Taking the earth's temperature and the influence of ocean sea surface temperature cycles

I had a go at charting the global mean temperature trend. An interesting thing to do as it gives you an insight into all those global mean temperature graphs you see.

I started off with the GISS temperature anomaly dataset that goes from 1880 up to the present. The temperature anomaly data is provided in monthly intervals based upon a 1951-1980 baseline of 14.0 deg-C, but I really only used the data from 1970 to the present.

Using monthly data you see the extremes that sometimes occurr, both on the warm side and the cold side. I added a 12 month running average trend line (red) and a 5 year running average trendline (dark blue) to make the temperature trend clearer.

Here is the result:

Development of El Niño in 2014

The El Niño Southern Oscillation (ENSO) is one of the important cycles affecting global weather, particularly around the Pacific region, but also having indirect impacts on a global level. Changes to winds and precipitation causing floods and droughts depending upon the region. El Niño also results in increasing global average temperatures, on top of the long term trend associated with climate change.

Cost estimates in US$ for 1982-1983 El Niño
Extreme Event / Country	Cost in $millions
Flooding
Bolivia	$300
Ecuador, Northern Peru	$650
Cuba	$170
U.S. Gulf States	$1,270
Hurricanes
Tahiti	$50
Hawaii	$230
Droughts/Fires
Southern Africa	$1,000
Southern India, Sri Lanka	$150
Philippines	$450
Indonesia	$500
Australia	$2,500
Southern Peru, Western Bolivia	$240
Mexica, Central America	$600
Total Costs	$8,110 million
Source: NASA via University of California San Diego

The El Niño cycle is usually 3 to 7 years. And occasionally we'll get an extreme response, a super El Niño. The 1982-83 and 1997-1998 produced super El Niños spiked global temperatures to record levels, causing floods, drought and increasing bushfire conditions. The back to back La Nina of 2010 and 2011 was also quite strong producing Australia's wettest two year period on record and reducing global sea level by 5mm.

he 1982-1983 event has been estimated to have caused about $8.1 billion in damages and was largely unexpected without the warning and forecasting systems we have in place today.

The last Super El Niño event in 1997-1998 resulted in about 23,000 people killed as a result of ENSO linked extreme weather events and caused about $45-50 billion in losses to global agricultural output according to a Canberra Times report.

Predicting El Niño events and issuing alerts allows communities to prepare for the worst. It is essential for farmers to know the forecast for rain or drought so that crop plantings can be varied and livestock rates altered to minimise losses.

Warming may spike when Pacific Decadal Oscillation moves to a positive phase

We are currently in a negative phase of the Pacific Decadal Oscillation, a cycle with phases that can last between 15 to 30 years. During a negative phase waters are cooler and heat mixes into deeper levels of the north Pacific ocean. When the next phase change ocurrs to a positive PDO we are likely to see some of the stored ocean heat released spiking atmospheric temperatures.

The Pacific Decadal oscillation was only identified by scientists in the 1990s, and we only have accurate observational data for identifying it going back some 50-60 years. Nathan J Mantua and SR Hare from the University of Washington in Seattle described the operation of the Pacific Decadal Oscillation in the Journal of Oceanography in 2002 (Mantua & Hare 2002 PDF). Read more about the PDO from the Climate Impacts Group from University of Washington.

El Niño Southern Oscillation activity and intensity increasing with Global Warming

A study by Australian and US researchers has found robust signs that global warming is having an increasing impact on the El Niño/La Nina (ENSO) cycle which drives a significant amount of changes to global weather. The El Nino cycle has been unusually active and intense in the 30 year period from 1979 to 2009, more than any time in the last 600 years, researchers found.

"Our research suggests in a warming world we are likely to see more extreme El Niño and La Nina events, which over the past decade in Australia have been related to extreme flooding, persistent droughts and dangerous fire seasons,” said lead author Dr Shayne McGregor from the University of NSW ARC Centre of Excellence for Climate System Science.

“Importantly, this study not only tells us how ENSO activity has behaved in the past in relation to global average temperature, it also opens the window for climate models to be able to estimate more accurately how this activity will change in the future." said Dr McGregor.

Related: El Niño intensification means stronger droughts for Australia, storms for Kiribati

El Niño intensification means stronger droughts for Australia, storms for Kiribati

El Niño is likely to become more intense with climate change, and produce drier conditions for Australia and the Western Pacific, with increases in rainfall in the central and eastern equatorial Pacific in the mid to late twenty first century, according to new research.

It is the first time climate scientists have produced robust results from modelling to conclude that climate change has a substantial impact on the El Niño-Southern Oscillation (ENSO) cycle in the future. But a 2010 study by scientists from NASA and NOAA provided some signs.

