El Nino

El Nino to El Nino – no net global warming

uahdec2016

The Earth experienced two super El Ninos recently: 1997/1998 and 2015/2016. It was expected that 2016 would be the hottest year in the satellite record which begins in 1979. It was, but by only 0.02°C over 1998. That is not statistically significant according to Dr. Roy Spencer, keeper of the UAH satellite system data. (The margin of error is 0.1°C, much larger than the difference between the El Nino years.) The graph above shows the UAH results. A separate satellite analysis by Remote Sensing Systems (RSS) came to the same conclusion.

Satellites measure the temperature of the lower troposphere, the portion of the atmosphere where weather takes place. These measurements give a more realistic picture of global temperature than do surface measurements. Essentially, global temperature now is the same as it was nearly 18 years ago.

The earlier El Nino had a sharp drop off as a strong La Nina cooling took effect. The 2016/2017 La Nina appears to has started in mid December, 2016, and we can expect more cooling during the first half of 2017, but the current La Nino is expected to be weaker.

The media may still proclaim 2016 as the hottest year ever (in a cherry-picked time frame). For some perspective on that let’s see a longer perspective.

CCIP fig1

One thing the media may not mention is that our carbon dioxide emissions seem to have had no effect on global temperature. This was recently noted by Australian Jo Nova in her article “Since 2000 humans have put out 30% of their total CO2 but there is nothing to show for it.” There has been an 18-year “pause” in global warming.

If CO2 is supposed to be the principal cause of global warming, why hasn’t this great outpouring of CO2 had a noticeable effect? According to the Department of Energy, “Since 1751 approximately 337 billion metric tonnes of carbon have been released to the atmosphere from the consumption of fossil fuels and cement production. Half of these emissions have occurred since the mid 1970s.” And 30% have occurred since the 1997/1998 El Nino. There is no indication that all this CO2 is producing global warming.

global-co2-human-emissionsBoth North America and Europe are experiencing record cold weather. The North Atlantic Ocean has been rapidly cooling since the mid-2000s. (Source) Also, Solar activity is now at a low point as the current cycle winds down. Many scientists are confident the next cycle will also be a weak one. Periods of weak solar cycles are associated with periods of global cooling.

It seems that any alleged warming effect that CO2 may have is overwhelmed by natural variation in climate.

See also:

An Illustrated Guide to El Nino and La Nina

 

NOAA’s trouble with numbers and the hottest year

[This is an updated version of an article originally published in the Arizona Daily Independent.]

On January 20, 2016, the National Oceanic Atmospheric Administration and NASA announced that 2015 was by far the hottest year in 136 years of record keeping. NOAA said 2015’s global temperature average was 58.62 degrees Fahrenheit.(Source)

Apparently, NOAA did not check its own temperature record, because their report on 1997 (another El Nino year) said that the global average temperature was 62.45 degrees Fahrenheit (and it was touted as the warmest year on record). (Source) Here is a screen capture, just in case the 1997 report disappears:

NOAA 1997 global temp

Even in the new math of “Common Core” 62.45 is still larger than 58.62.

NOAA bases its projections on surface temperatures and completely ignores satellite data. The satellites have been in operation since 1979. The UAH satellites show that 2015 is the third warmest year in the period, whereas the RSS satellite system puts 2015 in fourth place.

NOAA and NASA have been systematically “adjusting” the surface temperature record, making the past cooler so the present seems warmer, see The past is getting cooler and Temperature trends published by NOAA 50% too high.

Some caveats on the numbers game:

Just how does one calculate the average global temperature? Think about that. Is the number really of any use?

