Amazon rainforest recovering from its second 100-year drought in 5 years

By: Dr. Jeff Masters , 2:32 PM GMT on December 03, 2010

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Life-giving rains have returned over the past two months to Earth's greatest rainforest--the mighty Amazon--after it experienced its second 100-year drought in five years this year. The record drought began in April, during the usual start to the region's dry season, when rainfall less than 75% of average fell over much of the southern Amazon (Figure 2.) The drought continued through September, and by October, when the rainy season finally arrived, the largest northern tributary of the Amazon River--the Rio Negro--had dropped to thirteen feet (four meters) below its usual dry season level. This was its lowest level since record keeping began in 1902. The low water mark is all the more remarkable since the Rio Negro caused devastating flooding in 2009, when it hit an all-time record high, 53 ft (16 m) higher than the 2010 record low. The 2010 drought is similar in intensity and scope to the region's previous 100-year drought, which hit the Amazon in 2005, according to Brazil's National Institute of Space Research. Severe fires burned throughout the Amazon in both 2005 and 2010, leading to declarations of states of emergencies.


Figure 1. Hundreds of fires (red squares) generate thick smoke over a 1000 mile-wide region of the southern Amazon rain forest in this image taken by NASA's Aqua satellite on August 16, 2010. The Bolivian government declared a state of emergency in mid-August due to the out-of-control fires burning over much of the country. Image credit: NASA.

Causes of the great 2010 Amazon drought
During the 20th Century, drought was a frequent visitor to the Amazon, with significant droughts occurring an average of once every twelve years. These droughts typically occurred during El Niño years, when the unusually warm waters present along the Pacific coast of South America altered rainfall patterns. But 2010 was a La Niña year. The 100-year drought of 2005 occurred in an El Niño-neutral year. Subsequent analysis of the 2005 drought revealed that it was unlike previous El Niño-driven droughts, and instead was caused by record warm sea surface temperatures in the Atlantic (Phillips et al., 2009.) These warm ocean waters affected the southern 2/3 of the Amazon though reduced precipitation and higher than average temperatures. Very similar record Atlantic sea surface temperatures were observed in 2010, and likely were the dominant cause for the 2010 drought.


Figure 2. The great Amazon drought of 2010 began in April, when portions of the southern Amazon recorded precipitation amounts less than 75% of normal (brown colors). The drought spread northward and peaked during July and August, but drew to a close by November when the rainy season began. Image credit: NOAA Climate Prediction Center.

The importance of the Amazon to Earth's climate
We often hear about how important Arctic sea ice is for keeping Earth's climate cool, but the Amazon may be even more important. Photosynthesis in the world's largest rainforest takes about 2 billion tons of carbon dioxide out of the air each year. However, in 2005, the drought reversed this process. The Amazon emitted 3 billion tons of CO2 to the atmosphere, causing a net 5 billion ton increase in CO2 to the atmosphere--roughly equivalent to 16 - 22% of the total CO2 emissions to the atmosphere from burning fossil fuels that year. According to Phillips et al., 2009, "The exceptional growth in atmospheric CO2 concentrations in 2005, the third greatest in the global record, may have been partially caused by the Amazon drought effects documented here." The Amazon stores CO2 in its soils and biomass equivalent to about fifteen years of human-caused emissions, so a massive die-back of the forest could greatly accelerate global warming. In late 2009, before the 2010 drought, the World Wildlife Federation released a report, Major Tipping Points in the Earth's Climate System and Consequences for the Insurance Sector, which suggested that odds of extreme 2005-like droughts in the Amazon had increased from once every 40 - 100 years, to once every 20 years. The study projected that the extreme droughts would occur once every two years by 2025 - 2050. This year's drought gives me concern that this prediction may be correct. The occurrence of two extreme droughts in the past five years, when no El Niño conditions were present and record warm Atlantic sea surface temperatures occurred, are suggestive of a link between global warming and extreme Amazon drought. If the climate continues to warm as expected, the future health of Earth's greatest rainforest may be greatly threatened, and the Amazon may begin acting to increase the rate of global warming. According to Rosie Fisher, a scientist at the National Center for Atmospheric Research in Boulder, Colorado who specializes in interactions between climate and forests, "I'm genuinely quite alarmed by this. In some ways it kind of reminds me of when they figured out than the Greenland ice sheet was melting much faster than the climate models predicted it would."

