The year 2005 was the warmest year in over a century, according to NASA scientists studying temperature data from around the world.

Climatologists at NASA’s Goddard Institute for Space Studies (GISS) in New York City noted that the highest global annual average surface temperature in more than a century was recorded in their analysis for the 2005 calendar year.

Some other research groups that study climate change rank 2005 as the second warmest year, based on comparisons through November. The primary difference among the analyses, according to the NASA scientists, is the inclusion of the Arctic in the NASA analysis. Although there are few weather stations in the Arctic, the available data indicate that 2005 was unusually warm in the Arctic.

In order to figure out whether the Earth is cooling or warming, the scientists use temperature data from weather stations on land, satellite measurements of sea surface temperature since 1982, and data from ships for earlier years.

Previously, the warmest year of the century was 1998, when a strong El Nino, a warm water event in the eastern Pacific Ocean, added warmth to global temperatures. However, what’s significant, regardless of whether 2005 is first or second warmest, is that global warmth has returned to about the level of 1998 without the help of an El Nino.

The result indicates that a strong underlying warming trend is continuing. Global warming since the middle 1970s is now about 0.6 degrees Celsius (C) or about 1 degree Fahrenheit (F). Total warming in the past century is about 0.8° C or about 1.4° F.

“The five warmest years over the last century occurred in the last eight years,” said James Hansen, director of NASA GISS. They stack up as follows: the warmest was 2005, then 1998, 2002, 2003 and 2004.

Over the past 30 years, the Earth has warmed by 0.6° C or 1.08° F. Over the past 100 years, it has warmed by 0.8° C or 1.44° F.

Current warmth seems to be occurring nearly everywhere at the same time and is largest at high latitudes in the Northern Hemisphere. Over the last 50 years, the largest annual and seasonal warmings have occurred in Alaska, Siberia and the Antarctic Peninsula. Most ocean areas have warmed. Because these areas are remote and far away from major cities, it is clear to climatologists that the warming is not due to the influence of pollution from urban areas.

Original press release: 2005 Warmest Year in Over a Century (NASA)

Today at 21.00 CEST Mr Yuri Bakhvalov, First Deputy Director General of the Khrunichev Space Centre on behalf of the Russian State Commission officially confirmed that the launch of CryoSat ended in a failure due to an anomaly in the launch sequence and expressed his regret to ESA and all partners involved.

Preliminary analysis of the telemetry data indicates that the first stage performed nominally. The second stage performed nominally until main engine cut-off was to occur. Due to a missing command from the onboard flight control system the main engine continued to operate until depletion of the remaining fuel.

As a consequence, the separation of the second stage from upper stage did not occur. Thus, the combined stack of the two stages and the CryoSat satellite fell into the nominal drop zone north of Greenland close to the North Pole into high seas with no consequences to populated areas.

An investigating commission by the Russian State authorities has been established to further analyze the reasons for the failure, results are expected within the next weeks. This commission will work in close cooperation with a failure investigation board consisting of Eurockot, ESA and Khrunichev representatives.

This information is released at the same time by Eurockot and ESA.

Original press release: CryoSat Mission lost due to launch failure (ESA) 

Open University researchers have uncovered startling new evidence about an extreme period of a sudden, fatal dose of global warming some 180 million years ago during the time of the dinosaurs. The scientists’ findings could provide vital clues about climate change happening today and in the future.

The OU Department of Earth Sciences team, PhD student Dave Kemp and supervisors Drs. Angela Coe and Anthony Cohen, along with Dr. Lorenz Schwark of the University of Cologne, discovered evidence suggesting that vast amounts of methane gas were released to the atmosphere in three massive ‘methane burps’ or pulses. The addition of methane, a greenhouse gas, to the atmosphere had a severe impact on the environment, warming Earth about 10 C, and resulting in the extinction of a large number of species on land and in the oceans.

Dr Angela Coe says: “We’ve known about this event for a few years through earlier work by our team and others, but there’s been a great deal of uncertainty about its precise size, duration, and underlying cause. What our present study shows is that this methane release was not just one event, but 3 consecutive pulses. Importantly, our data demonstrate that each individual pulse was very rapid. Also, whilst the methane release was very quick, we’ve found that the recovery took much longer, occurring over a few hundred thousand years”.

The methane came from gas hydrate, a frozen mixture of water and methane found in huge quantities on the seabed. This hydrate suddenly melted, allowing the methane to escape. The OU researchers based their findings on geochemical analyses of mudrocks that are preserved along the Yorkshire coast near Whitby, UK, and date from the Jurassic Period of geological time.