NOAA and NASA usually show temperature anomalies rather than true temperature. They pick a base period and report how measured temperatures depart from that base average. For instance, for 2015 NOAA reports: “During 2015, the average temperature across global land and ocean surfaces was 1.62°F (0.90°C) above the 20th century average.” How does one determine a global average for the 20th century? NOAA and NASA also report numbers based on 30-year baselines. In 1997, NOAA used a base period of 1961-1990. Moving the goal posts of those base periods can lend itself to much mischief. “Without the adjustments and homogenization, the post-1960 US temperatures would be indistinguishable from the early 20th century.” David Middleton [link]

To put the 2015 global temperature in perspective, let’s take a look at the entire Holocene period. From this perspective 2015 looks like the 8000th warmest year.

 Cuffey and Clow

It seems that our Federal “scientists” are more into political science. “It is difficult to get a man to understand something, when his salary depends upon his not understanding it!”- Upton Sinclair.

UPDATE:

Dr. Roy Spencer writes:

Land measurements …that thermometers over land appear to have serious spurious warming issues from urbanization effects. Anthony Watts is to be credited for spearheading the effort to demonstrate this over the U.S. where recent warming has been exaggerated by about 60%, and I suspect the problem in other regions of the global will be at least as bad. Apparently, the NOAA homogenization procedure forces good data to match bad data. That the raw data has serious spurious warming effects is easy to demonstrate…and has been for the last 50 years in the peer-reviewed literature….why is it not yet explicitly estimated and removed?

– Ocean Measurements …that even some NOAA scientists don’t like the new Karlized ocean surface temperature dataset that made the global warming pause disappear; many feel it also forces good data to agree with bad data. (I see a common theme here.)

– El Nino …that a goodly portion of the record warmth in 2015 was naturally induced, just as it was in previous record warm years.

– Thermometers Still Disagree with Models …that even if 2015 is the warmest on record, and NOAA has exactly the right answer, it is still well below the average forecast of the IPCC’s climate models, and something very close to that average forms the basis for global warming policy. In other words, even if every successive year is a new record, it matters quite a lot just how much warming we are talking about.

I’m not claiming our satellite dataset is necessarily the best global temperature dataset in terms of trends, even though I currently suspect it is closer to being accurate than the surface record — that will be for history to decide. The divergence in surface and satellite trends remains a mystery, and cannot (in my opinion) continue indefinitely if both happen to be largely correct.

But since the satellites generally agree with (1) radiosondes and (2) most global reanalysis datasets (which use all observations radiosondes, surface temperatures, commercial aircraft, satellites, etc. everything except the kitchen sink), I think the fact that NOAA-NASA essentially ignores it reveals an institutional bias that the public who pays the bills is becoming increasingly aware of.

And this brings up the elephant in the room that I have a difficult time ignoring.

By now it has become a truism that government agencies will prefer whichever dataset supports the governments desired policies. You might think that government agencies are only out to report the truth, but if that’s the case, why are these agencies run by political appointees?

I can say this as a former government employee who used to help NASA sell its programs to congress: We weren’t funded to investigate non-problems, and if global warming were ever to become a non-problem, funding would go away. I was told what I could and couldn’t say to Congress…Jim Hansen got to say whatever he wanted. I grew tired of it, and resigned.

UPDATE 2:

NOAA’s own data show that temperatures of the stratosphere have been declining and temperatures of the troposphere have remained level since 1980.
See: http://www.star.nesdis.noaa.gov/smcd/emb/mscat/index.php

An Illustrated Guide to El Nino and La Nina and how they control climate

Bob Tisdale, author of Who Turned on the Heat?, has produced an excellent explanation of the solar-driven El Nino-La Nino events that arise in the Pacific Ocean and control global weather and climate on annual, decadal, and multidecadal time frames.

His long post contains 29 illustrations that take you through the process (three illustrations are reproduced below). Tisdale also provides explanatory text. I have read many papers on El Nino-La Nina (collectively called ENSO) and think Tisdale’s presentation is the most lucid and understandable explanation of the interplay between trade winds and ocean currents and their effects on ocean and air temperatures. It is aimed at the layman. Give it a look, read the whole post here.
A free preview of Tisdale’s book, in pdf format, is available here. The whole book is available for purchase here.

