That was the title of a session, purportedly on climate change, that I attended at the Netroots Nation 2012 conference for progressive bloggers in Providence several weeks ago.
While the session did contain some good info--in particular one segment that talked about how polling in California had found that African-Americans and Hispanics were more concerned about environmental issues than whites--the general thrust seemed to be more about the need to frame global warming as a social justice issue. I.e., if only you wine-and-cheese enviros would quit romanticizing about the environment, and join the great social justice movement, then everyone would pay attention to "your" issue.
That bugged me. It seemed patronizing, and it also seemed to largely miss the point. I was thinking about it today, and it struck me that it's like titling a session on coal mine safety "Miners, not canaries."
I'm sure some of us in the--what, pro-climate-science community?--have warm feelings about charismatic animals like polar bears, but for many of us, the issue is not so much the poor bears themselves, and what is going to happen to them, but the fact that they are, in essence, the canaries in the global coal mine. If something is going drastically wrong with their ecology, and threatening their existence, it's a sign that things are out of joint with the global climate system on which the lives of billions of people depend. Rapid warming in the Arctic is one of the first signs of global warming predicted by climate models, and it is what we are seeing today. As I've mentioned elsewhere, rapid Arctic warming also appears to be causing unexpected changes in the jet stream and in weather all around the Northern Hemisphere.
To be sure, the harshest impacts of global warming will likely be felt by poor people, and it's resulting from actions by industries run by industrial plutocrats, but that doesn't mean it's just a social justice issue. It's bigger than that. The canaries are dying, and it's time for all of us to get out of the coal mine. Now.
Saturday, July 21, 2012
Tuesday, July 17, 2012
In other news, the Arctic continues to melt
A friend posted a link to the executive summary of the Arctic Monitoring and Assessment Programme's (AMAP) 2011 report on Snow, Water, Ice and Permafrost in the Arctic (SWIPA). The executive summary is a mere 28 MB (the full document is 553 pages), which took approximately forever to download on my pathetic Internet connection, so let me save you a little time and trouble by quoting its key findings:
"1. The past six years (2005–2010) have been the warmest period ever recorded in the Arctic. Higher surface air temperatures are driving changes in the cryosphere.
2. There is evidence that two components of the Arctic cryosphere--snow and sea ice--are interacting with the climate system to accelerate warming.
3. The extent and duration of snow cover and sea ice have decreased across the Arctic. Temperatures in the permafrost have risen by up to 2°C. The southern limit of permafrost has moved northward in Russia and Canada.
4. The largest and most permanent bodies of ice in the Arctic – multiyear sea ice, mountain glaciers, ice caps and the Greenland Ice Sheet – have all been declining
faster since 2000 than they did in the previous decade.
5. Model projections reported by the Intergovernmental Panel on Climate Change (IPCC) in 2007 underestimated the rates of change now observed in sea ice. [Deniers rejoice! The IPCC was wrong. But alas, wrong in the wrong direction.]
6. Maximum snow depth is expected to increase over many areas by 2050, with greatest increases over Siberia. Despite this, average snow cover duration is projected to decline by up to 20% by 2050.
7. The Arctic Ocean is projected to become nearly ice-free in summer within this century, likely within the next thirty to forty years. [It's not hard to find people on the Web, who know what they are talking about, who believe this will happen before 2020. While 2012 is, at this writing, on a record pace for Arctic sea ice melt, it remains to be seen whether a new ultimate summer low will result. What we can say, however, is that there has been no recovery from the 2007 summer low, which was sharply lower than the summer lows in previous years going back to 1979 (when measurements began). You can check out sea ice area through this wonderful interactive graphic, which provides data by day and year. You can "erase" years by clicking on them at the right, and if you erase back to 2007, you will see that the summer low was roughly 3 million square kilometers, almost exactly a whopping 25% below the low of 4 million reached in 2006.]
