Weatherdem's Weblog

Bridging climate science, citizens, and policy


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48.2% of US in Moderate or Worse Drought – 17 Sep 2013 (Thank You, Monsoon!)

According to the Drought Monitor, drought conditions worsened slightly across the entire US compared to three weeks ago. As of September 17, 2013, 48.2% 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 11 percentage points lower than it was in the early spring. The percentage area experiencing extreme to exceptional drought decreased from 14.8% last month to 6.9% last week!  This is more than 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, assisted by a persistent upper level blocking pattern.  Instead of Exceptional drought in the West like there was earlier this summer, record rains and flash flooding was the story in September.  While this record-breaking series of events broke the drought in some areas of the West, long-term drought continues to exert its hold over the region.  Compared to earlier this summer, drought increased in area and intensity across the Midwest.

 photo USDrought20130917_zps29a0436a.gif

Figure 1US Drought Monitor map of drought conditions as of September 17th.

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 mid-August and early September, 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.  On the other hand, alleviation is evident in small places in the West, as the following map shows.

 photo west_drought_monitor_20130917_zpsd2784c0e.png

Figure 2 – US Drought Monitor map of drought conditions in Western US as of September 17th.

After worsening during late winter into spring 2013, drought conditions steadied in late summer.  The differences between this map and early September’s is the reduction in area and severity of drought, especially in the southern half of the West.  The area experiencing Exceptional drought decreased significantly over the West and the percent area with no drought increased.  Figure 2 also shows that the percent area with no drought is still lower since the start of the calendar year (24% to 18%).

Here are the current conditions for Colorado:

 photo co_drought_monitor_20130917_zps9d17a4ef.png

Figure 3 – US Drought Monitor map of drought conditions in Colorado as of September 17th.

There is evidence of substantial improvement in Colorado since just a few weeks ago and certainly compared to earlier this year, when drought conditions were their worst.  Compared to the start of the calendar year or even three months ago, the percent area of every drought category decreased significantly.  Only 1.5% of the state currently has Exceptional drought.  Only 84% of the state is even experiencing any drought condition today, a far cry from the 100% that lasted for well over one year.  The links in the first paragraph dealing with last week’s rains combine with this graphic to demonstrate that places that receive one year’s worth of precipitation in one week’s time bust their drought!  Many communities would trade those record rains for a little bit of drought, given the extensive damage to infrastructure and the eight people who, as of this morning, perished in the severe weather event.

Let’s compare Figure 3 to similar Colorado maps from earlier in the year.  First, this is what conditions looked like just two weeks ago:

 photo CO_drought_monitor_201309033_zps07464c14.png

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

The over-active monsoon season helped reduce drought severity from Denver northwest toward the Wyoming border.  I said at the time I hoped that trend continued, but I could never imagine what would happen in the interim.

Here is a look at some of the worst drought conditions Colorado experienced in the past year, from late April 2013:

 photo CO_drought_monitor_20130425_zpsbf9ccb2d.png

Figure 5 – US Drought Monitor map of drought conditions in Colorado as of April 25th.

Conditions were horrible earlier this year.  Reservoir levels declined and crops failed as a result of the higher than normal temperatures and much lower than normal precipitation.  I certainly don’t want to see additional flooding, but I would like to see normal precipitation return to the state and the region.

 photo midwest_drought_monitor_20130917_zpsf91b6be4.png

Figure 6 – US Drought Monitor map of drought conditions in the Midwest as of September 17th.

Drought expanded in the Midwest in the past two weeks: the percent area with no drought decreased significantly from 48% to 43%.  Three months ago, the value was 93%.  This region collected rainfall this month, but the amounts continued to track below average.

 photo south_drought_monitor_20130917_zps76d5a2cf.png

Figure 7 – US Drought Monitor map of drought conditions in the South as of September 17th.

Compared to early summer, drought as a whole expanded across the South in 2013.  Instead of 44% area with no drought three months ago, there is only 16% today.

Policy Context

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.


1 Comment

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.