El Nino

ENSO neutral

La Nina

Droughts in the Southwest put in perspective

The severe drought in Texas this year has fueled speculation that alleged human-caused global warming has somehow caused “unprecedented” conditions. But real research data show that the current drought is not unprecedented and is part of a natural cycle. There have been much more severe and persistent droughts in the past before humans began emitting signification amounts of carbon dioxide into the atmosphere. This post focuses on research from the University of Arizona and the Lamont-Doherty Earth Observatory of Columbia University.

From the University of Arizona and Arizona State University we have “A 1,200-year perspective of 21st century drought in southwestern North America.”

The Abstract reads in part:

A key feature of anticipated 21st century droughts in Southwest North America is the concurrence of elevated temperatures and increased aridity. Instrumental records and paleoclimatic evidence for past prolonged drought in the Southwest that coincide with elevated temperatures can be assessed to provide insights on temperature-drought relations and to develop worst-case scenarios for the future. In particular, during the medieval period, AD 900–1300, the Northern Hemisphere experienced temperatures warmer than all but the most recent decades. Paleoclimatic and model data indicate increased temperatures in western North America of approximately 1 °C over the long-term mean. This was a period of extensive and persistent aridity over western North America. Paleoclimatic evidence suggests drought in the mid-12th century far exceeded the severity, duration, and extent of subsequent droughts. The driest decade of this drought was anomalously warm, though not as warm as the late 20th and early 21st centuries. The convergence of prolonged warming and arid conditions suggests the mid-12th century may serve as a conservative analogue for severe droughts that might occur in the future. The severity, extent, and persistence of the 12th century drought that occurred under natural climate variability, have important implications for water resource management. The causes of past and future drought will not be identical but warm droughts, inferred from paleoclimatic records, demonstrate the plausibility of extensive, severe droughts, provide a long-term perspective on the ongoing drought conditions in the Southwest, and suggest the need for regional sustainability planning for the future.

This paper goes on to discuss the role of El Niño-La Niña cycles and sea-surface temperature, but the paper does not really address cause of the droughts. The theme of this paper is that past droughts are associated with warm periods and that continued warming may portend more severe droughts in our future. However, the authors partly contradict themselves by saying that the more severe droughts of the Medieval period occurred when the temperatures were cooler than the current warm period.

It seems we have a complex interplay of natural cycles which are not completely understood.

From Cornell, we have “The characteristics and likely causes of the Medieval megadroughts in North America.” and a very interesting graph:

Droughts in the west

  This graph shows that while the current drought is severe, it is much less severe than droughts during the Medieval Warm Period, a time before humans were emitting much carbon dioxide into the atmosphere.

The paper presents three conclusions:

1) The similarity of the spatial patterns suggests that the physical processes that caused the modern droughts also caused the medieval megadroughts.

2) The global atmosphere ocean conditions that currently cause modern droughts for a few years at a time were the prevailing ocean climate during the medieval period.

2) Despite the shift in the mean tropical ocean climate ENSO variability continued as now but oscillating about a colder mean state.

The authors also present an archaeological speculation:

The medieval megadroughts may also have left their signature on the human environment of the West. The great cliff cities in the four corners region of the West such as at Chaco Canyon and Mesa Verde were all abandoned towards the end of the drought. These societies were based on irrigated agriculture. Although there remains much debate about why these highly organized Indian societies collapsed, archaeologists are revisiting the idea that decades of dry conditions were part of the reason.

With both papers we see that data collection is one thing, interpretations are another.

See also:

Drought in the West

El Niño, bristlecone pines, and drought in the Southwest

EL NINO behavior, climate models predict opposite of what really happens

El Nino incites wars and the Post Office controls temperature

This post shows the length to which some researchers go to get on the climate change bandwagon. It also shows that statistics can be invented and manipulated, and that correlation does not prove causation.

El Nino incites wars:

We have a paper titled: “Civil conflicts are associated with the global climate” published in Nature (Vol. 476, 25 August 2011). Full paper here.