8. Changes in the cryosphere cause fundamental changes to the characteristics of Arctic ecosystems and in some cases loss of entire habitats. This has consequences for people who receive benefits from Arctic ecosystems. [OK, now I know we are getting into stuff many people who don't live in the Arctic don't care about. Before you lose interest, though, be sure to check out Key Findings 12 and 13 below.]
9. The observed and expected future changes to the Arctic cryosphere impact Arctic society on many levels. There are challenges, particularly for local communities and traditional ways of life. There are also new opportunities.
10. Transport options and access to resources are radically changed by differences in the distribution and seasonal occurrence of snow, water, ice and permafrost in the Arctic. This affects both daily living and commercial activities.
11. Arctic infrastructure faces increased risks of damage due to changes in the cryosphere, particularly the loss of permafrost and land-fast sea ice.
12. Loss of ice and snow in the Arctic enhances climate warming by increasing absorption of the sun’s energy at the surface of the planet. It could also dramatically increase emissions of carbon dioxide and methane and change large-scale ocean currents. The combined outcome of these effects is not yet known. [Emphasis added. For one of the apparent first unexpected impacts, see Linking Weird Weather to Rapid Warming of the Arctic, by Jennifer Francis, who is studying how the melting Arctic appears to be changing the behavior of the jet stream and causing weather patterns--drought, rainfall, heat--to stay in one place for longer periods. Oops.]
13. Arctic glaciers, ice caps and the Greenland Ice Sheet contributed over 40% of the global sea level rise of around 3 mm per year observed between 2003 and 2008. In the future, global sea level is projected to rise by 0.9–1.6 m by 2100 and Arctic ice loss will make a substantial contribution to this.
14. Everyone who lives, works or does business in the Arctic will need to adapt to changes in the cryosphere. Adaptation also requires leadership from governments and international bodies, and increased investment in infrastructure.
15. There remains a great deal of uncertainty about how fast the Arctic cryosphere will change in the future and what the ultimate impacts of the changes will be. Interactions (‘feedbacks’) between elements of the cryosphere and climate system are particularly uncertain. Concerted monitoring and research is needed to reduce this uncertainty."
"1. The past six years (2005–2010) have been the warmest period ever recorded in the Arctic. Higher surface air temperatures are driving changes in the cryosphere.
2. There is evidence that two components of the Arctic cryosphere--snow and sea ice--are interacting with the climate system to accelerate warming.
3. The extent and duration of snow cover and sea ice have decreased across the Arctic. Temperatures in the permafrost have risen by up to 2°C. The southern limit of permafrost has moved northward in Russia and Canada.
4. The largest and most permanent bodies of ice in the Arctic – multiyear sea ice, mountain glaciers, ice caps and the Greenland Ice Sheet – have all been declining
faster since 2000 than they did in the previous decade.
5. Model projections reported by the Intergovernmental Panel on Climate Change (IPCC) in 2007 underestimated the rates of change now observed in sea ice. [Deniers rejoice! The IPCC was wrong. But alas, wrong in the wrong direction.]
6. Maximum snow depth is expected to increase over many areas by 2050, with greatest increases over Siberia. Despite this, average snow cover duration is projected to decline by up to 20% by 2050.
7. The Arctic Ocean is projected to become nearly ice-free in summer within this century, likely within the next thirty to forty years. [It's not hard to find people on the Web, who know what they are talking about, who believe this will happen before 2020. While 2012 is, at this writing, on a record pace for Arctic sea ice melt, it remains to be seen whether a new ultimate summer low will result. What we can say, however, is that there has been no recovery from the 2007 summer low, which was sharply lower than the summer lows in previous years going back to 1979 (when measurements began). You can check out sea ice area through this wonderful interactive graphic, which provides data by day and year. You can "erase" years by clicking on them at the right, and if you erase back to 2007, you will see that the summer low was roughly 3 million square kilometers, almost exactly a whopping 25% below the low of 4 million reached in 2006.]