Deforestation in Brazilian Amazon falls to lowest rate on record
There is some good news from the Amazon--deforestation rates in the Brazilian Amazon have fallen 14% in the past year, and are at their lowest rate on record, according to mongabay.com, an environmental science and conservation news site that focuses on tropical forests. In 2009, Brazil passed a law committing to a 36 - 39% reduction in emissions of greenhouse gases. Reducing deforestation by 80% by 2020 was the primary method envisioned to achieve the reduction. Brazil is now four years ahead of that schedule, and no longer is the world's biggest deforester--Indonesia now cuts down more acreage of forest each year than Brazil does.

For more information
Nick Sundt at the WWF Climate Blog has a remarkably detailed post on this year's Amazon drought, and Dr. Joe Romm at climateprogress.org has another excellent post.

Phillips, et al., 2009, Drought Sensitivity of the Amazon Rainforest, Science 6 March 2009: Vol. 323 no. 5919 pp. 1344-1347 DOI: 10.1126/science.1164033.

I'll have new post Monday or Tuesday.

Jeff Masters

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396. eddye
where is everybody sleeping
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Quoting pottery:

Oh, OK! Thanks.
Got my wires crossed on that one...
Nah...There probably just wet...:)
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This morning's reminder: just 176 days, eight hours, and 52 minutes until the start of the 2011 hurricane season.

It'll be warm again before you know it...
Member Since: November 8, 2009 Posts: 4 Comments: 13529
393. eddye
jeff 9641
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Quoting KEEPEROFTHEGATE:


maybe 50 of these might be nice for up on the roof to go with the fans
Be more original. It's already been done.
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391. eddye
if i live in weston do u think i will see frost in the morning and also so december 18 when i go to orlando will it be cold
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Complete Update





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At least 140 missing after Colombia landslide

BOGOTA -- At least 140 people were missing in Colombia late Sunday after heavy rains caused a landslide in the northwest of the Andean nation, according to local reports.

Colombia has been experiencing torrential downpours due to the La Nina weather phenomenon. The rains and floods have killed around 170 people so far this year, mostly in recent months, and affected 1.5 million others.

More...
Member Since: November 8, 2009 Posts: 4 Comments: 13529
388. IKE
A gallon of gasoline...

Average per-gallon prices in other cities:

Albuquerque, New Mexico: $2.75

Atlanta, Georgia: $2.84

Baltimore, Maryland: $2.90

Chicago, Illinois: $3.09

Miami, Florida: $2.96

Minneapolis, Minnesota: $3.03

Philadelphia, Pennsylvania: $3.02

Portland, Oregon: $2.99

San Francisco, California: $3.19

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386. eddye
jeff 9641 how cold does the gfs show miami geting into tonight and also does the models show more cold air coming after this our is it over for a while
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383. jb410
Bring it on...
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380. jb410
I guess he was right...
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379. jb410


Here is a scene from outside my window in South Miami...
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maybe 50 of these might be nice for up on the roof to go with the fans
Member Since: July 15, 2006 Posts: 171 Comments: 53827
Quoting Jeff9641:


More like January I believe. December wasn't that bad last year just very rainy because of El-Nino.



Sure would be nice to get the southern branch involved with some of this cold air, like last year!
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Quoting KEEPEROFTHEGATE:
cold enough yet now for my next trick hmmmmm



Next tricK!

Do tell!
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didn't we have some very cold weather in December last year? Or was it November?

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Quoting PensacolaDoug:
AGW gonna freeze us to death!
cold enough yet now for my next trick hmmmmm
Member Since: July 15, 2006 Posts: 171 Comments: 53827
370. jb410
Ahhh, geeez... first, civilization ending hurricanes, and now, blizzards and frozen wastelands. Wow.
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For West Palm Beach

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AGW gonna freeze us to death!
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seen it colder this time of yr might see alot more cold before we burn up from gm
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364. IKE
Heads up for next weekend....6Z GFS @ 174 hours....another plunge of arctic air into the deep south....


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MINIMUM TEMPS DEC 7 DEC 8 DEC 9 (RECORDS/FORECASTED)

BELLE GLADE 31/31 32/35 33/38

CANAL POINT 40/36 34/35 38/39

CLEWISTON 44/32 42/32 40/44

DEVILS GARDEN 37/31 37/32 37/33

FORT LAUDERDALE 42/38 43/41 46/46

LA BELLE 37/29 36/28 34/33

MIAMI 35/40 38/42 43/46

MOORE HAVEN 35/30 38/29 34/35

NAPLES 41/38 42/38 43/39

WEST PALM BEACH 36/32 43/36 41/40
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Good morning...