So, a stronger El Niño is likely to bring more intense drying which may exacerbate drought and bushfire weather. In the central pacific island nation of Kiribati El Niño will bring more intense rain and floods. More intense Winter rain and floods may be felt in California, northwest Mexico and southwest United States, as well as down the west coast of South America, and even further afield.

Kevin Trenbeth on the 2011 Sea level Bump and Australia's wettest two year period

Did you know that during 2011 sea level rise went into reverse and lost 5mm from the global oceans? No? How about that since then, much to the chagrin of climate deniers, sea level rise has accelerated from 3.18mm per year - the rate from 1993 to 2010 - to increase to 10mm per year over the last two years. This acceleration more than makes up for the pothole. The primary cause of this sea level 'speed bump' was the back to back La Nina which moved a phenomenal amount of water from the global oceans to the land. The water has since been making it's way back into the world's oceans.

The question arises, does this explain the 10mm per year increase in sea level rise over the last 2 years? Is ocean thermal expansion or ice sheet melting perhaps contributing more? This may also be the start to an exponential sea level rise which NASA climatologist James Hansen has argued is a possibility. Rob Painting on Skeptical Science says that there is no evidence yet to suggest that ice loss from Greenland or Antarctica has added to the speed bump in any significant manner. We will have to wait and see what the impact of future El Nino or La Nina's will be on sea level rise, and keep watching the rate of mass loss from the ice sheets.

I came across this lecture by climatologist Kevin Trenbeth in which he talks about this sea level speed bump as a unique occurrence in recorded history. While previously there has been slight reductions in sea level rise corresponding to La Nina years, this event is a prominent change. Trenbeth discusses this extreme event near the end of his lecture on October 15, 2012. It is well worth watching the Youtube video if you have a spare 1 hour and 5 minutes. He provides an excellent introduction to climate change and extreme weather events and he is an animated speaker with clear and informative graphical and text slides.

Climate change causing increase in extreme weather in South Pacific

An international study led by CSIRO oceanographer Dr Wenju Cai has identified that global warming is causing shifts in the rain band of the South Pacific Convergence Zone causing an increase in extreme weather across the island nation states of the South Pacific. The result of the movement causes drought and higher prevalence of forest fire in some areas while other islands experience extreme floods and increased frequency of tropical cyclones.

"Due to its strong rainfall gradient, a small displacement in the [South Pacific Convergence Zone] SPCZ's position causes drastic changes to hydroclimatic conditions and the frequency of extreme weather events such as droughts, floods and tropical cyclones experienced by vulnerable island countries in the region." says the paper.

Sea Surface Temperatures around Australia remain elevated, La Niña builds slowly

The Sea Surface temperature Anomaly around Australia in November 2011 remains elevated. A slow cooling in the tropical mid Pacific indicates that La Niña is also slowly building. A persistently warm Indian Ocean is also a main driver for forecast wetter conditions in Australia this summer.

La Niña event likely to be strongest on record

The current La Niña weather pattern, part of the El Nino Southern Oscillation (El Nino) weather cycle that impacts weather around the Pacific, indeed around the globe, is likely to be the strongest on record, according to Professor Neville Nicholls, current President of the Australian Meteorological and Oceanographic Society.

September 2010 was Australia's wettest in 111 years

The USA based National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center have stated that September 2010 was Australia's wettest month in 111 years of precipitation records being kept.

A moderate to strong La Niña event - known scientifically as El Niño-Southern Oscillation (ENSO) - in the tropical Pacific Ocean is bringing wetter conditions across much of eastern Australia, according to the Bureau of Meteorology. "La Niña is the flipside to the well known drought-producing El Niño. It usually brings wetter than average spring and summer conditions to much of eastern Australia" said the Manager of the NSW Climate Services Centre, Clinton Rakich.

La Niña brings some rain, as Global Climate hots up

One of the important weather factors in the Pacific basin affecting global weather but particularly Pacific Rim countries is the El Niño/Southern Oscillation (ENSO). El Niño and La Niña are caused by a change in sea surface temperatures across the Pacific Ocean which affects trade wind patterns which bring rain and drought to regions around the Pacific and further afield. A La Niña condition has been developing since February 2007 and is likely to last to April 2008.

Related: El Nino-Southern Oscillation (ENSO)

La Niña operating until April 2008

In November/December 2007 we are experiencing La Niña with sea surface temperatures in the eastern tropical Pacific below average, and temperatures in the western tropical Pacific above average. La Niña brings rain to Indonesia and Australia and drought to the southwest of the United States, western Mexico, Peru and Chile. Effects are typically opposite to those associated with El Niño.