8. Changes in the cryosphere cause fundamental changes to the characteristics of Arctic ecosystems and in some cases loss of entire habitats. This has consequences for people who receive benefits from Arctic ecosystems. [OK, now I know we are getting into stuff many people who don't live in the Arctic don't care about. Before you lose interest, though, be sure to check out Key Findings 12 and 13 below.]
9. The observed and expected future changes to the Arctic cryosphere impact Arctic society on many levels. There are challenges, particularly for local communities and traditional ways of life. There are also new opportunities.
10. Transport options and access to resources are radically changed by differences in the distribution and seasonal occurrence of snow, water, ice and permafrost in the Arctic. This affects both daily living and commercial activities.
11. Arctic infrastructure faces increased risks of damage due to changes in the cryosphere, particularly the loss of permafrost and land-fast sea ice.
12. Loss of ice and snow in the Arctic enhances climate warming by increasing absorption of the sun’s energy at the surface of the planet. It could also dramatically increase emissions of carbon dioxide and methane and change large-scale ocean currents. The combined outcome of these effects is not yet known. [Emphasis added. For one of the apparent first unexpected impacts, see Linking Weird Weather to Rapid Warming of the Arctic, by Jennifer Francis, who is studying how the melting Arctic appears to be changing the behavior of the jet stream and causing weather patterns--drought, rainfall, heat--to stay in one place for longer periods. Oops.]
13. Arctic glaciers, ice caps and the Greenland Ice Sheet contributed over 40% of the global sea level rise of around 3 mm per year observed between 2003 and 2008. In the future, global sea level is projected to rise by 0.9–1.6 m by 2100 and Arctic ice loss will make a substantial contribution to this.
14. Everyone who lives, works or does business in the Arctic will need to adapt to changes in the cryosphere. Adaptation also requires leadership from governments and international bodies, and increased investment in infrastructure.
15. There remains a great deal of uncertainty about how fast the Arctic cryosphere will change in the future and what the ultimate impacts of the changes will be. Interactions (‘feedbacks’) between elements of the cryosphere and climate system are particularly uncertain. Concerted monitoring and research is needed to reduce this uncertainty."
Friday, July 13, 2012
Remote Siberian lake holds climate change clues
The following (fascinating) press release is from the National Academy of Sciences. It bears careful reading. In very brief, sediment cores from a unique Siberian lake that has never been covered by glaciers allow reconstruction of temperatures over a period of 3 million years, during which temperatures were 4-5 degrees C warmer than at present on at least two occasions. Such warm periods are too warm for the Greenland ice sheet and also coincide in some cases with melting of the West Antarctic Ice Sheet; this suggests the existence of major amplifying feedbacks in the global climate system.
Update - 13 July 2012: There is an update on the international ANDRILL Antarctic research program's findings available on Real Climate.
Press Release 12-115
Remote Siberian Lake Holds Clues to Arctic--and Antarctic--Climate Change
Remote Siberian Lake Holds Clues to Arctic--and Antarctic--Climate Change
Fates of polar ice sheets appear to be linked
 Credit and Larger Version |
June 21, 2012
Intense warm climate intervals--warmer than scientists thought possible--have occurred in the Arctic over the past 2.8 million years.
That result comes from the first analyses of the longest sediment cores ever retrieved on land. They were obtained from beneath remote, ice-covered Lake El'gygytgyn (pronounced El'gee-git-gin) ("Lake E") in the northeastern Russian Arctic.
The journal Science published the findings this week.
They show that the extreme warm periods in the Arctic correspond closely with times when parts of Antarctica were also ice-free and warm, suggesting a strong connection between Northern and Southern Hemisphere climate.
The polar regions are much more vulnerable to climate change than researchers thought, say the National Science Foundation-(NSF) funded Lake E project's co-chief scientists: Martin Melles of the University of Cologne, Germany; Julie Brigham-Grette of the University of Massachusetts Amherst; and Pavel Minyuk of Russia's North-East Interdisciplinary Scientific Research Institute in Magadan.
