean acidification, more plant stress, and more ecosystem stress.  The biggest difference between efforts in the 1980s and 1990s to scrub sulfur and CFC emissions and future efforts to reduce CO2 emissions is this: the first two yielded an almost immediate result while it will take decades before CO2 emission reductions produce tangible results humans can see.

55.7% of the Contiguous United States in Moderate or Worse Drought – 12 Feb 2013

According to the Drought Monitor, drought conditions are relatively unchanged in the past two weeks. As of Feb. 12, 2013, 55.7% of the contiguous US is experiencing moderate or worse drought (D1-D4). The percentage area experiencing extreme to exceptional drought increased from 19.4% to 17.7% in the last two weeks. Percentage areas experiencing drought across the West stayed mostly the same while snowpack increased. Drought across the Southwest decreased slightly. Meanwhile, storms improved drought conditions in the Southeast.

This post precedes a significant snow event across the High and Great Plains.  The NWS expects up to a foot of snow in some areas of the Plains over the next couple of days, which will provide about 1″ of liquid water equivalent.  Since these areas currently suffer from a 2-4″ liquid water deficit, this storm will not break the short-term drought.  Moreover, long-term drought will only be broken by substantial spring and summer rainfall.  After one or two more Drought Monitor updates, we should see some welcome differences in these maps.

Figure 1 – US Drought Monitor map of drought conditions as of the 12th of February.

Figure 2 – US Drought Monitor map of drought conditions in Western US as of the 12th of February.  Some small relief is evident in the past week, including some changes in the mountains as storms recently dumped snow across the region.  Mountainous areas and river basins will have to wait until spring for snowmelt to significantly alleviate drought conditions.

Figure 3 – US Drought Monitor map of drought conditions in Colorado as of the 12th of February.  Drought conditions held mostly steady across the state in the past week.  For the first time in over a month, less than 100% of CO is experiencing Severe drought conditions.  This improvement occurred over the southwestern portion of the state due to mid-season snow storms.  Unfortunately, Exceptional drought conditions expanded over the northeastern plains.

Figure 4 – US Drought Monitor map of drought conditions in Southeast US as of the 12th of February.  As mentioned above, drought conditions contracted a little and grew less severe in the past couple of weeks.  The worst hit area, in central Georgia, has experienced the longest duration drought conditions on this map.

Cooler than normal sea-surface temperatures (SSTs) are present in the eastern Pacific, according to current MJO and ENSO data.  Additionally, eastern Pacific SSTs are cooler than the climatic average due to the current negative phase of the IPO.  This in turn is due in part to global warming, which is causing warmer western Pacific and Indian Ocean SSTs than usual.  The cool SSTs in the eastern Pacific initiate and reinforce air circulations that generally keep precipitation away from the Southwest and Midwest US.  This doesn’t mean that drought will be ever-present; only that we are potentially forcing the climate system toward more frequent drought conditions in these regions.  Some years will still be wet or normal; other years (increasing in number) will be dry.  This counters skeptics who claim that more CO2 and warmer temperatures are better for plants.  If there is no precipitation, plants cannot take advantage of longer growing seasons.  Moreover, we will experience years with increased food pressure.  These conditions’ extent in the future is up to us and our climate policy (or lack thereof).

While MJO, ENSO, and IPO are all in phases that tend to deflect storm systems from the Southwest, this week’s storm demonstrates that the conditions are not ever-present.  Weather variability still occurs with the dryer regime.  Put another way, weather is not climate.

State of Polar Sea Ice – February 2013: Arctic Below and Antarctic Above Normal

Global polar sea ice area in early February 2013 mimics climatological normal conditions (1979-2009), after improvement in the past month.  Antarctic sea ice loss is occurring slower than the climatological normal rate.  Arctic sea ice gain is more rapid than normal.  Polar sea ice recovered from an extensive deficit of -2.5 million sq. km. area late last year to near-zero anomaly within the last week.

Arctic Ice

According to the NSIDC, weather conditions once again caused less freezing to occur on the Atlantic side of the Arctic Ocean and more freezing on the Pacific side than normal.  Similar conditions occurred during the past six boreal winters.  Sea ice creation during January measured 1.36 million sq. km.  Despite this rather rapid growth, January′s extent remained well below average for the month.  Instead of measuring near 14.84 million sq. km., January 2013′s extent was only 13.78 million sq. km., a 1.06 million sq. km. difference!  The Barents Sea recorded lower than average sea ice, which is an unusual condition for January.  Kara Sea ice recovered from low extent the past couple of months.  The Bering Sea, which saw ice extent growth due to anomalous northerly winds in 2011-2012, saw similar conditions in December 2012 and January 2013.  This has caused anomalously high ice extent in the Bering Sea.  Previously this winter, a negative phase of the Arctic Oscillation allowed cold Arctic air to move far southward and brought warmer than normal air to move north over parts of the Arctic.  The AO has returned to a more neutral phase in the past month, which has kept Arctic air closer to where it normally is this time of year.

In terms of longer, climatological trends, Arctic sea ice extent in January has decreased by 3.2% per decade.  This rate is closest to zero in the spring months and furthest from zero in late summer/early fall months.  Note that this rate also uses 1979-2000 as the climatological normal.  There is no reason to expect this rate to change significantly (more or less negative) any time soon, but increasingly negative rates are likely in the foreseeable future.  Additional low ice seasons will continue.  Some years will see less decline than other years (e.g., 2011) – but the multi-decadal trend is clear: negative.  The specific value for any given month during any given year is, of course, influenced by local and temporary weather conditions.  But it has become clearer every year that humans have established a new climatological normal in the Arctic with respect to sea ice.  This new normal will continue to have far-reaching implications on the weather in the mid-latitudes, where most people live.

Arctic Pictures and Graphs

The following graphic is a satellite representation of Arctic ice as of January 9, 2013:

Figure 1 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130109.