The Southern Oscillation has a global impact. NASA describes the effect as:

"Globally, La Niña is characterized by wetter than normal conditions west of the equatorial central Pacific over northern Australia and Indonesia during the northern hemisphere winter, and over the Philippines during the northern hemisphere summer. Wetter than normal conditions are also observed over southeastern Africa and northern Brazil, during the northern hemisphere winter season. During the northern hemisphere summer season, the Indian monsoon rainfall tends to be greater than normal, especially in northwest India. Drier than normal conditions are observed along the west coast of tropical South America, and at subtropical latitudes of North America (Gulf Coast) and South America (southern Brazil to central Argentina) during their respective winter seasons."

Australia: Higher than average temperatures and rainfall predicted

The widespread rains in Victoria and New South Wales over the last week were probably partly induced by La Niña. The POAMA model run daily at the Australian Bureau of Meteorology predicts "La Niña conditions to remain over the coming months, persisting until around April 2008." Read more about Australian rainfall patterns during La Niña events.

The Bureau of Meteorology is predicting higher than average temperatures over much of southern Australia from January to March 2008. The temperature on New Years Eve in Melbourne is predicted to be 38 degrees. There is also a greater chance for higher than the median rainfall "in a large area extending from southeast Queensland across both the northern inland and east of NSW. The southwest of WA also has similar chances, although it's a seasonally dry time of the year in this part of the country."

For North and South America "La Niña is the diva of drought,” explained Bill Patzert of NASA’s Jet Propulsion Laboratory. “It keeps the Pacific jet stream farther north, toward Oregon, Washington, and Canada, so the U.S. Southwest and Southeast get less moisture.”

Warmest Decade on Record

The World Meteorology Organisation announced in a press release on 13 December that the decade of 1998-2007 is the warmest on record. "The global mean surface temperature for 2007 is currently estimated at 0.41°C/0.74°F above the 1961-1990 annual average of 14.00°C/57.20°F." The statement also detailed "the record-low Arctic sea ice extent...., a relatively small Antarctic Ozone Hole; development of La Niña in the central and eastern Equatorial Pacific; and devastating floods, drought and storms in many places around the world."

"2007 global temperatures have been averaged separately for both hemispheres. Surface temperatures for the northern hemisphere are likely to be the second warmest on record, at 0.63°C above the 30-year mean (1961-90) of 14.6°C/58.3°F. The southern hemisphere temperature is 0.20°C higher than the 30-year average of 13.4°C/56.1°F, making it the ninth warmest in the instrumental record since 1850."

According to the WMO statement "Australia recorded its coldest ever June with the mean temperature dropping to 1.5°C below normal." and "while conditions were not as severely dry as in 2006, long term drought meant water resources remained extremely low in many areas. Below average rainfall over the densely populated and agricultural regions resulted in significant crop and stock losses, as well as water restrictions in most major cities."

Sea Level Rise and Greenland Ice melt Accelerating

The WMO highlighted that sea level continues to rise "substantially above the average for the 20th century of about 1.7 mm per year." According to satellite measurements "global averaged sea level has been rising at about 3 mm per year" since 1993. This comes hot on the news that the melting of the Greenland icecap is accelerating according to study by the Steffen Research Group from the University of Colorado at Boulder. "The amount of ice lost by Greenland over the last year is the equivalent of two times all the ice in the Alps, or a layer of water more than one-half mile deep covering Washington, D.C." said lead climate scientists Konrad Steffen. "The more lubrication there is under the ice, the faster that ice moves to the coast," said Steffen. "Those glaciers with floating ice 'tongues' also will increase in iceberg production." Greenland ice melt currently contributes to global sea levels by about 0.5 millimeters per year. Some climate scientists like James Hansen believe the Greenland ice sheet may disintegrate within 100 years leading to a sea level rise of several metres.

Sources:

* NASA Earth Observatory La Nina for November. See also from February 2007 El Nino May Be Morphing to La Nina and in October 2007 La Nina Strenghtens in Autumn 2007
* NASA Earth Observatory La Niña Factsheet
* Bureau of Meteorology El Nino-Southern Oscillation (ENSO)
* Bureau of Meteorology Dec 17, 2007 - Warmer season favoured in southern Australia
* Bureau of Meteorology Dec 17, 2007 - Mixed March quarter rainfall outlook
* World Meteorological Organization Dec 13, 2007Press Release No 805
* NASA Earth Observatory - Media Alert Dec 11, 2007 GREENLAND MELT ACCELERATING, ACCORDING TO CU-BOULDER STUDY