Weatherdem's Weblog

Bridging climate science, citizens, and policy

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Wildfire – Policy and climate change

I read a wildfire article today that was breathless about the scope of total acreage burned across the drought-stricken northwest US and of course included a climate change angle.  This is the first wildfire article I’ve read that did not include some mention of decades of ill-conceived fire policies in the intermountain West.

Let’s not mince words: a lot of fires are burning on a lot of acres this year primarily because of those man-made policies.  Millions of overcrowded acres of forest because people put tiny fires out for decades and allowed trees (fuel) to grow and grow.  Fire is a natural process that we purposefully interrupted.  Prior years with extensive fires also generated media and environmentalist attention.  As I stated above, the difference between then and now is climate activists politicized the science.  An EcoWatch article now contains no mention of historical decisions because it is more important to satisfy the environmentalist base by claiming nature is pure without humans and impure with us.

This is disappointing but not surprising.  For now, I am glad there are more responsible media outlets that continue to acknowledge the very real and dominant influence people have on forests (forest management), the very real and strong influence nature has on forests (drought), as well as the growing influence that people will have on forests in the future (climate change).


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Water efficiency

I saw a tweet last night that I found interesting.

“The only thing that can.”  I hope Peter means water-use efficiency for all users.  The graphic he includes with this tweet suggests he’s focused on household toilet usage in California.  I’ll round the numbers used in the graphic: 1980 usage was 800,000 acre-feet per year; current use (no efficiency) is 1,200,000 acre-feet per year.  Current savings from efficiency improvements: 640,000 acre-feet per year.  Additional potential savings: 290,000 acre-feet per year.

The 640,000 AFY is laudable.  That’s a lot of water that Californians don’t have to use and thankfully aren’t.  That is a real accomplishment.  An additional 290,000 AFY is a good goal to work on – why waste a resource when you don’t have to.

But toilet water usage isn’t the primary usage of California water – and it’s that small point that troubled me when I saw the tweet.  Total water usage in California is 40,00,000 AFY.  That 640,000 efficiency represents just 1.6% of the total usage.  It also represents >50% reduction from what water usage could be without any efficiency measures.  What I want to know is what efficiencies water-thirsty California agriculture implements.  Agriculture is by far the dominant user of water – if we achieved just 1% sector efficiency, how much more water could California save because of the scale of industry usage compared to residential usage?

Agriculture is a sizable part of the California economy – $43 billion industry that generates $100 billion in overall economic activity.  Because of that, agriculture wields political clout in Sacramento.  This means that while physical scientists can inform policymakers on the ongoing drought, we need the social sciences to inform policymakers how to deal with it.  I would also like to see quantitative results of efficiency gains by sector.

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2014 US National Climate Assessment Released

The US Global Change Research Program issued its latest National Climate Assessment today. There are lots of goodies in it.  I want to focus on a couple of things that caught my eye in an initial skim.

Impacts will increase in frequency and severity (no big surprise there). This assessment includes up-t0-date research results on those impacts.  Like most reports, they leave `Responses` as a final category.  I understand the logic of laying out the evidence of climate change and its impacts prior to discussing solutions, but as I’ve written before today, people primarily respond to solutions and not problems.  Only the most dedicated readers will make it all the way through the report to get to the Response section.  My worry is that the Response section will not be the focus of activists’ attention; a continuation of decades of wasted energy.

Extreme Weather

The report summarizes the state-of-the-science well: “Over the last 50 years, much of the U.S. has seen increases in prolonged periods of excessively high temperatures, heavy downpours, and in some regions, severe floods and droughts.”  That is accurate.  I do not think one example is valid, however.  The report discusses anomalous warmth and dryness in Texas and Oklahoma in 2011.  I do not argue that the event occurred; I blogged about it and the subsequent 2012 Great Plains drought.  Where I deviate from the Assessment is this: there is scant evidence that the 2011 Southern Plains drought had a strong climate signal.  The same goes for the 2012 Great Plains drought.  Instead, these droughts were strongly linked to drier summertime conditions during the recent decade as part of a regime shift, most probably due to natural decadal variability (Hoerling et al. 2014).  The 2011 Texas heat wave was more likely to occur than it was 40 years ago.  This is not the same thing as identifying a clear attribution – something that remains at the cutting edge of climate science.