Here is the similar image from February 11th 2013:

Figure 2 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130211.

The lack of sea ice in the Barents Sea (north of Europe) is problematic because wind and ocean currents typically pile sea ice up on the Atlantic side of the Arctic.  Sea ice presence in the Bering Sea (between Alaska and Russia) does not alleviate this problem because currents take ice from that area and transport it into the Arctic.  That sea ice will be among the first to melt completely come spring.  With sea ice missing on the Atlantic side, currents will more easily transport Arctic sea ice to southern latitudes where it melts.

Overall, the health of the ice pack is not healthy, as the following graph of Arctic ice volume from the end of January demonstrates:

Figure 3 – PIOMAS Arctic sea ice volume time series through January 2013.

As the graph shows, volume (length*width*height) hit another record minimum in June 2012.  Moreover, the volume remains far from normal since it just returned to the -2 standard deviation envelope (light gray).  I understand that most readers don’t have an excellent handle on statistics, but conditions between -1 and -2 standard deviations are rare and conditions outside the -2 standard deviation threshold (see the line below the shaded area on the graph above) are incredibly rare: the chances of 3 of them occurring in 3 subsequent years under normal conditions are extraordinarily low (you have a better chance of winning the Powerball than this).  Hence my assessment that “normal” conditions in the Arctic are shifting from what they were in the past few centuries; a new normal is developing.  Note further that the ice volume anomaly returned to near the -1 standard deviation envelope in early 2011, early 2012, and now early 2013.  In each of the previous two years, volume fell rapidly outside of the -2 standard deviation area with the return of summer.  That means that natural conditions are not the likely cause; rather, another cause is much more likely to be responsible for this behavior: human influence.

Arctic Sea Ice Extent

Take a look at January’s areal extent time series data:

Figure 4 – NSIDC Arctic sea ice extent time series through early February 2013.

As you can see, the extent (light blue line) grew rapidly in November but still remained at historically low levels through the winter.  The extent remained well below average values (thick gray line) throughout the fall and early winter.  The time series of sea ice extent for previous low years is also shown on this graph.  In this month’s version, NSIDC also plotted the previous four years’ data.  You can see the effect of the wintertime conditions that I described above: the difference between a year’s extent and the average value in January or February is smaller than the difference in October.  This leads us to examine the differences between the historical mean, the negative two standard deviation (light gray) below that mean, and the 2012-2013 time series.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from January 9, 2013:

Figure 5– UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130109.

And here is the corresponding graphic from February 11th:

Figure 6 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130211.

Ice loss is easily visible around the continent.  There is slightly more Antarctic sea ice today than there normally is on this date in the year.  The reason for this is the extra ice in the Weddell Sea (east of the Antarctic Peninsula that juts up toward South America).  This ice exists this winter due to an anomalous atmospheric circulation pattern: persistent high pressure west of the Weddell sea pushed sea ice north.  The same winds that pushed the sea ice north also moved cold Antarctic air over the Sea, which has kept ice melt rate well below normal.  A similar mechanism helped sea ice form in the Bering Sea so far this winter.

As a reminder, the difference between long-term Arctic ice loss and relative lack of Antarctic ice loss is largely and somewhat confusingly due to the ozone depletion that took place over the southern continent in the 20th century.  This depletion has caused a colder southern polar stratosphere than it otherwise would be, reinforcing the polar vortex over the Antarctic Circle.  This is almost exactly the opposite dynamical condition than exists over the Arctic with the negative phase of the Arctic Oscillation.  The southern polar vortex has helped keep cold, stormy weather in place over Antarctica that might not otherwise would have occurred to the same extent and intensity.  As the “ozone hole” continues to recover during this century, the effects of global warming will become more clear in this region, especially if ocean warming continues to melt sea-based Antarctic ice from below (subs. req’d).  For now, we should perhaps consider the lack of global warming signal due to lack of ozone as relatively fortunate.  In the next few decades, we will have more than enough to contend with from melting on Greenland.  Were we to face melting West Antarctic Ice Sheet at the same time, we would have to allocate many more resources.  Of course, in a few decades, we’re likely to face just such a situation.

Finally, here is the Antarctic sea ice extent time series from February 11th:

Figure 7 – NSIDC Antarctic sea ice extent time series through early February 2013.

Policy

Given the lack of climate policy development to date, Arctic conditions will likely continue to deteriorate for the foreseeable future.  The Arctic Ocean will soak up additional energy from the Sun due to lack of reflective sea ice.  Additional energy in the climate system creates cascading effects through the system.  The energy pushes the Arctic Oscillation to a negative phase, which allows anomalously cold air to pour south over Northern Hemisphere land masses while warm air moves over the Arctic.  This impacts weather patterns throughout the year.

More worrisome for long-term concerns is the heat that impacts land-based ice.  As glaciers and ice sheets melt, sea-level rise occurs.  Beyond the increasing rate of sea-level rise, storms have more water to push onshore as they move along coastlines.  We can continue to react to these developments as we’ve mostly done so far.  Or we can be proactive, minimize future global effects, and reduce societal costs.  The choice remains ours.

Errata

Here are my State of the Poles posts from January and September.

57.7% of Contiguous US in Moderate or Worse Drought – 29 Jan 2013

According to the Drought Monitor, drought conditions are relatively unchanged in the past two weeks. As of Jan. 29, 2013, 57.7% of the contiguous US is experiencing moderate or worse drought (D0-D4). The percentage area experiencing extreme to exceptional drought increased from 19.3% to 19.4%. Percentage areas experiencing drought across the West stayed mostly the same at the end of January as they were at in the middle. Drought across the Southwest decreased slightly. Meanwhile, drought across the Southeast grew due to relative lack of precipitation.

Figure 1 – US Drought Monitor map of drought conditions as of the 29th of January.