6 Comments

45.3% of the Contiguous United States in Moderate or Worse Drought – 15 Aug 2013

According to the Drought Monitor, drought conditions improved recently across some of the US. As of Aug 15, 2013, 45.3% 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 10 percentage points lower than it was in the early spring. The percentage area experiencing extreme to exceptional drought increased from 14.6% to 14.8%; this is approximately 4% lower than it was six months ago. The eastern third of the US was wetter than normal during July into 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.

 photo USDrought20130815_zpse8a61c7f.gif

Figure 1US Drought Monitor map of drought conditions as of August 13th.

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 despite recent rain events, drought expanded in the Midwest (into Iowa, Missouri, Illinois, and Minnesota) as well as Louisiana, Arkansas, and Mississippi.

Here is the Western US drought map this week:

 photo west_drought_monitor_20130815_zpsb980edee.png

Figure 2 – US Drought Monitor map of drought conditions in Western US as of August 15th.

After worsening during late winter into spring 2013, drought conditions steadied during the past month.  The differences between this map and early July’s is the spatial shift of conditions; the total percent area values are about the same.

Temporary drought relief occurred over parts of Arizona and Colorado as the summer monsoon brought moisture northward and interacted with cooler air masses than normal from Canada.

Here are the current conditions for Colorado:

 photo CO_drought_monitor_20130815_zps0644308d.png

Figure 3 – US Drought Monitor map of drought conditions in Colorado as of July 9th.

There is clear evidence of relief evident over the past three months here.  Severe drought area dropped from 72% to 69% (this was 100% about six months ago!).  Extreme drought area dropped slightly from 27% to 26% (also down from 50%+ six months ago).  Exceptional drought is down significantly from three and six months ago.  Instead of 17% of Colorado, 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 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 (1%) of Colorado does not currently have any drought condition.  This is great news – hopefully this area expands throughout the rest of the year.

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, millions of people 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, both options will not be available at the same time as they were 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.


2 Comments

44.9% of the Contiguous United States in Moderate or Worse Drought – 9 Jul 2013

According to the Drought Monitor, drought conditions improved recently across some of the US. As of Jul. 9, 2013, 47.3% of the contiguous US is experiencing moderate or worse drought (D1-D4), as the early 2010s drought continues month after month.  That is the lowest percentage in a number of months. The percentage area experiencing extreme to exceptional drought increased from 14.6% to 14.8%, but this is ~4% lower than it was six months ago. The eastern third of the US was wetter than normal during June, which helped keep drought at bay.  The east coast in particular was  much wetter than normal.  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.  Eight eastern states experienced their top-three wettest Junes on record.  The West is quite a different story.  Long-term drought continues to exert its hold over the region, as it remains warmer and drier than normal month after month.

 photo USDrought20130709_zpsc09f25c7.gif

Figure 1US Drought Monitor map of drought conditions as of July 9th.

If we focus in on the West, we can see recent shifts in drought categories:

 photo west_drought_monitor_20130709_zpse8877571.png

Figure 2 – US Drought Monitor map of drought conditions in Western US as of July 9th.

Early year snowmelt relief was short-lived, as drought conditions expanded as worsened in the past three months.  More than three-fourths of the West is in Moderate drought.  More than half of the West is now is Severe drought.  And one-fifth of the West is in Extreme drought.

Temporary drought relief might occur in New Mexico and southern Colorado due to the recent heavy rains brought by a retrograding low pressure system that also brought cooler than normal temperatures to Oklahoma and Texas.

Here are the conditions for Colorado:

 photo CO_drought_monitor_20130709_zps9faef3f3.png

Figure 3 – US Drought Monitor map of drought conditions in Colorado as of July 9th.

There is some evidence of relief evident over the past six months here.  Severe drought area dropped from 95-100% to 83%.  Extreme drought area dropped significantly from 53% to 39%.  Exceptional drought shifted in space from central Colorado to southeastern Colorado, which left the percentage area near 17%.  The good news for southeastern Colorado is the recent delivery of substantial precipitation.  It isn’t likely to alleviate the long-term drought, but will hopefully dent short-term drought.

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.

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.