In the paper, the three researchers use statistical methods to correlate civil wars in countries throughout the world with the El Nino (warm phase) of the El Nino/Southern Oscillation (ENSO).

From their abstract:

Historians have argued that ENSO may have driven global patterns of civil conflict in the distant past, a hypothesis that we extend to the modern era and test quantitatively. Using data from 1950 to 2004, we show that the probability of new civil conflicts arising throughout the tropics doubles during El Nino years relative to La Nina years. This result, which indicates that ENSO may have had a role in 21% of all civil conflicts since 1950, is the first demonstration that the stability of modern societies relates strongly to the global climate.

Doesn’t that mean El Nino had no role in 79% of all civil conflicts? So what is the real purpose of this paper?   This study is purely a statistical manipulation which pays no attention to socioeconomic data in the countries studied.

The authors invent a statistic which they call the “annual conflict risk” (ACR). To calculate that statistic:

We examine the Onset and Duration of Intrastate Conflict data set 17,which codes a country as experiencing ‘conflict onset’ if more than 25 battle-related deaths occur in a new civil dispute between a government and another organized party over a stated political incompatibility. Following common practice, a dispute is new if it has been at least 2 years since that dispute was last active; however, individual countries may experience conflict onset in sequential years if the government has disputes with different opposition groups.

Here is their graph correlating ACR with El Nino:

ACR-vs-elnino

 Not a bad apparent correlation. But, is this correlation a reflection of cause and effect, data manipulation, or merely coincidence? The study period is relatively short. Would the relation hold over a longer period? You can read the paper and decide. Notice also, that many of the ACR highs appear to precede the El Nino highs – oops.

According to the paper, this study was partially funded by the Environmental Protection Agency, the Soros Foundation, and the Environmental Defense Fund, organizations not known for their scientific integrity.

The Post Office controls temperature:

To show that correlations can develop by chance, no matter how absurd the relationship, I present a graph showing the correlation of U.S. first-class postage rates versus temperature for the period 1880 to 2005:

us_post_causes_global_warming_lrg

 The graph implies that there is a causal relationship. If so, then the Post Office has the solution to global warming: reduce first class postage cost back to 25 cents.

By massaging data and using statistics, you can find correlations (or anti-correlations if that is your goal) for almost anything.

For some real information on El Nino behavior versus climate models see here.

EL NINO behavior, climate models predict opposite of what really happens

The El Nino/La Nina cycle, more formally known as the El Nino/Southern Oscillation (ENSO) is an irregular cycle of sea surface temperature, atmospheric pressure, and wind direction in the tropical Pacific Ocean which has a profound affect on global weather. Both floods and droughts are associated with phases of ENSO.

ENSO2

 El Nino (warm phase)

In South America, this warm phase suppresses the normally cold upwelling currents that bring fish to the coasts of Peru and Ecuador. This phase brings unusually warm and wet weather during the South American winter.

In North America, El Nino brings warm, dry winters and wet summers to the northern region, and much wetter winters to the southwestern U.S. and northern Mexico.

Australia can experience droughts.

La Nina (cool phase)

In South America, La Nina brings drought to Peru and Chile but more rain to northern Brazil. In North America, La Nina brings above average precipitation to the north (hence our heavy snowfall during the winter of 2010-2011) and average to much below average precipitation to the southern U.S.

The influence of La Nina reaches Africa and produces more precipitation in south Africa and dryer conditions in equatorial Africa.

Climate models fail

Climate models, which are based on the assumption that carbon dioxide has a positive feedback, i.e., that carbon dioxide causes significant warming, make predictions on the behavior of ENSO. An analysis of those predictions versus what actually happened shows that the climate models predicted almost the exact opposite of what really happened.

