How volcanoes offset global warming

After a major rise of temperatures since the beginning of the 20th century, global warming seems to have taken a break for the last 15 years. Scientists have been looking into the possible causes of the warming hiatus over the past few years. Solar cycles, oceans storing up heat from global warming, are some of the possible explanations, but recently, volcanoes have emerged as a potential factor for this “cooldown”.

Volcanic eruptions spew small particles and aerosols into the stratosphere which scatter sunlight back into space and block Earth’s thermal radiation preventing the global average temperature from rising. For example, the Philippines’s Mount Pinatubo, cooled off Earth by a few tenths of a degree Celsius for months after it erupted on June 5, 1991.

Climate projections don’t include the effects of volcanic eruptions as they are almost impossible to anticipate. Only major eruptions such as Mount Pinatubo in 1991, were thought to impact global climate. However new observations have found that volcanic eruptions contributed to lower global surfaces temperatures by 0,08C during what is called the “global warming hiatus”.

Hopefully this new data will help scientists to build more robust climate models including also the impact of aerosols on climate change.

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Permafrost and biological methane : two carbon time-bombs


For the first time since records began, the parts per million (ppm) of CO2 in the atmosphere were over 400 in March 2015.

CO2 threat level

For 400 000 years, carbon dioxide concentrations have remained steady at a level beneath 280 ppm. In the 1980’s a major change occurred, carbon dioxide concentrations rose more than 120ppm since pre-industrial times. In 1988, we reached a first significant milestone with a global average of 350ppm which is considered as the last “safe” level of carbon dioxide in the atmosphere.

450ppm is the tipping point to an era with temperatures above 2C which is a critical threshold. Surpassing this level means a high level of uncertainty in with climate changes that might not be controlled or anticipated anymore.


On behalf of permafrost

Often referred as the “terrible child”, carbon dioxide is not the only one responsible for the climate change.

Indeed, methane is 28 times more potent as heat-trapping gas as carbon dioxide is. The problem is : methane is everywhere. Farming, agriculture, human activities, they all produce it and even worse: methane emissions are stored in the sea-ice.


The thing is, the more CO2 levels increase, the more temperatures increase. The more temperatures increase, the more methane escapes from the ice, contributing to a rise of temperatures. This “climate feedback loop” is even more dangerous because it is not yet fully understood.

That is why the thawing of permafrost in Siberia, Canada and the Arctic region, which is an ongoing project, is a real climate time-bomb.


Biological methane and Arctic lakes

New researches into the changing ecology of thousands of shallow lakes on the North slopes of Alaska suggest that in scenarios of increasing global temperatures, methane-generating microbes, found in thawing lake sediments, may ramp up production of the potent greenhouse gas.

A study published this month in Geobiology, resulting from five years of collaborative research illustrates how the decomposition of organic matter can produce up to three times more biological methane gas emissions when subjected to increased temperatures in a simulated environment.

“In scenarios of warming climate” the author of the study said, “our measurements indicate that biological methane production may play a larger role in the total of methane emissions in the future, which could have a significant impact on our climate”.

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Data show no recent slowdown in global warming


From 1951 to 2012, temperatures increased by an average of 0.12°C every decade. But from 1998 to 2012 this rise was of only 0.05°C. Though this discrepancy is often used as proof that climate change is not a current reality, researchers have found an explanation for this phenomenon and their conclusion is simple: global warming never took a break.

It appears that the earlier results showing a climate change hiatus may have resulted from a shift during the last couple of decades to a greater use of buoys for measuring sea surface temperatures. Buoys tend to give cooler readings than measurements taken from ships, which take their measurements from the temperature of the water in the oceans.

Thomas Karl, Director of the National Oceanic and Atmospheric Administration combined new data with improved calculations of air temperatures and land around the world, including land-based monitoring stations that extend into Arctic where observations have been sparse. They also included observations from 2013 and 2014, two of the warmest years ever recorded.

Furthermore, the year 1998 which was used as a reference was especially hot because of a strong El Niño that year. In comparison, the following years seemed cooler.


According to Thomas Karl, “global warming over the past 15 years is the strongest it has ever been since the latter half of the 20th century”. The overall global surface warming between 2000 and 2014 was 0.116°C per decade. For the authors of the study, this rise will probably be even higher when the data for Arctic’s warming will be complete.

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Natural gas now cooking with gas!

Currently made up of fossil fuels for more than 80%, the global primary energy mix has entered a period of transformation. In 2015, oil is still the first energy source with 33% of the total followed by coal (27%) and gas (21%). But by 2040, major changes could happen according to several studies anticipating a rise of the gas share in the energy mix. Natural gas could take the second place and oil would only account for 25% of the total.

Gas is often seen as the lesser of two evils. Indeed, while coal emits 1,12teqC per toe (ton of oil equivalent) and oil 0,83teqC per toe, natural gas only emits 0,65teqC per toe. Such a difference explains why natural gas is more and more preferred to the two other fossil fuels. This is why some projects based on the Clean Development Mechanism are replacing oil or coal by natural gaz. This substitution is often complementary with the setup of energy efficient technologies.

The discovery of shale gas has had a huge impact on gas markets. This silent revolution first began in the United States. It represented 23% of the US gas production in 2010 against only 14% one year before. In the future, shale gas exploitation will put pressure on traditional gas exporters which are Russia, Iran and Saudi Arabia. They have to anticipate this future competition and potentially declining prices. Currently, the European Union and Asia are not particularly concerned by this evolution of energy markets. In addition, several environmental threats caused by shale gas remain: contamination of water tables, release of greenhouse gas, increased risks of earthquakes. These well-founded fears remind us that, to prevent temperatures from rising above +2°C by 2100, 80% of fossil fuel reserves need to stay in the ground.

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