Global temperatures hit critical point, warn scientists

Tierney Smith in EcoWatch: As 2015 shapes up to be the hottest year on record, scientists warn the world could be halfway towards surpassing countries’ self-set red line of 2C temperature rise.  New research commissioned by the New Scientist shows that four out of the five major surface temperature records are set to pass the 1C point this year, measured from the 1850-1899 average.

At 1C climate change is already affecting the world’s poorest and most vulnerable populations as warming brings escalating sea level rise and more intense and volatile weather extremes. Rising temperatures and changing weather patterns already increase heat-related illnesses, enhance the spread of disease, reduce crop yields and threaten access to clean water and could result in forced migration, conflict and social disruption.

Bold climate action will save huge numbers of lives and produce significant cost savings in the health sector. Direct health impacts from climate change are expected to cost the world US$2-4 billion a year by 2030.

2014 was the hottest year since records began. Now with an El Nino underway and predicted to intensify, it looks as if the glob
al average surface temperature could jump by around 0.1C in just one year. And, 2015 is “shaping up to smash the old record.”

The latest research underscores the urgency for government’s to act and the solutions are ready and waiting....

A Chinese heat wave alert sign 

Warming of oceans due to climate change is unstoppable, say US scientists

Suzanne Goldenberg in the Guardian (UK): The warming of the oceans due to climate change is now unstoppable after record temperatures last year, bringing additional sea-level rise, and raising the risks of severe storms, US government climate scientists said on Thursday.

The annual State of the Climate in 2014 report, based on research from 413 scientists from 58 countries, found record warming on the surface and upper levels of the oceans, especially in the North Pacific, in line with earlier findings of 2014 as the hottest year on record.

Global sea-level also reached a record high, with the expansion of those warming waters, keeping pace with the 3.2 ± 0.4 mm per year trend in sea level growth over the past two decades, the report said. Scientists said the consequences of those warmer ocean temperatures would be felt for centuries to come – even if there were immediate efforts to cut the carbon emissions fuelling changes in the oceans.

“I think of it more like a fly wheel or a freight train. It takes a big push to get it going but it is moving now and will contiue to move long after we continue to pushing it,” Greg Johnson, an oceanographer at Noaa’s Pacific Marine Environmental Laboratory, told a conference call with reporters.

“Even if we were to freeze greenhouse gases at current levels, the sea would actually continue to warm for centuries and millennia, and as they continue to warm and expand the sea levels will continue to rise,” Johnson said....

Ocean warming leads to stronger precipitation extremes

A press release from the Helmholtz Centre for Ocean Research-Kiel: Due to climate change, not only atmospheric, but also oceanic, temperatures are rising. A study published in the international journal Nature Geoscience led by scientists at the GEOMAR Helmholtz Centre for Ocean Research Kiel shows that increases in sea surface temperature can contribute to the development of stronger precipitation events. Their findings are underpinned by flash-flooding in June in the Olympic city of Sochi, Russia.

That the temperatures on our planet are rising is clear. In particular, the increasing emissions of greenhouse gases such as carbon dioxide continue to warm the atmosphere. The effects of global warming on the hydrological cycle, however, are still not fully understood. Particularly uncertain is how the strength of extreme summertime thunderstorms have changed, and how it may change in the future. In coastal regions neighboring warm seas, the sea surface temperature can play a crucial role in the intensity of convective storms. The Black Sea and eastern Mediterranean have warmed by about 2 C since the early 1980s. Russian and German scientists investigated what impact this warming may have had on extreme precipitation in the region.

“Our showcase example was a heavy precipitation event from July 2012 that took place in Krymsk (Russia), near the Black Sea coast, resulting in a catastrophic flash food with 172 deaths”, said Edmund Meredith, lead author of the study. “We carried out a number of very-high-resolution simulations with an atmospheric model to investigate the impact of rising sea surface temperatures on the formation of intense convective storms, which are often associated with extreme rainfall”, Meredith continued. Simulations of the event with observed sea surface temperatures showed an increase in precipitation intensity of over 300%, compared to comparable simulations using sea surface temperatures representative of the early 1980s.  “We were able to identify a very distinct change, which demonstrates that convective precipitation responds with a strong, non-linear signal to the temperature forcing”, Prof. Douglas Maraun, co-author of the study added.