5 Comments

47.3% of the Contiguous United States in Moderate or Worse Drought – 25 Apr 2013

According to the Drought Monitor, drought conditions improved recently across some of the US. As of Mar. 12, 2013, 47.3% of the contiguous US is experiencing moderate or worse drought (D1-D4) as the 2011-2012 drought extended well into 2013.  That is the lowest percentage in a number of months. The percentage area experiencing extreme to exceptional drought increased from 14.6% to 14.7%, but this is ~3% lower than it was three months ago. Percentage areas experiencing drought across the West decreased in the past month as a series of late season cyclones impacted the region.  Drought across the Southwest worsened slightly while rain from storms maintained the low-level of drought conditions in the Southeast.

My previous post preceded the series of major winter storm that affected much of the US.  In some places in the High Plains and Midwest, 12″ or more of snow fell.  With relatively high liquid water equivalency, each storm dropped almost ~1″ of water precipitation, of which the area was in sore need.  Unfortunately, these same areas required 2-4″ of rain to break their long-term drought.  In other words, while welcome, recent snows have reduced the magnitude of the drought in many areas, but have not completely alleviated them.  Ironically, a very different problem arose from these storms: flooding.

 photo USDrought20130425_zps91e60b7e.gif

Figure 1US Drought Monitor map of drought conditions as of April 25th.

If we focus in on the West, we can see recent shifts in drought categories:

 photo west_drought_monitor_20130425_zpsf7678347.png

Figure 2 – US Drought Monitor map of drought conditions in Western US as of April 25th.

Some relief is evident in the past month (see table on left), 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.  As you can probably tell, this is a large area experiencing abnormally dry conditions for about one year now.

Here are conditions for Colorado:

 photo CO_drought_monitor_20130425_zpsbf9ccb2d.png

Figure 3 – US Drought Monitor map of drought conditions in Colorado as of April 25th.

There is some evidence of relief evident over the past three months here.  Instead of 100% of the state in Severe drought, only 78% is today.  The central & northern mountains, as well as the northern Front Range (Denver north to the border) enjoyed the most relief since February.  The percentage area in Extreme drought also dropped significantly from 59% to 38%.  Exceptional drought shifted in space from northeastern Colorado to central Colorado while southeastern Colorado remained very dry.

Drought conditions improved somewhat across the southwestern portion of the state in the past couple of weeks.  The percentage area that is experiencing less than Severe drought conditions continues to track downward, which is a good sign.  Unfortunately, Exceptional drought conditions continued their hold over the eastern plains.

Here are conditions for the High Plains states:

 photo high_plains_drought_monitor_20130425_zps845616a5.png

Figure 4 – US Drought Monitor map of drought conditions in the High Plains as of April 25th.

The large storms that moved over this area in the past month reduced the worst drought conditions across Nebraska, South Dakota, and Wyoming.  The percentage area with Exceptional drought dropped from 27% to 7%; Extreme drought dropped from 61% to 28%; and Severe drought dropped from 87% to 70%.

With rather significant areas still experiencing moderate or worse drought across much of the US west of the Mississippi River, drought remains a serious concern in 2013.  I previously hypothesized that much of the 2012 drought was partly a result of natural climate variability and underlying long-term warming.  I wrote about NOAA’s examination into the causes of the 2012 drought a couple of weeks ago in which the authors suggested it was not heavily influenced by long-term warming.

US drought conditions are more influenced by Pacific and Atlantic sea surface temperature conditions.  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.

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 when they turn 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 we will find 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.


4 Comments

51.4% of the Contiguous United States in Moderate or Worse Drought – 12 Mar 2013

According to the Drought Monitor, drought conditions improved recently across some of the US. As of Mar. 12, 2013, 51.4% of the contiguous US is experiencing moderate or worse drought (D1-D4).  That is the lowest percentage in a number of months. The percentage area experiencing extreme to exceptional drought increased from 17.7% to 16.5% in the last month. Percentage areas experiencing drought across the West stayed mostly the same while snowpack generally increased. Drought across the Southwest decreased slightly and rain from storms improved drought conditions in the Southeast.