Figure 2 – US Drought Monitor map of drought conditions in Western US as of the 29th of January.  Some small relief is evident in the past week, but note the lack of change of drought conditions across the regions, despite recent snows throughout the mountains.  Mountainous areas and river basins will have to wait until spring for snowmelt to help start to alleviate drought conditions.

Figure 3 – US Drought Monitor map of drought conditions in Colorado as of the 29th of January.  Drought conditions held steady across the state in the past week.  100% of Colorado experienced Severe or worse drought conditions for the past three weeks.

Figure 4 – US Drought Monitor map of drought conditions in Southeast US as of the 29th of January.  As mentioned above, drought conditions expanded and worsened in the past couple of weeks.  The worst hit area, in central Georgia, has experienced the longest duration drought conditions on this map.  Drought has expanded and contracted around this area during that time.

The latest seasonal (three-month) outlook from the National Weather Service predicts enhanced chances for above-average temperature and below-average precipitation for the central US.  This means that drought conditions are likely to continue for at least another three months and probably longer if prevailing conditions do not change.  One of the major weather stories of 2012 was drought; 2013 is shaping up to have the same story.

What is causing this?  A combination of factors: the Arctic Oscillation (AO), the Madden-Julian Oscillation (MJO), the El-Nino and Southern Oscillation (ENSO), the Interdecadal Pacific Oscillation (IPO), and background climate warming.

As I discussed in my last drought post:

The lack of sea ice in the Arctic back in September is part of what caused the negative phase of the AO.  The Arctic Ocean absorbed solar radiation instead of reflecting it back to space.  The ocean then slowly released that heat to the atmosphere before new ice could form.  That extra heat in the atmosphere changed how and where the polar jet stream established this winter.  Instead of a tight loop near the Arctic Circle, the jet stream has grown in North-South amplitude, allowing cold air to pour to latitudes more southerly than usual and warm air to move over northern latitudes.  The large amplitude jet has kept the normal type of storms from moving over locations that used to see them regularly during the winter.

An active MJO is keeping trade winds stronger than they otherwise would be, which piles up warm ocean water in the western tropical Pacific Ocean.  This causes cool, deep ocean water to rise in the eastern Pacific, as seen in Figure 5.

Figure 5 – Madden-Julian Oscillation conditions as of 2 Feb 2013 from NOAA-CPC.

Figure 6 – ENSO conditions as of 2 Feb 2013 from NOAA-CPC.

Cooler than normal sea-surface temperatures (SSTs) are present in the eastern Pacific due to the current MJO and ENSO data.  Additionally, eastern Pacific SSTs are cooler than the climatic average due to the current negative phase of the IPO.  This in turn is due in part to global warming, which is causing western Pacific and Indian Ocean SSTs warmer than usual.  The cool SSTs in the eastern Pacific initiate and reinforce air circulations that generally keep precipitation away from the Southwest and Midwest US.  This doesn’t mean that drought will be ever-present; only that we are potentially forcing the climate system toward more frequent drought conditions in these regions.  Some years will still be wet or normal; other years (increasing in number) will be dry.  This is a counter to skeptics who claim that more CO2 and warmer temperatures are necessarily better for plants.  If there is no precipitation, plants cannot take advantage of longer growing seasons.  Moreover, we will experience years with food pressure.  These conditions’ extent in the future is up to us and our climate policy (or lack thereof).

58.9% of Contiguous US in Moderate or Worse Drought – 15 Jan 2013

The storm systems that moved over the US in the past month alleviated some of the drought conditions across the US, according to the Drought Monitor. As of Jan 15, 2013, 58.9% of the contiguous US is experiencing moderate or worse drought (D0-D4). The percentage area experiencing extreme to exceptional drought decreased from 21.3% to 19.4%. Percentage areas experiencing drought across the West stayed mostly the same in the middle of January as they were at the end of December. Drought across the High Plains expanded slightly during the same period. Meanwhile, drought across the Southeast and Midwest shrank due to the aforementioned storm systems.

Figure 1 – US Drought Monitor map of drought conditions as of the 15th of January.

Figure 2 – US Drought Monitor map of drought conditions in Western US as of the 15th of January.  Note the lack of change of drought conditions across the regions, despite recent snows throughout the mountains.  Mountainous areas and river basins will have to wait until spring for snowmelt to help start to alleviate drought conditions.

Figure 3 – US Drought Monitor map of drought conditions in Midwest US as of the 15th of January.  This region also has not seen any meaningful shift in drought conditions recently.  The Plains will likely have to wait until spring and summer for drought relief.  This sector of the country does plant a significant amount of crops.  The winter wheat crop has already been devastated.

Figure 4 – US Drought Monitor map of drought conditions in Colorado as of the 15th of January.  Drought conditions worsened slightly across the state in the past week.  Now, 100% of Colorado is experiencing Severe or worse drought conditions.  The percentage area with Extreme drought conditions is 5% higher than last week.  There was no significant difference in Exceptional drought area since last week.

Figure 5 – US Drought Monitor map of drought conditions in Colorado as of July 31, 2012.  This figure shows how extensive the current drought is – both in space and time.  Severe or worse drought has afflicted close to 100% of the state for almost six months now.  While specific regions of the state have received some rain or snow, it hasn’t been enough to break the drought yet.  The percent area with Extreme or worse drought has decreased from 73.67% on July 24th to 65.35% on July 31st to 58.64% on January 15th.  The southeast part of the state has seen the worst of conditions, as Figure 5 and 6 demonstrate.

Figure 6 – US Drought Monitor map of drought conditions in Colorado as of June 14, 2011.  Eighteen months ago, more than half of Colorado was drought-free.  As you can see, the southeast part of the state has seen Severe or worse drought conditions for a long time now.