At the end of June 2015, the nearby Olympic city of Sochi experienced an unusually intense precipitation event. Over 175 mm of rain was recorded in 12 hours, showing the relevance of the scientists work.  “Due to ocean warming, the lower atmosphere has become more unstable over the Black Sea and eastern Mediterranean. We therefore expect that events like those in Krymsk or Sochi will become more frequent in the future”, added the Kiel-based climate scientist.

Rain near a San Francisco beach, shot by the incomporable Brocken Inaglory, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Volcanic eruptions slow down climate change - temporarily

Space Daily via SPX: Although global concentration of greenhouse gases in the atmosphere has continuously increased over the past decade, the mean global surface temperature has not followed the same path. A team of international reseachers, KIT scientists among them, have now found an explanation for this slowing down in global warming: the incoming solar radiation in the years 2008-2011 was twice as much reflected by volcanic aerosol particles in the lowest part of the stratosphere than previously thought. ....

For the lowest part of the stratosphere - i. e. the layer between 10 and 16 kilometres - little information was available so far, but now the international IAGOS-CARIBIC climate project combined with satellite observations from the CALIPSO lidar provided new essential information. According to the study, the cooling effect due to volcanic eruptions was clearly underestimated by climate models used for the last Intergovernmental Panel on Climate Change (IPCC) report.

Led by the University of Lund, Sweden, and supported by the NASA Langley Research Center, USA, and the Royal Netherlands Meteorological Institute, three major German atmospheric research institutes were also involved: the Max Planck Institute for Chemistry in Mainz (
MPI-C), the Leibniz Institute for Tropospheric Research in Leipzig (TROPOS) and the Karlsruhe Institute of Technology (KIT). Since more frequent volcanic eruptions and the subsequent cooling effect are only temporary the rise of Earths' temperature will speed up again. The reason is the still continuously increasing greenhouse gas concentration, the scientists say.

..."Overall our results emphasize that even smaller volcanic eruptions are more important for the Earth's climate than expected", summarize CARIBIC coordinators Dr. Carl Brenninkmeijer, MPI-C, and Dr. Andreas Zahn, KIT. The IAGOS-CARIBIC observatory was coordinated and operated by the MPI-C until the end of 2014, since then by the KIT....

Unknown 1830 painting of an eruption in Italy, a Wellcome Image, Wikimedia Commons, under the Creative Commons Attribution 4.0 International license

Heat still on despite warming slowdown

University of New South Wales Newsroom: The recent slowdown in the rise of global average air temperatures will make no difference to how much the planet will warm by 2100, a new study has found.

The peer-reviewed study, published today in Nature Climate Change, compared climate models that capture the current slowdown in warming to those that do not. The study found that long-term warming projections were effectively unchanged across the two groups of models.

“This shows that the slowdown in global warming has no bearing on long-term projections – it is simply due to decadal variability. Greenhouse gases will eventually overwhelm this natural fluctuation,” said lead author and Chief Investigator with the ARC Centre of Excellence for Climate System Science, UNSW Scientia Professor Matthew England.

To separate the long-term temperature outcomes from short-term variability the researchers took 200 climate simulations and re-evaluated them out to 2100 by comparing those that captured the current slowdown to those that did not.

The models were analysed using one of two IPCC carbon emission projections. The first was a scenario where greenhouse gas concentrations continue to rise unabated through the 21st Century. The second assumes emissions are reduced to address global warming, peaking by 2040 before declining sharply.

Under the high emissions scenario, the difference in average projected end-of-century warming between the two groups of models is less than 0.1°C; a tiny fraction of the projected 5°C global warming if emissions are not curbed. Warming of this magnitude is well beyond the 2°C threshold that is considered a target by the Australian Government and a safe limit by the IPCC....