Citation: McPhaden, M. J., T. Lee, and D. McClurg (2011), El Niño and its relationship to changing background conditions in the tropical Pacific Ocean, Geophys. Res. Lett., 38, L15709, doi:10.1029/2011GL048275

The abstract reads:

This paper addresses the question of whether the increased occurrence of central Pacific (CP) versus Eastern Pacific (EP) El Niños is consistent with greenhouse gas forced changes in the background state of the tropical Pacific as inferred from global climate change models. Our analysis uses high-quality satellite and in situ ocean data combined with wind data from atmospheric reanalyses for the past 31 years (1980–2010). We find changes in background conditions that are opposite to those expected from greenhouse gas forcing in climate models and opposite to what is expected if changes in the background state are mediating more frequent occurrences of CP El Niños. A plausible interpretation of these results is that the character of El Niño over the past 31 years has varied naturally and that these variations projected onto changes in the background state because of the asymmetric spatial structures of CP and EP El Niños.

In another paper:

Wolter, K. and Timlin, M.S. 2011. El Niño/Southern Oscillation behavior since 1871 as diagnosed in an extended multivariate ENSO index (MEI.ext). International Journal of Climatology 31: 1074-1087.

The researchers were able to extend analysis of ENSO events back to 1871 and found: “none of the behavior of recent ENSO events appears unprecedented, including duration, onset timing, and spacing in the last few decades compared to a full century before then.” Climate models predict that ENSO events should become more frequent and intense with global warming.

In other words, the climate model assumption of a positive feedback for carbon dioxide is wrong. And once again there is evidence that our carbon dioxide emissions have little actual effect on global temperature, and, there is still no physical evidence that carbon dioxide does have a significant effect. We, therefore, should not be basing policy decisions on flawed model scenarios.

ENSO is just one of several recognized oscillations driven by the sun and the earth’s position relative to the sun. To see other oscillations go here.

See Tisdales guide: An Illustrated Guide to El Nino and La Nina

See also:

A Basic Error in Climate Models

Climate Model Projections vs Real World Observations

Climate Data, Fact or Fiction

Natural Climate Cycles

NASA satellite data show climate models are wrong – again

Carbon Dioxide and the Greenhouse Effect

Humans and the Carbon Cycle

El Niño, bristlecone pines, and drought in the Southwest

While the Southwest is experiencing drought conditions, unusual flooding is occurring along the Mississippi River.  This is part of the natural La Niña cycle.

Research from the University of Hawaii’s International Pacific Research Center  has found an 1100-year correlation between El Niño-La Niña cycles and tree rings in bristlecone pines in the American Southwest.  This may allow better prediction of the cycles and a better understanding of past cycles and their implications.

El Niño and its partner La Niña, the warm and cold phases in the eastern half of the tropical Pacific,  play havoc with  climate worldwide. Predicting El Niño events more than several months ahead is now routine, but predicting how it will change  in a warming world has been hampered by the short instrumental record. An international team of climate scientists has now shown that annually resolved tree-ring records from North America, particularly  from  the US Southwest, give a continuous representation of the intensity of El Niño events over the past 1100 years and can be used to improve El Niño prediction.

Tree rings in the US Southwest, the team found, agree well with the 150-year instrumental sea surface temperature records in the tropical Pacific. During El Niño, the unusually warm surface temperatures in the eastern Pacific lead to changes in the atmospheric circulation, causing unusually wetter winters in the US Southwest, and thus wider tree rings; unusually cold eastern Pacific temperatures during La Niña lead to drought and narrower rings. The tree-ring records, furthermore, match well existing reconstructions of the El Niño-Southern Oscillation and correlate highly, for instance, with [oxygen 18] isotope concentrations of both living corals and corals that lived hundreds of years ago around Palmyra in the central Pacific.

The graph below shows the correlation.

El nino amplitude from tree rings

The tree rings reveal that the intensity of El Niño has been highly variable, with decades of strong El Niño events and decades of little activity. The weakest El Niño activity happened during the Medieval Climate Anomaly in the 11th  century, whereas the strongest activity has been since the 18th  century.