The US is not likely to see drought relief through March (drought predictions are accurate for ~3 months at a time) .  A negative Arctic Oscillation (AO; Figure 7) is challenging the return to ENSO-neutral conditions, which should allow normal precipitation to fall over the US.  The AO has been negative in previous winters and it has caused the severe winter storms that affected the northeastern US as well as UK (record wet year in 2012) and Scandinavia.

Figure 7 – Arctic Oscillation time series from NOAA’s Climate Prediction Center.

The lack of sea ice in the Arctic back in September is part caused the negative phase of the AO.  The Arctic Ocean absorbed solar radiation instead of reflecting it back to space.  The ocean then slowly released that heat to the atmosphere before new ice could form.  That extra heat in the atmosphere changed how and where the polar jet stream established this winter.  Instead of a tight loop near the Arctic Circle, the jet stream has grown in N/S amplitude, allowing cold air to pour to latitudes more southerly than usual and warm air to move over northern latitudes.  The large amplitude jet has kept the normal type of storms from moving over locations that used to see them regularly during the winter.

Hence, the drought we see now over the US is causally linked to the Arctic Oscillation as well as the long-lasting, moderate La Niña (2010-2012).  Both of the natural variations exist on top of the background climate, which we are warming (this is why there was record low Arctic sea ice in 2012).  We will continue to see the climate modulate normal weather conditions until we stop emitting greenhouse gases.  As I’ve written, that isn’t likely to happen any decade soon.

NASA & NOAA: 2012 Was In Top-10 Warmest Years For Globe On Record

According to data released by NASA and NOAA this week, 2012 was the 9th and 10th warmest years (respectively) globally on record.  NASA’s analysis produced the 9th warmest year in its dataset; NOAA recorded the 10th warmest year in its dataset.  The two agencies have slightly different analysis techniques, which in this case resulted in not only different temperature anomaly values but somewhat different rankings as well.

The details:

2012’s global average temperature was +0.56°C (1°F) warmer than the 1951-1980 base period average (1951-1980), according to NASA, as the following graphic shows.  The warmest regions on Earth (by anomaly) were the Arctic and central North America.  The fall months have a +0.68°C temperature anomaly, which was the highest three-month anomaly in 2012 due to the absence of La Niña.  In contrast, Dec-Jan-Feb produced the lowest temperature anomaly of the year because of the preceding La Niña, which was moderate in strength.  And the latest 12-month period (Nov 2011 – Oct 2012) had a +0.53°C temperature anomaly.  This anomaly is likely to grow larger in the first part of 2013 as the early months of 2012 (influenced by La Niña) slide off.  The time series graph in the lower-right quadrant shows NASA’s 12-month running mean temperature index.  The recent downturn (2010 to 2012) shows the effect of the latest La Niña event (see below for more) that ended in early 2012.  During the summer of 2012, ENSO conditions returned to a neutral state.  Therefore, the temperature trace (12-mo running mean) should track upward again as we proceed through 2013.

Figure 1. Global mean surface temperature anomaly maps and 12-month running mean time series through December 2012 from NASA.

According to NOAA, 2012’s global average temperatures were 0.57°C (1.03°F) above the 20th century mean of 13.9°C (57.0°F).  NOAA’s global temperature anomaly map for 2012 (duplicated below) reinforces the message: high latitudes continue to warm at a faster rate than the mid- or low-latitudes.

Figure 2. Global temperature anomaly map for 2012 from NOAA.

The two different analyses’ importance is also shown by the preceding two figures.  Despite differences in specific global temperature anomalies, both analyses picked up on the same temperature patterns and their relative strength.

The continued anomalous warmth over Siberia is especially worrisome due to the vast methane reserves locked into the tundra and under the seabed near the region.  Methane is a stronger greenhouse gas than carbon dioxide over short time-frames (<100y),which is the leading cause of the warmth we’re now witnessing. As I discussed in the comments in post this summer, the warming signal from methane likely hasn’t been captured yet since the yearly natural variability and the CO2-caused warming signals are much stronger.  It is likely that we will not detect the methane signal for many more years.

These observations are also worrisome for the following reason: the globe came out of a moderate La Niña event in the first half of the year.  During the second half of the year, we remained in a ENSO-neutral state (neither El Niño nor La Niña):

Figure 3. Time series of weekly SST data from NCEP (NOAA).  The highest interest region for El Niño/La Niña is NINO 3.4 (2nd time series from top).

As the second time series graph (labeled NINO3.4) shows, the last La Niña event hit its highest (most negative) magnitude more than once between November 2011 and February 2012.  Since then, SSTs peaked at +0.8 in September (y-axis).  You can see the effect on global temperatures that the last La Niña had via this NASA time series.  Both the sea surface temperature and land surface temperature time series decreased from 2010 (when the globe reached record warmth) to 2012.  So the globe’s temperatures were affected by a natural, low-frequency climate oscillation during the past couple of years.  And yet temperatures were still in the top-10 warmest for a calendar year in recorded history.

Indeed, this was the warmest La Niña year on record:

Figure 4. Anomalies of annual global temperature as measured by NOAA.  Blue bars represent La Niña years, red bars represent El Niño years, and gray bars represent ENSO-neutral years.

This figure shows that 2012 edged out 2011 as the warmest La Niña year on record (since 1950).  It also shows a clear trend seen in every temperature record of this length: La Niña years are getting warmer with time (note the difference between 2012 and 1956, for instance).  El Niño years are getting warmer with time (note the difference between 2010 and 1958).  ENSO-neutral years are getting warmer with time.  The globe got warmer throughout the 20th and into the 21st century.  Do not pay too much attention to any single year as “evidence” that global warming stopped.  As I stated above, natural low-frequency climate oscillations introduce a lot of noise into the temperature signal.  Climate is measured over decades and the decadal trend is obvious here: warmer with time.