Barbecue photo by Emilian Robert Vicol  Emilian Robert Vicol, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

January-October 2014 temperatures break records

A press release from the World Meteorological Organization: The global average temperature over land and ocean surfaces for January to October 2014 was the highest on record, according to the U.S. National Oceanic and Atmospheric Administration (NOAA). It said October was the hottest since records began in 1880.

NOAA said the combined global land and ocean average surface temperature for the January–October period was 0.68°C (1.22°F) above the 20th century average of 14.1°C (57.4°F).  For October, it was 0.74°C (1.33°F) above the 20th century average of 14.0°C (57.1°F).

The high October temperature was driven by warmth across the globe over both the land and ocean surfaces and was fairly evenly distributed between the Northern and Southern Hemispheres. The Southern Hemisphere had its hottest October on record and the Northern Hemisphere its third warmest. October marked the third consecutive month and fifth of the past six with a record high global temperature for its respective month (July was fourth highest).

The Tokyo Climate Center, which is a WMO Regional Climate Centre, also reported that October was the hottest on record. The record was also confirmed by data from NASA’s Goddard Institute for Space Studies.

WMO uses a combination of datasets to compile its annual Statement on the Status of the Global Climate. Additional information is drawn from the ERA-Interim reanalysis-based data set maintained by the European Centre for Medium-Range Weather Forecasts. WMO will issue its provisional statement for 2014 on 2 December at simultaneous press conferences in Lima (0930 local time) and Geneva (1530 CET)....

Temperature map from NOAA

Groundwater warming up in synch

Peter Ruegg at ETH in Zurich: Global warming stops at nothing – not even the groundwater, as a new study by researchers from ETH Zurich and KIT reveals: the groundwater’s temperature profiles echo those of the atmosphere, albeit damped and delayed.

For their study, the researchers were able to fall back on uninterrupted long-term temperature measurements of groundwater flows around the cities of Cologne and Karlsruhe, where the operators of the local waterworks have been measuring the temperature of the groundwater, which is largely uninfluenced by humans, for forty years. This is unique and a rare commodity for the researchers. “For us, the data was a godsend,” stresses Peter Bayer, a senior assistant at ETH Zurich’s Geological Institute. Even with some intensive research, they would not have been able to find a comparable series of measurements. Evidently, it is less interesting or too costly for waterworks to measure groundwater temperatures systematically for a lengthy period of time. “Or the data isn’t digitalised and only archived on paper,” suspects the hydrogeologist.

Based on the readings, the researchers were able to demonstrate that the groundwater is not just warming up; the warming stages observed in the atmosphere are also echoed. “Global warming is reflected directly in the groundwater, albeit damped and with a certain time lag,” says Bayer, summarising the main results that the project has yielded. The researchers published their study in the journal Hydrology and Earth System Sciences.

The data also reveals that the groundwater close to the surface down to a depth of around sixty metres has warmed up statistically significantly in the course of global warming over the last forty years. This water heating follows the warming pattern of the local and regional climate, which in turn mirrors that of global warming.

The groundwater reveals how the atmosphere has made several temperature leaps at irregular intervals. These “regime shifts” can also be observed in the global climate, as the researchers write in their study. Bayer was surprised at how quickly the groundwater responded to climate change....

The Portuguese cistern of El Jadida, shot by Fulvio Attisani, Wikimedia Commons, under the Creative Commons 3.0 license

Scientists suggest ocean warming in Southern Hemisphere underestimated

Anne M. Stark at Lawrence Livermore Laboratory: Using satellite observations and a large suite of climate models, Lawrence Livermore scientists have found that long-term ocean warming in the upper 700 meters of Southern Hemisphere oceans has likely been underestimated.

