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Research: Antarctic Glaciers – What’s The Real Story?

Two new papers examine historical and projected Antarctic glacier behavior.  The research is illuminating.  Some of the commentary about it is downright confusing.  I’ll sort it out in this post.

From the source: West Antarctic Ice Sheet Is Collapsing at the highly respected journal Science.  This news intern’s article references a paper published in Science this week, “Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica.”  You can already see where some confusion arose: the actual science article itself used the key work “potentially” while the news piece trumpeting the article used the word “is”.  Potentially implies there is a chance the marine ice sheet may not collapse.  The news article headline completely misses that critical descriptive adverb.

Just as importantly, the news headline misses the operative time scale, which is of course of great importance.  The decision to not include the time scale leads casual readers to assume this collapse will happen soon.  Well, what is soon?  It depends on one’s perspective.  I think the time scale omission was purposeful, so as to boost readership.  Because if the headline had included the article’s values, few people would have paid much attention to it: 200 to 900 years.  Based on a computer model simulation, the authors suggest that the Thwaites Glacier may finish its collapse in two to nine centuries – nowhere near the operative time frame that people think about.  The article dances around the issue a bit in the first three paragraphs – long enough for the author to come out and report on what the paper actually said in my opinion.

If you’re interested, I’ve covered previous research findings on Antarctic glaciers, including in January 2009, November 2009, January 2010, and December 2012.

What is not in question is the science results.  The glacier is indeed melting faster than snowfall can replenish it, and this is increasingly due to human influence.  Once the edge of the glacier recedes past a ridge, the glacier’s melt will accelerate.  As most sea-based glaciers do, Thwaites holds back land-based ice.  As this ice melts, sea level rises.  Thus, the rate of sea level rise could increase from <0.25mm per year to >1mm per year due to all melting land-based glaciers.

The second paper, published in Geophysical Research Letters, Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith and Kohler glaciers, West Antarctica from 1992 to 2011, the authors report on satellite data analysis showing that

Pine Island Glacier retreated 31 km at its center, with most retreat in 2005–2009 when the glacier un-grounded from its ice plain. Thwaites Glacier retreated 14 km along its fast-flow core and 1 to 9 km along the sides. Haynes Glacier retreated 10 km along its flanks. Smith/Kohler glaciers retreated the most, 35 km along its ice plain

Upstream of the 2011 grounding line, there remain no more physical obstacles (higher sea bed regions) that will hold back the glaciers.  Thus nothing remains to stop further melting of the basin.  These results are an independent corroboration of the Science paper results and build the body of literature on Antarctic glaciers.  Once Thwaites melts, the rest of the West Antarctic ice sheet is at risk of melt.  There are other researchers who think the 200-900 year timeline is too slow because important feedbacks are not properly modeled.  But so far no evidence suggests the time scale is off by an order of magnitude (i.e., not 20-90 years).

Absent significant climatological shifts away from anthropogenically forced climate change, West Antarctic and Greenland ice sheets will continue to melt for centuries.  Sea levels will rise, probably at a faster rate than what we’ve seen historically.

But the presentation of these studies is disappointing.  Here are some places that covered this news.  I found probably the best headline at Slate: “Huge Antarctic Glacier Slow-Speed Collapse May Now Be Past Point of No Return“.  That gives the reader all the critical information.  Thwaites is huge, it will undergo slow-speed collapse, and that process is likely now irreversible.  Good on Slate.  The normally staid Jeff Masters’ somewhat less accurate headline: “Slow-Motion Collapse of West Antarctic Glaciers is Unstoppable, 2 New Studies Say“.  This is better than Science’s own headline, but notice the “is” in this one.  Again, I don’t think we can justifiably conclude based on science to date that the collapse is definitely unstoppable, as this headline claims.  Is it likely?  Yes, it is.  This headline doesn’t convey that.

And now the worst example, from an Environment America fundraising email: “Antarctica to melt completely”.  What?!  These two studies do not say Antarctica will melt completely; such an event will take at least thousands of years, even under the highest GHG emissions scenarios.  And again, there is no mention of any time line in the email header.  The email includes this nonsense: “The melting of the West Antarctic ice sheet is now unstoppable – but we can still prevent even worse disasters, and President Obama is taking action right now.”  I’m not sure what they consider a worse disaster than the entire Antarctic ice sheet melting (they certainly don’t make a specific claim in their fundraising request).  They go on to include the worst type of messaging: “This is the nightmare scenario”.  Fantastic – shut down everybody’s response mechanisms with the worst possible language.  Moreover, if this is the nightmare scenario, what is the “worse disaster” they can prevent if only I send them money?  The email continues “As bad as this news is, we simply don’t have time for despair.”  Then why use language that causes despair?