Dave Kemp, whose PhD is funded by the Natural Environment Research Council (NERC), says: “The methane was released because slight wobbles in the Earth’s orbit periodically bring our planet closer to the Sun, warming the oceans sufficiently to melt the vast reserves of hydrate. We believe that this effect was compounded by warming from greenhouse gases from volcanoes. After the methane was released into the atmosphere from the seabed it reacted rapidly with oxygen to form carbon dioxide. Carbon dioxide is also a powerful greenhouse gas that persists in the atmosphere for many hundreds of years, and it was this gas which caused such a massive global warming effect”.

Dr Anthony Cohen adds: “One of the most important aspects of the study is that it provides an accurate timescale for how the Earth, and life, reacted to a sudden increase in atmospheric carbon dioxide. Today we are releasing large amounts of carbon dioxide to the atmosphere, primarily through the burning of fossil fuels. It is possible that the rate at which carbon dioxide is being added to the atmosphere now actually outstrips the rate at which it was added 180 million years ago. Given that the effects were so devastating then, it is extremely important to understand the details of past events in order to better comprehend present-day climate change. With this information, we are better informed about what action needs to be taken to mitigate or avoid some of the potential detrimental future effects”.

Original press release: Earth’s Wobble Burps (NASA – Open University)

ESA’s Envisat satellite has been continuously observing the Earth with a suite of ten instruments for the last three and a half years. A major workshop is about to bring together users of Envisat’s two most complementary sensors: MERIS, which acquires multispectral imagery of the planet’s ocean, land and atmosphere, and AATSR, a radiometer measuring global surface and cloud temperatures down to a fraction of a degree.

The five-day MERIS/AATSR Workshop is scheduled to take place in ESRIN, the European Centre for Earth Observation in Frascati overlooking Rome, from Monday 26 September. More than 200 Principal Investigators from over 30 countries, including ESA’s 17 member states and Canada, as well as India, New Zealand, Nigeria and Japan are expected to attend. There will be 90 presentations during the Workshop and around 65 posters on show. The Medium Resolution Imaging Spectrometer (MERIS) takes visible-light images of the precise ‘colour’ of the ocean and coastal zones, enabling determination of the biological and sediment loading of the water.

The instrument also acquires land-based images showing land use and vegetation cover. Because these images are acquired in up to 15 spectral bands, they provide additional environmental information such as chlorophyll levels, plant health and local geology. MERIS can also monitor the distribution of atmospheric aerosols and otherwise invisible water vapour concentrations.

The Advanced Along Track Scanning Radiometer (AATSR) also has a visible-light imaging capability for land surfaces and atmospheric clouds and aerosols, but its view also extends further than that of MERIS into near and thermal-infrared wavelengths.

Working day and night AATSR measures global sea surface temperature (SST) to an accuracy of 0.3º K, constantly extending a 14-year satellite dataset commenced by predecessor ATSR instruments flown aboard ERS-1 and 2. The top two metres of the ocean alone contain more energy than the entire atmosphere, and so this long, continuous time-series of SST data is important for predicting the magnitude of climate change. AATSR also delivers land-based images, and is especially sensitive to soil moisture, vegetation extent and anomalous heat sources such as volcanoes or the central cores of forest fires.

AATSR is also used to study clouds and aerosol concentrations in the atmosphere. It has a dual view design which means it can takes forward as well as nadir-looking images. Because its twin views of the same scene pass through different atmospheric path lengths, the instrument has an enhanced ability to estimate and correct for distortion effects from the atmosphere – information which could potentially be applied to improve MERIS data quality in turn.

“Following on from a successful MERIS event in November 2003, this Workshop is an opportunity for us to have a dialogue with the scientific community,” explains Workshop organiser Peter Regner of ESA. “The event will begin with updates on the status of the spacecraft and instruments, data quality and dissemination. The emphasis then splits to us receiving ideas from the users – in particular what can be done with the MERIS and AATSR datasets. Research utilising data from one or both sensors will be presented over a series of thematic sessions.

“We are particularly interested in stimulating discussion on what can be done by merging data from the two instruments. For MERIS products over land we still need to improve our algorithms to deal with the effects of atmospheric aerosols, and here it is possible that merging MERIS with AATSR data could be a way forward.”