This is going to be a very cold week in CFL... upper 20's for a couple days... sure is unusual this early.
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361. IKE
From Tallahassee discussion.....

A FEW
AREAS COULD SEE SOME MINIMUM RECORDS TIED OR BROKEN. THE FOLLOWING
ARE SELECTED RECORD LOW TEMPERATURES FROM AROUND THE REGION:




LOCATION DEC 7TH DEC 8TH

TALL. AIRPORT 18 22
ALBANY 27 25
VALDOSTA 25 24
CROSS CITY 26 24
DEFUNIAK SPRINGS 15 19
APALACHICOLA 27 28
DOTHAN 28 23
MOULTRIE 18 22

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360. IKE
I have a complaint to make about my area's weather forecasting(Tallahasse office). They do a poor job forecasting winds.

Saturday they forecasted winds to 10 mph. They were gusting to at least twice that. Maybe slightly more than 20 mph. I know...I was out in it for about 3 hours.

Yesterday they were calling for 10-15 mph winds. The winds were gusting to about 30 mph. They weren't even close. I take my dog out numerous times a day and it was much higher than forecasted.

Gotta do better. They do good on temps and conditions, but not winds.
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Quoting FLPandhandleJG:
Would be nice to get some snow for the gulf coast states :)



^^^ That would be nice.. if it keeps it up..


Whoa that would be awesome ^.^
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Think Snow!
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Would be nice to get some snow for the gulf coast states :)



^^^ That would be nice.. if it keeps it up..
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Quoting AWeatherLover:
Slight (and I mean slight) chance of snow looks to be in the forecast here in Baton Rouge, LA on Wednesday morning. Has been in the forecast on and off for a few days now. Wonder if it will materialize.


I've been monitoring this closely. Even if it does, do not expect any accumulation.
Member Since: March 7, 2007 Posts: 575 Comments: 20571
Slight (and I mean slight) chance of snow looks to be in the forecast here in Baton Rouge, LA on Wednesday morning. Has been in the forecast on and off for a few days now. Wonder if it will materialize.
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well I bought GRLevel3 tonight :D
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Quoting beell:


You can always invite them down to the northshore-they can bring a locust plague...

Did the rain freeze on contact?
On everything but the pavement, thankfully.

Remote start, and the Subaru, itself (AWD), were wonderful investments for a couple of days...
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352. beell
Quoting atmoaggie:
I'm going to Tulsa for Christmas, again. Last time I was in Tulsa in Dec, 3 days of 28 F and raining constantly. (Dec 2007)

Be warned of a pending freezing rain event between Christmas and New Year's...(if that happens, I'll prolly not be welcome there anymore.)


You can always invite them down to the northshore-they can bring a locust plague...

Did the rain freeze on contact?
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Quoting beell:


For sure,atmo. Usually a very tiny droplet size as a difference in rime and freezing rain. Made up of an almost fog-like super cooled droplet.
I'm going to Tulsa for Christmas, again. Last time I was in Tulsa in Dec, 3 days of 28 F and raining constantly. (Dec 2007)

Be warned of a pending freezing rain event between Christmas and New Year's...(if that happens, I'll prolly not be welcome there anymore.)
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Quoting PrivateIdaho:
And to add my 2 cents....it often snows with the temperature at ground level well above freezing. I have seen moderate snow hitting the ground (not sticking) at 42 degrees.


Yep, I don't think it's all that uncommon. Happens here with some regularity and does stick, like yesterday. It snowed an inch or so and temp was constant around 37-38F.
Member Since: September 21, 2010 Posts: 1 Comments: 3690
349. beell
Quoting atmoaggie:
Same mechanism with rime ice...


For sure,atmo. Usually a very tiny droplet size as a difference in rime and freezing rain. Made up of an almost fog-like super cooled droplet.
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And to add my 2 cents....it often snows with the temperature at ground level well above freezing. I have seen moderate snow hitting the ground (not sticking) at 42 degrees.
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Quoting beell:
There you go, DAM. Would only add that as the ice crystals melt from falling throught the warm layer and into the shallow sub-freezing layer the rain drops become super-cooled.

Liquid that is actually at or below 0&degC. They don't freeze because of an absence of ice nuclei-tiny microscopic particles of dust, salt, etc that the ice can "grow" on. Except when they strike objects on the ground. Like flagpoles and roads and weather bloggers. In effect, great big ice nuclei!
Same mechanism with rime ice...
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.