This is exactly what the Science news piece tried to generate, and it worked.  Unfortunately, that’s where the working stops.  People that know about Antarctic glaciers melting are already taking action.  People that don’t won’t do so just because of this email.  It operates from the wrong frame and doesn’t engage alternative values.  It doesn’t engage and it doesn’t present opportunities.  But it’s what prominent environmental groups do and it’s why there has been polarization and inaction surrounding the issue. They continue to squander time and resources.


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Denver’s September 2013 Climate Summary

Temperature

During the month of September 2013, Denver, CO’s (link updated monthly) temperatures were 2.8°F above normal (66.4°F vs. 63.6°F).  The National Weather Service recorded the maximum temperature of 97°F on the 5th and 6th; they recorded the minimum temperature of 38°F on the 28th.  Here is the Denver temperature September 2013 time series:

 photo Denver_Temps_201309_zps687d6b03.png

Figure 1. Time series of temperature at Denver, CO during September 2013.  Daily high temperatures are in red, daily low temperatures are in blue, daily average temperatures are in green, climatological normal (1981-2010) high temperatures are in light gray, and normal low temperatures are in dark gray. [Source: NWS]

The month started off with a heat wave, as a result of an anomalous high pressure ridge over the western US.  It’s not obvious on this chart, but the week of September 8th ushered in a big change from the early month heat wave, which I discuss in the precipitation section below.

Denver’s temperature was above normal for the past five consecutive months.  May 2013 ended a short streak of four months with below normal temperatures.  Looking back a little further in time, October 2012 broke last year’s extreme summer heat including the warmest month in Denver history: July 2012 (a mean of 78.9°F which was 4.7°F warmer than normal!).

Through September, 2013, there were 57 90°F+ days in 2013, which means 2013 gained sole 4th place status of most 90°F days in one year.  Last year, the hottest summer on record for Denver, there was an astounding 73 90°F+ days!  Thankfully, this year also featured far fewer 100°F+ days than 2012: 2 instead of 13 (a record number).  After last year’s record hot summer, summer 2013 felt comparatively cool, which just goes to show how truly monumental last year’s records were.

I haven’t determined if the NWS (or anyone else) collects record high minimum temperatures (warm nighttime lows) in a handy table, chart, or time series.  Denver’s 68°F on Sep. 3rd was such a record (previously 67, set in 1947), as was Sep. 4th’s 69°F (previously 64°F, set in 1995 and previous years).  I’m curious how Denver’s nightly lows have changed in the past 100+ years.  If I find or put something together, I’ll include it in a future post.

Precipitation

Instead of amazing temperature records (although 97°F in September is very hot!), September saw precipitation records.  Total precipitation was much greater than normal during September 2013: 5.61″ precipitation fell at Denver during the month instead of the normal 0.92″!  Most of this fell at DIA on the 14th and 12th of the month (2.01″ and 1.11″).  As I wrote about after the event, Denver and other communities with similar rain totals paled in comparison to southern Aurora and Boulder, which received over 18″ of rain in one week, and more for the month!  Given that the normal annual total precipitation for these places is 15″, Denver and other places received over 1/3 of their yearly annual precipitation total in one month – a month that is normally relatively dry.

During the week of the 8th, the confluence of a slow-moving upper-level low, a surface stationary front, and tropical moisture from both the Pacific Ocean and Gulf of Mexico generated record rainfall over the northern Front Range of Colorado, including Denver.  This rainfall led to devastating flooding, from which communities are just beginning to recover.  About the only good news from this natural disaster is it busted the area’s long-term drought.

Interannual Variability

I have written literally hundreds of posts on the effects of global warming and the evidence within the temperature signal of climate change effects.  This series of posts takes a very different look at conditions.  Instead of multi-decadal trends, this series looks at highly variable weather effects on a very local scale.  The interannual variability I’ve shown above is a part of natural change.  Climate change influences this natural change – on long time frames.  The climate signal is not apparent in these figures because they are of too short of duration.  The climate signal is instead apparent in the “normals” calculation, which NOAA updates every ten years.  The most recent “normal” values cover 1981-2010.  The temperature values of 1981-2000 are warmer than the 1971-2000 values, which are warmer than the 1961-1990 values.  The interannual variability shown in the figures above will become a part of the 1991-2020 through 2011-2040 normals.  If temperatures continue to track warmer than normal in most months, the next set of normals will clearly demonstrate a continued warming trend.