"This underestimation is a result of poor sampling prior to the last decade and limitations of the analysis methods that conservatively estimated temperature changes in data-€sparse regions," said LLNL oceanographer Paul Durack, lead author of a paper appearing in the October 5 issue of the journal Nature Climate Change.

Ocean heat storage is important because it accounts for more than 90 percent of the Earth's excess heat that is associated with global warming. The observed ocean and atmosphere warming is a result of continuing greenhouse gas emissions. The Southern Hemisphere oceans make up 60 percent of the world's oceans.

The team found that climate models simulate the relative increase in sea surface height -- a leading indicator of climate change -- between Northern and Southern hemispheres is consistent with highly accurate altimeter observations. However, separating the simulated upper-€ocean warming in the Northern and Southern hemispheres is inconsistent with observed estimates of ocean heat content change. These sea level and ocean heat content changes should be consistent, and suggest that until recent improvements occurred in the observational system in the early 21st century, Southern Hemisphere ocean heat content changes were likely underestimated.

Since 2004, automated profiling floats (named Argo) have been used to measure global ocean temperatures from the surface down to 2,000 meters. The 3,600 Argo floats currently observing the global ocean provide systematic coverage of the Southern Hemisphere for the first time. Argo float measurements over the last decade, as well as data from earlier measurements, show that the ocean has been gradually warming, according to Durack.

"Prior to 2004, research has been very limited by the poor measurement coverage," he said. "By using satellite data, along with a large suite of climate model simulations, our results suggest that global ocean warming has been underestimated by 24 to 58 percent. The conclusion that warming has been underestimated agrees with previous studies, however it's the first time that scientists have tried to estimate how much heat we've missed."

Deploying an Argo float. Akin to having a fleet of miniature research vessels, the global flotilla of more than 3,600 robotic profiling floats provides crucial information on upper layers of the world's ocean currents. Photo by Alicia Navidad/CSIRO

No more pause: Warming will be non-stop from now on

Michael Slezak in New Scientist: Enjoy the pause in global warming while it lasts, because it's probably the last one we will get this century. Once temperatures start rising again, it looks like they will keep going up without a break for the rest of the century, unless we cut our greenhouse gas emissions.

The slowdown in global warming since 1997 seems to be driven by unusually powerful winds over the Pacific Ocean, which are burying heat in the water. But even if that happens again, or a volcanic eruption spews cooling particles into the air, we are unlikely to see a similar hiatus, according to two independent studies.

Masahiro Watanabe of the University of Tokyo in Japan and his colleagues have found that, over the past three decades, the natural ups and downs in temperature have had less influence on the planet's overall warmth. In the 1980s, natural variability accounted for almost half of the temperature changes seen. That fell to 38 per cent in the 1990s and just 27 per cent in the 2000s.

Instead, human-induced warming is accounting for more and more of the changes from year to year, says Watanabe. With ever-faster warming, small natural variations have less impact and are unlikely to override the human-induced warming.

"The implication is that we will get fewer hiatus periods, or hiatus periods that last for a shorter period," says Wenju Cai at the CSIRO in Melbourne, Australia, who wasn't involved in the work...

Hokusai's "The Wave"

Museum specimens, modern cities show how an insect pest will respond to climate change

A press release from North Carolina State University: Researchers from North Carolina State University have found that century-old museum specimens hold clues to how global climate change will affect a common insect pest that can weaken and kill trees – and the news is not good. “Recent studies found that scale insect populations increase on oak and maple trees in warmer urban areas, which raises the possibility that these pests may also increase with global warming,” says Dr. Elsa Youngsteadt, a research associate at NC State and lead author of a paper on the work.

“More scale insects would be a problem, since scales can weaken or kill the trees they live on,” Youngsteadt says. “But cities are unique, so we wanted to know whether warming causes scale insect population explosions in rural forests, the way it does in cities.”

To address that question, Youngsteadt examined more than 300 museum specimens of red maple branches collected between 1895 and 2011 in rural areas of North Carolina, South Carolina and Georgia. By evaluating the scale insect remains attached to each specimen, Youngsteadt estimated scale population density and compared it to the average August temperature for the year and place where the specimen was collected. Youngsteadt then compared the findings from the historical specimens with more recent data from urban Raleigh, North Carolina.