Skeptics have pointed out that warming has “stopped” or “slowed considerably” in recent years, which they hope will introduce confusion to the public on this topic.  What is likely going on is quite different: if an energy imbalance exists (less outgoing energy than incoming) and the surface temperature rise has seemingly stalled, the excess energy has to be going somewhere.  That somewhere is likely to be the oceans, and specifically the deep ocean.  Before we all cheer about this (since few people want surface temperatures to continue to rise quickly), consider the implications.  If you add heat to a material, it expands.  The ocean is no different; sea-levels are rising because of heat added to it in the past.  The heat that has entered in recent years won’t manifest as sea-level rise for some time, but it will happen.  Moreover, when the heated ocean comes back up to the surface, that heat will then be released to the atmosphere, which will raise surface temperatures as well as additional water vapor.  Thus, the immediate warming might have slowed down, but we have locked in future warming.

In my previous post on global temperatures, I pointed a few things out and asked some questions.  The Conference of Parties summit produced no meaningful climate action.  Countries agreed to have something on paper by 2015 and enacted by 2020.  If everything goes as planned, significant carbon reductions wouldn’t occur until later in the 2020s – too late to ensure <2°C warming by 2100.  If, as is much more likely, everything doesn’t go as planned, reductions wouldn’t occur until later than the 2020s.  Additional meetings are scheduled for later this year, but I maintain my expectation that nothing meaningful will come from them.  The international process is ill-equipped to handle all the legitimate interest groups in one fell swoop.

The northeast continues to recover from Superstorm Sandy.  New York and New Jersey began to plan for infrastructure with increased resilience from the next storm, which will eventually hit the area.  Congress took way too long to approve relief money (months, instead of days as it did after Katrina).  $60 billion will go a long ways toward assisting the region, especially if people take seriously the threat of living next to the ocean, which has been uncharacteristically quiet for decades.

Paying for recovery is and always will be more expensive than paying to increase resilience from disasters.  As drought continues to impact US agriculture, as Arctic ice continues to melt to new record lows, as storms come ashore and impacts communities that are not prepared for today’s high-risk events (due mostly to poor zoning and destruction of natural protections), economic costs will accumulate in this and in future decades.  It is up to us how much grief we subject ourselves to.  As President Obama begins his second term and climate change “will be a priority in his second term”, he tosses aside the tool most recommended by economists: a carbon tax.  Every other policy tool will be less effective than a Pigouvian tax at minimizing the actions that cause future economic harm.  It is up to the citizens of this country, and others, to take the lead on this topic.  We have to demand common sense actions that will actually make a difference.  But be forewarned: even if we take action today, we will still see more warmest La Niña years, more warmest El Niño years, more ENSO-neutral years.

State of Polar Sea Ice – January 2013: Arctic Below and Antarctic Above Normal

Global polar sea ice area in early January 2013 remains below climatological normal conditions (1979-2009), but has improved in the past month.  Antarctic sea ice loss is occurring at a climatological normal rate.  Arctic sea ice gain is slightly more rapid than normal, but we should expect this given the record low extent that occurred in September 2012.  Polar sea ice recovered from an extensive deficit of -2.5 million sq. km. area late last year to a -500,000 sq. km. anomaly within the last week.

In March-April 2012, global sea ice area was above normal, but sea ice area anomaly quickly turned negative and then spent an unprecedented length of time near the -2 million sq. km. deficit in the modern era in 2012.  Generally poor environmental conditions (warm surface temperatures and certain wind patterns) established and maintained this condition, predominantly across the Arctic last year.  For the third time in modern history, the minimum global sea ice area fell below 17.5 million sq. km. and for the fourth time in modern history, the anomalous global sea ice area fell below -2 million sq. km.  This is a significant development given that Antarctic sea ice area has been slightly above average during the past few years.  This means that the global anomaly is almost entirely due to worsening Arctic ice conditions.

The rapid ice melt and record-setting area and extent values that occurred in 2012 are the top weather/climate story for 2012, in my opinion.  I think we have clearly seen a switch to new conditions in the Arctic.  Whether these events will occur in similar magnitude or are merely transitory as the Arctic continues to move to a new stable state that the climate will not achieve for years or decades remains to be seen.  The problem is we don’t know all of the ramifications of moving toward or achieving that new state.  Additionally, I don’t think we want to know.

Arctic Ice

According to the NSIDC, weather conditions once again caused less freezing to occur on the Atlantic side of the Arctic Ocean and more freezing on the Pacific side.  Similar conditions occurred during the past six years.  Sea ice creation during December measured 2.33 million sq. km.  Despite this rather rapid growth, December′s extent remained far below average for the month.  Instead of measuring near 13.36 million sq. km., December 2012′s extent was only 12.2 million sq. km., a 1.16 million sq. km. difference!  The Barents and Kara Seas remained ice-free, which is a very unusual condition for them in December.  Recent ice growth in the Seas has slightly alleviated this state, but this is happening very late in the season.  The Bering Sea, which saw ice extent growth due to anomalous northerly winds in 2011-2012, saw similar conditions in December 2012.  This has caused anomalously high ice extent in the Bering Sea.  Temperatures over the Barents and Kara Seas were 5-9°F above average while temperatures over Alaska were 4-13°F below average.  The reason for this is another negative phase of the Arctic Oscillation, which allows cold Arctic air to move southward.  This allows warm sub-arctic air to move north.

In terms of longer, climatological trends, Arctic sea ice extent in December has decreased by 3.5% per decade.  This rate is closest to zero in the spring months and furthest from zero in late summer/early fall months.  Note that this rate also uses 1979-2000 as the climatological normal.  There is no reason to expect this rate to change significantly (more or less negative) any time soon, but increasingly negative rates are likely in the foreseeable future.  Additional low ice seasons will continue.  Some years will see less decline than other years (like this past year) – but the multi-decadal trend is clear: negative.  The specific value for any given month during any given year is, of course, influenced by local and temporary weather conditions.  But it has become clearer every year that humans have established a new climatological normal in the Arctic with respect to sea ice.  This new normal will continue to have far-reaching implications on the weather in the mid-latitudes, where most people live.