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Denver’s August 2013 Climate Summary

Temperature

During the month of August 2013, Denver, CO’s (link updated monthly) temperatures were 2.1°F above normal (74.6°F vs. 72.5°F).  The National Weather Service recorded the maximum temperature of 99°F on the 20th and they recorded the minimum temperature of 52°F on the 9th.  Here is the time series of Denver temperatures in August 2013:

 photo Denver_Temps_201308_zps974cdaa4.png

Figure 1. Time series of temperature at Denver, CO during August 2013.  Daily high temperatures are in red, daily low temperatures are in blue, daily average temperatures are in green, climatological normal (1981-2010) high temperatures are in light gray, and normal low temperatures are in dark gray. [Source: NWS]

The month started off cooler than normal as this year’s very active monsoon continued well into August 2013.  High pressure began to dominate the region again in the middle of the month.  Note the large number of days with daily mean temperatures equal to or greater than 78°F.  This was mainly due to the excessive nighttime heat (note the blue line above the climatological normal lows), but also the daily high temperatures in the mid to upper-90s.

Denver’s temperature was above normal for the past four months in a row.  May 2013 ended a short streak of four months with below normal temperatures.  October 2012 broke last year’s extreme summer heat including the warmest month in Denver history: July 2012 (a mean of 78.9°F which was 4.7°F warmer than normal!).

Through September 4th, 2013, there were 50 90°F+ days in 2013, which ties three other years (1960, 1964, 2011) for 10th most 90°F days.  As of September 5th, the NWS forecast calls for an additional four days with maximum temperatures equal to or greater than 90°F, which would push the yearly total to 54, good for a tie for sixth place.  Last year, the hottest summer on record for Denver, there was an astounding 73 90°F+ days!  Thankfully, this year also featured far fewer 100°F+ days than 2012: 2 instead of 13 (a record number).

I haven’t determined if the NWS (or anyone else) collects record high minimum temperatures (warm nighttime lows) in a handy table, chart, or time series.  Denver’s 68°F on Sep. 3rd was such a record (previously 67, set in 1947), as was Sep. 4th’s 69°F (previously 64°F, set in 1995 and previous years).  I’m curious how Denver’s nightly lows have changed in the past 100+ years.  If I find or put something together, I’ll include it in a future post..

Precipitation

Precipitation was greater than normal during August 2013: 2.78″ precipitation fell at Denver during the month instead of the normal 1.69″.  Most of this fell at DIA on the 22nd of the month (1.94″).  This wasn’t the case for every location in the Denver metro area however since precipitation is such a variable phenomenon.

Precipitation that fell during the past couple of months alleviated some of the worst drought conditions in northern Colorado.  The link goes to a mid-August 2013 post.  Almost all of Colorado continues under at least some measure of drought in early September 2013 (the exception being along the Front Range in northern Colorado, which received almost daily monsoon rainfall in August).  The worst drought conditions (D4: Exceptional) continue to impact southeast Colorado however.  The good news is this area shrank in the last month or so.  Colorado still needs the jet stream to substantially shift position this fall and next spring in order to receive the amount of precipitation required to break the long-term drought.  The last NWS 3-month projection didn’t indicate that this was likely to happen.  Hopefully, for the state’s sake, I hope the NWS is wrong.

Interannual Variability

I have written hundreds of posts on the effects of global warming and the evidence within the temperature signal of climate change effects.  This series of posts takes a very different look at conditions.  Instead of multi-decadal trends, this series looks at highly variable weather effects on a very local scale.  The interannual variability I’ve shown above is a part of natural change.  Climate change influences this natural change – on long time frames.  The climate signal is not apparent in these figures because they are of too short of duration.  The climate signal is instead apparent in the “normals” calculation, which NOAA updates every ten years.  The most recent “normal” values cover 1981-2010.  The temperature values of 1981-2000 are warmer than the 1971-2000 values, which are warmer than the 1961-1990 values.  The interannual variability shown in the figures above will become a part of the 1991-2020 through 2011-2040 normals.  If temperatures continue to track warmer than normal in most months, the next set of normals will clearly demonstrate a continued warming trend.