“Scale insect density in rural areas was not as high as it was in the city, but there was a common pattern,” Youngsteadt says. “Scale insects were most likely to be present on specimens collected during warm historical time periods, and scales were most abundant when temperatures were similar to modern, urban Raleigh.”

Given the shared urban and historical pattern, the researchers also predicted that scale insects would be more abundant in rural forests today than in the past, as a result of recent climate warming. To test this prediction, Youngsteadt went to 20 sites where historical specimens were collected from 1970 to 1997 and sampled their modern scale insect populations.

“Sure enough, scale abundance had increased at 16 of the 20 sites,” Youngsteadt says. “Overall, we found a total of about five times more scale insects in 2013 than on the historical specimens from the same locations. The urban and historical data are so well-aligned that we can view scale insect populations in cities as a preview of what to expect elsewhere,” Youngsteadt adds. “It also suggests that we should begin looking at cities for clues to how other insect species will respond to higher global temperatures.”...

A red maple museum sample of evaluated as part of the study. Image credit: North Carolina State University Herbarium. 

New study confirms water vapor as global warming amplifier

A press release from the Rosenstiel School of Marine and Atmospheric Science at the University of Miami: A new study from scientists at the University of Miami Rosenstiel School of Marine and Atmospheric Science and colleagues confirms rising levels of water vapor in the upper troposphere – a key amplifier of global warming – will intensify climate change impacts over the next decades. The new study is the first to show that increased water vapor concentrations in the atmosphere are a direct result of human activities.

“The study is the first to confirm that human activities have increased water vapor in the upper troposphere,” said Brian Soden, professor of atmospheric sciences at the UM Rosenstiel School and co-author of the study.

To investigate the potential causes of a 30-year moistening trend in the upper troposphere, a region 3- 7 miles above Earth’s surface, Soden, UM Rosenstiel School researcher Eui-Seok Chung and colleagues measured water vapor in the upper troposphere collected by NOAA satellites and compared them to climate model predictions of water circulation between the ocean and atmosphere to determine whether observed changes in atmospheric water vapor could be explained by natural or man-made causes. Using the set of climate model experiments, the researchers showed that rising water vapor in the upper troposphere cannot be explained by natural forces, such as volcanoes and changes in solar activity, but can be explained by increased greenhouse gases, such as CO2.

Greenhouse gases raise temperatures by trapping the Earth’s radiant heat inside the atmosphere. This warming also increases the accumulation of atmospheric water vapor, the most abundant greenhouse gas. The atmospheric moistening traps additional radiant heat and further increases temperatures. Climate models predict that as the climate warms from the burning of fossil fuels, the concentrations of water vapor will also increase in response to that warming. This moistening of the atmosphere, in turn, absorbs more heat and further raises the Earth's temperature....

A NASA color-enhanced image of upper tropospheric water vapor

Phytoplankton and zooplankton biomass are expected to decrease

Space Daily via SPX: It is estimated that ocean temperature warming will cause phytoplankton and zooplankton biomass to decrease by 6% and 11% respectively by the end of the century. A lower amount of these two main elements in the marine food web could reduce fish biomass in certain regions. These are some of the main conclusions drawn by research led by Azti-Tecnalia within the European MEECE project and recently published in the prestigious Global Change Biology Journal.

Sea surface temperature is expected to increase 2 + C on average globally by 2080-2100. Some of the consequences of this increase include changes in ocean circulation and higher water column stratification, thus affecting the nutrient availability for the growth of marine phytoplankton.

The research team led by Azti-Tecnalia points out the effects to primary production (phytoplankton mass produced annually by photosynthetic single-celled organisms that are suspended in the ocean), and to secondary production (zooplankton biomass, made up of small animal organisms that feed mainly on phytoplankton and which fish feed on).