Researchers already combine results from the two sensors in many cases. While MERIS detects smoke and burned areas from wildfires, AATSR can identify central hot spots. The spread of colourful phytoplankton blooms across the face of the sea can be better forecast utilising SST data. And merged optical and thermal infrared views of the sea and the clouds above it give an enhanced understanding of the dynamics of storms and hurricanes.

The workshop will include training sessions for using the software tools used to process images from both sensors – known as the Basic ERS & Envisat AATSR and MERIS (BEAM) toolbox. An additional half-day course will cover how to programme new processing algorithms using the BEAM Application Programming Interface as a basis.

Original press release: MERIS/AATSR Workshop: focus on Envisat sensors measuring heat and light (ESA)

The number of Category 4 and 5 hurricanes worldwide has nearly doubled over the past 35 years, even though the total number of hurricanes has dropped since the 1990s, according to a study by researchers at the Georgia Institute of Technology and the National Center for Atmospheric Research (NCAR). The shift occurred as global sea surface temperatures have increased over the same period. The research appears in the September 16 issue of Science.

Peter Webster, professor at Georgia Tech’s School of Earth and Atmospheric Sciences, along with NCAR’s Greg Holland and Georgia Tech’s Judith Curry and Hai-Ru Chang, studied the number, duration, and intensity of hurricanes (also known as typhoons or tropical cyclones) that have occurred worldwide from 1970 to 2004. The study was supported by the National Science Foundation (NSF), NCAR’s primary sponsor.

“What we found was rather astonishing,” said Webster. “In the 1970s, there was an average of about 10 Category 4 and 5 hurricanes per year globally. Since 1990, the number of Category 4 and 5 hurricanes has almost doubled, averaging 18 per year globally.”

Category 4 hurricanes have sustained winds from 131 to 155 miles per hour; Category 5 systems, such as Hurricane Katrina at its peak over the Gulf of Mexico, feature winds of 156 mph or more.
Katrina damage
Greg Holland. (Photo by Carlye Calvin.)

“This long period of sustained intensity change provides an excellent basis for further work to understand and predict the potential responses of tropical cyclones to changing environmental conditions”, said NCAR’s Holland.

“Category 4 and 5 storms are also making up a larger share of the total number of hurricanes,” said Curry, chair of the School of Earth and Atmospheric Sciences at Georgia Tech and coauthor of the study. “Category 4 and 5 hurricanes made up about 20% of all hurricanes in the 1970s, but over the last decade they accounted for about 35% of these storms.”

The largest increases in the number of intense hurricanes occurred in the North Pacific, Southwest Pacific, and the North and South Indian Oceans, with slightly smaller increases in the North Atlantic Ocean.

All this is happening as sea surface temperatures have risen across the globe between one-half and one degree Fahrenheit, depending on the region, for hurricane seasons since the 1970s.

“Our work is consistent with the concept that there is a relationship between increasing sea surface temperature and hurricane intensity,” said Webster. “However, it’s not a simple relationship. In fact, it’s difficult to explain why the total number of hurricanes and their longevity has decreased during the last decade, when sea surface temperatures have risen the most.”

“NCAR is now embarking on a focused series of computer experiments capable of resolving thunderstorms and the details of tropical cyclones,” said Holland. “The results will help explain the observed intensity changes and extend them to realistic climate change scenarios.”

The only region that is experiencing more hurricanes and tropical cyclones overall is the North Atlantic, where they have become more numerous and longer-lasting, especially since 1995. The North Atlantic has averaged eight to nine hurricanes per year in the last decade, compared to six to seven per year before the increase. Category 4 and 5 hurricanes in the North Atlantic have increased at an even faster clip: from 16 in the period of 1975-89 to 25 in the period of 1990-2004, a rise of 56%.

A study published in July in the journal Nature came to a similar conclusion. Focusing on North Atlantic and North Pacific hurricanes, Kerry Emanuel (Massachusetts Institute of Technology) found an increase in their duration and power, although his study used a different measurement to determine a storm’s power.

But whether all of this is due to human-induced global warming is still uncertain, said Webster. “We need a longer data record of hurricane statistics, and we need to understand more about the role hurricanes play in regulating the heat balance and circulation in the atmosphere and oceans.”

“Basic physical reasoning and climate model simulations and projections motivated this study,” said Jay Fein, director of NSF’s climate and large scale dynamics program, which funded the research. “These results will stimulate further research into the complex natural and anthropogenic processes influencing these tropical cyclone trends and characteristics.”