The exceptional climate warming in the Arctic, and the inter-hemispheric interdependencies, weren't known before the Lake E studies, the scientists say.
Lake E was formed 3.6 million years ago when a huge meteorite hit Earth, leaving an 11-mile-wide crater. It's been collecting layers of sediment ever since.
The lake is of interest to scientists because it has never been covered by glaciers. That has allowed the uninterrupted build-up of sediment at the bottom of the lake, recording hitherto undiscovered information on climate change.
Cores from Lake E go far back in time, almost 30 times farther than Greenland ice cores covering the past 110,000 years.
The sediment cores from Lake El'gygytgyn reflect the climate and environmental history of the Arctic with great sensitivity, say Brigham-Grette and colleagues.
The physical, chemical and biological properties of Lake E's sediments match the known global glacial/interglacial pattern of the ice ages.
Some warm phases are exceptional, however, marked by extraordinarily high biological activity in the lake, well above that of "regular" climate cycles.
To quantify the climate differences, the scientists studied four warm phases in detail: the two youngest, called "normal" interglacials, from 12,000 years and 125,000 years ago; and two older phases, called "super" interglacials, from 400,000 and 1.1 million years ago.
According to climate reconstructions based on pollen found in sediment cores, summer temperatures and annual precipitation during the super interglacials were about 4 to 5 degrees C warmer, and about 12 inches wetter, than during normal interglacials.
The super interglacial climates suggest that it's nearly impossible for Greenland's ice sheet to have existed in its present form at those times.
Simulations using a state-of-the-art climate model show that the high temperature and precipitation during the super interglacials can't be explained by Earth's orbital parameters or variations in atmospheric greenhouse gases alone, which geologists usually see as driving the glacial/interglacial pattern during ice ages.
That suggests that additional climate feedbacks are at work.
"Improving climate models means that they will better match the data that has been collected," says Paul Filmer, program director in NSF's Division of Earth Sciences, which funded the "Lake E" project along with NSF's Office of Polar Programs.
"The results of this collaboration among scientists in the U.S., Austria, Germany and Russia are providing a challenge for researchers working on climate models: they now need to match results from Antarctica, Greenland--and Lake El'gygytgyn."
Adds Simon Stephenson, director of the Division of Arctic Sciences in NSF's Office of Polar Programs, "This is a significant result from NSF's investment in frontier research during the recent International Polar Year.
"'Lake E' has been a successful partnership in very challenging conditions. These results make a significant contribution to our understanding of how Earth's climate system works, and improve our understanding of what future climate might be like."
The scientists suspect the trigger for intense interglacials might lie in Antarctica.
Earlier work by the international ANDRILL program discovered recurring intervals when the West Antarctic Ice Sheet melted. (ANDRILL, or the ANtarctic geological DRILLing project, is a collaboration of scientists from five nations--Germany, Italy, New Zealand, the United Kingdom and the United States--to recover geologic records from the Antarctic margin.)
The current Lake E study shows that some of these events match with the super interglacials in the Arctic.
The results are of global significance, they believe, demonstrating strong indications of an ongoing collapse of ice shelves around the Antarctic Peninsula and at the margins of the West Antarctica Ice Sheet--and a potential acceleration in the near future.
The Science paper co-authors discuss two scenarios for future testing that could explain the Northern Hemisphere-Southern Hemisphere climate coupling.
First, they say, reduced glacial ice cover and loss of ice shelves in Antarctica could have limited formation of cold bottom water masses that flow into the North Pacific Ocean and upwell to the surface, resulting in warmer surface waters, higher temperatures and increased precipitation on land.
Alternatively, disintegration of the West Antarctic Ice Sheet may have led to significant global sea level rise and allowed more warm surface water to reach the Arctic Ocean through the Bering Strait.
Lake E's past, say the researchers, could be the key to our global climate future.