Likewise, the largest determinant of Atlantic hurricanes remains natural variability.  The Assessment’s statement that Atlantic hurricane activity increased since the early 1980s is true, but there are important details to consider.  The Atlantic signal is opposite the global signal (a small reduction in overall hurricane activity in that same time period), so regional effects are important to consider.  The Atlantic Multidecadal Oscillation is currently in a positive phase (since the early 1980s – isn’t that interesting?), which includes a warmer than usual Atlantic Ocean.  All else equal, this facilitates tropical storm development, which we’ve seen.

The Assessment’s conclusion stands in direct contrast to a couple of peer-reviewed papers, including Chylek and Lesins 2008 (we find no increase in the number of major hurricanes (category 3–5); If there is an increase in hurricane activity connected to a greenhouse gas induced global warming, it is currently obscured by the 60 year quasi-periodic cycle.) and Enfield and Cid-Serrano 2009 (Projections to the year 2025 show that the cumulative change in summer warm pool size since 1975 will depend critically on whether a subsequent cooling in the multidecadal cycle occurs, comparable to the warming between 1975 and 2000 AD.)  In other words, determining how man-made warming affects Atlantic hurricanes will not be detectable from the natural signal for many years to come.

That doesn’t mean we do nothing.  To the contrary, I argue that we need to adapt our current infrastructure to our current climate.  Multi-billion dollar events occur today.  Most of that is related to increases in population and wealth, as the Assessment reports.  We can lessen impacts by hardening our infrastructure (taking the likeliest climate effects into account) today while simultaneously mitigating future climate effects.  One should not happen without the other, but at a minimum, we need to adapt to today’s climate while recognizing tomorrow’s climate will be different.


I want to cite the impacts the Assessment identifies for the Southwest, which includes California, Nevada, Utah, Colorado, New Mexico, and Arizona.  This region is the hottest and driest of the US.  They include: “increased heat, drought, insect outbreaks, and wildfires.  Declining water supplies, reduced agricultural yields, health impacts in cities due to heat, and flooding and erosion in coastal areas are additional concerns.”

Key messages:

  • Reduced snowpack and streamflow
  • Agricultural threats
  • Increased wildfire
  • Sea level rise
  • Heat threats to health

Southwest Responses

I really want to highlight one of the responses.  Without having read through all the responses carefully, I want to point out that I hope other responses are better than this one.  The selected response shows one scenario that could theoretically achieve 80% GHG reductions from 1990 levels by 2050:

 photo SW_energy-generation-by-2045_12447_v10-hi_0_zps2c73bc2c.jpg

I’ll discuss Colorado here; the Assessment included references to exhaustive reports for California, which I’ll cover in the future.

The latest data for Colorado’s net generation shares (2012) demonstrate the immense challenge confronting the scenario shown above.  Broken down by percentage: coal (64.3%), natural gas (20.1%), wind (11.2%), hydroelectric (3.7%), solar (0.3%), biomass and other (0.1% each).  The scenario above (still trying to pin down units) shows that wind can become the dominant source of electricity generation.  In principle, I agree.  But wind would have to switch places with coal as the dominant generation type by 2050 to achieve 80% GHG reductions.  Wind has penetrated the electricity generation market, which I fought for and applaud.  But it still trails natural gas (1/2 the generation) and significantly trails coal (1/5 the generation).  Changing those ratios requires a policy upheaval which I don’t think is likely.  Renewables will eventually supplant fossil fuels as primary generation technologies.  At this time, I don’t think it will happen in Colorado or anywhere else (California has an outside shot) by 2050.


This Assessment is useful for academics and activists, but is probably not useful for the general public.  A brief review of the Response section didn’t convince me that the writers and editors had the public as their primary audience.  I’ve seen Twitter explode today with comments regarding how people were at the forefront of this report, how actionable the information is, etc.  I’m not convinced yet.  Hopefully that will change.