Globally, it is estimated that the sea temperature rise will cause phytoplankton and zooplankton biomass to decrease by 6% and 11% respectively. This suggests that there will be a negative amplification of climate change, which will spread through the marine food web, i.e. zooplankton biomass will decrease more than phytoplankton. This process will take place mainly in tropical oceans, which cover 47% of the global ocean surface....

Uwe kils shot this image of an amphipod, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Greenland melting due equally to global warming, natural variations

Hannah Hickey at the University of Washington: ....University of Washington atmospheric scientists have estimated that up to half of the recent warming in Greenland and surrounding areas may be due to climate variations that originate in the tropical Pacific and are not connected with the overall warming of the planet. Still, at least half the warming remains attributable to global warming caused by rising carbon dioxide emissions. The paper is published May 8 in Nature.

Greenland and parts of neighboring Canada have experienced some of the most extreme warming since 1979, at a rate of about 1 degree Celsius per decade, or several times the global average. “We need to understand why in the last 30 years global warming is not uniform,” said first author Qinghua Ding, a UW research scientist in atmospheric sciences. “Superimposed on this global average warming are some regional features that need to be explained.”

The study used observations and advanced computer models to show that a warmer western tropical Pacific Ocean has caused atmospheric changes over the North Atlantic that have warmed the surface by about a half-degree per decade since 1979.

...“Our work shows that about half of the warming signal in Greenland comes from the predictable part – forcing of climate by anthropogenic greenhouse gases – but about half comes from the unpredictable part,” Steig said....

A NASA image of ice melting in Greenland

Deforestation could intensify climate change in Congo Basin by half

A press release from KU Leuven (Belgium): Explosive population growth and inefficient agricultural practices are causing large-scale destruction of tropical rainforests in Central Africa. A team of KU Leuven researchers examined how these practices will affect longer-term temperatures in the region. Using a sophisticated computer model, they forecasted Congo Basin temperatures anno 2050.

Their findings: Central Africa of 2050 will be an average of 1.4 °C hotter than today as a result of global greenhouse gas emissions. Deforestation will add an extra 0.7 °C to that figure. The results also show a strong spatial correlation between deforestation and global warming. In certain deforestation ‘hot spots’, increases caused by deforestation could rise to 1.25 °C, in addition to the war
ming caused by greenhouse gases. Such drastic temperature increases will drive off plant and animal species and may even threaten some with extinction, warn the researchers.

The researchers used an advanced computer model based on realistic projections of the speed and the spatial pattern of deforestation to forecast changes in the Congo Basin climate. The study also maps the region’s vegetation mix – which has largely replaced felled rainforest in much of the region – for the first time.

The deforestation-induced warming forecasted by the model can be attributed in large part to reduced evaporation, say the researchers. Once deforestation has occurred, the solar energy that rainforests would otherwise use to evaporate water accumulates near the Earth’s surface, causing the atmosphere to warm.

This reduced evaporation also threatens precipitation levels in the region, the study predicts. However, because of the complexities of air circulation and cloud formation, the link between the spatial pattern of change and the deforestation pattern is less pronounced.

The researchers used an average forecast of future emissions of CO2 and other greenhouse gases to arrive at their calculations. Their deforestation scenario is far from extreme. “The results point to the need to address the causes of deforestation in the Congo Basin,” says Tom Akkermans of the Regional Climate Studies research group at KU Leuven, and lead author of the study. “Not only does deforestation in this region contribute to the global rise in temperature through CO2 emissions from wood burning, it also has a direct impact on the climate of Central Africa.”...

NASA image of the Congo rainforest and the Lualaba River

Amazon rain forest's biggest enemies are fire and climate change

James Maynard in Tech Times: The Amazon rain forest is facing dangers from climate change and droughts, which are leading to frequent wildfires in the ecosystem.  Fires are normally rare in the rain forest, due to thick tree cover that keeps the ground cool and wet.