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Denver’s July 2013 Climate Summary

Temperature

During the month of July 2013, Denver, CO’s (link updated monthly) temperatures were 0.1°F above normal (74.3°F vs. 74.2°F).  The National Weather Service recorded the maximum temperature of 100°F on the 11th and they recorded the minimum temperature of 55°F on the 2nd.  Here is the time series of Denver temperatures in July 2013:

 photo Denver_Temps_201307_zps3eecd5f9.png

Figure 1. Time series of temperature at Denver, CO during July 2013.  Daily high temperatures are in red, daily low temperatures are in blue, daily average temperatures are in green, climatological normal (1981-2010) high temperatures are in light gray, and normal low temperatures are in dark gray. [Source: NWS]

Compared to spring 2013, June and July brought less extreme weather to the Denver area.   After a very warm start to the month’s temperature due to high pressure that covered the area since mid-June, cooler temperatures were the rule for the 2nd half of the month.  This change was due to an active monsoon season.  Clouds formed nearly every day and the NWS measured rain 9 out of the last 18 days of the month – a big change from last year.

Denver’s temperature was above normal for the past three months (May- June-July).  May 2013 ended a short streak of four months with below normal temperatures.  Seven of the past twelve months were warmer than normal.  October finally broke last year’s extreme summer heat, which included the warmest month in Denver history: July 2012 (a mean of 78.9°F which was 4.7°F warmer than normal!).

Precipitation

Precipitation was lighter than normal during July 2013: only 1.98″ precipitation fell at Denver during the month instead of the normal 2.16″.  Precipitation is a highly variable quantity though.  The west side of the Denver Metro area received rainfall on days that the official Denver recording site did not, which is the usual case for convective-type precipitation.

Precipitation that fell during the past couple of months alleviated some of the worst drought conditions in northern Colorado.  The link goes to a mid-August 2013 post.  Almost all of Colorado continues under at least some measure of drought in early September 2013.  The worst drought conditions (D4: Exceptional) continue to impact southeast Colorado however and the area with D4 conditions slowly expanded during the past few months.  Absent a significant shift in the upper-level jet stream’s position, the NWS expects dry conditions to persist over CO during the next one to three months, which will likely worsen drought conditions.


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Denver’s June 2013 Climate Summary

Temperature

During the month of June 2013, Denver, CO’s (link updated monthly) temperatures were 3.7°F above normal (71.1°F vs. 67.4°F).  The National Weather Service recorded the maximum temperature of 100°F on the 11th and they recorded the minimum temperature of 39°F on the 2nd.  Here is the time series of Denver temperatures in June 2013:

 photo Denver_Temps_201306_zpsee96454c.png

Figure 1. Time series of temperature at Denver, CO during June 2013.  Daily high temperatures are in red, daily low temperatures are in blue, daily average temperatures are in green, climatological normal (1981-2010) high temperatures are in light gray, and normal low temperatures are in dark gray. [Source: NWS]

In comparison to April 2013, June 2013 brought less extreme weather to the Denver area.   After a moderate start to the month’s temperature, high pressure began to dominate the area by the 11th through the end of the month.  This high pressure brought warmer than average temperatures, which offset the early month cool snap.  This same pattern brought warmer than average temperatures to much of the southwestern United States, culminating in extremely dangerous heat at the end of the month from Idaho to Arizona.

Denver’s temperature was above normal for the past two months in a row.  May 2013 ended a short streak of four months with below normal temperatures.  Seven of the past twelve months were warmer than normal.  October broke last year’s extreme summer heat including the warmest month in Denver history: July 2012 (a mean of 78.9°F which was 4.7°F warmer than normal!).

Precipitation

Precipitation was lighter than normal during June 2013: only 0.75″ precipitation fell at Denver during the month instead of the normal 1.98″.  Precipitation is a highly variable quantity though.  The west side of the Denver Metro area received rainfall on days that the official Denver recording site did not, which is the usual case for convective-type precipitation.

Precipitation a couple of months ago alleviated some of the worst drought conditions in northern Colorado.  The link goes to a late April 2013 post; further relief occurred in May with regular rain events.  With below average precipitation in June for most areas, drought conditions unfortunately worsened during the month.  All of Colorado continues under at least some measure of drought in early July 2013.  The worst drought conditions (D4: Exceptional) continue to impact southeast Colorado however and the area with D4 conditions slowly expanded during the past few months.  Absent a significant shift in the upper-level jet stream’s position, the NWS expects dry conditions to persist over CO during the next one to three months, which will likely worsen drought conditions.  I will write an updated drought post within the week.