The El'gygytgyn Drilling Project also was funded by the International Continental Scientific Drilling Program (ICDP), the German Federal Ministry for Education and Research, Alfred Wegener Institute, GeoForschungsZentrum-Potsdam, the Russian Academy of Sciences Far East Branch, the Russian Foundation for Basic Research, and the Austrian Ministry for Science and Research.
-NSF-
Media ContactsCheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Related Websites"Lake E": UMass Amherst, USA:http://www.geo.umass.edu/lake_e/
"Lake E": ICDP: http://www.icdp-online.org/front_content.php?idcat=512
DFG Science TV: "Lake E": http://www.dfg-science-tv.de/en/projects/polar-archive
"Lake E" on YouTube: www.youtube.com/playlist?list=PLA32489E0A3B3358A&feature=plcp
"Lake E": ICDP: http://www.icdp-online.org/front_content.php?idcat=512
DFG Science TV: "Lake E": http://www.dfg-science-tv.de/en/projects/polar-archive
"Lake E" on YouTube: www.youtube.com/playlist?list=PLA32489E0A3B3358A&feature=plcp
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget is $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives over 50,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards nearly $420 million in professional and service contracts yearly.
Short course in climate at An Open Mind
Tamino, who runs an excellent blog on climate and weather statistical analysis (most of it over my head mathematically :)) at An Open Mind (listed on the right of this page in the blog roll), has a lengthy response today to a lengthy comment on a post concerning the recent U.S. heat wave. While his response is, as usual, very good, several of the comments are also very educational and provide a good short course on key indicators of climate change. Recommended.
Monday, July 9, 2012
Hottest 12 months on record, again
Andrew Freedman at Climate Central and Jeff Masters at Weather Underground are both up today with breakdowns and graphics from the National Oceanic and Atmospheric Administration's (NOAA) monthly State of the Climate summary for June, which has just been released.
The big news is that for the second month in a row, the U.S. has racked up its warmest 12-month period on record (that is, July 2011 through June 2012 topped June 2011 through May 2012, the previous record holder). June 2012 also marked the close of the warmest January-June period on record.
Two of the most notable graphics:
This shows the degree to which 2012--so far--is departing from the four warmest years in the temperature record.
And this shows how far the two 12-month periods ending in May 2012 and June 2012 exceed other 12-month periods in the historical record.
The big news is that for the second month in a row, the U.S. has racked up its warmest 12-month period on record (that is, July 2011 through June 2012 topped June 2011 through May 2012, the previous record holder). June 2012 also marked the close of the warmest January-June period on record.
Two of the most notable graphics:
This shows the degree to which 2012--so far--is departing from the four warmest years in the temperature record.
And this shows how far the two 12-month periods ending in May 2012 and June 2012 exceed other 12-month periods in the historical record.
Sunday, July 8, 2012
By the numbers: U.S. warming
OK, I admit it--I'm a numbers geek, er, guy.
Graphics are good, but numbers are better. It's fun to poke around them and try to understand the story they are telling.
A while ago, inspired by the Great March 2012 Heat Wave, I expressed concern about the ratio of new high daily temperatures across the U.S. to new low daily temperatures. I reposted a graphic from the blog Capital Climate that seemed to me to suggest that the high ratios of months like March 2012 (35:1, here after just "35") and January 2012 (22) indicated that wild swings in temperature are growing greater--that the weather system was looking more and more unstable due to global warming.
The Capital Climate graphic, however, didn't show everything I needed to confirm that hypothesis. In this particular iteration (the blog has published others previously, covering different time periods), only ratios from 2011 and 2012 were shown--not enough to get a feel for just how unusual the March and January ratios were. So I decided to go digging.
A week later (this is tedious and time-consuming work), I've created an Excel spreadsheet that shows new daily highs, new daily lows, and their ratio for months in the years 1993-2012. I also flipped ahead and took a peek at 1988 and 1936, two previous years with remarkable heat waves. All data is from the National Climate Data Center (NCDC) of the National Oceanic and Atmospheric Administration (NOAA), which maintains an online database of temperature extremes at http://www.ncdc.noaa.gov/extremes/records/.
