Climate & Climate Change

Temperatures in the Arctic are rising far faster than in other parts of the world. Climate models produced by the Intergovernmental Panel on Climate Change (IPCC), which are tuned to reproduce the human-made greenhouse effect, predict the region should have warmed by 1.4 °C between 1960 and 2000. In fact, the Arctic’s average air temperature rose by 2.2 °C.

Vladimir Semenov of the Obukhov Institute of Atmospheric Physics in Moscow, Russia, says that ocean currents carrying warm water from lower latitudes into polar regions could have played a part in this increase. He analysed air temperature data from the north Atlantic, which revealed a cyclic pattern of highs and lows over the past century. He argues the length of such cycles must be explained by ocean currents, which also fluctuate over a timescale of decades.

Between 1970 and 2000, the average temperature of the northern hemisphere increased by 0.5 °C. Semenov calculates that the natural process he outlined may have been responsible for around 0.2 °C.

New Scientist Environment: Arctic currents may be warming the world (subscription required to read full article).

Conference poster: A mechanism for the early 20th century warming in the Arctic: a missing link Lennart Bengtsson, Vladimir A. Semenov and Ola M. Johannessen

Thanks to Luke for alerting us to this interesting research.

One of the basic working rules in empirical science is the Donald Duck Factor, that when something novel looks, waddles and sounds like a duck, then in all probability it might also be a duck, or at least of the same species. And when a similar structure or shape is found in two disparate phenomena, there is a good chance that both might be formed by a similar process. Such might be in the case of tropical cyclones and spiral galaxies.

cyclone Nargis

spiral galaxy

It is cyclone season in the northern hemisphere of the equatorial regions and yet again humanity has discovered how puny it is in the face of a tropical cyclone when Cyclone Nargis devastated parts of Burma recently. However tropical cyclones, or hurricanes, are not well understood weather phenomena and the formation of tropical cyclones is the topic of extensive ongoing research.

A spiral galaxy is a one belonging to one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work “The Realm of the Nebulae” and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk of stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside in globular clusters.

The origin of the spiral arms in galaxies is not as easy to identify as one may first think. After all, whatever it is that creates the spiral arms must be able to account for a wide variety of spiral structures. Some galaxies have a well-organised spiral structure (grand design spirals), while others are patchy (flocculent spirals). The arms may be wound tightly around the galaxy or may be more open. Some spiral arms originate at the end of bars, others directly from the galactic bulge.

Louis Hissink
Perth

The once-green Sahara turned to desert over thousands of years rather than in an abrupt shift as previously believed, according to a study on Thursday that may help understanding of future climate changes. And there are now signs of a tiny shift back towards greener conditions in parts of the Sahara, apparently because of global warming, said the lead author of the report about the desert’s history published in the journal Science. The findings, about one of the biggest environmental shifts of the past 10,000 years, challenge past belief based on evidence in marine sediments that a far quicker change created the world’s biggest hot desert.

Reuters: Sahara dried out slowly, not abruptly: study

Science: Climate-Driven Ecosystem Succession in the Sahara: The Past 6000 Years

Abstract:

Desiccation of the Sahara since the middle Holocene has eradicated all but a few natural archives recording its transition from a “green Sahara” to the present hyperarid desert. Our continuous 6000-year paleoenvironmental reconstruction from northern Chad shows progressive drying of the regional terrestrial ecosystem in response to weakening insolation forcing of the African monsoon and abrupt hydrological change in the local aquatic ecosystem controlled by site-specific thresholds. Strong reductions in tropical trees and then Sahelian grassland cover allowed large-scale dust mobilization from 4300 calendar years before the present (cal yr B.P.). Today’s desert ecosystem and regional wind regime were established around 2700 cal yr B.P. This gradual rather than abrupt termination of the African Humid Period in the eastern Sahara suggests a relatively weak biogeophysical feedback on climate.

A TOP Indian advocacy group that monitors climate change in south Asia warned last night that the Nargis cyclone that devastated Burma was “a sign of things to come”, as climate change caused extreme weather to increase in intensity.

“Nargis is a sign of things to come. Last year, Bangladesh was devastated by the tropical cyclone Sidr,” CSE director Sunita Narain said in a statement.

“The victims of these cyclones are climate change victims and their plight should remind the rich world that it is doing too little to contain its greenhouse gas emissions.”

The Australian: Cyclone ‘is a sign of things to come’

Meanwhile:

The 20 Deadliest Tropical Cyclones in World History

Notice: All but one or two occurred before so called “global warming”.

http://www.wunderground.com/hurricane/deadlyworld.asp

Rank: Name / Areas of Largest Loss: Year: Ocean Area: Deaths:

1. Great Bhola Cyclone, Bangladesh 1970 Bay of Bengal 550,000
2. Hooghly River Cyclone, India and Bangladesh 1737 Bay of Bengal 350,000
3. Haiphong Typhoon, Vietnam 1881 West Pacific 300,000
3. Coringa, India 1839 Bay of Bengal 300,000
5. Backerganj Cyclone, Bangladesh 1584 Bay of Bengal 200,000
6. Great Backerganj Cyclone, Bangladesh 1876 Bay of Bengal 200,000
7. Chittagong, Bangladesh 1897 Bay of Bengal 175,000
8. Super Typhoon Nina, China 1975 West Pacific 171,000
9. Cyclone 02B, Bangladesh 1991 Bay of Bengal 140,000
10. Great Bombay Cyclone, India 1882 Arabian Sea 100,000
11. Hakata Bay Typhoon, Japan 1281 West Pacific 65,000
12. Calcutta, India 1864 Bay of Bengal 60,000
13. Swatlow, China 1922 West Pacific 60,000
14. Barisal, Bangladesh 1822 Bay of Bengal 50,000
15. Sunderbans coast, Bangladesh 1699 Bay of Bengal 50,000
16. Bengal Cyclone, Calcutta, India 1942 Bay of Bengal 40,000
17. Canton, China 1862 West Pacific 37,000
18. Backerganj (Barisal), Bangladesh 1767 Bay of Bengal 30,000
19. Barisal, Bangladesh 1831 Bay of Bengal 22,000
20. Great Hurricane, Lesser Antilles Islands 1780 Atlantic 22,000
21. Devi Taluk, SE India 1977 Bay of Bengal 20,000
21. Great Coringa Cyclone, India 1789 Bay of Bengal 20,000

Death counts from large killer cyclones are highly uncertain, particulary for those before 1900. The above rankings are somewhat speculative. Information sources: Banglapedia, Wikipedia, and Encyclopedia of Hurricanes, Typhoons, and Cyclones (1999), by David Longshore.

Talking carbon claptrap isn’t helping the victims of the natural disaster in Burma.

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BOULDER – Computer analyses of global climate have consistently overstated warming in Antarctica, concludes new research by scientists at the National Center for Atmospheric Research (NCAR) and Ohio State University. The study can help scientists improve computer models and determine if Earth’s southernmost continent will warm significantly this century, a major research question because of Antarctica’s potential impact on global sea-level rise.

The study was published on April 5 in Geophysical Research Letters. It was funded by the National Science Foundation, NCAR’s primary sponsor, and the Department of Energy.

The authors compared recently constructed temperature data sets from Antarctica, based on data from ice cores and ground weather stations, to 20th century simulations from computer models used by scientists to simulate global climate. While the observed Antarctic temperatures rose by about 0.4 degrees Fahrenheit (0.2 degrees Celsius) over the past century, the climate models simulated increases in Antarctic temperatures during the same period of 1.4 degrees F (0.75 degrees C).

The error appeared to be caused by models overestimating the amount of water vapor in the Antarctic atmosphere, the new study concludes. The reason may have to do with the cold Antarctic atmosphere handling moisture differently than the atmosphere over warmer regions.

This map of Antarctica shows the approximate boundaries of areas that have warmed or cooled over the past 35 years. The map is based on temperatures in a recently-constructed data set by NCAR scientist Andrew Monaghan and colleagues. The data combines observations from ground-based weather stations, which are few and far between, with analysis of ice cores used to reveal past temperatures. (Illustration by Steve Deyo, UCAR.)

Read the entire NCAR News Release: Climate Models Overheat Antarctica, New Study Finds
May 07, 2008

Study Title: “Twentieth century Antarctic air temperature and snowfall simulations by IPCC climate models”
Authors: Andrew Monaghan, David Bromwich, and David Schneider

Publication: Geophysical Research Letters, April 5, 2008

Abstract:

We compare new observationally-based data sets of Antarctic near-surface air temperature and snowfall accumulation with 20th century simulations from global climate models (GCMs) that support the Intergovernmental Panel on Climate Change Fourth Assessment Report. Annual Antarctic snowfall accumulation trends in the GCMs agree with observations during 1960–1999, and the sensitivity of snowfall accumulation to near-surface air temperature fluctuations is approximately the same as observed, about 5% K−1. Thus if Antarctic temperatures rise as projected, snowfall increases may partially offset ice sheet mass loss by mitigating an additional 1 mm y−1 of global sea level rise by 2100. However, 20th century (1880–1999) annual Antarctic near-surface air temperature trends in the GCMs are about 2.5-to-5 times larger-than-observed, possibly due to the radiative impact of unrealistic increases in water vapor. Resolving the relative contributions of dynamic and radiative forcing on Antarctic temperature variability in GCMs will lead to more robust 21st century projections.

In part 1 of this series ‘Measuring the Surface Air Temperature’ I wrote that James Hansen of NASA’s Goddard Space Institute explains that it is not easy to measure surface air temperature particularly in the presence of vegetation because the temperature above the vegetation may be very different from the temperature below the vegetation.

So, I thought, maybe it is easier to measure the surface temperature where there is not much vegetation, for example, at the Antarctic.

But apparently knowing the average temperatures on Antarctica has its own challenge including the sparseness of ground-based weather stations particularly in the continent’s high altitude interior and the harsh environment also takes its toll on equipment.

So NASA relies on satellites that measure energy radiated from the ice surface and estimate a level of uncertainty in these measurements between 2-3 degree Celsius (read more here).

Given this level of uncertainty I find it extraordinary that NASA can suggest a warming trend of a fraction of a degree over the last 20 years in the following image.

Bill Kininmonth, former head of Australia’s Bureau of Meteorology’s National Climate Centre, recently emailed me that because it is very difficult to assess surface temperature over ice surfaces using satellite radiometers it is more realistic to consider sea surface temperatures and to also exclude regions of seasonal sea ice.

In the same email he provided the following image of the sea surface temperatures.

Bill also explained that the Larsen B ice shelf at the Antarctic shattered rather than melted earlier this year, with the comment “shattering is not related to melting”.