My previous post preceded a major winter storm that affected much of the US.  In some places in the High Plains and Midwest, 12″ or more of snow fell.  With relatively high liquid water equivalency, this snow represented ~1″ of water precipitation.  Unfortunately, these same areas required 2-4″ of rain to break their long-term drought.  In other words, while welcome, recent snows have not substantially reduced drought severity affecting the middle of the nation, as the following map shows.

 photo USDrought20130312_zps72bb93c6.gif

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

If we focus in on the West, we can see recent shifts in drought categories:

 photo west_drought_monitor_20130312_zps8abffb70.png

Figure 2 – US Drought Monitor map of drought conditions in Western US as of the 12th of March.

Some small relief is evident in the past couple of weeks, 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.  As you can probably tell, this is a large area experiencing abnormally dry conditions for almost a year now.

Here are conditions for Colorado:

 photo CO_drought_monitor_20130312_zps0a6b5cbd.png

Figure 3 – US Drought Monitor map of drought conditions in Colorado as of the 12th of March.

Drought conditions improved somewhat across the southwestern portion of the state in the past couple of weeks.  The percentage area that is experiencing less than Severe drought conditions continues to track downward, which is a good sign.  Unfortunately, Exceptional drought conditions continued their hold over the eastern plains.

Here are conditions for the High Plains states:

 photo high_plains_drought_monitor_20130312_zpsa5bbbbdc.png

Figure 4 – US Drought Monitor map of drought conditions in the High Plains as of the 12th of March.

Again, even with large snowfalls in the past month, little drought relief is evident across this region.  What these states need are frequent soaking rains in the spring and summer to alleviate their long-term drought.  Agriculture certainly could use that relief this year.

And finally the area that experienced the most relief in the past month, the Southeast:

 photo southeast_drought_monitor_20130312_zps8dcedfaf.png

Figure 5 – US Drought Monitor map of drought conditions in the Southeast as of the 12th of March.

The shifts in the numbers in the table tell a good story.  Frequent storms tracked over this region recently, which helped bust the worst conditions (Severe and worse).  Look at the ‘None’ category now versus three months ago: the percent area doubled!  Now the rains need to continue through the rest of the year.

US drought conditions are related to Pacific and Atlantic sea surface temperature conditions.  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 Nino-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.

As drought affects regions differentially, their policy responses vary.  A growing number of water utilities recognize the need to be proactive with respect to drought impacts.  The last thing they want is their reliability to suffer.  Americans are privileged in that clean, fresh water flows when they turn their tap.  Crops continue to show up at their local stores despite terrible conditions in many areas of their own nation.  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.  Warmer conditions include warmer water today than what existed 30 years ago.  Warmer water into a plant either mean warmer water out or a longer time spent in the plant, which reduces the amount of energy the plant can produce.  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.


4 Comments

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.

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

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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.

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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.

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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.


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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.

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

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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.

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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.

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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.

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

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Figure 6ENSO 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).


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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.

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

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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.

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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.

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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.

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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.

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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.

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Figure 7Arctic 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.


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Agricultural and Economic Effects of US Drought

In the wake of the hottest year on record for the contiguous US:

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Figure 1 – NOAA Graph showing year-to-date average US temperatures from 1895-2012.

Plus extensive moderate and worse drought conditions across the US agricultural region heading into early 2013:

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Figure 2 – US Drought Monitor map of drought conditions as of the 8th of January.

The US Department of Agriculture released estimates for 2013 crops.  The larger picture isn’t pretty, as the link explains.  Due to climatological as well as global market pressures, crop prices have risen leading up to 2013.  We can expect those prices to rise further in 2013, especially if there is limited or nonexistent drought relief.  Consider the following:

Corn prices are 3x what the average price from 1988-2006.

Soybean prices are more than 2X their average price from 1988-2006.

Wheat prices are more than 2X their average price from 1988-2006.

If nothing else, we will likely see a great deal of price volatility in crop prices in 2013.  But any further price increases will pinch most of our bank accounts more so than they already are.  This is another downstream effect of climate change and the lack of a national climate policy.  Moreover, how are farmers supposed to stay afloat if they never take climate change effects (record high temperatures and widespread drought) into account?  As elected officials in D.C. continue to think there is not enough political capital in return for climate change action, crop prices double and triple, impacting every person in the country.  We need to remove the politicization surrounding the issue.

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