There's still quite a bit of work to do (the database covers years back to 1850!), but even with the limited portion I've completed, there are some interesting results:
First, ratios of new highs to lows in recent years are not toooo extreme. While March 2012 (35) and January 2012 (22) are definitely unusual, there are other wilder outliers in the historical record. January 2006 (58:1) is the biggest I've found so far, and November 1999 (53) and February 2000 (50) also achieved ratios of 50 or better.
Second, there is a clear warming trend. That trend is, I think, best illustrated by looking at some yearly records:
Most recent year in which new daily lows exceeded new daily highs: 1997, with 16,469 new lows versus 15,964 new highs. That's a stopper right there, since if the climate were stable, it would be unusual for there to be 14 straight years (1998 through 2011) in which new highs exceeded new lows.
Most recent year with 20,000 or more new daily lows: 1996 (23,160).
Most recent year with 20,000 or more new daily highs: 2007 (26,067).
One might speculate that the number of new records is decreasing over time as the temperature data set gets longer/larger, but there's no reason for highs to exceed lows unless the average temperature is increasing.
Most recent year with 15,000 or more new daily lows: 2002 (18,166).
Most recent year with 15,000 or more new daily highs: 2012 (18,164 and counting, through July 7).
Pretty hard to refute this very impressive data. 2003, 2005, 2006, 2007, and 2011 also had more than 15,000 new daily highs.
Most recent year with 10,000 or more new daily lows: 2007 (10,355).
2010, 2011, 2012 all surpassed 10,000 new daily highs.
Number of months since January 1, 1993, with a ratio of new lows to new highs exceeding 10:1: 1 (March 1997, with a ratio of 12.7:1).
The following months since that date have had ratios of new highs to new lows exceeding 10:1: January 1995 (17), February 1997 (16), January 1998 (12), July 1998 (16), September 1998 (17), November 1998 (21), December 1998 (14), November 1999 (53), January 2000 (12), February 2000 (53), March 2000 (40), November 2001 (14), December 2001 (12), January 2002 (15), August 2003 (12), October 2003 (11), March 2004 (21), February 2005 (18), January 2006 (58), August 2007 (13), June 2011 (10), August 2011 (22), January 2012 (22) and March 2012 (35)--a total of 24 months in all.
Highest ratio of new highs to new lows for a year: 1998 (4.04).
At the moment, 2012 is on track to easily surpass 1998 (currently, its ratio is a remarkable 11.7), but the record makes it clear that significant changes can take place in a few months.
More generally, this work is inspired not only by the Great June-July 2012 Heat Wave, which we have just finished, but by a study of the ratio of new highs to new lows completed in 2009 by authors from the National Center for Atmospheric Research (NCAR), Climate Central, The Weather Channel, and NOAA. That study found the following ratios by decade:
1950s: 1.09 (to 1)
1960s: 0.77
1970s: 0.78
1980s: 1.14
1990s: 1.36
2000s: 2.04
The decadal record has the effect of smoothing variations and making it clear that since the 1990s, the ratio has taken a jump, with a larger increase from the 1990s to 2000s than any previous change. (I hope to extend this back to at least the 1930s and 1940s, since the Dust Bowl era of the 1930s had multiple very hot summers.)
I'll be continuing to build out my spreadsheet in the coming weeks, and will keep you posted on what I find.
Graphics are good, but numbers are better. It's fun to poke around them and try to understand the story they are telling.
A while ago, inspired by the Great March 2012 Heat Wave, I expressed concern about the ratio of new high daily temperatures across the U.S. to new low daily temperatures. I reposted a graphic from the blog Capital Climate that seemed to me to suggest that the high ratios of months like March 2012 (35:1, here after just "35") and January 2012 (22) indicated that wild swings in temperature are growing greater--that the weather system was looking more and more unstable due to global warming.