Arctic Pictures and Graphs

The following graphic is a satellite representation of Arctic ice as of September 17, 2012 (yes, it’s been that long since I’ve written a Polar post):

Figure 1 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20120917.

Here is the similar image from January 9, 2013:

Figure 2 – UIUC Polar Research Group‘s Northern Hemispheric ice concentration from 20130109.

September’s picture shows the minimum extent that occurred in 2012.  You can easily see the substantial growth of sea ice since then.  This comparison provides a good opportunity to point out something important: even in an epoch of anthropogenic global warming, the Arctic will continue to see wintertime sea ice.  There is no solar radiation warming the surface directly and temperatures fall well below freezing for a long time.  The loss of sea ice will continue to occur and will worsen significantly in the summer.  That loss of ice when the sun is overhead is what climate scientists expect to drive numerous changes around the globe.  Incoming solar radiation, instead of being largely reflected back out into space, will instead be mostly absorbed by a darker ocean.  That radiation will stay in the Earth’s climate system as heat, which will cause many cascading effects to occur – effects we largely do not know about because we’ve never lived on a planet with missing summer sea ice at a pole.

The lack of sea ice in the Barents and Kara Seas (north of Europe and far western Russia) is problematic because wind and ocean currents typically pile sea ice up on the Atlantic side of the Arctic.  Sea ice presence in the Bering Sea (between Alaska and Russia) does not alleviate this problem because currents take ice from that area and transport it into the Arctic.  That sea ice will be among the first to melt completely come spring.  With sea ice missing on the Atlantic side, currents will transport Arctic sea ice to southern latitudes where it melts.  The possibility that January’s picture will look similar to September’s picture is therefore higher in 2013 than it was in say 1983.

Overall, the health of the remaining ice pack is not healthy, as the following graph of Arctic ice volume from the end of December demonstrates:

Figure 3 – PIOMAS Arctic sea ice volume time series through December 2012.

As the graph shows, volume (length*width*height) hit another record minimum in June 2012.  Moreover, the volume is far, far outside the 2 standard deviation envelope (lighter gray contour surrounding the darker gray contour and blue median value).  I understand that most readers don’t have an excellent handle on statistics, but conditions between -1 and -2 standard deviations are rare and conditions outside the -2 standard deviation threshold (see the line below the shaded area on the graph above) are incredibly rare: the chances of 3 of them occurring in 3 subsequent years under normal conditions are extraordinarily low (you have a better chance of winning your state lottery than this).  Hence my assessment that “normal” conditions in the Arctic are shifting from what they were in the past few centuries; a new normal is developing.  Note further that the ice volume anomaly returned to near the -1 standard deviation envelope in early 2011, early 2012, and now early 2013.  In each of the previous two years, volume fell rapidly outside of the -2 standard deviation area with the return of summer.  That means that natural conditions are not the likely cause; rather, another cause is much more likely to be responsible for this behavior: human influence.

Arctic Sea Ice Extent

Take a look at December’s areal extent time series data:

Figure 4 – NSIDC Arctic sea ice extent time series through early January 2013.

As you can see, the extent (light blue line) grew rapidly in October, then remained at historically low levels through November and December.  The extent remained well below average values (thick gray line) throughout the fall and early winter.  The time series of sea ice extent for previous low years is also shown on this graph, which is what I term NSIDC’s supplemental graph.  In this month’s version, they also plotted the previous five years’ data.  You can see the effect of the winter-time conditions that I described above: the difference between a year’s extent and the average value in Jan/Feb is smaller than the difference in October.  This leads us to examine the differences between the historical mean, the negative two standard deviation (light gray) below that mean, and the 2012-2013 time series.  I can come up with a number of adjectives to describe that difference, but I’ll settle with “stunning”.

Antarctic Pictures and Graphs

Here is a satellite representation of Antarctic sea ice conditions from September 17th:

Figure 5 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20120917.

And here is the corresponding graphic from January 9th:

Figure 6 – UIUC Polar Research Group‘s Southern Hemispheric ice concentration from 20130109.

Ice loss is easily visible around the continent, the more so since there is a 3+ month time difference between Figures 5 and 6.  There is slightly more Antarctic sea ice today than there normally is on this date in the year.  As a reminder, the difference between long-term Arctic ice loss and relative lack of Antarctic ice loss is largely and somewhat confusingly due to the ozone depletion that took place over the southern continent in the 20th century.  This depletion has caused a colder southern polar stratosphere than it otherwise would be, reinforcing the polar vortex over the Antarctic Circle.  This is almost exactly the opposite dynamical condition than exists over the Arctic with the negative phase of the Arctic Oscillation.  The southern polar vortex has helped keep cold, stormy weather in place over Antarctica that might not otherwise would have occurred to the same extent and intensity.  As the “ozone hole” continues to recover during this century, the effects of global warming will become more clear in this region, especially if ocean warming continues to melt sea-based Antarctic ice from below (subs. req’d).  For now, we should perhaps consider the lack of global warming signal due to lack of ozone as relatively fortunate.  In the next few decades, we will have more than enough to contend with from melting on Greenland.  Were we to face melting West Antarctic Ice Sheet at the same time, we would have to allocate many more resources.  Of course, in a few decades, we’re likely to face just such a situation.

Finally, here is the Antarctic sea ice extent time series from January 9th:

Figure 8 – NSIDC Antarctic sea ice extent time series through early January 2013.

Antarctic sea ice extent remained at or above average to some extent through the austral spring and early summer, which is good news.