Deforestation and climate change are combining to create "tinderbox" conditions in many areas of the Amazon, according to researchers from Penn State University. The ecosystem may reach a "tipping point" where fires create enough damage to make recovery difficult, new research reveals.

"We documented one of the highest tree mortality rates witnessed in Amazon forests. Over the course of our experiment, 60 percent of the trees died with combined drought and repeated fire. Our results suggest that a perfect firestorm, caused by drought conditions and previous fire disturbance, crossed a threshold in forest resistance," Jennifer Balch, an assistant geography professor at Penn State who led the study, said.

Over eight years, researchers set fire to plots of the Amazon rain forest, each of which was nearly 125 acres in size. By studying deaths of the trees, investigators were able to study how drought affects both the intensity of fire and tree mortality. The southeast area of the Amazon, where the experiment was performed, is especially vulnerable to climate change, according to the study.

The period of time during which the research was conducted included 2007, during which there was a severe drought in southeastern regions of the Amazonian rain forest. That year, fires destroyed 10 times more forest than in an average year, according to Douglas Morton at NASA. That amounts to an area the size of a million soccer fields....

Fires along the Xingu River, viewed by NASA

Massive UN report says climate risks go beyond red alert

NBC News: Global warming is driving humanity toward a whole new level of many risks, a U.N. scientific panel reports, warning that the wild climate ride has only just begun. Disasters such as killer heat waves in Europe, wildfires in the United States, droughts in Australia and deadly flooding in Mozambique, Thailand and Pakistan highlight how vulnerable humanity is to extreme weather, a Nobel Prize-winning group of scientists says in a massive new report released early Monday. The dangers are going to worsen as the climate changes even more, the report's authors say, and no one is immune.

"We're all sitting ducks," Princeton University professor Michael Oppenheimer, one of the main authors of the 32-volume report from the Intergovernmental Panel on Climate Change, said in an interview.

After several days of late-night wrangling, more than 100 governments unanimously approved the scientist-written 44-page summary — which is aimed at world political leaders. The summary mentions the word "risk" an average of about five times per page. "Changes are occurring rapidly and they are sort of building up that risk," said the overall lead author of the report, Chris Field of the Carnegie Institution for Science in California.

These risks are both big and small, according to the report. They are now and in the future. They hit farmers and big cities. Some places will have too much water, some not enough, including drinking water. Other risks mentioned in the report involve theprice and availability of food, and to a lesser and more qualified extent some diseases, financial costs and even world peace.

"Things are worse than we had predicted" in 2007, when the group of scientists last issued this type of report, said report co-author Saleemul Huq, director of the International Centre for Climate Change and Development at the Independent University in Bangladesh. "We are going to see more and more impacts, faster and sooner than we had anticipated."....

Canberra bush fires in 2003, public domain

Long-term warming likely to be significant despite recent slowdown

NASA-Goddard Space Center: A new NASA study shows Earth's climate likely will continue to warm during this century on track with previous estimates, despite the recent slowdown in the rate of global warming.

This research hinges on a new and more detailed calculation of the sensitivity of Earth's climate to the factors that cause it to change, such as greenhouse gas emissions. Drew Shindell, a climatologist at NASA's Goddard Institute for Space Studies in New York, found Earth is likely to experience roughly 20 percent more warming than estimates that were largely based on surface temperature observations during the past 150 years. Shindell's paper on this research was published March 9 in the journal Nature Climate Change.

Global temperatures have increased at a rate of 0.22 Fahrenheit (0.12 Celsius) per decade since 1951. But since 1998, the rate of warming has been only 0.09 F (0.05 C) per decade -- even as atmospheric carbon dioxide continues to rise at a rate similar to previous decades. Carbon dioxide is the most significant greenhouse gas generated by humans.

Some recent research, aimed at fine-tuning long-term warming projections by taking this slowdown into account, suggested Earth may be less sensitive to greenhouse gas increases than previously thought. The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), which was issued in 2013 and was the consensus report on the state of climate change science, also reduced the lower range of Earth's potential for global warming.