Webster is currently attempting to determine the basic role of hurricanes in the climate of the planet. “The thing they do more than anything is cool the oceans by evaporating the water and then redistributing the oceans’ tropical heat to higher latitudes,” he said.

“But we don’t know a lot about how evaporation from the ocean surface works when the winds get up to around 100 miles per hour, as they do in hurricanes,” said Webster, who adds that this physical understanding will be crucial to connecting trends in hurricane intensity to overall climate change.

“If we can understand why the world sees about 85 named storms a year and not, for example, 200 or 25, then we might be able to say that what we’re seeing is consistent with what we’d expect in a global warming scenario. Without this understanding, a forecast of the number and intensity of tropical storms in a future warmer world would be merely statistical extrapolation.”

Original press release: Hurricanes Are Getting Stronger, Study Says (UCAR)

Until now satellites have not been able to monitor melting of ice at the very point where it is most significant: at the ice edge. CryoSat’s ability to do just that thrills scientists working in the field.

“CryoSat will pave the way for a better understanding of what happens to the ice at the exact point where things are the most interesting: at the ice edge where the majority of the melting takes place,” says Danish glaciologist Carl Egede Bøggild.

Part of the Geological Survey of Denmark and Greenland (GEUS) Bøggild heads a large-scale monitoring programme on the Greenland Ice. The programme utilises a combination of on-site measurements and satellite data.

“In principle you would prefer satellite data when you want to monitor large-scale developments,” explains Bøggild. “However it has been a major problem that satellites have had trouble monitoring the very ice edge zone.”

In order to measure the thickness of a given ice layer, a radar altimeter satellite emits a radar signal and later records it being reflected back out to space. The time taken for the signal to return can be utilised to calculate the exact ice height, from which its thickness can in turn be derived.

However the topography at the edge of an ice sheet can be very steep and uneven, making it difficult for the satellite to catch the reflected signal, or know precisely from which point within the ten-kilometre signal ‘footprint’ the signal is returning from. Often the uncertainty would be too large for the results to be reliable. The practical implication was that the entire ice edge remained inaccessible for satellite monitoring.

However the science team behind CryoSat has managed to tackle this problem. Its double-antenna design means it can measure the angle of the returning signal to put an exact location on where it comes from relative to the spacecraft track. The satellite will still be able to carry out its measurements, no matter how steep the ice surface may be.

“To my mind the ice edge is the most interesting place to do science,” the Danish glaciologist states. “In the middle of the inland ice things are very stable. As climate changes, the edge is where you will be able to observe the effect first.

“American airborne measurements have shown a thinning of the Greenland glaciers by one metre per year. However our measurements on location at the ice edge show melting on an even larger scale. Now we are anxious to learn what the measurements from CryoSat will show.”

According to on-site measurements the Sermilik glacier in Southern Greenland is thinning between two and eight metres a year. Not all of this change is linked to climate change caused by human activities. The glaciologist compares the inland ice to dough for making a loaf of bread laid out on a kitchen table: “You see a slow movement from the middle towards the edge. In the case of the inland ice it may take thousands of years from a snow flake falls in the centre until it reaches the edge.

“You might say that the system has a certain built-in memory. Some of the melting we witness now is actually an aftermath of the last, mini Ice Age which ended in the last half of the 19th century”.

Systematic monitoring of air temperature has taken place since 1875. Comparing the temperature levels with the actual melting one can determine that about half of the melting is linked to changes in climate. The other half will then have other causes – primarily the aftermath of the last Ice Age.

The Danish ice monitoring effort has found thinning of large areas of the inland ice. That goes for practically the entire ice edge zone. One interesting twist to the story is that in some areas thinning is taking place despite a drop in mean temperatures.

“This goes to show the complexity of the system,” Bøggild adds. “Normally one would use the number of days with temperatures above zero degrees as an indicator of melting. Generally these two factors would be linked. However factors other than temperature may also be influencing melting. One of them is the amount of incoming solar radiation. This would make it possible to see these kind of surprising results locally”.

Despite his great expectations for CryoSat, Carl Egede Bøggild underlines that satellites will not replace ground measurements: “Satellites will give us a far more accurate view of the amount of melting but they will not tell us why the melting is taking place. In order to improve your understanding of the causes you have to do research on site. Also we will have to keep on doing measurements on site in order to verify the findings of the satellites. We are talking about two different kinds of tools supplementing each other very well.”

Original press release: CryoSat: the ice edge holds the key (ESA)