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California’s Ongoing Drought & Related Climate News

California’s drought is severe and lengthy.  2013 was a record dry year for areas in the state with extensive data records: Los Angeles’s 3.60″ (14.93″ normal) and San Francisco’s 5.59″ (23.65″ normal) among others.  Recent research characterized California as drier than at any time in the past 500 years (an important point that I’ll return to below).  California experienced three consecutive very dry years (2011-2013), and 2014 provided little difference so far.  This dryness and the ensuing drought conditions are part of a longer term decadal-plus drought affecting the southwest US since 2000.

Additional metrics include:

Seventeen rural communities in California are in danger of running out of water within 60 to 120 days, according to a list compiled by state officials. As the drought goes on, more communities are likely to be added to the list.

With only about seven inches of rain in California in 2013 — far below the average of 22 inches — wells are running dry and many reservoirs are about 30 percent full (including Folsom Lake, shown above).

The Sierra snowpack, where California gets about a third of its water, was 88 percent below average as of Jan. 30.

Soon, people will face a lack of fresh water to their homes.  With reservoirs at record low levels, farmers will not be able to plant the crops they want which will reduce our food availability and increase food prices later this year.  This means the impacts will be local and national.  Moving forward, legal fights over very limited water will likely occur.  Folks are about to find out they water they’ve taken for granted is legally obligated to other users.  No one knows what the results will be, but many people have feared this very set of circumstances for a long time.

It would take between 8″ and 16″ of liquid water across most of California to break the drought.  That is unlikely to happen any time soon.  California’s drought is directly related to the snowy winter the eastern half of the nation experienced due to the persistent high-amplitude anomalous jet stream.  High pressure pushed the jet stream to the north over the western US while low pressure allowed the jet stream to dive south over the eastern US.  Usually such a pattern breaks down after a short time.  This winter’s jet stream has been essentially stuck for months now.

In related news, Arctic albedo decreased more than previously thought due to melting Arctic sea ice.  This phenomenon warms the Arctic, including the Arctic Ocean, which affects other parts of the globe, including the US.

And now back to the interesting point I wrote about above: CA is drier than at any point in the past 500 years.  Not forever, 500 years.  That means CA has been this dry in the past (the relatively recent past, in geologic time scales).  Moreover, we should all recall that CO2 concentrations were much lower 500 years ago than they are today.  That means that CA’s dryness is to some extent caused by natural variability.  The scientific question then becomes: “How much?”  Climate attribution studies remain at the forefront of climate research, which is another way of saying we don’t know how much natural variability plays a role in today’s dryness.

A NY Times article captured this recently:

While a trend of increasing drought that may be linked to global warming has been documented in some regions, including parts of the Mediterranean and in the Southwestern United States, there is no scientific consensus yet that it is a worldwide phenomenon. Nor is there definitive evidence that it is causing California’s problems.

The article notes that there are significant similarities between this drought and a similar drought in 1976-77.  What we do know is that temperatures are higher during this drought than they were in 1976-77, which exacerbates the drought’s effects.  What precipitation fell in 2013 evaporated more quickly than before because of warmer temperatures.  So we can say that a similar drought is occurring in a warmer environment, which is something relatively new and noteworthy.

An important point is that this drought is occurring in a world with higher CO2 concentrations than in 1976 or in the 1500s.  But this drought is similar to previous droughts.  Today’s higher CO2 concentrations aren’t the dominant cause of this drought.  Droughts later this century will likely have a more noticeable human fingerprint, but this drought could have (and did) occur in contemporary history.  There is nothing about today’s state of the climate (or 1970’s or 1930’s state of the climate) that precludes this drought.  Quite the opposite is true: this drought belongs to the state of the climate today, not tomorrow.