Interannual Variability

I have written hundreds of posts on the effects of global warming and the evidence within the temperature signal of climate change effects.  This series of posts takes a very different look at conditions.  Instead of multi-decadal trends, this series looks at highly variable weather effects on a very local scale.  The interannual variability I’ve shown above is a part of natural change.  Climate change influences this natural change – on long time frames.  The climate signal is not apparent in these figures because they are of too short of duration.  The climate signal is instead apparent in the “normals” calculation, which NOAA updates every ten years.  The most recent “normal” values cover 1981-2010.  The temperature values of 1981-2000 are warmer than the 1971-2000 values, which are warmer than the 1961-1990 values.  The interannual variability shown in the figures above will become a part of the 1991-2020 through 2011-2040 normals.  If temperatures continue to track warmer than normal in most months, the next set of normals will clearly demonstrate a continued warming trend.


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Denver’s May 2013 Climate Summary

Temperature

During the month of May 2013, Denver, CO’s (link updated monthly) temperatures were 0.8°F above normal (57.9°F vs. 57.1°F).  The maximum temperature of 88°F was recorded on the 17th while the minimum temperature of 19°F was recorded on the 2nd.  Here is the time series of Denver temperatures in May 2013:

 photo Denver_Temps_201305_zpsacd74199.png

Figure 1. Time series of temperature at Denver, CO during May 2013.  Daily high temperatures are in red, daily low temperatures are in blue, daily average temperatures are in green, climatological normal (1981-2010) high temperatures are in light gray, and normal low temperatures are in dark gray. [Source: NWS]

In comparison to March and April 2013, May 2013 brought much less extreme weather to the Denver area.   After a cold start to the month, there was a general regime change that allowed high pressure to dominate in the middle and at the end of the month.  This high pressure brought warmer than average temperatures, which offset the early month cold snap.

Precipitation

Precipitation was lighter than normal during May 2013: only 0.82″ precipitation fell at Denver during the month instead of the normal 2.12″.  Precipitation is a highly variable quantity though.  The west side of the Denver Metro area received higher than normal precipitation during the same time period.

Precipitation in the past couple of months alleviated some of the worst drought conditions in northern Colorado.  The link goes to a late April 2013 post; further relief occurred in May with regular rain events.  All of Colorado continues under at least some measure of drought in early June 2013.  The worst drought conditions (D4: Exceptional) continue to impact southeast Colorado however.

Interannual Variability

I have written hundreds of posts on the effects of global warming and the evidence within the temperature signal of climate change effects.  This series of posts takes a very different look at conditions.  Instead of multi-decadal trends, this series looks at highly variable weather effects on a very local scale.  The interannual variability I’ve shown above is a part of natural change.  Climate change influences this natural change – on long time frames.  The climate signal is not apparent in these figures because they are of too short duration.  The climate signal is instead apparent in the “normals” calculation, which NOAA updates every ten years.  The most recent “normal” values cover 1981-2010.  The temperature values of 1981-2000 are warmer than the 1971-2000 values, which are warmer than the 1961-1990 values.  The interannual variability shown in the figures above will become a part of the 1991-2020 through 2011-2040 normals.


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Can scientific issues be up for political debate?

The short answer should obviously be yes.  But within the climate change realm, there are some folks who think that scientific realities should dictate political attitudes:

Even as some studies suggest the potential for double-digit warming across the globe, the media has been stubbornly silent, treating climate change as an issue that is still up for political debate, instead of a scientific reality.

That is a dangerous viewpoint to hold and to operate from.  This isn’t an either-or choice to make.  Politics and science are two very different enterprises for many different reasons.  Would these same advocates accept dictated political attitudes based on religious reality?  Of course they wouldn’t.  So why should others blindly adopt their viewpoint?

This is but one example of climate advocates trying to silence others’ opinions, the same charge that they accuse the fossil fuel industry of doing to them.  Which leads us to a rather inevitable conclusion: the fight isn’t about “reality” vs. politics (note the frame – if you don’t agree, you’re not a part of someone’s “reality”).  The fight is over value systems.  Many climate activists are using science as a proxy in a battle which demands other tools.

Another note: if the media isn’t paying “enough attention” to your BIG problem, perhaps the problem lies in your messaging and not the media’s bias.  Doubling down on used-up rhetoric isn’t going to sell your story any better.

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