Policy

I just read an opinion piece in Scientific American regarding the sorry state of Arctic sea ice. The author, a scientist, advocated that we do not have time to negotiate mitigation treaties. In order to save the ice, we have to research and deploy geoengineering technologies. Let me state by position on this clearly and strongly: we do not know the effects from geoengineering (solar radiation management or carbon dioxide removal) and more than the know the range and magnitude of effects from greenhouse gas emissions. Moreover, basic governance structures for geoengineering research do not currently exist, to say nothing of deployment. If you think international climate policy is complex and hasn’t moved forward quickly, you should think long and hard before advocating for geoengineering research and deployment. Single-actors are probably the biggest worry when you consider the lack of accountability if somebody conducts an experiment. The few small-scale experiments that have come close to real-world execution by national government scientists around the world caused quick and severe public outcries. The main reason for this is something that affects most scientific endeavors: the lack of effective communication with the public prior to carrying out research.  Engaging the public could be viewed as surrendering power and autonomy.  But I view it as a critical component to continued public funding of science and technology research.

Errata

Here are my State of the Poles posts from September and July.

You can find NSIDC’s January report here.

61% of Contiguous US in Moderate or Worse Drought

The storm systems that moved over the US since the 20th of December didn’t do much to alleviate drought conditions across the US, according to the Drought Monitor.  As of Jan 1, 2013, 61% of the contiguous US is experiencing moderate or worse drought (D0-D4).  The percentage area experiencing exceptional drought edged up slightly from 6.7% to 6.8%.  Percentage areas experiencing drought across the West stayed mostly the same at the end of December as they were the 11th of December.  Drought across the High Plains expanded slightly during the same period.  Meanwhile, drought across the Southeast and Northeast improved somewhat.  Midwest drought remained largely unchanged.

The snow that fell over the intermountain west will have to melt in the spring before conditions improve there.  Additional help will have to come this summer via the monsoon before this wide expanse of severe drought is alleviated.

The snow that fell over these areas prior to Christmas didn’t help with drought conditions – yet.  Above-average snow will also have to fall over the High Plains before conditions improve much.  It was simply too hot and dry over these states last year for one storm to significantly impact drought conditions.

According to the US Climate Prediction Center’s Seasonal Outlook issued yesterday, little relief is likely through March 2013:

As this figure shows, the edges of the drought affecting the western 2/3 of the nation could see some improvement.  Conditions over the southeast, which experienced drought for a couple of years, could also improve in the next three months.

I’ve been reading a large number of scientific papers on drought.  While extensive and severe in absolute magnitude, the current drought isn’t worse than the droughts of the 20th century (1950s and 1930s).  So far, enough precipitation has fallen in the right areas at the right times to alleviate severe impacts on societies.  In contrast, 20th century droughts affected people quickly – largely because they were unprepared for the conditions they experienced.  Those prior circumstances helped inform decision makers so that future effects would not be as severe as quickly.  That said, people would not be adequately prepared if conditions revert back to those last seen in the 1100s.  Multidecadal droughts have occurred over substantial parts of the US.  The relative wetness of the 19th and 20th centuries are not likely to continue into the 21st, especially as global temperatures continue to rise.  How will we prepare and respond?

How the IPCC Underestimated Climate Change – Scientific American article

Scientific American published an article summarizing what I’ve written about for a couple of years: the IPCC’s projections aren’t 100% correct.  Gasp – the horror!  But, contrary to what skeptics think, the direction the IPCC’s reports were wrong are opposite of what they claim.  The projections time and again underestimated future changes.  I think a valid complaint, and one I’ve made many times myself, is that the IPCC process is too conservative – it takes too long to get the kind of consensus they’re looking for.  Rapidly changing conditions are not well handled by the IPCC process.  When there is conflicting evidence of something, the IPCC has tended to say nothing in an effort not to upset anybody.  The good news is there are indications this is changing.  The list:

1. Emissions

This is the biggest one.  Too many studies focused on moderate emission pathways, when yearly updates showed our actual emissions were on the high range of those considered by the IPCC.  I actually posted on this two days ago: CO2 Emissions Continue to Track At Top of IPCC Range.  This has implications for every other process that follows.

2. Temperature

More accurately, energy in the climate system is the variable of interest.  It is easy to point out that temperatures since 2000 haven’t increased as much as projected.  It is also easy to compare observed trends since 1980 and claim AR4 models over-predicted temperature rise.  This conflates a couple of issues: the AR4 wasn’t used to project since 1980.  More importantly, the difference between observed trends since 1980 and projected temperatures from half of the AR4 models was less than 0.04°C (0.072°F).  That’s pretty darned small.  With respect to the trend since 2000, the real issue is energy gain.  The vast majority of energy has accumulated in the oceans:

More specifically, if the heat is transported quickly to the deep ocean (>2000ft), the sea surface temperature doesn’t increase rapidly.  Nor does atmosphere or land temperatures change.  This is true at least in the short-term.  When the ocean transports this heat from the deep back to the surface, we should be able to more easily measure that heat.  Put simply, the temporary hiatus of temperature rise is just that: temporary.  Are we prepared for when that hiatus ends?

The relatively small increase in near-surface air and land temperatures is thus explained.  The IPCC never claimed the 4.3° to 11.5°F temperature rise (AR4 projection) would happen by 2020 – it is likely to happen by 2100.  Expect more synergy between projected temperatures and observed temperatures in the coming years.  Also remember that climate is made up of long-term weather observations.

Additionally, aerosols emitted by developing nations have been observed to reflect some of the incoming solar radiation back to space.  Once these aerosols precipitate out of the atmosphere or are not emitted at some point in the future, the absorption of longwave radiation by the remaining greenhouse gases will be more prominent.  The higher the concentration of gases, the more radiation will be absorbed and the faster the future temperature rise is likely to be.  These aerosols are thus masking the signal that would otherwise be measured if they weren’t present.