It is true that the southwest has been in some level of drought condition for 15 years or so.  Those conditions also exist in today’s climate.  They might also exist in the end of the century’s climate, but they will exhibit characteristics that we can’t foresee with any accuracy today.  That said, there are people today in the southwest US that this drought impacts.  That is the reality regardless of the anthropogenic or natural influence on the climate system.  The demand on annual available water now exceeds the supply.  That reality will increasingly shape the southwest in the near future, not the distant future.  Increasingly restrictive water usage policies are more likely than not.

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Denver’s September 2013 Climate Summary


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.


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.


Epic Rain Event in Boulder, CO

A local emergency quickly became national news today: record-setting rainfall caused overnight flash flooding at multiple locations in and around Boulder, CO todaySome homes were swept away and reports list three people killed so far.  6.8 inches of rain fell in 24 hours by early morning today after rain fell for more than two previous days along the Front Range.  The previous rains saturated the ground, which set the stage for today’s life-threatening emergency.

From Monday through 11:30A today, eight to nine inches of rain fell over Boulder County.  This shattered the previous September record of 4.8″ of rain set in 1919!  These values are simply stunning in magnitude.  The rain continued to fall through the day today.  Additional rain is forecasted for tonight through Sunday, which means this disaster may not be over for days yet.

The flash floods and ongoing rainfall hampered rescue efforts since roads were washed out by creeks and helicopters were grounded.  Previous years’ wildfires left mountainsides outside of Boulder devoid of plant life, which allowed the majority of water that fell to flow directly into streams that are not equipped for these rainfall rates.  The cities of Lyons and Longmont are currently cut off from surrounding areas by flooding waters.  The effects spread this afternoon into north and east Denver suburbs.

These conditions were in stark contrast to different record-setting weather just last week.  Three daily high temperatures were set or tied at DIA: 97 on the 5th and 6th, 95 on the 7th.  Two record high low temperatures (nighttime) were also set: 68F on the 3rd and 69F on the 4th.  Daily average temperatures were 12 and 13 degrees warmer than normal during this late-season heat spell.  These were caused by a ridge of high pressure that previously slid west over the Front Range.

The same ridge of high pressure moved back to the east earlier in the week.  This allowed a cool front from Canada to slide south over the Denver metro area Monday.  It also allowed subtropical monsoon moisture flowing north to move over the Front Range.  The cool front brought moist low-level air in from the east and forced it up against the mountains.  The combination of low-level and high-level moisture with decent instability generated rains that started on Monday and haven’t really stopped very long since then.  The only good news is these rains will lessen the severity of the ongoing drought over the region.

This event harkens back to the Big Thompson River Flood of 1976.  More than 100 people died in that event, but it also occurred overnight.

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50.1% of the Contiguous United States in Moderate or Worse Drought – 3 Sep 2013

According to the Drought Monitor, drought conditions worsened slightly across the entire US compared to three weeks ago. As of September 3, 2013, 50.1% of the contiguous US is experiencing moderate or worse drought (D1-D4), as the early 2010s drought continues month after month.  This value is about 9 percentage points lower than it was in the early spring. The percentage area experiencing extreme to exceptional drought decreased from 14.8% three weeks ago to 9.9% last week; this is approximately 10% lower than it was six months ago. The eastern third of the US was wetter than normal during August, which helped keep drought at bay.  The east coast in particular was much wetter than normal and the summer monsoon was much more active this summer compared to 2012.  Instead of Exceptional drought in Georgia and Extreme drought in Florida two years ago, there is flash flooding and rare dam water releases in the southeast.  Four eastern states experienced their top-four wettest Julys on record.  The West presents a different story.  Long-term drought continues to exert its hold over the region, as it remained warmer than normal but six southwestern states received top-20 July precipitation this year.  Meanwhile, Oregon recorded its driest July on record.  Compared to three weeks ago, drought area increased in the Midwest.

 photo USDrought20130903_zpsf4845451.gif

Figure 1US Drought Monitor map of drought conditions as of September 3rd.