...Shindell's paper further focuses on improving our understanding of how airborne particles, called aerosols, drive climate change in the Northern Hemisphere. Aerosols are produced by both natural sources – such as volcanoes, wildfire and sea spray – and sources such as manufacturing activities, automobiles and energy production. Depending on their make-up, some aerosols cause warming, while others create a cooling effect. In order to understand the role played by carbon dioxide emissions in global warming, it is necessary to account for the effects of atmospheric aerosols.

While multiple studies have shown the Northern Hemisphere plays a stronger role than the Southern Hemisphere in transient climate change, this had not been included in calculations of the effect of atmospheric aerosols on climate sensitivity. Prior to Shindell's work, such calculations had assumed aerosol impacts were uniform around the globe....

A new NASA study suggests that projections of Earth's future warming should be more in line with previous estimates that indicated a higher sensitivity to increasing greenhouse gas emissions. Image Credit: NASA SVS/NASA Center for Climate Simulation

Global warming slowdown 'does not invalidate climate change'

Adam Vaughan in the Guardian (UK): The slowdown in rising global surface temperatures is not a sign that climate change is no longer happening, the national science academies of the US and the UK have said. Publishing a guide on the state of climate change science, the National Academy of Sciences and the Royal Society said the short-term slowdown this century did not "invalidate" the long-term trend of rising temperatures caused by man-made climate change.

"Despite the decadal slowdown in the rise of average surface temperature, a longer-term warming trend is still evident. Each of the last three decades was warmer than any other decade since widespread thermometer measurements were introduced in the 1850s," the publication, Climate Change Evidence and Causes, said.

Scientists have been investigating reasons for the slowdown in temperature rises. Peer-reviewed papers over the last year have suggested 17 sun-dimming volcanic eruptions since 2000, "unusual" trade winds in the Pacific Ocean burying surface heat deep underwater and the world's oceans absorbing greater amounts of heat in recent years may have contributed.

Thomas Stocker, the co-chair of working group one of the UN's climate science panel, said at the launch of the Intergovernmental Panel on Climate Change's landmark report last September that the recent slowdown in surface temperature rises was not significant because it was over too short a period of time. "Climate relevant trends should not be calculated for periods of less than 30 years," he said.....

A painting by Lazlo Mednyanszky (1852-1919), "Snow Landscape with Boats"

Volcanoes contribute to recent warming ‘hiatus’

Alli Gold Roberts in MIT News: By the late 1990s, scientists had observed more than two decades of rapid global warming, and expected the warming trend to continue. Instead, despite continuing increases in greenhouse gas emissions, the Earth’s surface temperatures have remained nearly flat for the last 15 years. The International Panel on Climate Change verified this recent warming “hiatus” in its latest report.

Researchers around the globe have been working to understand this puzzle — looking at heat going into the oceans, changes in wind patterns, and other factors to explain why temperatures have stayed nearly stable, while greenhouse gas concentrations have continued to rise. In a study published today in Nature Geoscience, a team of scientists from MIT and elsewhere around the U.S. report that volcanic eruptions have contributed to this recent cooling, and that most climate models have not accurately accounted for the effects of volcanic activity.

“This is the most comprehensive observational evaluation of the role of volcanic activity on climate in the early part of the 21st century,” says co-author Susan Solomon, the Ellen Swallow Richards Professor of Atmospheric Chemistry and Climate Science at MIT. “We assess the contributions of volcanoes on temperatures in the troposphere — the lowest layer of the atmosphere — and find they’ve certainly played some role in keeping the Earth cooler.”

There are many components of the Earth’s climate system that can increase or decrease the temperature of the globe. For example, while greenhouse gases cause warming, some types of small particles, known as aerosols, cause cooling. When volcanoes erupt explosively enough, they enhance these aerosols — a phenomenon referred to as “volcanic forcing.”...

A 2002 eruption of Mt. Etna viewed from the International Space Station