These different periods of El Niño activity are related to long-term changes in Pacific climate. Cores taken from lake sediments in the Galapagos, northern Yucatan, and the Pacific Northwest reveal that the eastern–central tropical Pacific climate swings between warm and cool phases, each lasting from 50 to 90 years. During warm phases, El Niño and La Niña events were more intense than usual. During cool phases, they deviated little from the long-term average as, for instance, during the Medieval Climate Anomaly when the eastern tropical Pacific was cool.

While correlation does not necessarily prove causation, these results are compelling.  Many factors such as temperature and amount of precipitation affect the width of tree rings.  The researchers say in this case, that precipitation is the controlling factor.  They rely on Liebig’s Law  which states that yield is proportional to the amount of the most limiting nutrient, and in the desert southwest, water is the limiting factor.

We are currently experiencing the La Niña phase which means a dry southwest and colder, wetter conditions in the north and mid-west.

For more background on drought see: Drought in the West.

Winter Snowstorms and Global Warming

The heavy snowstorms in the northern hemisphere this winter have been blamed on global warming. Al Gore says so; the New York Times says so; ABC news says so; the Washington Post says so; even Science Daily News said so.

But, the CSI team (climate scene investigators) at the National Oceanic and Atmospheric Administration (NOAA) says not so.

NOAA says:

They found no evidence — no human ‘fingerprints’ — to implicate our involvement in the snowstorms. If global warming was the culprit, the team would have expected to find a gradual increase in heavy snowstorms in the mid-Atlantic region as temperatures rose during the past century. But historical analysis revealed no such increase in snowfall. Nor did the CSI team find any indication of an upward trend in winter precipitation along the eastern seaboard.”

The CSI team turned its attention to natural factors that control the ordinary ups and downs of weather. Many extreme weather events are due to cyclical, large-scale anomalies in air pressure and sea surface temperature across large tracts of ocean. Such fluctuations spawn weather systems that can cause droughts, floods, and massive snowstorms. While El Niño is the most famous, scientists have identified other climate anomalies throughout Earth’s climate system as well. Their names may seem unimpressive — the Arctic Oscillation, North Atlantic Oscillation, Pacific Decadal Oscillation, to name a few — but they can pack quite a punch!

The CSI team focused on two suspects known to be at large this winter — the negative phase of the North Atlantic Oscillation (NAO) and El Niño. El Niño, with its warming of tropical Pacific Ocean temperatures, may be best known for delivering heavy rains across the southern United States. El Niño events can trigger mudslides in California, floods along the Gulf Coast, and unusual warmth and drought in the Pacific Northwest. The latter should sound familiar: an unusually warm winter from Portland to Seattle was part of the same climate pattern affecting the venue of the Winter Olympics. The CSI Team suspected that El Niño was a conspirator in the United States’ unusual winter weather, and that it had an accomplice.

The North Atlantic Oscillation is a fluctuating air-pressure pattern that alternatively enhances or blocks the storm-steering jet stream over North America. So the NAO is particularly relevant in understanding eastern U.S. wintertime climate variations. The NAO describes the contrast in surface air pressure between Iceland and the Azores as well as the vigor of the jet stream that normally flows between them.

The CSI team focused on two suspects known to be at large this winter — the negative phase of the North Atlantic Oscillation (NAO) and El Niño. El Niño, with its warming of tropical Pacific Ocean temperatures, may be best known for delivering heavy rains across the southern United States. El Niño events can trigger mudslides in California, floods along the Gulf Coast, and unusual warmth and drought in the Pacific Northwest. The latter should sound familiar: an unusually warm winter from Portland to Seattle was part of the same climate pattern affecting the venue of the Winter Olympics. The CSI Team suspected that El Niño was a conspirator in the United States’ unusual winter weather, and that it had an accomplice.

False-color map showing El Niño pattern of sea-surface height anomalies in the equatorial Pacific Ocean on February 15, 2010. Higher areas, shown in red, are warmer than average, and lower areas, shown in blue, are cooler than average. White areas show average heights and temperatures. Image courtesy of NASA Earth Observatory.