If we compare this week’s maps with previous dates (here and here, for example), we can see recent shifts in drought categories.  Compared to early July and mid-August, and despite recent rain events, drought expanded or worsened in the Midwest (Iowa, Missouri, Illinois, Minnesota, and the Dakotas) as well as Louisiana, Arkansas, and Mississippi.

 photo west_drought_monitor_20130903_zps6a3a6205.png

Figure 2 – US Drought Monitor map of drought conditions in Western US as of September 3rd.

After worsening during late winter into spring 2013, drought conditions steadied during the past month.  The differences between this map and mid-August’s is the spatial shift of conditions; the total percent area values are about the same.  The area experiencing Exceptional drought decreased slightly over the West and the percent area with no drought increased slightly, but remains at low levels.  Figure 2 also shows that the percent area with no drought decreased since the start of the year (24% to 14%).

Here are the current conditions for Colorado:

 photo CO_drought_monitor_201309033_zps07464c14.png

Figure 3 – US Drought Monitor map of drought conditions in Colorado as of September 3rd.

There is clear evidence of relief evident over the past three months here.  Severe drought area dropped from 72% to 60% (this was 100% about last year!).  Extreme drought area dropped from 27% to 22% (also down from 50%+ six months ago).  Exceptional drought decreased significantly from three and six months ago.  Instead of 16% of Colorado (and as much as 17% earlier this year), Exceptional drought now covers only 3% of the state.  The good news for southeastern Colorado was the recent delivery of substantial precipitation.  I didn’t think it would be enough to completely alleviate the worst conditions, but they received enough precipitation that drought conditions improved from Exceptional to Extreme.  Their drought is not over yet, but they are finally trending in a good direction.  And for the first time in over one year, some small percentage (2%; up from 1% three weeks ago) of Colorado does not currently have any drought.  This is great news – hopefully this area expands throughout the rest of the year.

 photo midwest_drought_monitor_20130903_zpseafbaad1.png

Figure 4 – US Drought Monitor map of drought conditions in the Midwest as of September 3rd.

Drought expanded and worsened slightly in the Midwest in the past few months: the percent area with no drought decreased significantly from 91% to 52%.  The percent area with Moderate drought increased significantly from 3% to 29% this week.  Severe drought now impacts most of Iowa and small portions of Missouri, Wisconsin and Minnesota.

US drought conditions are more influenced by Pacific and Atlantic sea surface temperature conditions than the global warming observed to date.  Different natural oscillation phases preferentially condition environments for drought.  Droughts in the West tend to occur during the cool phases of the Interdecadal Pacific Oscillation and the El Niño-Southern Oscillation, for instance.  Beyond that, drought controls remain a significant unknown.  Population growth in the West in the 21st century means scientists and policymakers need to better understand what conditions are likeliest to generate multidecadal droughts, as have occurred in the past.  Without comprehensive planning, dwindling fresh water supplies will threaten millions of people.  That very circumstance is already occurring in western Texas where town wells are going dry.  An important factor in those cases is energy companies’ use of well water for natural gas drilling.  This presents a dilemma more of us will face in the future: do we want cheap energy or cheap water?  In the 21st century, we will not have both options available at the same time as happened in the 20th century.  This presents a radical departure from the past.

As drought affects regions differentially, our policy responses vary.  A growing number of water utilities recognize the need for a proactive mindset with respect to drought impacts.  The last thing they want is their reliability to suffer.  Americans are privileged in that clean, fresh water flows every time they turn on their tap.  Crops continue to show up at their local stores despite terrible conditions in many areas of their own nation (albeit at a higher price, as found this year).  Power utilities continue to provide hydroelectric-generated energy.

That last point will change in a warming and drying future.  Regulations that limit the temperature of water discharged by power plants exist.  Generally warmer climate conditions include warmer river and lake water today than what existed 30 years ago.  Warmer water going into a plant either means warmer water out or a longer time spent in the plant, which reduces the amount of energy the plant can produce.  Alternatively, we can continue to generate the same amount of power if we are willing to sacrifice ecosystems which depend on a very narrow range of water temperatures.  As with other facets of climate change, technological innovation can help increase plant efficiency.  I think innovation remains our best hope to minimize the number and magnitude of climate change impacts on human and ecological systems.