3. Arctic Meltdown

This is the big story of 2012.  The Arctic sea ice melted in summer 2012 to a new record low: an area the size of the United States melted this year!  Even as late as 2007 (prior to the previous record-low melt), the IPCC projected that Arctic ice wouldn’t decrease much until at least 2050.  Instead, we’re decades ahead of this projection – despite only a relatively small global temperature increase in the past 25 years (0.15°C or so).  What will happen when temperatures increase by multiple degrees Centigrade?

4. Ice sheets

These are the land-based sheets, which are melting up to 100 years faster than the IPCC’s first three reports.  2007′s report was the first to identify more rapid ice sheet melt.  The problem is complex cryospheric dynamics.  Understandably, the most remote and inhospitable regions on Earth are the least studied.  Duh.  That’s changing, with efforts like the fourth International Polar Year, the results of which are still being studied and published.  Needless to say, modern instrumentation and larger field campaigns have resulted in advances in polar knowledge.

5. Sea Level Rise

It’s nice being relevant.  I just posted something new on this yesterday: NOAA Sea-Level Rise Report Issued – Dec 2012.  The 3.3mm of sea-level rise per year is higher than the 2001 report’s projection of 2mm per year.  Integrated over 100 years, that 1mm difference results in 4″ more SLR.  But again, with emission and energy underestimates, the 3.3mm rate of SLR is expected to increase in future decades, according to the latest research.  Again, another mm per year results in another 4″ 100 years from now.  Factors affecting SLR that the IPCC didn’t address in 2007 includes global ocean warming (warmer water takes up more volume), faster ice sheet melt, and faster glacial melt.  Additionally, feedback mechanisms are still poorly understood and therefore not well represented in today’s state-of-the-art models.

6. Ocean Acidification

The first 3 IPCC reports didn’t even mention this effect.  In the past 250 years, ocean acidity has increased by 30% – not a trivial amount!  As the article points out, research on this didn’t even start until after 2000.

7. Thawing Tundra

Another area that is not well-studied and therefore not well understood.  The mechanics and processes need to be observed so they can be modeled more effectively.  1.5 trillion tons of carbon are locked away in the currently frozen tundra.  If these regions thaw, as is likely since the Arctic has observed the most warming to date, methane could be released to the atmosphere.  Since methane acts as a more efficient GHG over short time frames, this could accelerate short-term warming much more quickly than projected (See temperatures above).  The SciAm article points out the AR5, to be released next year, will once again not include projections on this topic.

8. Tipping Points

This is probably the most controversial aspect of this list.  Put simply, no one knows where potential tipping points exist, if they do at all.  The only way we’re likely to find out about tipping points is by looking in the past some day in the future.  By then, of course, moving back to other side of the tipping point will be all but impossible on any time-frame relevant to people alive then.

Summary

There are plenty of problems with the UNFCCC’s IPCC process.  Underestimation of critical variables is but one problem plaguing it.  Blame it on scientists who, by training, are very conservative in their projections and language.  They also didn’t think policymakers would fail to curtail greenhouse gas emissions.  Do policymakers relying on the IPCC projections know of and/or understand this nuance?  If not, how robust will their decisions be?  The IPCC process needs to be more transparent, including allowing more viewpoints to be expressed, say in an Appendix compendium.  The risks associated with underestimating future change are higher than the opposite.

NOAA Sea-Level Rise Report Issued – Dec 2012

This is a busy time of year for the sciences with the annual American Geophysical Union’s and the international Conference of Parties meetings occurring simultaneously.  NOAA has issued a number of reports in recent days, none of which are overflowing with good news.  Today, NOAA released their Global Sea Level Rise Scenarios for the United States National Climate Assessment.  It was produced in response to a request from the U.S. National Climate Assessment Development and Advisory Committee and consists of a review and synthesis of recent scientific publications examining global sea level change.

Why is this report important?  “More than 8 million people in the US live in areas at risk of coastal flooding. Along the Atlantic Coast alone, almost 60 percent of the land that is within a metre of sea level is planned for further development, with inadequate information on the potential rates and amount of sea level rise.”  The public, policymakers and planners need to know what to expect with respect to sea-level rise this century: where should development occur or be restricted and why?

The report is based on four plausible scenarios.  Scenario 1 is simply a linear extrapolation of the historical sea-level rise (SLR) rate out to 2100.  Scenario 2 is based only on projected ocean warming.  Scenario 3 builds on 2 by adding recent ice sheet loss (land-based).  Scenario 4 reflects ocean warming and the maximum plausible contribution of ice sheet loss and glacial melting.  Scenario 1 is appropriate for communities which can assume high risk or for short-term projects.  Scenario 4, in contrast, is meant for places which can’t accept risk.

Here are the scenario SLR values by 2100:

Note that these values are not predictions, but are projections.  That is, NOAA isn’t saying that if X and Y happen, then the Intermediate-High scenario is a prediction.  The scenarios present a framework for policymakers and the public to use to make decisions.

Here is a time series graph of historical and projected SLR:

The range of potential SLR shown in the table and figure above might lead some to conclude that ‘high confidence” in that range is misplaced by NOAA.  This is a gross misinterpretation of what is presented.  The level of uncertainty, which will always exist, is actually useful to policymakers.  Given this range of projections, people can leverage local and regional knowledge to come to better decisions than they would without this range.  Something quantified is better than a big shrug when planning, after all.

With the governors of New York, New Jersey, and Connecticut requesting $80 Billion to clean up and rebuild (better) after Hurricane Sandy, future projections of sea-level rise can obviously provide guidance regarding what and how to rebuild in addition to where to rebuild.  Policy development and planning will have to take these and other projections into heavier account this century than they did last century.  An estimate of how many billions of dollars can potentially be saved by incorporating this information would also be useful.