The Capital Climate graphic, however, didn't show everything I needed to confirm that hypothesis. In this particular iteration (the blog has published others previously, covering different time periods), only ratios from 2011 and 2012 were shown--not enough to get a feel for just how unusual the March and January ratios were. So I decided to go digging.
A week later (this is tedious and time-consuming work), I've created an Excel spreadsheet that shows new daily highs, new daily lows, and their ratio for months in the years 1993-2012. I also flipped ahead and took a peek at 1988 and 1936, two previous years with remarkable heat waves. All data is from the National Climate Data Center (NCDC) of the National Oceanic and Atmospheric Administration (NOAA), which maintains an online database of temperature extremes at http://www.ncdc.noaa.gov/extremes/records/.
There's still quite a bit of work to do (the database covers years back to 1850!), but even with the limited portion I've completed, there are some interesting results:
First, ratios of new highs to lows in recent years are not toooo extreme. While March 2012 (35) and January 2012 (22) are definitely unusual, there are other wilder outliers in the historical record. January 2006 (58:1) is the biggest I've found so far, and November 1999 (53) and February 2000 (50) also achieved ratios of 50 or better.
Second, there is a clear warming trend. That trend is, I think, best illustrated by looking at some yearly records:
Most recent year in which new daily lows exceeded new daily highs: 1997, with 16,469 new lows versus 15,964 new highs. That's a stopper right there, since if the climate were stable, it would be unusual for there to be 14 straight years (1998 through 2011) in which new highs exceeded new lows.
Most recent year with 20,000 or more new daily lows: 1996 (23,160).
Most recent year with 20,000 or more new daily highs: 2007 (26,067).
One might speculate that the number of new records is decreasing over time as the temperature data set gets longer/larger, but there's no reason for highs to exceed lows unless the average temperature is increasing.
Most recent year with 15,000 or more new daily lows: 2002 (18,166).
Most recent year with 15,000 or more new daily highs: 2012 (18,164 and counting, through July 7).
Pretty hard to refute this very impressive data. 2003, 2005, 2006, 2007, and 2011 also had more than 15,000 new daily highs.
Most recent year with 10,000 or more new daily lows: 2007 (10,355).
2010, 2011, 2012 all surpassed 10,000 new daily highs.
Number of months since January 1, 1993, with a ratio of new lows to new highs exceeding 10:1: 1 (March 1997, with a ratio of 12.7:1).
The following months since that date have had ratios of new highs to new lows exceeding 10:1: January 1995 (17), February 1997 (16), January 1998 (12), July 1998 (16), September 1998 (17), November 1998 (21), December 1998 (14), November 1999 (53), January 2000 (12), February 2000 (53), March 2000 (40), November 2001 (14), December 2001 (12), January 2002 (15), August 2003 (12), October 2003 (11), March 2004 (21), February 2005 (18), January 2006 (58), August 2007 (13), June 2011 (10), August 2011 (22), January 2012 (22) and March 2012 (35)--a total of 24 months in all.
Highest ratio of new highs to new lows for a year: 1998 (4.04).
At the moment, 2012 is on track to easily surpass 1998 (currently, its ratio is a remarkable 11.7), but the record makes it clear that significant changes can take place in a few months.
More generally, this work is inspired not only by the Great June-July 2012 Heat Wave, which we have just finished, but by a study of the ratio of new highs to new lows completed in 2009 by authors from the National Center for Atmospheric Research (NCAR), Climate Central, The Weather Channel, and NOAA. That study found the following ratios by decade:
1950s: 1.09 (to 1)
1960s: 0.77
1970s: 0.78
1980s: 1.14
1990s: 1.36
2000s: 2.04
The decadal record has the effect of smoothing variations and making it clear that since the 1990s, the ratio has taken a jump, with a larger increase from the 1990s to 2000s than any previous change. (I hope to extend this back to at least the 1930s and 1940s, since the Dust Bowl era of the 1930s had multiple very hot summers.)
I'll be continuing to build out my spreadsheet in the coming weeks, and will keep you posted on what I find.
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