The North Atlantic Oscillation is a fluctuating air-pressure pattern that alternatively enhances or blocks the storm-steering jet stream over North America. So the NAO is particularly relevant in understanding eastern U.S. wintertime climate variations. The NAO describes the contrast in surface air pressure between Iceland and the Azores as well as the vigor of the jet stream that normally flows between them.

The winter of 2009-10 witnessed the most extreme negative (blocked) NAO phase since at least 1950. (Graph courtesy of Marty Hoerling, NOAA Earth System Research Lab.)

This winter the NAO was in its negative phase and the jet stream flowed further south than usual, pushed toward the Azores by a massive “block” of high surface pressure over Greenland. It’s an unusual atmospheric circulation pattern, but one that has been implicated before. For example, remarkably cold winters persisted over Europe and Russia in the early 1940s, helping to turn the tide of World War II. The NAO, in a blocked phase, was one conspirator in those cold events. Likewise, the CSI Team suspected the pattern was a co-conspirator in the extreme winter weather conditions this year in the mid-Atlantic region. But could they find the evidence they would need to finger El Niño and NAO?

See here for the rest of NOAAs story.

See also the Rutgers University global snow lab. There you can click on a series of graphs showing snowfall data for the northern hemisphere since 1967. You will see that snowfall in 1978 exceeded the current winter so far.

Hurricanes, are the numbers unusual?

With hurricane Earl sweeping up the East Coast, we might ask if, in recent years, we have experienced an unusual number of hurricanes. According to the meteorology department of the University of Florida, tropical cyclone activity remains at a 30-year low, see graph below.

global_major_freq 1978-2014

The Florida University study says, “August ACE for the Northern Hemisphere was 63 which is much less than the climatological average of 115. The Western Pacific again was much below average. It was indeed the Atlantic that produced two long-lived storms, Danielle and Earl that picked up some of the slack. The global and NH ACE remains at/near 30-year lows.”

ACE is the “accumulated cyclone energy” which is a measure used by NOAA to express the activity of a cyclone, and is an approximation of the system’s total energy.

Some researchers correlate hurricane frequency with sea surface temperatures. Holland and Webster, for instance, report: “We find that long-period variations in tropical cyclone and hurricane frequency over the past century in the North Atlantic Ocean have occurred as three relatively stable regimes separated by sharp transitions. Each regime has seen 50% more cyclones and hurricanes than the previous regime and is associated with a distinct range of sea surface temperatures (SSTs) in the eastern Atlantic Ocean.” They were studying the period 1850 to present, see graph below (gray line is SST).

Hurricane-frequency

A longer study, however, concludes that El Nino and the West African Monsoon controls hurricanes in the Atlantic. (Donnelly, J.P. and Woodruff, J.D. 2007. Intense hurricane activity over the past 5,000 years controlled by El Niño and the West African Monsoon. Nature 447: 465-468.) These researchers, from Woods Hole Oceanographic Institution, based their study on sea sediment cores and corals. They found three major intervals of intense hurricane strikes: one between 5,400 and 3,600 calendar years before present, one between 2,500 and 1,000 yr BP, and one after 250 yr BP. They also say that “an analysis of Caribbean hurricanes documented in Spanish archives indicates that 1766-1780 was one of the most active intervals in the period between 1500 and 1800, when tree-ring-based reconstructions indicate a negative (cooler) phase of the Atlantic Multidecadal Oscillation.”

So, are there more hurricanes now than in the past? The answer seems to depend on the time period studied. Overall, neither the number of hurricanes nor their frequency is unusual.

Oceans Warmer?

A front page story in the Arizona Daily Star today (9-2109) proclaims “World’s Oceans Warmer Than Ever.” Well, not exactly, it depends on which data set you are reading.  The graph below from NOAA (NOAA’s ERSST.v3b version) shows that past July ocean temperatures have exceeded current values.

To see an analysis of this Associated Press story, see http://tinyurl.com/mautss

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